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Suggestions for power supply for AP 900 GTO

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#26 WadeH237

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Posted 25 August 2013 - 05:52 PM

Just after I got my AP1600, I bought two Pyramid 12 amp power supplies. I've switch all of my equipment - laptop, camera and everything - to 12 volts with no inverters. The power supply feeds a RigRunner for distribution and everything is connected with Anderson PowerPoles. The average current draw during a session is about 5 amps, and the peak draw has never exceeded 7.5 amps - well within the power supply's specs.

I was using the power supply a few weeks ago, when it started buzzing softly. At the same time, several of my pieces of gear either set off warning lights or shut down. I have an accurate current meter inline with the power supply, and it showed that the Pyramid unit had jumped to about 19.5 volts.

Fortunately, none of my gear was damaged, but I will never use a Pyramid power supply again. I could understand if it failed to a lower voltage, but it is completely unacceptable to fail to a much higher voltage than rated.

I've since replaced the Pyramid unit with one from PowerWerx. The PowerWerx unit is smaller and lighter, is rated for 30 amps, and runs very cool (it never seems to exceed ambient temperature, while both of the Pyramid units were quite hot to the touch in operation). The PowerWerx unit was more than triple the cost of the Pyramid power supply, but I've got nearly $20k of equipment set up and after watching the Pyramid unit fail (it's fortunate I was right there, because I run fully automated and typically unattended), I'm willing to pay for a better unit.

Regarding batteries, I've had a great experience with Universal Battery UB-12350's to power my mounts in the field. They are 35ah AGM batteries designed for wheelchairs. They're plenty for a mount and my are 6 years old and still going strong. For a fully battery powered field setup, I have two Universal UB-12750's that are 75ah AGMs. This is the first year that I've had them, so I don't have a long term report. I am hoping to have the same success that I've had with the smaller ones.

-Wade

#27 Peter in Reno

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Posted 25 August 2013 - 07:08 PM

I use Optima D34M Marine Deep Cycle battery from:

http://www.1st-whole...-batteries.com/

It costs $210 including shipping. It lasts a long time. I use it to power the Mach1GTO, CCD camera, and USB powered hub. My laptop is powered by house current.

The battery box is from Wal-Mart and two outlets are from Home Depot. I absolutely hate cigarette lighter plugs/sockets. You can use any other types of outlets but I find A/C outlet to power 12V devices very durable and simple. Each outlet is protected by 10A inline fuse. No, I never accidentally plug into house outlet. :o

Peter

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#28 Peter in Reno

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Posted 25 August 2013 - 07:08 PM

Another view.

Peter

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#29 Starhawk

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Posted 25 August 2013 - 07:16 PM

AP says marine deep cycle batteries are a hybrid starter/ deep cycle battery, so they are damaged by real deep cycle use, so you have to use a pure deep cycle battery, as made for golf carts and personal mobility scooters.

-Rich

From what AP says, that's the wrong type of battery.

-Rich


Which battery are you referring to? I have used these batteries for G-11, MI-250 and AP900
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#30 Peter in Reno

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Posted 25 August 2013 - 07:57 PM

A-P did not really say NOT to use a Marine Deep Cycle batteries. This is a snippet from A-P document:

"Marine deep-cycle batteries are generally a hybrid design. They attempt to both provide the current to start a boat motor and the deep discharge capability for trolling motors or houseboat electrical systems. These are not as good a choice as true deep-cycle batteries, but are often much less expensive than true deep-cycle batteries. Note also that many batteries marketed as “marine deep-cycle” are actually hybrid designs that are really more for starting than deep discharge. If the battery advertises its cranking power (i.e. CCA or cold cranking amps), then it is a hybrid at best, regardless of what the label says. Marine deep-cycle batteries are suitable for powering your mount, but should not be discharged as deeply as true deep-cycle batteries."

I've had Wal-Mart Deep Cycle Marine battery (hybrid) to last at least 5 years without any issues. Deep Cycle Marine (hybrid) batteries are more than acceptable for astronomy use. They are easier to find and cheaper than true deep cycle marine batteries. You do NOT have to use true deep cycle to power astronomical devices.

