# Thread: question on battery choices

1. ## question on battery choices

No such thing as a dumb question? Let's test that.

I have an older Marwi dual bar mount with a NiMH battery that no longer holds a charge. I pulled the battery apart and it looks like (10) 4/3A cells. I assume this to be a 12V setup. I'm thinking of replacing with a 13.2 for a little more light. Is it necessary to purchase a new charger too? The old one says 7.25 VDC/500mA on it, if that helps.

2. With a 7.2 V charger you're probably running a 6V system. Check with someone like batteryspace.com for a replacement battery.

3. I've had two Marwi systems over the years and they were both 6V with a 7.25V or 7.5V charger.

Pretty sure it is 6V

Cheers
Dave

4. ## ok, so if it's a 6V why are there 10 individual cells?

I poked around on batteryspace and all the 6V packs are 5 cells. As I said, mine is (10) 4/3A. The bulbs appear to be MR11 and do say 6V right on them. One's a 20W and one's a 15.

Did I get the light assembled on a Monday morning? Maybe Friday afternoon?

5. ## you've got a set wired in parallel

I poked around on batteryspace and all the 6V packs are 5 cells. As I said, mine is (10) 4/3A. The bulbs appear to be MR11 and do say 6V right on them. One's a 20W and one's a 15.

Did I get the light assembled on a Monday morning? Maybe Friday afternoon?
I think your set is pretty much standard for a lot of light/battery manufacturers. Five 1.2 V cells wired in series gives you 6 V. Two of these sets of five wired in parallel still gives you 6 V, but the effective capacity of the pack is the sum of each strand of 5 cells. So if one set of the 6 V cells has a capacity of 2.2 Ah (and you have an additional identical set), two of these in parallel would be 6 V at 4.4 Ah. This method is regularly used in battery packs, provided all cells involved are the same kind (voltage and capacity, and brand to be on the safe side) and in the same condition. Ideally, new. Problems seem to occur when mismatched batteries are used in this way. People probably do it, but its not the best or safest idea.

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