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-   -   Charger charging lead acid 12v battery? (https://www.rc-monster.com/forum/showthread.php?t=8695)

Superbasher 11.19.2007 01:58 PM

Charger charging lead acid 12v battery?
 
Hi guys,
I've been looking at an Ansmann xBase charger, and it says on the product description that I can use it to charge a 1-6cell PB (lead) battery, so would I be able to charge a 12 lead acid leisure battery to run the charger when I am at a bash or out for a few hours?
Thanks
Matt

BrianG 11.19.2007 02:33 PM

Most chargers specify the pb battery as 2v/cell. Since that charger will do 6 cells, that is 12v. So, it should work just fine.

Superbasher 11.19.2007 02:41 PM

Awesome, might have to keep an eye on it just to make sure (if i end up getting the battery)

BrianG 11.19.2007 02:49 PM

Of course, the battery you use to power the charger will have to have more Ah capacity than whatever battery you are charging, depending on the pack voltage too.

You can use a cheap modded PC power supply if AC is available, or use your car battery as long as you're not charging packs all day. :smile:

Superbasher 11.19.2007 02:58 PM

I forgot about that MAH thing! As the ansmann has a 5amp charge limit. I may end up not bothering, as most bashes I got to there is a power supply there.

BrianG 11.19.2007 04:23 PM

lol, that darn mAh thing! To make sure you have a 12v battery large enough, multiply your max pack voltage (4.2v/cell for lipos or ~1.4v/cell for NiMH) by the Ah rating, multiply that by 1.2 (for charger efficiency), then devide that by 12v to get the minimum Ah rating of the 12v battery. So, if charging a 4s 8Ah pack, you need a 12v battery Ah rating that is at least 12Ah.

Superbasher 11.19.2007 04:34 PM

So for my IB3800's it's
(~7.2 x 3.8) x 1.2 / 12 = 2.736ah - Sounds kinda low? Unless my math is wrong, which it could be.

BrianG 11.19.2007 06:01 PM

No, it's fine, sorta. I use 1.4v/cell for NiMHs since that is what they generally peak to, but the math itself looks good.

8.4v x 3.8A x 120% / 12v = 3.2Ah.

Let's say you were charging 6s lipos at 10A, you'd need:
25.2v x 10A x 120% / 12v = 25.2Ah

Superbasher 11.20.2007 01:18 PM

Now that a lot of power! Thankfully I am not thinking about going LiPo any time soon :lol:


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