Helix; Re: 1200GTO stalls


May 21, 2002

 


----------------------------

#4917 May 21, 2002

Hi Roland,



My 1200GTO mount has given me incredible performance and pleasure

ever since I received it 6 months ago. It is permanently set up on a

concrete pier in a roll-off roof observatory.



During the last observing session something odd happened: when

setting up for a CCD session and performing the first slew of the

night both motors started to move with audible difficulty,

sometimes "stuttering" and eventually stopping: the power LED went

yellow indicating an overload situation.

Further intents (after restarting the mount) produced the same

effects, even when lowering the slewing speed to "600".

"64" button speed worked OK.

Manually "helping" the mount eventually got me to my target object

and I was able to track/guide/image no problem for 5 hours.



No gear mesh problem: I first suspected a too tight tight mesh of the

RA worm/gear since I had recently taken the hammer ;-) to the RA worm

housing to eliminate some excessive play. However, in spite of the

cold, I could still turn the shaft with my fingers AND the stalling

occurred in DEC as well (which I never touched).



No voltage problem: the mount is run off three 115Ah deep cycle

batteries that are in the warm room and supplied power to everything

all night (and then some).



No balance problem: I carefully RA/DEC balance before each session.



No weight problem: scopes mounted are AP155 + Traveler



Temperature problem ? With only a few degrees below O.C, it was still

the first really cold night here since I received the mount (we're

headed into winter). When trying to troubleshoot the mount the next

(late) morning with temperatures up around 15.C, the mount happily

slewed as if nothing had happened.



What is wrong here ?



Daniel

Observatorio Antilhue

Chile



----------------------------

#4918 May 21, 2002

In a message dated 5/21/2002 1:03:15 PM Central Daylight Time,

Daniel_V@... writes:



> During the last observing session something odd happened: when

> setting up for a CCD session and performing the first slew of the

> night both motors started to move with audible difficulty,

> sometimes "stuttering" and eventually stopping: the power LED went

> yellow indicating an overload situation.

> Further intents (after restarting the mount) produced the same

> effects, even when lowering the slewing speed to "600".

>



I strongly suspect that you had a low voltage situation. Under very cold

conditions, the mount will draw much more current than normal because the

bearings are stiffer (grease gets stiff) and are harder for the motor to

move. If your power source is far from the mount, the extra current will

cause a voltage drop in the power lines under cold conditions. By the time

the power gets to the servo connection, it may have lost one or two volts in

the wires. Best thing to do is to use a power supply delivering more than 12

volts (13.8v seems to be a standard). You can use up to 18 volts, which will

really help on those cold nights.



Roland Christen





[Non-text portions of this message have been removed]



----------------------------

#4919 May 21, 2002

Thanks for the input, Roland.



I use only 3 meter real heavy gauge twin cable from the battery bank

to the mount: there can never be a voltage loss of 1 V or more, even

with a 10 A current. I consider car cigarette lighter type plugs and

jacks too unreliable/lossy: so I have replaced all that hardware by

specialized DC connectors with contacts rated at 30 A.

All other equipment worked flawlessly during the whole night and

there's a low voltage automatic load cut-off on the solar

charger/regulator box that would have tripped when voltage would have

dropped below 11 VDC.



So I'm inclined to exclude low voltage as the cause. I will however

put a voltmeter on the jack at the mount's base next cold night to

check.

I have no mains electricity at the observatory (yet), so I'm limited

to 12 V maximum now.



Daniel

Observatorio Antilhue

Chile

--- In ap-gto@y..., chris1011@a... wrote:

> In a message dated 5/21/2002 1:03:15 PM Central Daylight Time,

> Daniel_V@c... writes:

>

>

> > During the last observing session something odd happened: when

> > setting up for a CCD session and performing the first slew of the

> > night both motors started to move with audible difficulty,

> > sometimes "stuttering" and eventually stopping: the power LED

went

> > yellow indicating an overload situation.

> > Further intents (after restarting the mount) produced the same

> > effects, even when lowering the slewing speed to "600".

> >

>

> I strongly suspect that you had a low voltage situation. Under very

cold

> conditions, the mount will draw much more current than normal

because the

> bearings are stiffer (grease gets stiff) and are harder for the

motor to

> move. If your power source is far from the mount, the extra current

will

> cause a voltage drop in the power lines under cold conditions. By

the time

> the power gets to the servo connection, it may have lost one or two

volts in

> the wires. Best thing to do is to use a power supply delivering

more than 12

> volts (13.8v seems to be a standard). You can use up to 18 volts,

which will

> really help on those cold nights.

>

> Roland Christen

>

>

> [Non-text portions of this message have been removed]







----------------------------

#4920 May 21, 2002

--- In ap-gto@y..., "daniel_verschatse" Daniel_V@c...> wrote: > I have no mains electricity at the observatory (yet), so I'm limited

> to 12 V maximum now.

>



The cold batteries terminal voltage maybe very low, in the sub 12 volt

range.



Would using two 12 V batteries to deliver 24 V followed by a high

efficiency switcher to 18 volts be a good solution?





Tim



----------------------------

#4923 May 22, 2002

Actually:



just upconvert it to 120 V AC and then

down convert it to 12 V AC.



24 to 12 V switchers are available at

Ham Radio Outlet for Radio Amateurs

running on 24 electrical system trucks.