Peter

#31 Starhawk

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Posted 25 August 2013 - 08:08 PM

Wade,

This was the kind of info I have wanted to find on battery power. The combination of a minnekota box and a UB-12350 would appear to be quite practical at around 30 lbs. I even found a place selling the batteries in pairs for $135 because a hoveround apparently needs two.

http://www.replaceup...ctiva-Foreru...

As for the pyramid power supply, I was out at 106 F photographing Venus passing Mercury with my AP 130 EDFGT on the AP MAch1 GTO (after clearing with AP that level of heat was OK) at noon in Tucson the Friday before the transit of Venus and had finally gotten the two of them in the same frame. Then the Pyramid power supply decided it was too warm and up and quit on me until I could cool it down. The fiasco with crashing the OTA into the tube came up after this as a result of having to restart an observing technique which required going between the sun and Venus, and using an earlier version of Sky Safar which sent "Sync" when "Align" was pressed instead of RCAL.

So, my CGEM got to do the transit a couple days later. It never complained even when its far less impressive little power supply was toasted by direct sun on a 108F day.

So, the reason I mention this is this power supply question is a potential Achilles heel for AP mounts for some reason. There are moments when I do ask myself why a modified lantern is enough to power a CGEM all night while planning an outing with a Mach1 GTO is like setting up a National Geographic expedition.

-Rich

Just after I got my AP1600, I bought two Pyramid 12 amp power supplies. I've switch all of my equipment - laptop, camera and everything - to 12 volts with no inverters. The power supply feeds a RigRunner for distribution and everything is connected with Anderson PowerPoles. The average current draw during a session is about 5 amps, and the peak draw has never exceeded 7.5 amps - well within the power supply's specs.

I was using the power supply a few weeks ago, when it started buzzing softly. At the same time, several of my pieces of gear either set off warning lights or shut down. I have an accurate current meter inline with the power supply, and it showed that the Pyramid unit had jumped to about 19.5 volts.

Fortunately, none of my gear was damaged, but I will never use a Pyramid power supply again. I could understand if it failed to a lower voltage, but it is completely unacceptable to fail to a much higher voltage than rated.

I've since replaced the Pyramid unit with one from PowerWerx. The PowerWerx unit is smaller and lighter, is rated for 30 amps, and runs very cool (it never seems to exceed ambient temperature, while both of the Pyramid units were quite hot to the touch in operation). The PowerWerx unit was more than triple the cost of the Pyramid power supply, but I've got nearly $20k of equipment set up and after watching the Pyramid unit fail (it's fortunate I was right there, because I run fully automated and typically unattended), I'm willing to pay for a better unit.

Regarding batteries, I've had a great experience with Universal Battery UB-12350's to power my mounts in the field. They are 35ah AGM batteries designed for wheelchairs. They're plenty for a mount and my are 6 years old and still going strong. For a fully battery powered field setup, I have two Universal UB-12750's that are 75ah AGMs. This is the first year that I've had them, so I don't have a long term report. I am hoping to have the same success that I've had with the smaller ones.

-Wade



#32 Starhawk

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Posted 25 August 2013 - 08:35 PM

Yep, that would be the paragraph in question.

And that would be a perfect example of my general problem with the "Read the manual" attitude. Yeah, you can read the manual. Does it tell you something useful? In this case, it means either you have to have more information from elsewhere, or you just overpay to do the same thing an equivalent would have done just fine at. While at the same time, it apparently has someone thinking they have the last word on being right, so, fixing the real problem doesn't happen.

Like I said, practical experience is what I wanted, so thank you for writing back. This is just the sort of thing which annoys me since the AP mounts are so solid and practical, but when some of these side issues come up, the given answers are ridiculous since you aren't given and indication of whether you're standing on the edge of the Grand Canyon or they're spun up about a crack in the sidewalk.

What I was really imagining was getting my act together so my Mach1 GTO could go out as easily as the CGEM does. That thing is far from perfect, but I've got a small enough footprint to take it somewhere and if needed load scope and all on a single dolly with everything I need for the mount and an evening's observing.

-Rich

A-P did not really say NOT to use a Marine Deep Cycle batteries. This is a snippet from A-P document:

"Marine deep-cycle batteries are generally a hybrid design. They attempt to both provide the current to start a boat motor and the deep discharge capability for trolling motors or houseboat electrical systems. These are not as good a choice as true deep-cycle batteries, but are often much less expensive than true deep-cycle batteries. Note also that many batteries marketed as “marine deep-cycle” are actually hybrid designs that are really more for starting than deep discharge. If the battery advertises its cranking power (i.e. CCA or cold cranking amps), then it is a hybrid at best, regardless of what the label says. Marine deep-cycle batteries are suitable for powering your mount, but should not be discharged as deeply as true deep-cycle batteries."

