trickle charger

It would be much more reliable for you to buy a trickle charger that is UL or CSA approved. Use a 1 or 2 amp charger that is designed for motor cycle batteries with an auto cut-off. If you build one yourself, and there are defects, you can end up damaging the battery, and having a chance for a safety hazard.

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Greetings,

Jerry Greenberg GLG Technologies GLG ========================================= WebPage

Damien

You can use the 4A charger you have to trickle charge. Just add a 20 watt automotive tail lamp between the charger and battery. That will keep the current below 2 amps and if you want less, use two light bulbs in series.

-Bill

well

except

This is not a good idea. If you want a trickle charger that you can leave connected to your battery for extended periods of time, then it's best to get a charger that has two charge modes.. full charge and trickle. Or, have a trickle charger handy to connect when your 4A charger has done its job. The reason is that a lead-acid battery needs a constant voltage charge... one that limits the charging voltage to the "float level" of lead-acid batteries... 13.6 - 13.8 volts. The lamps will do nothing to limit the voltage to the battery after full charge has been reached. Fully charged batteries have a terminal voltage of 13.6 - 13.8 volts (the float level). After that state has been reached, more charging will result in boiling the electrolyte, outgassing, quickly damaging the battery. The current needed at a float charge rate is only a few milliamps... significantly less than the 2A suggested. It's the voltage that needs to be limited, not the current. When you have the correct float voltage applied, the battery will draw only the current it needs to stay fully charged. The lamps will serve to limit charging current when the battery is discharged, but your 4A charger really doesn't need the lamps.. it's self-limiting. Harbor Freight has a trickle charger in their online store that would do the job for you. It's their item # 42292-0VGA, $14.99 USD.

Add a resistor to one of the leads and continue to use your charger.

Peter

except

well

Google [motorcyle battery trickle charger schematic]

the

Yes, I could buy one, but where's the fun in that?! :-) Also, I'm in Australia so by the time you factor in exchange rates and postage, I'm looking at a good $50, not to mention a wait of at least several weeks. There are trickle chargers available here for around $65AUD, but it would be a lot more fun and satisfying to make one myself! I'll buy one eventually if I have to, but I'd rather make one if I can find a good design that is cheap to build.

Damien

I was assumming the charger shuts off at 13.6 volts. If not, he could use a LM317T voltage regulator and two resistors to set the voltage to 13.6. The current is limited to 1.5 amps but the input must be at least

See this link:

-Bill

I've also found circuits at:

and

Only problem with the first one is the scanned image of the schematic is a bit too fuzzy to read. Of course, the other problem is that I have no idea which would be the best to build - yours seems to be the simplest, and would certainly do what I want, but would there be any advantages to using one of the others? Or any particular reasons why I should _not_ use them?

And thanks to everyone else who has also posted replies - I've got a hell of a lot more to go on now than I did before!

Damien