More grist for the battle of the battery

"Don Johnstone" wrote in
message ...
At 02:12 15 November 2005, Marc Ramsey wrote:

There is a cure for that, a fuse.

True, but there is no fuse that can protect from an internal short circuit.
Any type of battery can (at least rarely) do this. I have seen both lead acid
and NIMH batteries burn up this way. (It the case of the NIMH it was an irate
firefighter whose portable radio had nearly caught fire.) Naturally, the more
energy in the cell, the more heat, smoke, and (possibly) flames you can expect.
Lithium batteries have a very high energy density and the innards love to burn,
so internal shorts are a particular concern with them.

How great is the danger as a practical matter? That is the true question
here!

Vaughn

Vaughn wrote:

"Don Johnstone" wrote in
message ...


There is a cure for that, a fuse.

True, but there is no fuse that can protect from an internal short circuit.
Any type of battery can (at least rarely) do this. I have seen both lead acid
and NIMH batteries burn up this way. (It the case of the NIMH it was an irate
firefighter whose portable radio had nearly caught fire.) Naturally, the more
energy in the cell, the more heat, smoke, and (possibly) flames you can expect.
Lithium batteries have a very high energy density and the innards love to burn,
so internal shorts are a particular concern with them.

How great is the danger as a practical matter? That is the true question
here!

Indeed; however, there are a jillion laptop batteries in use, but very
few problems (I haven't heard of any, but there must be some). For
glider use, I'd want to know what the usable temperature range is (some
units specify only up to 95 deg. F), what altitude they can be used to
(haven't seen any specifications for that), and what safety features are
built into them (fuses, both for amps and overheating, might be
standard, and welcome, features, for example).


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Eric Greenwell
Washington State
USA