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At What Temp Do I Need 15V For My AP 1100 Mount?


Kent10
 

In the winter, I often observe in below freezing temperatures.  So my 1st battery was one from Kendrick where I could use 15v instead of 12v.  15v was recommended in the AP 1100 manual.

 

I am looking at getting a new battery.  I could just replace the Kendrick battery but am considering the LiFePO4 batteries that so many people like. 

 

If I buy the LiFePO4 battery, I assume I can no longer use 15v.  Can I successfully use 12v in 20 degree F temperatures?  I don’t usually observe much below that.  I prefer not to slow down the slewing speed.  Or is there a way to use 15V with the LiFePO4 battery?

 
Thanks, Kent

 

 


Alex
 

Hi Kent,

I use LiFePO4 batteries and the average voltage is higher than 12V. It is above 12.8V for most of its discharge curve. Here is a graph highlighting this nice feature of LiFePO4 batteries:

How to Find Happiness With LiFePO4 (Lithium-Ion) Batteries - Solacity Inc.

I'm from California so I rarely get into low temperatures to test the AP1100 mount but I have never had a problem with the mount when using LiFeO4 batteries so long as I do not deplete the battery below 10% charge.  Actually, I have never come close to depleting the battery to 10% when running all night.

Best,
Alex


Kent10
 

Thanks very much, Alex.  That is good to know and the LiFePO4 may do just fine for me in my cold.  The last few days I have been observing for a couple of hours each night in temps below freezing but still above 20 degrees.  I am using my old battery but at 12V instead of my usual 15V and all seems fine so far.  I'll keep using it like this for a while and if I don't have any issues then all must be fine.  I haven't heard from anyone else with issues at below freezing with 12V so maybe it is not normally a problem.  Or it takes much colder temps.

Next, I have to look into how to use the
LiFePO4 with the mount.  They don't have cigarette lighter sockets or Powerpole connectors.  Maybe an adapter with alligator clips like they have on the AP website?  https://www.astro-physics.com/accessories/mount-accessories/power-supplies/

Thanks again, Kent


Luca Marinelli
 

Kent,

I have used a Bioenno LiFePO4 battery for imaging year round with a Mach1GTO and 1100 mounts. I live upstate NY and in the Winter it is not unusual to reach 0F and occasionally below 0 temperatures. The battery is absolutely fine for all-night imaging runs even at those temperatures. An excellent case for LiFePO4 batteries is this one:

https://powerwerx.com/pwrbox-portable-power-bioenno-batteries

It has both Powerpole and cigarette plug connectors.

Luca


Kent10
 

Thanks, Luca.  That is a perfect recommendation.  I didn't want to use alligator clips.  Glad to hear you have no problems in your very cold temps.  Thanks!


Alex
 

As a side note, I make my own cables which is pretty easy to do.  I use Powerpole connectors on the side that connects to the AP1100 mount and I use ring connectors that I crimp onto 10 gauge wire on the side that connects to the LiFePO4 battery. At one time, I noticed some pre-made options on Amazon? Also, if you do not want to bother making your own cables Powerwerx allows you to design your own custom cable online and have it shipped to your home. Nice feature! Here is a link to the site: https://powerwerx.com/dual-conductor-custom-cable

Best,
Alex


Alex
 

Hi Kent,

Here is another app (http://www.westmountainradio.com/find_cable_size.php) that I find useful when designing cables as it shows you the amount of voltage and power loss associated with various cable gauges based upon length, voltage at source, and current. Because you are concerned with maintaining a high voltage at the mount this app will highlight the amount of voltage drop associated with the length of cable, the gauge, and the current of the cable you will be using to connect your battery to the mount. The thicker the gauge the less voltage drop. That is why I use high quality, thin strand, 10 gauge pure copper wire to connect my battery to the mount. Not a huge difference, but every little bit helps.

One note, this app does not calculate losses due to the termination techniques used. You could Google the connectors or get a good meter and measure them if you were interested. Once again, typically not a big issue unless poorly terminated.

One last note, I use an inline power meter to monitor voltage, current, power of my batteries. At first, I would pay attention to the meter but after a while I discovered I was always in the sweet spot of the power draw on the battery and was typically at 13.2 or higher volts for most of the evening, night and paid less attention to the meter.

Best,
Alex


Kent10
 

Hi Alex,

This is great.  Thanks so much for all your help!

Kent