$3 battery charger

3 Dollar lead acid Battery Charger
formatting link
Ace, WH2T

from one of the radio ngs.

Really neat.

Alternative subject line: Fuck Sears. :)

Reply to
Proctologically Violated©®
Loading thread data ...

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.

Reply to
anumber1

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.

Reply to
<HLS

In fact one 40 watt (117vac) bulb across the battery, connected to two 150 watt bulbs in parallel, would achieve this voltage division. Current isnt much, but for a couple of bucks????

Reply to
<HLS

And, you can heat up a cold garage, while yer at it! :) And read, whilst the battery is charging! :) :)

Reply to
Proctologically Violated©®

Yeah, this technology is cheap and dirty. For only a few bucks you can buy or put together a proper battery charger.

Reply to
<HLS

I think its main value is educational, IR drop, load vs. no load, current reg vs voltage reg, and all that. Elegant, in that regard.

Reply to
Proctologically Violated©®

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.