"Michael A. Terrell" wrote in message
...
David Brodbeck wrote:

Homer J Simpson wrote:
"David Brodbeck" wrote in message
t...

Had one explode on a travel trailer once, too. The battery was in a
plastic battery box on the front A-frame and had been on trickle
charge
for about three months. This was in the middle of winter. It threw
shrapnel a foot or two on either side.

Froze up?

Probably. To say that the battery chargers in RV power converters are
often poorly designed would be, perhaps, too kind.


All of the RV power converters I've had were nothing more than the
transformer, a pair of diodes and a power switch. The were intended to
run 12 VDC motors and lights, so they had no filter capacitors They
were not intended to charge a battery.


All of the 'off-vehicle' battery chargers that I've seen here in the UK, are
just a transformer, couple of diodes and a fuse and meter. I've never even
thought about them having filter caps. I don't actually see why they would
need them. The battery being charged represents a very low impedance cap
(electrically) anyway, doesn't it ? For this reason, all of the electronic
circuitry in modern cars, runs quite happily, with not a sign of a big cap
anywhere, including on the alternator output, to where the battery is glued
pretty much directly. I've also read somewhere I think, that charging with a
'pulsy' waveform is good for breaking down inter-plate sulphation. Could be
wrong on any of this - auto electrics not really my subject, but have owned
and maintained cars for more years than I care to remember.

Interesting about the exploding batteries. I'm sure that temperature must be
a big factor in this. I've been in Florida when there has been sustained
heat. The UK does get that hot, but only for a day or so at a time. I have
never had a car battery explode on me, and I can't think of ever having
heard of any friends or colleagues that have either. On the other hand, we
do get sustained periods of cold ( or at least we used to ) in the winter,
and I don't recall ever having heard of a battery freezing. Looking around
on the net, the freezing point of sulphuric acid, seems to be around
the -20C mark depending on concentration, so that might be why batteries
don't typically freeze here, but what happens when these things are in use
up in the north of Canada or wherever ? Do freeze inhibitors have to be
added ? Does a frozen battery cease to produce any current at all, and does
it recover if left to unfreeze ?

Arfa