Battery charging

[AcidRainLiTE]

I have 6 Nimh AA 1.25V batteries and a 1 hour charger for them that charges 4 at a time. You put each battery in its own individual charging slot for it to charge. I want to permanently wire the 6 batteries in series for a total of 7.5V (I uploaded a diagram: http://hostitwith.us/files/373/battery.bmp ). How do I wire the charger to charge them when they are wired in series? Will it charge them to their full potential?

Thanks.

[timmeh87]

if you put 3 in parallel, then somehow hooked it to the contacts on the charger for one battery, it should work, and take 3 times as long. so youd have two groups of 3 connected to the two spots for a battery on the charger.

(or four if you have a "fancy" charger... but those do four at once or two groups of two? the point is that as many batterys you need to make a "charging" light go on, you need that many evenly distributed groups connected to the right contacts. they cant be odd numbers like 2 and 4, because the charger would either overcharge one group or not charge the other enough. or just charge into infinity.)

[AcidRainLiTE]

The only thing about wiring 2 groups of 3 in parallel is that all of the batteries need to be wired in series so i get a total 7.5 volts. 2 groups of 3 in parallel would only give me 3.75 volts.

[Sparkfist]

Not to hijack the thread but anyone know where I can find a universal Li-ion charger. I've got a 14.4v Li-ion battery and would like to make use of it, but I don't know if the RadioShack charger will work, it has a built in chip to I guess regulate charging.

It also looks like this http://images.amazon.com/images/P/B0000 ... ZZZZZ_.jpg

[timmeh87]

acid rain:
well you could buy a charger that can handle a 7.2v pack, or buld you own. its been discussed around here before, with plans. it dosent look that hard.

sparkfist:
http://www.batteryspace.com/index.asp?P ... rodID=1944

what you have is a laptop battery, right? it can easily handle 1.5A, and i wouldnt give it any less. (mine draws 2.3A when charging.) the one thats $5 less will take 3 times as long to charge it.

[AcidRainLiTE]

Ok, maybe I will build a charger. I just tested the batteries with my setup and they arn't working properly. They actually are providing 8.2V, is that too much for the psone and psone lcd? When I power it from the batteries, the backlight of the lcd turns on and then it starts flashing and the psone wont boot up. The setup isnt fried or anything because I tested it with the AC power adaptor and it still works fine. Any ideas?

[timmeh87]

perhaps 6 looks like 8 on your multimeter.

the voltage of 8.2 is confusing, since it corresponds to roughly (at least) seven cells in series. you dont even have seven cells do you? check it with a different multimeter.

[AcidRainLiTE]

There are only 6 batteries. A single battery is giving me 1.36V. Unfortunatly, I don't have another multimeter. Do you think it could be the extra voltage that's making the system not work?

[timmeh87]

nimh batteries??

your multimeter has got to be broken.

[AcidRainLiTE]

Yes, they are NiMh batteries (1.25V).
The multimeter measures a brand new akaline 9V at 9.57V. Does that sound correct?

[forrest]

Replace the battery that's inside your multimeter and measure the voltages again.

[superdeformed]

There's nothing wrong with the multimeter; most batteries (at full capacity) read higher than their specified voltage with no load on them.

[timmeh87]

ive never had a nimh battey read 1.4v, load or no load

[superdeformed]

Maybe it depends on the meter then. The 7.2V NiMH pack I have reads around 8.5V straight off the charger with no load on my digital meter.

[timmeh87]

well, measure the voltage under load, acidrain