[amsat-bb] Re: Lithium polymer batteries

[Amir K9CHP]

I've been using a LiPo battery for my FT-817. No problems recharging it with it's own charger, no heat above the ambient temperature. I take some precautions like not letting it discharge too low and using a flame proof container when charging but as I said no problems.

Sent from my iPod
Amir K9CHP

On Jun 24, 2010, at 10:51, Gregg Wonderly <w5ggw at cox.net> wrote:

> The most predominate problem is people using the wrong chargers for them.  They 
> think to themselves, "This is a rechargable battery, I can just use my expensive 
> NiMh/NiCd charger I already bought".  The problem is, of course, that the LiPo 
> cells have a completely different charging profile that is short-high and then 
> long-low, instead of the previous long-high, short-low of the other common cell 
> types.  Thus, people end up charging them for too long at High-C and boom, they 
> overheat and catch fire.
> 
> The Radio Controlled Model industry has already gone through large failure 
> occurrences with the charging problem, burning up multi-hundred dollar/hour 
> investments, catching houses on fire etc.
> 
> Most people now charge LiPo batteries outside the models, and use a fired-clay 
> pot or other heat tolerant container just to be safe.
> 
> Using the correct charger goes a long ways towards nearly eliminating all 
> problems.  You have to have a temperature monitor to really do it right, but any 
> production battery charging facility needs that.
> 
> Gregg Wonderly
> 
> whiteld at usa.net wrote:
>> Following up on the Lithium polymer battery mention I Googled them and was
>> disturbed to find:
>> 
>> -high fire risk. One seller offers flame retardant bags to put the cells in
>> while charging them... for $25
>> 
>> -(as warned) high prices especially considering the more-unique balanced
>> charger / discharger devices at ~$100 and up being required in addition to the
>> cells themselves
>> 
>> -a hazardous materials uplift for FedEx shipment ranging from $25-$45
>> depending on destination, on top of normal shipping rates
>> 
>> All of that tells me they're "not ready for prime time" though the current
>> capacity vs weight looks very promising.
>> 
>> I will wait and watch, hoping the technology matures into something safer and
>> less costly as time goes on. Likely it will, particularly the cheaper part,
>> though it appears some safety issues have to be addressed meaningfully.
>> 
>> Thanks for the mention. It is interesting. 
>> 
>> Lowell
>> K9LDW
>> 
>> 
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