Does this Discharge Curve Look Right - NiMh

Hello,

I just bought a few 2500mAh D-cell and C-cell NiMh batteries from HF and was wondering if this discharge curve looks right? Normally I really like HF NiMh batteries.

But these never seem to charge up past about1.42v and as you can see, the discharge curve starts at 1.38v and after about an hour at 500mA drain, they're down to 1.24v

Battery Internal Resistance shows 65. This is a D cell. The other D cell shows an IR of 78.

I was expecting them to charge to about 1.5v and hold at at least 1.42 or so for a good while. These seem to fall to 1.35 or so very quickly after a full charge.

But after almost 6 hours, they're still at about 1.17v and showing 2900mAh capacity and still climbing.... (does that mean it's a pretty good battery, or somethings fishy?)

Usually d cells that small of mah have a smaller aa cell inside. You see this with the energizer 2500 mah d cells.

It is strange it won’t charge higher. Have you tried it in another charger? Sometimes I’ve had to restart a nihm that terminated early compared to the other cells and after I do that it takes the same charge as the other cells with it

It’s Harbor Freight, so who knows what you’re getting? And yes, I have their 900w Storm Cat genny and their free DMM. The former being a nice little unit, the latter not killing me while working on an outdoor duplex.

Honestly, you’re better off getting some Duracell Ion Core AAs and some Eneloop D adapters and going that route. At least for a couple/few years, you’ll have some quality stuff.

Either that, or pony up for some Tenergy Centuras/Premiums, some Maha Imedions, or the Ansmann D batteries, at albeit…a higher cost outlay.

Chris

Oh yeah. Forgot about that.
I do have some of those D Cell adapters that takes 3 AA’s so if I put 3 - 2500 AA’s I get a 7500mAh D Cell (I think)
Not sure why I ever bought them….at HF and $$$ burning a hole in my pocket :partying_face:

Agreed.
I do have a few high end D cells for my Convoy Big Boy Mega Flashlight haha!
I got these (I think) mainly to throw in my wife’s swiffer etc when she needs batts.
No way I’m gonna put my good batts in her toys!!!

After break in and a few cycles, I can tell that these DEFINITELY do not have an AA inside these D cells from Harbor Freight
After running them through break in and testing them with two good chargers I’m impressed.
The first cycle yielded 2900mAh and it’s been rising since. Now well over 4000mAh

This one is still about 500mAh left in this discharge cycle so it’ll reach 4,500mAh……at $3.50 per cell Not bad huh?
I think I’ll run over tomorrow and grab some more of this batch.

Comments?