mixing differnt voltage batteries?

[computers4life]

I know this isn't probably the best place to ask but i love the community here so here goes.

these are rechargable NiMH batteries.

I want to take 16 rechargeable AA batteries from the same manufacture. they are 3100 mAh at 1.2 V. I want to set 8 of them in series and 8 of them in parallel, giving one set at 9.6 V @ 3100 mAh and the other set at 1.2 V @ 24,800 mAh. i want to then run them in parallel hoping to give me 9.6 V @ 27,900 mAh. My question will this work or will i need to put some diodes or something in front of the high amp one to keep the high volt one from trying to charge it and damage it and will the diodes or whatever i use mess with the amps or volts or anything like that. My other question is will it be that amps at that voltage or will it be 9.6 V and 24800 or will this system not work at all and is there anything special i have to do to make it work?

Also can 9.6 V power a 12 V amp without much issue?

 

[i7Baby]

No - they'd have to be the same voltage to run them in parallel. Else they'll short out.

edit - oh yeah they might explode so be careful with what you're doing!

 

[computers4life]

is there a board i can use that takes in the power from them separately and puts them together making them run at that voltage and amperage without harming the batteries?

 

[i7Baby]

What voltage do you want out of them?

 

[Someone Somewhere]

No; that fundamentally isn't how batteries work.

If you think of it in terms of watt-hours, you'll see why this doesn't work.

 

[computers4life]

so there is no way i can get AA batteries to produce 9.6 V with at least 20,000 mAh? and i was hoping to get 9.6 V out of them

 

[Someone Somewhere]

Yes, you can - sets of 8 in parallel, and then put 8 of those sets in series. Total of 64 batteries.

I'd just get a car battery and a float charger.

 

[computers4life]

yea i see the issue here now. maybe i could us button batteries in series and then put a bunch i series

 

[Someone Somewhere]

Don't think that will work well either. They tend to be very low capacity.

Why can't you use a single large lead acid?

 

[computers4life]

I'm not trying to run a car and acid wont work. I'm trying to make a system of mine portable, i could always use D batteries but they are a bit big but i guess i will go with that unless you have a better option

 

[i7Baby]

For 9.6V from 1.2V batteries, 8 x 1.2 = 9.6V

So with 16 batteries, I'd put make 2 lots of batteries in series - 8 batteries each. Then I'd put those two lots together in parallel.

+battery-+battery-+battery-+ ....battery- - 8 of them in series

two lots
+battery-+battery-+battery-+ ....battery- - 8 of them in series (=9.6v)
< 9.6v |
+battery-+battery-+battery-+ ....battery- - 8 of them in series (=9.6v)

 

[computers4life]

that might work.

 

[i7Baby]

I do similar to make my own portable chargers - to run video cams foe longer. But I use Lithium batteries - more energy density.

 

[Someone Somewhere]

I'm not trying to run a car and acid wont work. I'm trying to make a system of mine portable, i could always use D batteries but they are a bit big but i guess i will go with that unless you have a better option

Do you know how much power you need out of them? Do you have a multimeter to measure the current you're using?

Also, does whatever you're driving have a low-voltage cutoff? Do you know where it's set?

Other option is a LiPo (or a couple in parallel), like this: http://www.hobbyking.com/hobbyking/store/__15521__Turnigy_5000mAh_4S1P_14_8v_20C_Hardcase_Pack.html