NiMh Battery Charger

Ben,
Yes, the battery is simply a capacitor; the charger puts a voltage potential across the poles of the battery until the current is zero and the voltage is constant. Your batteries will be fully charged.
The problem is, my friend, that all MY AA rechargable batteries are 2300mah! These new 2500s have a higher capacity/weight ratio, so now I must upgrade, and send all the 2300's to the landfill! Darn it Ben, you are evil.

No argument that the charger will recharge the batteries, but …
> The problem is, my friend, that all MY AA rechargable
> batteries are 2300mah! These new 2500s have a higher
> capacity/weight ratio, so now I must upgrade,
Ah … how about number of discharge/recharge cycles? If the 2300 mAh ones will recharge twice as often as the 2500 mAh ones, the wisdom may not be so good.
What about leakage rate? If the 2300 mAh ones will hold 50% capacity for a month, while the 2500 mAh ones will hold it only for a week, one wonders.

2700mAH are very common now. 2900mAH are the highest capacity currently available.

I’m currently using 2700mAH & 2900mAH NiMH AA batts. The 2900mAH have nearly the capacity of non-rechrg Li and alkaline AA batts. The flatter discharge curve (that’s why “cavers” use NiMH – IF NOT using NiCD which can provide even more current, but, generally, have lower capacity), even at higher current draws, of the NiMH batts generally give better performance, IME, in regulated headlamps. Initial brightness in non-regulated headlamps is less though, but, generally speaking, after 30-60 min, depending upon the application/headlamp, the NiMH appear brighter in non-regulated headlamps.

I have a couple of sophisticated chargers. I ALWAYS charge on “SOFT” charging mode, so it takes twice as long (~2hr).

These chargers have a “recovery” mode to attempt to recover deep discharged batts that are just shy of pole reversal.

They can also keep a maintenance charge going, but i don’t use them this way.

Here’s a link to Thomas Distributing from which i’ve purchased a fair amount of chargers and NiMH and Li batts (AAA, AA, C, CR123A).

Have fun w/the Tho. Dist. website. Read carefully about ALL of your options (there are several – both batts & chargers) b/f settling on a particular purchase.

I have a 30min Duracell charger and 4 2500mAH Duracell NiMH batts. I don’t like to charge those batts in that charger though. The idea of 30min (even though the charger actually has a fan that attempts to keep the batts cool, and really does a pretty fair job) for a recharge (even a high-current “pulse” recharge) just makes me think that it will shorten the batts’ life.

Generally after about 50-200 recharges, sometimes more (i’ve read up to 500 recharges for some batts) depending upon the particular batt, their capacity can be greatly diminished. Charging slower helps to prolong a batt’s life and storage capacity.

Periodic recharges of stored batts is recommended. Rechrg batts if discharged over a long period of time in a non-loaded (i.e., not discharged as part of using it) condition, can become very deeply discharged and many chargers won’t be able to recover them. Furthermore, rechrg batts can also, under the same circumstances just mentioned, can undergo “pole reversal” where the neg. & pos. terminals actually switch polarity. Before i knew this, i “lost” a lot of NiCd and NiMH batts from ignorance of this effect/phenomenon. Recovery of a “pole reversed” batt is generally not possible, though i’ve read of chargers which claims that it can do it. I personally recovered 2 out of 3 very deep discharged 2300mAH AA batts, but the third one had experienced pole reversal (based upon my DMM – digital multimeter) and my expensive microprocessor controlled charger couldn’t recover it.

Thanks, everyone!

'The problem is, my friend, that all MY AA rechargable batteries are 2300mah!'

So I wonder what everyone would think of me when they find out I have 1800mah NIMH AA's. Oh and I also have the old school Rayovac Renewal batteries…