More grist for the battle of the battery

Bill Daniels wrote:
Yes, in EXTREMELY rare occasions there can be a problem - usually a product
recall for a 'warm' device with a wiring problem. A shorted 7AH SLA won't
be pretty either. The safety issue is an old story that has been almost
completely overcome with new designs.

Most "Li-ion" batteries contain Li-polymer cells these days. Having
witnessed the spectacular results of incorrectly charging a 6 cell model
airplane Li-poly battery pack (luckily, outdoors on concrete), I can
easily see Tom's point. I've found a video (complete with kewl music),
the batteries we'd use would be about 5 or 10 times this size:

http://www.helihobby.com/videos/LithiumBattery.wmv

A battery pack produced by a reputable manufacturer with a matched
charger, and proper short circuit protection, is probably safe. But, if
people start lashing up Li-poly packs and chargers the way we do with
SLAs, sooner or later someone will regret it. NiMH is much safer when
mishandled, and still offers an improvement in size/capacity over SLA...

Marc

"Marc Ramsey" wrote in message
...
Bill Daniels wrote:
Yes, in EXTREMELY rare occasions there can be a problem - usually a
product
recall for a 'warm' device with a wiring problem. A shorted 7AH SLA
won't
be pretty either. The safety issue is an old story that has been almost
completely overcome with new designs.

Most "Li-ion" batteries contain Li-polymer cells these days. Having
witnessed the spectacular results of incorrectly charging a 6 cell model
airplane Li-poly battery pack (luckily, outdoors on concrete), I can
easily see Tom's point. I've found a video (complete with kewl music),
the batteries we'd use would be about 5 or 10 times this size:

http://www.helihobby.com/videos/LithiumBattery.wmv

A battery pack produced by a reputable manufacturer with a matched
charger, and proper short circuit protection, is probably safe. But, if
people start lashing up Li-poly packs and chargers the way we do with
SLAs, sooner or later someone will regret it. NiMH is much safer when
mishandled, and still offers an improvement in size/capacity over SLA...

Marc

I'm not suggesting lash-ups. A discrete 'brick' or 'slab' battery pack with
matched charger is what I am talking about.

I've read the warnings from the model airplane sites. The warnings seem to
all be about charging. I never charge a battery in the glider.

Bill Daniels

Bill Daniels wrote:
I'm not suggesting lash-ups. A discrete 'brick' or 'slab' battery pack with
matched charger is what I am talking about.

Well, that is what you would do, but you are more careful than most...

I've read the warnings from the model airplane sites. The warnings seem to
all be about charging. I never charge a battery in the glider.

Look more carefully, there are also warnings about explosions resulting
from short circuits. I've seen a similar video where they just shorted
the terminals together, and let the cell sit for a minute or two...

Marc