/diy/ - Do It Yourself

for what purpose are you doing this?

>>1467234
those SLA batteries always put out like 14v

>>1467234

gotta love when some dumbfuck comes here asking what to do with something without providing a single detail on what they plan to use it for or what power needs they have or what they are powering with it or whatever

>>1467382
just assume that OP isn't getting enough mmmm out of her "C" batteries, so she wants to turbocharge.

>>1467234
>Do I need to get a BMU(battery management unit)?

Only if the device(s) are trying to draw more than the batteries can provide at one point or another. A drill or other motor can do that if they stall out. Or, an LED that will pop if you hook it up without a resistor. If the device doesn't do something like that then no.

>>1467248
>>1467382
Doesn't matter.

>>1467478
>Doesn't matter.
Only if the device(s) are trying to draw more than the batteries can provide at one point or another. A drill or other motor can do that if they stall out. Or, an LED that will pop if you hook it up without a resistor. If the device doesn't do something like that then no.
>says it doesn't matter what OP is using it for, and then goes to explain that it matters what he's using them for in regards to if he needs a BMU or not

>>1467234
>Do I need to get a BMU(battery management unit)?
I'm guessing not. All the 24v trucks I've seen just have the 2x12V batteries in series.
>How am I going to charge them?
The trucks just run 28v or so across the two batteries straight off the alternator. I know cause I ran some high draw 12V shit off one battery and the other one went up to about 20V and that's why I don't think they have any kind of electronics on them.

this is all the BMU the OP needs.

>>1467478
It matters because I don't want to help anon do something stupid and dangerous, asking how to charge two batteries in series ramps up the possibility of that

>>1467596
Fuck OP he should have googled it instead of coming to 4chan of all places for advice.

>>1467234
>Do I need to get a BMU(battery management unit)?
No. See >>1467534 for good advice on only safety component you actually need.
>How am I going to charge them?
Easy as pie, you need :
- big-ass Mains to 24V in the 25-50VA range.
- big-ass rectifier, 7A proof
- power resistor to limit charging current according to batteries datasheet.
- 6A ceramic fuse, temporised (as 7A continous current is very unlikely to happen beside batteries shorting circuit, so fuse can hold it a little of time before fusing). Note that 6A is a somewhat high value in a 7Ah charger application, consider lowering this value closer to 2 or 3*max charging current your batteries allow.

Not giving schematic, because obvious and fuck ms-paint.

/thread

sage goes in all fields

>>1467648

look out we got an oldfag here

Thanks for the replies. I honestly love this board.

>>1467234

Great news, each one of your 12v batteries is already 6 cells, in series. They're not going to know or care if you wire up another 6

>>1467234
That doesn't sound eco friendly, Anon.

>>1467382
you must be new to the internet in general