Re: $3 battery charger

I think that you could circumvent a lot of the risks with this circuit by
a few simple changes.

A second lamp of different wattage could be used to create a voltage
divider circuit so that the voltage across the charger "terminals" (and
therefore the battery ) could never exceed 12-15 volts, so long as both
lamps were intact. There would be no high voltage, high current conditions.

This would help personal safety as much as anything else. To touch
the terminals of that unit, as designed and, without the battery in place
could be interesting.

You can limit the current to practically anything you wish, so the fear of
overcharging could be controlled.

DC would be low voltage half sine waves, not high voltage spikes,
so that would really not be a problem either.

We made a little "crackerbox" welder that functioned like this some years
ago. It worked fine, but without the voltage divider provision, it would
knock you for a loop if you touched the terminals and the machine was not
throwing an arc.



"anumber1" <anumber1*NOSPAM*@bigfoot.com> wrote in message
news:ZRhbi.26$hF1.11@xxxxxxxxxxxxxxx
Proctologically Violated©® wrote:
3 Dollar lead acid Battery Charger
http://www.alpharubicon.com/elect/3dollarbattggn.htm

Ace, WH2T

from one of the radio ngs.

Really neat.

Alternative subject line:
Fuck Sears.
:)
Yup, it'll work but beware of the caveats:

1.) Stand back when powering it up, the high voltage (much higher than
an ordinary transformer based battery charger) may/will cause an arc
internally to a battery that has a marginal/broken connection. If any
hydrogen gas is present inside the case, it will explode.

2.) It will easily overcharge a battery and the margin between a heavy
charge and damaged is very narrow. This cheap and dangerous method will
destroy a battery in minutes if you are not attentive enough to remove
it the instant your battery boils excessively or shows any other signs
of distress.

3.) I would bargain that if you used this device while the battery was
still in circuit in a modern automobile you would damage the vehicle's
computer due to the unregulated, high voltage DC spikes inherent of the
circuit.

This backwoods cobble may work but it is far from fool-proof and lacks
the most basic safety features.





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