[time-nuts] Li-ion Battreries

[Brooke Clarke]

Hi Mark:

I agree.
The Vietnam era PRC-25 radio had a solid metal battery box that was water tight and used a BA-4386 battery with 
Magnesium chemistry.
http://www.prc68.com/I/PRC25.shtml#DCP
The problem was that as a normal part of its operation the battery releases hydrogen gas.  I know someone who has a scar 
on his head because when he opened the battery box the pressure shot it into his face.  No chemical explosion, just gas 
pressure.

The more modern radios that use the BA-5590 (BA is military speak for primary) Li-SO4 battery where the sulfur is 
compressed to make it a liquid have been known to explode if you try to charge them. This has resulted in a requirement 
for all battery boxes/spaces to allow for one cell to "vent" and not cause a problem.  This is even more important with 
the current BB-2590 (secondary/rechargeable) battery made up of a couple dozen 18650 Li cells.
http://www.prc68.com/I/BA5590.shtml#BB-2590Inside

PS This "5590" family of batteries are all form-fit-function interchangeable and are made up of two "12 Volt" batteries 
in one 5.0 x 4.4 x 2.45" box.  It's the standard battery in the military for non vehicle applications that need vehicle 
compatibility (ie either 12 or 24 volts).  The radio or host device can wire its plug so the battery appears as either a 
12 or 24 volt battery.  While the long in the tooth BA-5590 can only supply a couple of amps (internal fuse) the newer 
BB-2590 can supply maybe 35 Amps for a short time, I think to start a motor.

Rather that buying raw 18650 cells and connecting them getting a BB-2590 may be a better option.  There are numerous 
military chargers that can charge them as well as hobby grade chargers that work with Li cells.

There are some very low cost battery capacity testers on eBay:
http://www.prc68.com/I/BatTst.shtml#Resistor - good for 18650 cell testing

http://www.prc68.com/I/BatTst.shtml#EL - good for BB-2590 testing

-- 
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
The lesser of evils is still evil.

-------- Original Message --------
> They can be if you store them in something like an ammo box.   If they "go off" in the sealed box the pressure builds,  the reaction rate increases exponentially,  and voila... shrapnel time.   There's a video out there showing the results.
>
> Most people recommend storing them in nomex/kevlar "cell bags".   I keep mine, bagged,  in an unused/unplugged oven!  If one goes off,  hopefully the flames won't spread to the rest of the property and the hinged oven door allows pressure to escape.
>
> Hobby RC packs are one of the most dangerous type of rechargeable lithium cells out there... even from "reputable" sources and brands.   A local hobby shop twice had  brand new name brand packs sitting on the shelf go off.  A friend of mine had the same thing happen carrying a just purchased pack home in his car.
>
> --------------------
>
>> They aren't bombs, guys.  Use sensible precautions and get on with it
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