LiFePO4 Battery Ah Rating

[Mark Bennett]

I am going to try a LiFePO4 battery source for the KT, but since my build has yet to get to a running stage, I have no idea what Ah to use. Can someone please give an estimate for the energy (Ah) that would run the KT for an hour? I have the old style spur gear final drives and not the newer energy-efficient system.

Thanks,

Mark

[Stephen White]

Mark

Had I been going for a lead acid gel battery array, I'd have used two 12v 22ah batteries. Those have given me endurance week over the hour in my Pz III.

With LiFePO4, you can probably afford to undermatch the capacity as the discharge curve is much flatter. I've gone for a single 24v 20ah pack made by Tracer. See the thread on the subject.

All the best.

Stephen

[Fredrik Jorgensen]

Hi
you get much more punch out of the LiPo batteries, i myself use 2x 30 amp batteries
but be careful with the lipos
ive had 2 fires while charging my other radio controlled models, they BURN like hell with almost a explosive speed. Its a little scary but with a good pulse charger it would be fine.

so id look at 30 to 40 amps.

gives you a runtime of 1,5 to 2 hours

Regards
Fredrik

[Stephen White]

Mark

There seems to be a common confusion between LiPo and LiFePO4 - the latter, lithium iron, with a built in battery condition meter, is perfectly safe. Lithium Polymer on the other hand, can produce spectacular spontaneous disassembly if abused. If you've flown recently, you'll have seen the stack of prohibitions about flying with LiPo batteries but LiFePO4 are not mentioned. They're the way forward.

Best regards

Stephen

[Mark Bennett]

Hi Stephen,

Your original post is what got me started on the LiFePO4 path. After some research on LiFePO4 cells, I finally decided to go with two 20Ah (10C) battery packs. The cells and PCM are below:

http://www.batteryspace.com/lifepo4-pri ... d-dgr.aspx

http://www.batteryspace.com/pcmwithequi ... mited.aspx

They have a 40A discharge rate so it should be more than adequate for my purposes. I am currently designing the power distribution since I will create a hybrid of the standard 4 Armortek modules plus a separate microprocessor control network.

[Stephen White]

Mark, good on you. Sounds like a fine installation. It would be interesting to do a price and weight comparison with an equivalent lead acid gel array. Certainly the price you've got there is very favourable by comparison with what's available in UK. I bought a pre-assembled pack with a dedicated charger for about 20% higher cost but I'm either lazy or risk averse or both!

It would be good to see some photos once you're up and running.

Best regards

Stephen