# I have a 1300mah battery charger, will it charge 2500mah batteries?

I'm looking for cheap rechargeable digital camera batteries online, and 2500mah is the most abundant option. In fact, I haven't been able to find any 1300mah nimh batteries, nor 1600mah(which is what the now-dead ones are). I only have about 6 dollars to spare on this at the moment, as that's all I have in my paypal account, so there isn't much else I can do...

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8 years ago
The charger is rated in Volts and mA (voltage and flowrate) - not mAh - (total capacity) batteries are rated in voltage and total capacity, which is 'flow rate for x amount of time'.

The charger puts out 1300mA, so a 2500 mAh battery will take 2500mah/1300ma = 1.92 hours. (see how the units cancel out?)
8 years ago
Not sure I see what you are saying here. All things being equal, If they charge for a period below full charge, this unit will only half charge his batteries. If he waits twice as long they'll end up just as charged.
8 years ago
Think of batteries as buckets, they have a capacity.

Think of a charger as the hose filling the buckets.

The charger is rated in flowrate, how much it can put into the battery. Some chargers say 'quick 15 minute charger' but that's just extrapolated from the flowrate and expected size of the battery. Since you can't have a definitive battery size, that 15 minutes is bunk - it all comes down to flow rate and capacity.

Lemonie says below: Since not all battery(s/packs) are created equal voltage, each charger must match the voltage required by the given battery. Analogy again: Voltage is the pressure in the pipe required to raise the 'head' of water to the lip of the bucket. Not enough pressure, you can only fill the bucket partway.

Again, 'amps' being flowrate, not total quantity, you need another factor, TIME, to extrapolate capacity - flowrate times time. 1 amp for 1 hour is one amp-hour. 2 amps for 1 hour is 2 amp hours. 2 amps for 2 hours is 4 amp hours.

Back to our charger, the charger charges at 'x' speed (amps), a battery of 'y' capacity (amp hours), the charge time will be 'y' A(mp)H(ours) / 'x' A(mps) = 'z' H(ours)
chrispaccord (author)  frollard8 years ago
I'm still fuzzy-headed, and will be until the coffee kicks in, but I'm starting to get what you are saying. Thank you for explaining it with a few analogies, that helped out big time!
8 years ago
...so as I said, and DIY Dave said, left long enough it will charge. You are getting really hung up on Ah for some reason that I can't fathom.
8 years ago
its mislabeled units. "how far is 35 miles per hour?" "how fast is 12 pounds?" there is a fundamental difference between 'rates' such as speed or amperage, and 'totals' like volume or amp-hours. Long story short - you are correct, so long as the voltage is correct, it will eventually charge the battery.
Rainh2o8 years ago
If you have a real dead battery and it tries to pull more amperage then the charger can deliver, it may burn out unless its a constant current type charger.
lemonie8 years ago
If it'll put out more voltage than the batteries, it'll work. L
DIY Dave8 years ago
Yes, but it will take longer than usual.
steveastrouk8 years ago
It'll charge them eventually.