I know some military vehicles use this

but I think some long haul trucks might

also which might indicate where the

market for these is.



I've decided to brute force the problem

into non existance by using a 20 amp

linear power supply for amateur radio.

It's output voltate was something like 13

volts. This higher voltage is the prefered

operating voltage for radios since it is

within spec for a car with it's alternator

running and allows the transmitters to

produce more power. It is also a very good

voltage to run the AP mounts on since it gives

more head room.



A 24 to 12 down converver is nice but it

means that the power system would need to

be revamped.



A linear power supply would be a poor

choice for a off grid system since it is

so inefficient.



So, a switching up converter and a switching

down converter sounds good even thought it

is wildly inefficient and complex.



What you really need is a 12 volt to 12 volt

switching converter. Not many of those

around I'm afraid.



Larry



limunary wrote: >

> --- In ap-gto@y..., "daniel_verschatse" Daniel_V@c...> wrote:

> > I have no mains electricity at the observatory (yet), so I'm limited

> > to 12 V maximum now.

> >

>

> The cold batteries terminal voltage maybe very low, in the sub 12 volt

> range.

>

> Would using two 12 V batteries to deliver 24 V followed by a high

> efficiency switcher to 18 volts be a good solution?

>

> Tim

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/



----------------------------

#4925 May 22, 2002

I mean 12V DC.



"Lawrence D. Lopez" wrote: >

> Actually:

>

> just upconvert it to 120 V AC and then

> down convert it to 12 V AC.



----------------------------

#4927 May 22, 2002

Tim,

The amp-hr. requirements of the mount are moderate. Why not use a

battery source dedicated to only the mount. Gelled electrolyte batterys are

available in 4v and 6v versions. One 6v and two 4v in series will give 14v

which should handle the cold temp. problem. Smart chargers are available for

the 14v string. This is a common solution for small aircraft and gliders

which have no generator. The radios and avionics used are designed to

operate at about 13.8v and some can begin to malfunction at 10.5 to 11v.

Also, the switching converters are notorious electrical noise

generators which may couple to sensitive CCD cables.

Regards,

EC. ----- Original Message -----

From: Lawrence D. Lopez lopez@...>

To: ap-gto@yahoogroups.com>

Sent: Wednesday, May 22, 2002 5:37 AM

Subject: Re: [ap-gto] Re: 1200GTO stalls





> Actually:

>

> just upconvert it to 120 V AC and then

> down convert it to 12 V AC.

>

> 24 to 12 V switchers are available at

> Ham Radio Outlet for Radio Amateurs

> running on 24 electrical system trucks.

> I know some military vehicles use this

> but I think some long haul trucks might

> also which might indicate where the

> market for these is.

>

> I've decided to brute force the problem

> into non existance by using a 20 amp

> linear power supply for amateur radio.

> It's output voltate was something like 13

> volts. This higher voltage is the prefered

> operating voltage for radios since it is

> within spec for a car with it's alternator

> running and allows the transmitters to

> produce more power. It is also a very good

> voltage to run the AP mounts on since it gives

> more head room.

>

> A 24 to 12 down converver is nice but it

> means that the power system would need to

> be revamped.

>

> A linear power supply would be a poor

> choice for a off grid system since it is

> so inefficient.

>

> So, a switching up converter and a switching

> down converter sounds good even thought it

> is wildly inefficient and complex.

>

> What you really need is a 12 volt to 12 volt

> switching converter. Not many of those

> around I'm afraid.

>

> Larry

>

> limunary wrote:

> >

> > --- In ap-gto@y..., "daniel_verschatse" Daniel_V@c...> wrote:

> > > I have no mains electricity at the observatory (yet), so I'm limited

> > > to 12 V maximum now.

> > >

> >

> > The cold batteries terminal voltage maybe very low, in the sub 12 volt

> > range.

> >

> > Would using two 12 V batteries to deliver 24 V followed by a high

> > efficiency switcher to 18 volts be a good solution?

> >

> > Tim

> >

> > To UNSUBSCRIBE, or for general information on the ap-gto list

> > see groups.yahoo.com/group/ap-gto

> >

> > Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>







----------------------------

#4928 May 22, 2002

Larry, Tim & Roland,



Yes, being an electronics engineer myself I have considered those

options but:



a. most of the mentioned equipment is non-existent/hard to find on

the chilean marketplace

b. as you say, they are wildly inefficient, produce a high additional

current drain on my solar battery bank.

c. most importantly: it's not correcting the root cause. Isn't the

mount supposed to work flawlessly off a well charged 12VDC - 115 Ah

battery in the field under far lower temperatures than a few degrees

below freezing?

The specifications on page 4 of the manual say:

Power consumption: 0.4A sidereal, 2A with both motors slewing

Power requirements: 12 VDC (no temperature range specified)

What do the "mobile" imagers on this run their AP900GTO's and

AP1200GTO's on in "arctic" conditions?



I am still not convinced I had a power/voltage problem, but haven't

been able to go back to check yet. The observatory is 60 miles away

AND I need a cold night.



Daniel

--- In ap-gto@y..., "Lawrence D. Lopez" lopez@m...> wrote:

> Actually:

>

> just upconvert it to 120 V AC and then

> down convert it to 12 V AC.

>

> 24 to 12 V switchers are available at

> Ham Radio Outlet for Radio Amateurs

> running on 24 electrical system trucks.