I've had Wal-Mart Deep Cycle Marine battery (hybrid) to last at least 5 years without any issues. Deep Cycle Marine (hybrid) batteries are more than acceptable for astronomy use. They are easier to find and cheaper than true deep cycle marine batteries. You do NOT have to use true deep cycle to power astronomical devices.

Peter



#33 WadeH237

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Posted 25 August 2013 - 09:05 PM

In this case, it seems like the documentation from AP over complicates the issue.

Everything that is written in the paragraph above about hybrid versus true deep cycle batteries is completely true, according to reading I've done on the subject over the years.

The thing is, that the mount really doesn't care. It just wants a power source that can supply enough current to keep the voltage stable. My observation of the AP1600 is that it's really efficient. It's been a while since I measured it directly, but if I recall, it's under 0.5 amps at 12 volts while tracking. Even during 1200x slews, I've never seen it go over 2 amps. This is pretty similar to my CGE, or your CGEM.

I should say that I'm only running about 30lb of payload on it at the moment. I imagine that it would draw more during slews with a couple hundred pounds. But it balanced, I would think that it would still be quite efficient while tracking. And I have to believe that a Mach1 would be the same.

I can't think of any reason that a 17ah battery would be a problem for the mount. It could be a problem battery longevity, but that's just because those batteries tend to be designed for high current discharge for short periods of time (like needed for a jump start), rather than a slow and continuous discharge. And in any case, it's a good idea to plan your capacity such that you don't discharge to below 50% capacity. That will dramatically increase your battery longevity, even for true deep cycles.

-Wade

#34 Peter in Reno

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Posted 25 August 2013 - 09:08 PM

Well said Wade. That's exactly my thinking.

Peter

#35 Starhawk

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Posted 25 August 2013 - 10:37 PM

The other part I see in this is I have a limited number of trips I can do beyond AC range for imaging in any given year, so the whole questions definitely rings of the absurd while I have little kids who get dibs on my time.

And yes, the question of how to power an AP mount seems more extreme than it has any right to. The mount is practically airplane ready if you break it down and look at just he mount head. But there needs to be a pile of other gear waiting for you at the other end of the flight.

I suppose it's the missing pieces which are annoying- first rate mount, scabbed together home-made power supply. Kind of ridiculous, no?

-Rich

#36 blueman

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Posted 26 August 2013 - 12:27 AM

If you can hold the voltage to the minimum requirement for the mount without hurting the battery, then it should be fine.

Remember one thing. Increased voltages = decreased amps.
Decreased voltage = increased amps.

This is the real problem. If the voltage goes down the amps go up and that is not good.
Blueman

#37 Starhawk

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Posted 26 August 2013 - 09:08 AM

That's another voyage of discovery in the AP manual.

I remember power= current x voltage, and its evil counterpart, heating power = resistance of the load x current ^ 2

So, AP has these warnings about the smaller mounts getting flakey if the voltage is too high, while the bigger mounts apparently can tolerate this. I am guessing what is going on is the CP3 performance is partly based on the mechanical drag in the mount, so if the mount is small and low resistance, it's actually possible to overpower the mount.

So, battery discussion aside, it seems to sound like the mount itself would be really happy if it was powered by a car and was getting something around 14 volts. And, of course, there is a large array of gear made for converting automotive power to what every piece of gear you have needs.

The hoveround scooter batteries look pretty convenient at 25 lbs, and apparently can survive deep cycling. A minnekota box would have some extra space inside with one in there, and the 35 AH should be about 2x what's actually needed to get through a night.

So, I'll go ahead and touch the third rail and ask about charging...

-Rich

#38 WadeH237

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Posted 26 August 2013 - 07:01 PM

For a charger, I use a BatteryMINDer model 12448. It has specific settings for battery type and supports AGM (the proper type for the UB-12350 batteries). You can select between 2, 4 or 8 amps for the bulk charge. For small batteries like the 12350s, I typically use 2 amps, but sometimes use 4 amps if I am in a hurry. The charger will detect when the battery is fully charged and switch into float mode.

