[Milsurplus] Li Ion batteries

[Peter Gottlieb]

I disagree. Draw it out. Any series switching element must be rated for the string voltage. This is also a code requirement. 


Peter

> On Nov 4, 2017, at 2:47 PM, Bill Cromwell <wrcromwell at gmail.com> wrote:
> 
> An FET inside a 12 volt pack won't see or crae about and batteries in series above or below it.
> 
> 73,
> 
> Bill  KU8H
> 
>> On 11/04/2017 01:01 PM, Peter Gottlieb wrote:
>> Generally yes. During normal use everything is fine; it is during charge and at end of discharge where things can go wrong. You already mentioned separate charging so that’s off the table. At end of discharge packs have electronics which open up a FET to keep cells from getting too and being damaged or posing a hazard. The FETs may not be rated for the higher voltage of series packs and fail shorted, posing the hazard. See if you can find out what their max voltage is.
>> 
>> Also use iron phosphate cells, they are much safer.
>> 
>> 
>> Peter
>> 
>>> On Nov 4, 2017, at 12:43 PM, John Watkins via Milsurplus <milsurplus at mailman.qth.net> wrote:
>>> 
>>> Just wondering if you could series up 2 12 volt Li Ion batteries?  I need a 24 volt unit, but have seen 12 volt units complete with chargers and thought can I use those.  Would have to charge separately I think.  Any ideas?
>>> 
>>> Thanks,
>>> 
>>> John WD5ENU
>>> 
>>> Sent from my iPad
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> 
> -- 
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