> I know some military vehicles use this

> but I think some long haul trucks might

> also which might indicate where the

> market for these is.

>

> I've decided to brute force the problem

> into non existance by using a 20 amp

> linear power supply for amateur radio.

> It's output voltate was something like 13

> volts. This higher voltage is the prefered

> operating voltage for radios since it is

> within spec for a car with it's alternator

> running and allows the transmitters to

> produce more power. It is also a very good

> voltage to run the AP mounts on since it gives

> more head room.

>

> A 24 to 12 down converver is nice but it

> means that the power system would need to

> be revamped.

>

> A linear power supply would be a poor

> choice for a off grid system since it is

> so inefficient.

>

> So, a switching up converter and a switching

> down converter sounds good even thought it

> is wildly inefficient and complex.

>

> What you really need is a 12 volt to 12 volt

> switching converter. Not many of those

> around I'm afraid.

>

> .Larry

>

> limunary wrote:

> >

> > --- In ap-gto@y..., "daniel_verschatse" Daniel_V@c...> wrote:

> > > I have no mains electricity at the observatory (yet), so I'm

limited

> > > to 12 V maximum now.

> > >

> >

> > The cold batteries terminal voltage maybe very low, in the sub 12

volt

> > range.

> >

> > Would using two 12 V batteries to deliver 24 V followed by a high

> > efficiency switcher to 18 volts be a good solution?

> >

> > Tim

> >

> > To UNSUBSCRIBE, or for general information on the ap-gto list

> > see groups.yahoo.com/group/ap-gto

> >

> > Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/



----------------------------

#4930 May 22, 2002

In a message dated 5/21/2002 8:24:11 PM Central Daylight Time,

potentate@... writes:



>

> The cold batteries terminal voltage maybe very low, in the sub 12 volt

> range.

>

> Would using two 12 V batteries to deliver 24 V followed by a high

> efficiency switcher to 18 volts be a good solution?

>



Yes, that would work, or even a linear power supply that would drop the

voltage below 20 volts. Too bad they don't make a good 6 volt battery, you

could put that in series with a 12v one to get 18v.



Roland Christen





[Non-text portions of this message have been removed]



----------------------------

#4931 May 22, 2002

Elvin,



For batteries checkout www.dcbattery.com and checkout

lifeline AGM batteries. I use a group 27 to power the

inverter which runs my Laptop, 115v oscillating fan,

CCD, STV, Dew heaters (12v side). I also use a

separate 32 amphr battery for to run the 1200 mount.

This is good for two full nights without a recharge.

Note, that you can fast charge these batteries, unlike

gelcells.



About dc-dc convertors, I have found several different

DC-DC convertors grades, some bad, some good, some

excellent. I've noticed that the good ones do not

deliver enough power.



Tim (in FL)



--- Elvin Welch ecw2f@...> wrote: > Tim,

> The amp-hr. requirements of the mount are

> moderate. Why not use a

> battery source dedicated to only the mount. Gelled

> electrolyte batterys are

> available in 4v and 6v versions. One 6v and two 4v

> in series will give 14v

> which should handle the cold temp. problem. Smart

> chargers are available for

> the 14v string. This is a common solution for small

> aircraft and gliders

> which have no generator. The radios and avionics

> used are designed to

> operate at about 13.8v and some can begin to

> malfunction at 10.5 to 11v.

> Also, the switching converters are

> notorious electrical noise

> generators which may couple to sensitive CCD cables.

> Regards,

> EC.

> ----- Original Message -----

> From: Lawrence D. Lopez lopez@...>

> To: ap-gto@yahoogroups.com>

> Sent: Wednesday, May 22, 2002 5:37 AM

> Subject: Re: [ap-gto] Re: 1200GTO stalls

>

>

> > Actually:

> >

> > just upconvert it to 120 V AC and then

> > down convert it to 12 V AC.

> >

> > 24 to 12 V switchers are available at

> > Ham Radio Outlet for Radio Amateurs

> > running on 24 electrical system trucks.

> > I know some military vehicles use this

> > but I think some long haul trucks might

> > also which might indicate where the

> > market for these is.

> >

> > I've decided to brute force the problem

> > into non existance by using a 20 amp

> > linear power supply for amateur radio.

> > It's output voltate was something like 13

> > volts. This higher voltage is the prefered

> > operating voltage for radios since it is

> > within spec for a car with it's alternator

> > running and allows the transmitters to

> > produce more power. It is also a very good

> > voltage to run the AP mounts on since it gives

> > more head room.

> >

> > A 24 to 12 down converver is nice but it

> > means that the power system would need to

> > be revamped.

> >

> > A linear power supply would be a poor

> > choice for a off grid system since it is

> > so inefficient.

> >

> > So, a switching up converter and a switching

> > down converter sounds good even thought it

> > is wildly inefficient and complex.

> >

> > What you really need is a 12 volt to 12 volt

> > switching converter. Not many of those

> > around I'm afraid.

> >

> > Larry

> >

> > limunary wrote:

> > >

> > > --- In ap-gto@y..., "daniel_verschatse"

> Daniel_V@c...> wrote:

> > > > I have no mains electricity at the observatory

> (yet), so I'm limited

> > > > to 12 V maximum now.

> > > >

> > >

> > > The cold batteries terminal voltage maybe very

> low, in the sub 12 volt

> > > range.