Here is a link.

I wanted to really understand my power usage, so I also purchased a couple of these power meters. You can use them inline between the power source and your gear to get a very accurate look at your power usage. Or, you can put them between your charger and battery if you want to get a very accurate look at the behavior and state of the battery.

I've switched to Anderson Powerpoles for all of my 12 volt connections. They are convenient, make a positive connection (much better than a cigarette lighter) and cannot be plugged in with reverse polarity. Each of my power meters has one on the source and load wires. Also, each of my device power cables has one.

To distribute power, I use RigRunners. The power source supplies one RigRunner at my work table, and I have a second one attached to the mount that powers each device on the mount. If I want to run with two power sources, I can have each RigRunner connected to it's own power source. Or, I ran run with one power source feeding the RigRunner at the table, and a power cord to connect the mount's RigRunner to one of the ports on the table's RigRunner.

I know that AP suggests giving the mount its own power supply, but to be honest, I usually don't bother. The mount's power needs are quite modest as compared to the laptop and camera. And with the power meters, I have confirmed that the current draw does not noticeably drop or spike the voltage - even with everything running, the mount slewing, and the CCD cooler at maximum.

Another benefit of using the power meters is that I was able to optimize the laptop for minimum power consumption over night. Setting the laptop's power management modes turns out to make a big difference - nearly an amp. Turning down the frame rate in TheSkyX Professional also makes a big difference on the current draw - about an amp. Shutting down unneeded services also saves some power, but not as much as the above. Also, I noted that the 12 volt SBIG power supply draws about an amp less than running the A/C power supply with an inverter (the inverter claimed to be 97% efficient...which turned out to be fantasy when I acutally measured it).

All told, I was able to drop my average current draw from nearly 10 amps, to about 5.5 amps. And when I dim the screen down to minimum, I often see it drawing less than 4 amps while doing automated image captures.

When you are running on battery in the field, minimizing current draw makes a huge difference on the demands you place on the battery.

I hope some of this is useful,
-Wade

#39 urassner

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Posted 26 August 2013 - 09:13 PM

Thank you for all the helpful suggestions and insights. I have decided to try a lithium iron phosphate battery. They are somewhat pricey at $260 for 12V 36 Ah, but we want to use it for some other stuff as well. The battery only weighs 5 lbs and should be able to be charged 1500-2000 times. It also does not have much voltage drop as it empties. I will built a little power tank, with 2 lighter sockets and 2 USB charging port (in case my IPad goes down and for other uses).
I will post some pictures when I have it together (if it works).

#40 Starhawk

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Posted 27 August 2013 - 07:33 PM

Well, if you're going to get an exotic battery, that would be the one to get, it looks like. Making sure it is usable for more everyday tasks in a power outage is definitely a good idea. Are you going to modify an existing battery box?

-Rich

#41 urassner

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Posted 27 August 2013 - 11:37 PM

I looked at the battery boxes, but decided on a 16 inch Stanley toolbox, which is a little bit smaller and has two lid organizes in which I am planning to put a main power switch and resettable fuse switches, so that they do not get pressed accidentally. Depending on how much room there is in the lid organizer, I might put the lighter sockets in there as well.

#42 Starhawk

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Posted 30 August 2013 - 08:11 PM

I was thinking extra room in the trolling motor boxes could be used to put some styrofoam insulation around the battery and maybe build the charger into the box with it.

-Rich

#43 frobi6852

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Posted 01 September 2013 - 04:59 AM

Pyramid PS15KX 10A 13.8-Volt Power Supply $60.00 at Amazon

#44 Chris.Baron

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Posted 01 December 2013 - 12:41 PM

I know this is a late post to this thread, but I just took ownership of one of these beauties myself and was looking for power solutions. I only need to power the mount itself, yet given what it cost me, really wanted to make sure I didn't buy something cheap that could end up damaging the mount. I was also concerned about dew/frost as most of the power supplies out there state "do NOT expose to moisture"

THIS might work very nicely. You'd just need a spade to cigarette lighter adapter to plug in the mount.

The operating temp range is very wide (and it gets quite cold here so that too was a concern) and it's fully waterproof based on its typical marine usage.

I'm going to snag one. I'll let you know how it works out.

Cheers,
Chris






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