Mixing 4AA's with 2 D's, is it safe?

Mixing 4AA\'s with 2 D\'s, is it safe?

Hey guy's i was thinking of using 4 AA's in a battery holder wired in series to produce 6 volts along with 2 D's to give me a total of 9 volts to power a 5 watt luxeon star in a 3D mag. But i'm wondering would it be safe to do with alkaline batteries? Would one set of batteries try to charge the other because of the voltage difference? /ubbthreads/images/graemlins/thinking.gif Any input would be appreciated!

Re: Mixing 4AA\'s with 2 D\'s, is it safe?

the danger is not in the poss of one batt to charge the other. It is just that D cells have a LOT more caps than AA cells, so you will prolly end up over_discharging your AA when it runs out of its juice and the D still kicking its own.
Danger: leakage, over discharge, *may* explode.

Re: Mixing 4AA\'s with 2 D\'s, is it safe?

Don't do it. Always try and match capacities. The possibility of reverse charging is there. The possibility of exploding is also there but shouldn't be too high because the AA cells at the end of their life exhibit high resistance, so the D cells shouldn't be able to discharge high currents in to them, which is the main cause of explosions. The final possibility, and this is the most likely to occur, is leakage, which means another ruined flashlight. Not worth it.

With a 3D mag and 4 AA to D holder, why not try to get 3 such holders, re-wire them so that you have 3V coming out of each, ie paired series-parallel configuration? You use 12 AA cells in 2 banks of 6. You get 9V, you get matched capacities, you get the benefits of a "Double barrel" configuration (shared current draw). And if you know where to look, you can get AA primaries in packs of 12 at a price-per-cell that is cheaper than buying packs of 4. In fact, could be cheaper than buying 4 AA plus 2 D.

And with this configuration, if you are short on cells, you only need to load up one bank.

Re: Mixing 4AA\'s with 2 D\'s, is it safe?

Hmm.. never thought of that config b4. I think i'll give it a shot and see how it goes. Thanks! /ubbthreads/images/graemlins/grin.gif

Re: Mixing 4AA\'s with 2 D\'s, is it safe?

I'm using 2 sets of 3 AA NiMh rechargeables with 2 dummy C cells to power a 5W in a M@g 3D. This configuration puts out 900mA. It's easy to hook 3 AA's in series, and they end up being snug in the barrel.

3 sets of 4 AA's with 6 cells in parallel will require more skill. One solution is to make 2 sticks which are 2 wide by 3 long, and hook them in parallel.