> > >

> > > Would using two 12 V batteries to deliver 24 V

> followed by a high

> > > efficiency switcher to 18 volts be a good

> solution?

> > >

> > > Tim

> > >

> > > To UNSUBSCRIBE, or for general information on

> the ap-gto list

> > > see groups.yahoo.com/group/ap-gto

> > >

> > > Your use of Yahoo! Groups is subject to

> docs.yahoo.com/info/terms/

> >

> > To UNSUBSCRIBE, or for general information on the

> ap-gto list

> > see groups.yahoo.com/group/ap-gto

> >

> > Your use of Yahoo! Groups is subject to

> docs.yahoo.com/info/terms/

> >

>

>

> To UNSUBSCRIBE, or for general information on the

> ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to

> docs.yahoo.com/info/terms/

>

>





---------------

Do You Yahoo!?

LAUNCH - Your Yahoo! Music Experience

launch.yahoo.com







----------------------------

#4935 May 22, 2002

In a message dated 5/22/2002 1:35:52 PM Central Daylight Time,

Daniel_V@... writes:



> Isn't the

> mount supposed to work flawlessly off a well charged 12VDC - 115 Ah

> battery in the field under far lower temperatures than a few degrees

> below freezing?

>



Yes, and my mount does just that in my observatory. I run it off a marine

battery which is located right under my pier, a few feet away. On really cold

nights, the battery voltage drops to about 11 volts, and I sometimes switch

to 600x when slewing. If you put 12 volts DC at the input of the servo, the

mount should run and slew properly, unless the supply cannot supply the

current and still produce 12 volts at the terminals of the servo. It is no

good to provide 12 volts some distance away, and have the voltage at the

terminals drop 1 or 2 volts just when you need extra power on those cold

nights.



Roland Christen





[Non-text portions of this message have been removed]



----------------------------

#4937 May 22, 2002

SNIP>

Yes, that would work, or even a linear power supply that would drop the

voltage below 20 volts. Too bad they don't make a good 6 volt battery, you

could put that in series with a 12v one to get 18v.



Roland Christen

SNIP>



Actually, "they" do make a good 6v battery. I went through Dyno Battery here

in Seattle www.dynobattery.com/marine.htm (206-283-7450), and got a

pair of deep cycle 6v - 245amp/hour golf cart batteries wired in series to

give me 12v at 245amp/hours. They fit in a Dyno supplied heavy duty battery

box, and the cost was very reasonable. Since they manufacture these

batteries on demand, they can customize them for you with different terminal

styles, voltages, case designs etc.



Adding a third battery to get 18v isn't yet necessary for my humble

equipment needs, but should provide someone else a good deep cycle solution.



~ Jay E. Potts

www.whirlpoolgalaxy.com - Astrophotography

www.americanfocus.com - Fine Art Landscape and Wildlife Photography



----------------------------

#4938 May 22, 2002

--- In ap-gto@y..., chris1011@a... wrote: > Yes, that would work, or even a linear power supply that would drop

the > voltage below 20 volts. Too bad they don't make a good 6 volt

battery, you > could put that in series with a 12v one to get 18v.



My only power generation is through solar panel: the charger system

is for 12 VDC deep-cycle batteries (3 pcs parallel bank).

Even if a good 6 V battery were available, the charging wouldn't work.

Putting 2 batteries in series (+ power supply, etc) for mount

operation then back to parallel for charging is too much of a hassle

and may provoke very high currents/damage the batteries as they are

coupled with different levels of discharge.



Daniel



----------------------------

#4939 May 22, 2002

--- In ap-gto@y..., chris1011@a... wrote: > In a message dated 5/22/2002 1:35:52 PM Central Daylight Time,

> Daniel_V@c... writes:

>

>

> > Isn't the

> > mount supposed to work flawlessly off a well charged 12VDC - 115

Ah > > battery in the field under far lower temperatures than a few

degrees > > below freezing?

> >

>

> Yes, and my mount does just that in my observatory. I run it off a

marine > battery which is located right under my pier, a few feet away. On

really cold > nights, the battery voltage drops to about 11 volts, and I

sometimes switch > to 600x when slewing. If you put 12 volts DC at the input of the

servo, the > mount should run and slew properly, unless the supply cannot supply

the > current and still produce 12 volts at the terminals of the servo.

It is no > good to provide 12 volts some distance away, and have the voltage

at the > terminals drop 1 or 2 volts just when you need extra power on those

cold > nights.



Roland,



my three batteries are new (Dec 2001, March 2002)and fully charged at

start-up. They are physically 6 feet away from the pier and are NOT

out in the cold. The connecting cable is 10 ft of AWG14 cable: much,

much heavier than the AP1200's power cord which was shortened a full

2 feet, lowering series resistance even more. I don't see where a low

voltage situation may be provoked. But let me check the voltage next

time I'm out there in the cold and I'll report back.



Thanks to all for trying to help.



Daniel



----------------------------

#4941 May 22, 2002

From: chris1011@...

> Date: Wed, 22 May 2002 16:21:59 EDT

>

> Yes, that would work, or even a linear power supply that would drop the

> voltage below 20 volts. Too bad they don't make a good 6 volt battery, you

> could put that in series with a 12v one to get 18v.



Optima makes a deep cycle one. The product name is D6V



www.optimabatteries.com/products/pdf/D6V.pdf



Put a D6V in series with the Optima D34 12v deep cycle battery

and you are in business.



