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Post by admiralev on Oct 5, 2008 21:02:05 GMT 1
can a 5 amp charger be used with a 3 amp power supply? i figured charging would just take longer, but it would still work
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Post by cjg on Oct 6, 2008 0:24:08 GMT 1
If you overtax the power supply you can damage it. If you charged at less than 3 amps you might be ok. Charge at 5 amps might be iffy, depending on how close the voltage of the battery is to 12v, and how efficient your charger is. Pulling too much amps can also cause the power supply to give irregular voltage, which could cause problems with a peak charging operations.
Long and short, always use a power supply as large, or larger than the specs require.
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Post by flydiver on Oct 6, 2008 1:58:49 GMT 1
I have used lower rated power supplies. As long as you use the amps 'consumed' a reasonable level below the PS rating it might be OK.
Some chargers may complain and not work. Some cheap PS may burn up after awhile. Best bet is to suck up and get a decent power supply. It's not as flashy as a new plane or cool TX but without a good charging system you electric plane is.....nonfunctional.
fly
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Post by duck9191 on Oct 6, 2008 2:36:29 GMT 1
old computer power supplies make good battery charger power supplies if you have one laying around, its fairly simple if your ok with soldering.
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Post by admiralev on Oct 6, 2008 3:02:57 GMT 1
well, a charger im considering is 5A and 50W. it has an input voltage of 11-17 volts. i have a laptop charger that is 15 volts, 3 amps output. i think that would work?
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Post by flydiver on Oct 6, 2008 5:06:52 GMT 1
Unless you can find someone that has tried your exact experiment-well, you are the researcher.
Too many variable to call.
fly
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Post by duck9191 on Oct 6, 2008 7:18:57 GMT 1
that laptop psu is good for about 45 watts, to get 50 watts you would only need 3.3 amps. but unless you have some 5000mah batteries or like to keep you nimah's hot i dont think you would be pulling the full 5 amps, so you should be ok. are you gonna use it to charge the stock batterys?
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Post by admiralev on Oct 6, 2008 13:22:32 GMT 1
i could, but i really dont think im going to be needing the nimhs once i have lipos. they're only going to be 2200 mah lipos
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Post by mrmugen on Oct 6, 2008 13:44:00 GMT 1
Well your most likely going to charge those lipo's at 2.2 amps.....no more. So you be the judge. If you plan to charge more than one at a time then you will need a bigger one. Since you shouldn't leave lipo's unattended while charging you should be safe to do the research.
Kevin
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Post by admiralev on Oct 6, 2008 21:25:22 GMT 1
great thanks all im going to give it a try
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Post by cjg on Oct 7, 2008 1:04:45 GMT 1
Remember volts x amps = watts
so.. a 50watt powersupply at 15 volts is 50/12= 3.33 amps.
the same 50 watt powersupply at 12 volts is 50/12=4.15 amps
Mr Mugen is correct, if you are charging well below the rated amperage of the power supply you should be ok, unless you have a really inefficient charger!
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Post by duck9191 on Oct 7, 2008 1:27:22 GMT 1
good old ohms law lol.
laptop psu's make good power supplies for battery chargers because they are small and pretty power full. keep an eye out for one of the bigger ones. mine is rated at 6amps at 19.5 volts, I use it when I travle.
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