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Alkaline Battery Help

S

Schnoogledeck

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I want to supply my laser (lpc815) with alkaline batteries. They have 1.5 volts, but I want my laser to be able to still use them when the voltage from each battery drops to 1.2v, so I'll need 4 AA or AAA's (which is a lot, but, oh well). I'll be running it at ~400mA-450mA (with a heat sink, of course). My diode (lpc815 ~2.5v) + my driver with a silicon diode (~2.0v) = ~4.5 volts.

In order to increase the voltage of the batteries, I need to connect them in series, right? So, if I connected, say, two with a capacity of 1000mAh in series, I would get 3.0v with 1000mAh, no? If I connected two batteries with 1000mAh in parallel, they would still give me 1.5v, but with a capacity of 2000mAh, yes? I'm asking because this is what makes sense to me, but I have no idea if this is actually how this works or not.

I read somewhere on the 'net that AA's have ~2000mAh and AAA's have ~1000mAh. So, I should use 3 AA's and take out the silicon diode, then, which will give me much more battery life than the AAA's, right? (4 hours instead of 2)

~420mA isn't way too much current to get a good life out of an alkaline, is it? I don't want to use rechargeable NiMH or Lithium batteries, though...

Any help is greatly appreciated.

EDIT: maybe i just answered my own questions... Can someone verify, though? I don't know if what I'm sayin' is correct.
 
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Bionic-Badger

Bionic-Badger

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In theory that's correct, but in practice you don't want to put batteries in parallel unless they're "matched" (have the same draining characteristics). Why? If they're unmatched, you'll have a case where one battery drains faster than the other, causing a voltage difference between the two batteries. So the higher voltage battery will actually be "charging" the lower voltage one, which is bad for the batteries and could possibly burn out the connection between the two batteries, as it is essentially a short.

So don't do it unless you've got matched battery sets.

For extra mAh, a better solution is to just find a higher capacity single battery, like a C or D cell. For maintaining sufficient voltages as the battery depletes, you should use 1) more batteries or higher voltage batteries for your driver to have sufficient voltage even at their lowest voltage point, 2) use a boost-based driver that accepts low voltages (such as Dr. Lava's Lavadrives) so it works across the entire range.

Finally, you might look into some rechargeable batteries such as Eneloops, which are like Alkalines in their storage characteristics. I know you don't like rechargeables, but the NiMH batteries have better high-current characteristics than Alkalines. Alkalines are made for long shelf life. They'll still work fine even with high current drains, but they won't last as long, and they're not made for that.
 
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Krutz

Krutz

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exactly what bionic-badger says!

what driver do you want to use? most of the efficiency depends on that.

what host do you have in mind? a single, big battery often is the most effective solution!

manuel
 
D

Deleted member 8382

Guest
Bionic-Badger said:
In theory that's correct, but in practice you don't want to put batteries in parallel unless they're "matched" (have the same draining characteristics). Why? If they're unmatched, you'll have a case where one battery drains faster than the other, causing a voltage difference between the two batteries. So the higher voltage battery will actually be "charging" the lower voltage one, which is bad for the batteries and could possibly burn out the connection between the two batteries, as it is essentially a short.

So don't do it unless you've got matched battery sets.

For extra mAh, a better solution is to just find a higher capacity single battery, like a C or D cell. For maintaining sufficient voltages as the battery depletes, you should use 1) more batteries or higher voltage batteries for your driver to have sufficient voltage even at their lowest voltage point, 2) use a boost-based driver that accepts low voltages (such as Dr. Lava's Lavadrives) so it works across the entire range.

Finally, you might look into some rechargeable batteries such as Eneloops, which are like Alkalines in their storage characteristics. I know you don't like rechargeables, but the NiMH batteries have better high-current characteristics than Alkalines. Alkalines are made for long shelf life. They'll still work fine even with high current drains, but they won't last as long, and they're not made for that.
Click to expand...
excellent explanation, some rep on your way :)
 
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