On Tuesday, October 16, 2012 12:40:54 PM UTC-5, Eric Greenwell wrote:
On 10/16/2012 8:06 AM, Evan Ludeman wrote:



Dear Unknown, Here is the battery I just ordered with the intent to

replace my 10Ah NiMH battery dedicated to the transponder. It is

ready for usage, no soldering except for the fuse and the

plug.http://www.hobbyking.com/hobbyking/s...dproduct=20645





This is a 8400mAh 4S cell with a 30C discharge rate, you can fry your

eggs on the discharge of that thing (over 200A).



I've fooled around with RC model batteries enough to know that I

will never put one of these in my full scale glider. In addition to

chemistry -- we'll presume for the moment that the HK LiFePO4

batteries are discharge & overcharge safe -- there's the issue of

short circuit protection *in* the battery pack. K2 puts all the

balance circuitry and such inside a sealed box where the connections

can be strain relieved, solidly anchored and protected in a way that

simply cannot be done in a hobby pack like this.



Electrically, I like your idea. But mechanically I think it needs

to be more robust.



THe HobbyKing pack is designed toys that don't have people in them. I'd

have more confidence in it if it had a battery management system built

into it and there was a datasheet listing the manufacturer, charging

requirements, cycle life, etc.



--

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to

email me)

Eric and Evan: you can't have it both ways, either the LiFePo chemistry is safe or it isn't. If you agree that there is no safety difference between the cheap HK cells and those you find in the referenced motorcycle batteries, the fact that HK is used in "toys" should not make a difference. Apropos toys, what do you think the average American Joe is calling our gliders? I will of course encase the HK battery and provide a 5A fuse inside that enclosure before trying it in my glider. I'll let you all know how it goes.