-Doug



USPS: Douglas W. Forehand INTERNET: dwf@...

Sun Microsystems Inc. VOICE: (408) 774-8015

901 San Antonio Road, MS USUN02-301 FAX: (408) 774-2099

Palo Alto, California 94303-4900







----------------------------

#4942 May 22, 2002

--- In ap-gto@y..., "Douglas W. Forehand" dwf@e...> wrote:



I was thinking of my own situation using a 7.0 amp hour gel cell

doesn't leave a lot of time to run the mount on cold nights. A second

7.0 amp battery (at 12 v) in series followed by an 18 V switcher would

leave a lot of head room (voltage wise). A compact,3A bucking

regulator/switcher is easy to find. My charger is setup for 12V

batteries, hence staying with 12V ones is desirable.



The Optimas are top notch and a 12V in series with the 6V would be

good also.



Thanks Doug, Roland, et. al. for the great info.





Tim



>

>

> > From: chris1011@a...

> > Date: Wed, 22 May 2002 16:21:59 EDT

> >

> > Yes, that would work, or even a linear power supply that would

drop the

> > voltage below 20 volts. Too bad they don't make a good 6 volt

battery, you

> > could put that in series with a 12v one to get 18v.

>

> Optima makes a deep cycle one. The product name is D6V

>

> www.optimabatteries.com/products/pdf/D6V.pdf

>

> Put a D6V in series with the Optima D34 12v deep cycle battery

> and you are in business.

>

> -Doug

>



----------------------------

#4943 May 22, 2002

I still don't see why his setup would

stall. 110 ampere hour batteries should

power it just fine especially through

14 gauge wire.



Perhaps the batteries weren't getting charged.

Perhaps the drive is overloaded.



It's very strange.



I suspect the power system should have been

designed with more headroom but then again

you do have to draw the line somewhere.



----------------------------

#4944 May 22, 2002

The chemistry of a lead-acid battery works at 2.1 volts not 12v.

You get 6v as easily as 12v by combining only 3 cells instead of 6.

6v is a common battery (autos used to be 6v).



There's no problem using 6v and 12v batteries in series for 18v but

finding a good charger is another matter. Deltran could possibly

do it with a PROM change on their 24v charger if it were worth

their while (UL etc means it's not worth their while).



Date: Wed, 22 May 2002 16:21:59 EDT

From: chris1011@...

Subject: Re: Re: 1200GTO stalls



Too bad they don't make a good 6 volt battery, you could put that in

series with a 12v one to get 18v.



----------------------------

#4945 May 22, 2002

Guys,



I think we are missing Daniel's point here. He has an electrical

background. He has used better wire than supplied by AP. Has new

batteries. The batteries are NOT in the cold. So I tend to agree

that he probably does NOT have a low voltage problem.



Is there anything else that would support this mount behavior?



Mark

> Roland,

>

> my three batteries are new (Dec 2001, March 2002)and fully charged

at > start-up. They are physically 6 feet away from the pier and are NOT

> out in the cold. The connecting cable is 10 ft of AWG14 cable:

much, > much heavier than the AP1200's power cord which was shortened a

full > 2 feet, lowering series resistance even more. I don't see where a

low > voltage situation may be provoked. But let me check the voltage

next > time I'm out there in the cold and I'll report back.

>

> Thanks to all for trying to help.

>

> Daniel



----------------------------

#4946 May 22, 2002

Is there any chance of RF interferance? You might try placing a choke coil

(ferrite bead) over each end of the cable or wrapping the cable several

turns around the coil.



-----Original Message-----

From: markws7m [mailto:markh@...]

Sent: Thursday, May 23, 2002 12:33 AM

To: ap-gto@yahoogroups.com

Subject: [ap-gto] Re: 1200GTO stalls





Guys,



I think we are missing Daniel's point here. He has an electrical

background. He has used better wire than supplied by AP. Has new

batteries. The batteries are NOT in the cold. So I tend to agree

that he probably does NOT have a low voltage problem.



Is there anything else that would support this mount behavior?



Mark

> Roland,

>

> my three batteries are new (Dec 2001, March 2002)and fully charged

at > start-up. They are physically 6 feet away from the pier and are NOT

> out in the cold. The connecting cable is 10 ft of AWG14 cable:

much, > much heavier than the AP1200's power cord which was shortened a

full > 2 feet, lowering series resistance even more. I don't see where a

low > voltage situation may be provoked. But let me check the voltage

next > time I'm out there in the cold and I'll report back.

>

> Thanks to all for trying to help.

>

> Daniel





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----------------------------

#4947 May 23, 2002

Daniel,



I'm not convinced that you are having a battery problem either. I run all

my equipment and an AP1200 all from one battery between the ranges of 13.3

and 11.7 volts at temperatures, so far, down to 12 degrees F. I have had no

problem with the temperature. I also use a battery bank of 115 AH with a

battery manager system that shuts down before the battery reaches 20%

capacity (state of charge) and below, this occurs at about 11.7 volts DC.

Can't say what your problem is but, lack of power does not seem like the

right explanation IMO. I also charge with 150 watts of solar about 5 to 10

AH depending on sun. Panels are flat on roof.



Regards Andy



-----Original Message-----

From: daniel_verschatse [mailto:Daniel_V@...]

