What battery to use to power mount

[Chefliam]

Hello everyone! 

I'm looking for what kind of battery to buy to power two equitorial mounts. 

I first thought of buying a car battery with about 40ah. But after a little more research I realized that deep cycle boat batteries were preferred because they were designed to discharge more than car batteries and over a longer period of time. 

I have also heard of lithium ion and gel batteries but have not found much information on them. 

What type of battery would be best for my needs?

Thanks in advance, 
Have a nice day

 

[barbulo]

I believe that LiFePO4 is the word. Not cheap though.

[Chefliam]

Yeah, definitely not cheap, quite out of my price range though. But looks nice

[JimothyC]

If you want a cheaper Lifepo4 option, have a look at Golf Trolley batteries. Tiny bit of wiring required to create the necessary cables to connect to your mount/power distribution box. But will do the job perfectly. 

 

https://www.amazon.co.uk/ULTRAMAX-Lithium-Battery-perfect-MotoCaddy/dp/B082WH2YSX/ref=sr_1_5?dchild=1&keywords=golf+trolley+batteries&qid=1626792315&sr=8-5

[powerlord]

If you dont mind the size, a leisure battery will work (caravan/motorhome battery). those are built for deep cycle.

However, carting even a small one of them in and out to charge is gonna get old quickly ?

I use custom built lipo packs based on large capacity lipo batteries from hobbyking.com. But I wouldn't recommend it to anyone unless they were familiar with lipos, had a lipo charger, new how to make a buck regulator to step it down to 12v, etc.

So easy way - get something like this for 60 quid:

https://www.tayna.co.uk/leisure-batteries/exide/er350/

stick it in a big tupperware box, and charge when required.

I'm not sure I'd trust that wee 22ah one for 2 mounts for a night. In winter, thats gonna be say 10 hours, and maybe 5-6 amps load average across your mounts, not including cameras, dew heaters and the like.

I'd be working off 10amps and hour.. maybe 15. so for 10 hours, maybe 150ah to be super safe, though prob that 80ah one above enough.

stu

 

Edited July 20, 2021 by powerlord

[JimothyC]

18 hours ago, powerlord said:

I'm not sure I'd trust that wee 22ah one for 2 mounts for a night. In winter, thats gonna be say 10 hours, and maybe 5-6 amps load average across your mounts, not including cameras, dew heaters and the like.

I'd be working off 10amps and hour.. maybe 15. so for 10 hours, maybe 150ah to be super safe, though prob that 80ah one above enough.

stu

 

Didn't realise he was power such a large setup. It generally does my mount, NUC computer, ASI1600mm cooler and a dew heater on main and guidescope all night. Not sure about  Skywatcher mounts, but my iOptron only really draws much current when it's slewing, when tracking the power draw drops way off. 

One the big advantages of LifePo4 over lead acid, is you can routinely draw down 95% of the capacity without ill effect, wheras a lead-acid is only really good for 50-60% of the quoted capacity. Also the voltage is much more stable throughout the delivery of that capacity. 

Edited July 21, 2021 by JimothyC

[Chefliam]

Thank you guys for your comments. I opted for something similar to what powerlord said and got a gel deep cycle battery. So with that I can discharge 80 percent of the battery without ill affect. 

[powerlord]

yeh you're no doubt right - its all worse case init. without measuring the load difficult to know.  No doubt lifepo4 is better - but also heck of a lot more expensive.

all the gear has built in regulators so voltage varying shouldn't be a problem I'd have thought. That said, my own self build uses lipos wired up at 26v, so I have a DC to DC regulator on that to give a clean 12v out anyway regardless of input voltage. You can't really do that with 12v battery though as there's not enough headroom.