Sent: Wednesday, May 22, 2002 11:34 AM

To: ap-gto@yahoogroups.com

Subject: [ap-gto] Re: 1200GTO stalls





Larry, Tim & Roland,



Yes, being an electronics engineer myself I have considered those

options but:



a. most of the mentioned equipment is non-existent/hard to find on

the chilean marketplace

b. as you say, they are wildly inefficient, produce a high additional

current drain on my solar battery bank.

c. most importantly: it's not correcting the root cause. Isn't the

mount supposed to work flawlessly off a well charged 12VDC - 115 Ah

battery in the field under far lower temperatures than a few degrees

below freezing?

The specifications on page 4 of the manual say:

Power consumption: 0.4A sidereal, 2A with both motors slewing

Power requirements: 12 VDC (no temperature range specified)

What do the "mobile" imagers on this run their AP900GTO's and

AP1200GTO's on in "arctic" conditions?



I am still not convinced I had a power/voltage problem, but haven't

been able to go back to check yet. The observatory is 60 miles away

AND I need a cold night.



Daniel

--- In ap-gto@y..., "Lawrence D. Lopez" lopez@m...> wrote:

> Actually:

>

> just upconvert it to 120 V AC and then

> down convert it to 12 V AC.

>

> 24 to 12 V switchers are available at

> Ham Radio Outlet for Radio Amateurs

> running on 24 electrical system trucks.

> I know some military vehicles use this

> but I think some long haul trucks might

> also which might indicate where the

> market for these is.

>

> I've decided to brute force the problem

> into non existance by using a 20 amp

> linear power supply for amateur radio.

> It's output voltate was something like 13

> volts. This higher voltage is the prefered

> operating voltage for radios since it is

> within spec for a car with it's alternator

> running and allows the transmitters to

> produce more power. It is also a very good

> voltage to run the AP mounts on since it gives

> more head room.

>

> A 24 to 12 down converver is nice but it

> means that the power system would need to

> be revamped.

>

> A linear power supply would be a poor

> choice for a off grid system since it is

> so inefficient.

>

> So, a switching up converter and a switching

> down converter sounds good even thought it

> is wildly inefficient and complex.

>

> What you really need is a 12 volt to 12 volt

> switching converter. Not many of those

> around I'm afraid.

>

> .Larry

>

> limunary wrote:

> >

> > --- In ap-gto@y..., "daniel_verschatse" Daniel_V@c...> wrote:

> > > I have no mains electricity at the observatory (yet), so I'm

limited

> > > to 12 V maximum now.

> > >

> >

> > The cold batteries terminal voltage maybe very low, in the sub 12

volt

> > range.

> >

> > Would using two 12 V batteries to deliver 24 V followed by a high

> > efficiency switcher to 18 volts be a good solution?

> >

> > Tim

> >

> > To UNSUBSCRIBE, or for general information on the ap-gto list

> > see groups.yahoo.com/group/ap-gto

> >

> > Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/





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----------------------------

#4948 May 23, 2002

In a message dated 5/23/2002 1:24:04 AM Central Daylight Time,

markh@... writes:



> So I tend to agree

> that he probably does NOT have a low voltage problem.

>



Until the voltage has been measured to be 12 volts, I can't agree. I had a

situation where my car would not start - voltage was 12 volts on the battery,

wire was adequate to the starter motor, etc. Would not start because the

battery connector was corroded underneath where I could not see it. When

things don't work, everything should be checked out - don't assume anything.



Roland Christen





[Non-text portions of this message have been removed]



----------------------------

#4949 May 23, 2002

I agree with Roland, that's why I proposed to report back after I

have had a chance to be with the mount in the cold and actually put a

voltmeter at the mount's power input when the 1200x slewing starts.

May take awhile, I'm leaving to the USA this Sunday....



Daniel

Santiago - Chile

--- In ap-gto@y..., chris1011@a... wrote:

> In a message dated 5/23/2002 1:24:04 AM Central Daylight Time,

> markh@s... writes:

>

>

> > So I tend to agree

> > that he probably does NOT have a low voltage problem.

> >

>

> Until the voltage has been measured to be 12 volts, I can't agree.

I had a

> situation where my car would not start - voltage was 12 volts on

the battery,

> wire was adequate to the starter motor, etc. Would not start

because the

> battery connector was corroded underneath where I could not see it.

When

> things don't work, everything should be checked out - don't assume

anything.

>

> Roland Christen

>

>

> [Non-text portions of this message have been removed]



----------------------------

#4950 May 23, 2002

RF-interference cannot occur (and wouldn't matter): the battery bank

acts as one huge capacitor, effectively swallowing all RF (and most

AC as a matter of fact)



Daniel

Santiago - Chile

--- In ap-gto@y..., Hi-Fi_Guru thx1326@s...> wrote:

> Is there any chance of RF interferance? You might try placing a

choke coil

> (ferrite bead) over each end of the cable or wrapping the cable

several

> turns around the coil.

>

> -----Original Message-----

> From: markws7m [mailto:markh@s...]

> Sent: Thursday, May 23, 2002 12:33 AM

> To: ap-gto@y...

> Subject: [ap-gto] Re: 1200GTO stalls

>

>

> Guys,

>

> I think we are missing Daniel's point here. He has an electrical

> background. He has used better wire than supplied by AP. Has new

> batteries. The batteries are NOT in the cold. So I tend to agree

> that he probably does NOT have a low voltage problem.

>

> Is there anything else that would support this mount behavior?

>

> Mark

>

> > Roland,

> >

> > my three batteries are new (Dec 2001, March 2002)and fully charged

> at

> > start-up. They are physically 6 feet away from the pier and are

NOT

> > out in the cold. The connecting cable is 10 ft of AWG14 cable:

> much,

> > much heavier than the AP1200's power cord which was shortened a

> full

> > 2 feet, lowering series resistance even more. I don't see where a

> low

> > voltage situation may be provoked. But let me check the voltage

> next

> > time I'm out there in the cold and I'll report back.

> >

> > Thanks to all for trying to help.

> >

> > Daniel

>

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/



----------------------------

#4951 May 23, 2002

Hi Andy,



we seem to have identical set-ups !

Good to hear that yours is working way down in the arctic

temperatures.

I run only two (inclined) panels with a Siemens solar

charger/regulator at 110 W total, but since I never operate more than

two nights in a row (week-ends) the battery bank is always at or very

near full charge.

Will let the list know what I find out.



Thanks to all for the nice helping posts..



Daniel

Santiago - Chile

--- In ap-gto@y..., "Andy Forsberg" CS-Imaging@p...> wrote:

> Daniel,

>

> I'm not convinced that you are having a battery problem either. I

run all

> my equipment and an AP1200 all from one battery between the ranges

of 13.3

> and 11.7 volts at temperatures, so far, down to 12 degrees F. I

have had no

> problem with the temperature. I also use a battery bank of 115 AH

with a

> battery manager system that shuts down before the battery reaches

20%

> capacity (state of charge) and below, this occurs at about 11.7

volts DC.

> Can't say what your problem is but, lack of power does not seem

like the

> right explanation IMO. I also charge with 150 watts of solar about

5 to 10

> AH depending on sun. Panels are flat on roof.

>

> Regards Andy

>

> -----Original Message-----

> From: daniel_verschatse [mailto:Daniel_V@c...]

> Sent: Wednesday, May 22, 2002 11:34 AM

> To: ap-gto@y...

> Subject: [ap-gto] Re: 1200GTO stalls

>

>

> Larry, Tim & Roland,

>

> Yes, being an electronics engineer myself I have considered those

> options but:

>

> a. most of the mentioned equipment is non-existent/hard to find on

> the chilean marketplace

> b. as you say, they are wildly inefficient, produce a high

additional

> current drain on my solar battery bank.

> c. most importantly: it's not correcting the root cause. Isn't the

> mount supposed to work flawlessly off a well charged 12VDC - 115 Ah

> battery in the field under far lower temperatures than a few degrees

> below freezing?

> The specifications on page 4 of the manual say:

> Power consumption: 0.4A sidereal, 2A with both motors slewing

> Power requirements: 12 VDC (no temperature range specified)

> What do the "mobile" imagers on this run their AP900GTO's and

> AP1200GTO's on in "arctic" conditions?

>

> I am still not convinced I had a power/voltage problem, but haven't

> been able to go back to check yet. The observatory is 60 miles away

> AND I need a cold night.

>

> Daniel

>

> --- In ap-gto@y..., "Lawrence D. Lopez" lopez@m...> wrote:

> > Actually:

> >

> > just upconvert it to 120 V AC and then

> > down convert it to 12 V AC.

> >

> > 24 to 12 V switchers are available at

> > Ham Radio Outlet for Radio Amateurs

> > running on 24 electrical system trucks.

> > I know some military vehicles use this

> > but I think some long haul trucks might

> > also which might indicate where the

> > market for these is.

> >

> > I've decided to brute force the problem

> > into non existance by using a 20 amp

> > linear power supply for amateur radio.

> > It's output voltate was something like 13

> > volts. This higher voltage is the prefered

> > operating voltage for radios since it is

> > within spec for a car with it's alternator

> > running and allows the transmitters to

> > produce more power. It is also a very good

> > voltage to run the AP mounts on since it gives

> > more head room.

> >

> > A 24 to 12 down converver is nice but it

> > means that the power system would need to

> > be revamped.

> >

> > A linear power supply would be a poor

> > choice for a off grid system since it is

> > so inefficient.

> >

> > So, a switching up converter and a switching

> > down converter sounds good even thought it

> > is wildly inefficient and complex.

> >

> > What you really need is a 12 volt to 12 volt

> > switching converter. Not many of those

> > around I'm afraid.

> >

> > .Larry

> >

> > limunary wrote:

> > >

> > > --- In ap-gto@y..., "daniel_verschatse" Daniel_V@c...> wrote:

> > > > I have no mains electricity at the observatory (yet), so I'm

> limited

> > > > to 12 V maximum now.

> > > >

> > >

> > > The cold batteries terminal voltage maybe very low, in the sub

12

> volt

> > > range.

> > >

> > > Would using two 12 V batteries to deliver 24 V followed by a

high

> > > efficiency switcher to 18 volts be a good solution?

> > >

> > > Tim

> > >

> > > To UNSUBSCRIBE, or for general information on the ap-gto list

> > > see groups.yahoo.com/group/ap-gto

> > >

> > > Your use of Yahoo! Groups is subject to

> docs.yahoo.com/info/terms/

>

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/







----------------------------

#4952 May 23, 2002

I could even be an intermediate connection

on the battery to mount cable.



I had to spread the center contact slightly

to make a better contact.



But Roland is right attack the problem like

a child and explore everything without

preconceived notions or you'll miss it.





chris1011@... wrote: >

> In a message dated 5/23/2002 1:24:04 AM Central Daylight Time,

> markh@... writes:

>

> > So I tend to agree

> > that he probably does NOT have a low voltage problem.

> >

>

> Until the voltage has been measured to be 12 volts, I can't agree. I had a

> situation where my car would not start - voltage was 12 volts on the battery,

> wire was adequate to the starter motor, etc. Would not start because the

> battery connector was corroded underneath where I could not see it. When

> things don't work, everything should be checked out - don't assume anything.

>

> Roland Christen

>

> [Non-text portions of this message have been removed]

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/



----------------------------

#4953 May 23, 2002

RF-interference cannot occur (and wouldn't matter): the battery bank

> acts as one huge capacitor, effectively swallowing all RF (and most

> AC as a matter of fact)



I wouldn't be so sure about that. That big battery probably exhibits

a fairly high impedence at high frequencies.



If you all really want to be afraid, put an oscilloscope on your

DC power supply, and look at all the hash that get generated by

the various devices you're running.



My Kendrick dew remover controller generates spikes on the order of

100mv or so as it switches on and off (with varying duty cycle). The

rise and fall times are *really* steep and seeing those spikes at the

battery is surprising.



The 110VAC inverter generates a noise, too. The Robofocus controller

cranks out some noise as well, as it use PWM to vary the power on the

stepper motor coils. The 12VDC laptop power supply also contributes a

bit of it's own.



It was a very enlightening experience. I'm going to try to run some

tests with the CCD camera on it's own battery to see if there's any

effect on the noise in the images. I'll also try to capture some of the

oscilloscope traces and put them up on a web page somewhere..



louie



----------------------------

#5117 Jun 15, 2002

--- In ap-gto@y..., chris1011@a... wrote: > Too bad they don't make a good 6 volt battery, you

> could put that in series with a 12v one to get 18v.

>

> Roland Christen



Well, I suppose it depends on your definition of "good", but

golf cars run off 6V batteries which are rechargeable and

*extremely* tough. They're built to withstand lots of charge/

discharge cycles, whereas car batteries expect to be kept fully

charged all the time.



I don't use my 1200GTO in the field, but I would think that 3

golf car batteries would be a good 18V power source, modulo the

physical work involved in carrying them around.



If you're using a 12V lead-acid battery, your best choice is the

marine deep-cycle version, which is OK with being deeply dis-

charged.



We've found Optima batteries to be the best in off-road use; they

take the pounding of boncing over rocks and through ruts better

than any other battery we've tried, and last longer in the desert

heat, too. Those qualities are useful for portable astronomy -

I use one to power my G-11.



Terry R. Friedrichsen



----------------------------

#5365 Aug 3, 2002

Hi all,



I finally had a chance to check voltage at my AP1200 power input last

Thursday: same set-up as before and about 5.C colder! No problem at

all: the mount happily slewed all night. Voltage dropped from an

initial 13.2V at dusk to 12.6V at dawn.



I did some thinking/checking and the only explanation I can think of

is a low voltage situation due to snow covering up my solar panel. I

believe Roland's assumption was correct and the AP1200 is a champ.



BTW, here's a picture of that night: NGC7293 - Helix nebula with the

AP155 and ST10XE (love those download times!)



makeashorterlink.com/?X2C852E61



Daniel

Santiago - Chile

--- In ap-gto@y..., "daniel_verschatse" Daniel_V@c...> wrote:

> I agree with Roland, that's why I proposed to report back after I

> have had a chance to be with the mount in the cold and actually put

a

> voltmeter at the mount's power input when the 1200x slewing starts.

> May take awhile, I'm leaving to the USA this Sunday....

>

> Daniel

> Santiago - Chile

>

> --- In ap-gto@y..., chris1011@a... wrote:

> > In a message dated 5/23/2002 1:24:04 AM Central Daylight Time,

> > markh@s... writes:

> >

> >

> > > So I tend to agree

> > > that he probably does NOT have a low voltage problem.

> > >

> >

> > Until the voltage has been measured to be 12 volts, I can't

agree.

> I had a

> > situation where my car would not start - voltage was 12 volts on

> the battery,

> > wire was adequate to the starter motor, etc. Would not start

> because the

> > battery connector was corroded underneath where I could not see

it.

> When

> > things don't work, everything should be checked out - don't

assume

> anything.

> >

> > Roland Christen

> >

> >

> > [Non-text portions of this message have been removed]







----------------------------

#5371 Aug 5, 2002

In a message dated 8/3/2002 11:17:18 PM Central Daylight Time,

daniel@... writes:



> BTW, here's a picture of that night: NGC7293 - Helix nebula with the

> AP155 and ST10XE (love those download times!)

>

> makeashorterlink.com/?X2C852E61

>



Excellent image.



Roland Christen





[Non-text portions of this message have been removed]



----------------------------

#5387 Aug 7, 2002

Daniel,



I love the helix in general. Especially your picture. Thank you for

sharing it.



Best regards

Stefan

--- In ap-gto@y..., "daniel_verschatse" daniel@r...> wrote:

> BTW, here's a picture of that night: NGC7293 - Helix nebula with

the

> AP155 and ST10XE (love those download times!)

>

> makeashorterlink.com/?X2C852E61



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