internal resistance changes depending on state of charge,
True.but not enough to cause that lousy reading. We need to know how the op got that reading.that function on analyzing chargers is notoriously unreliable.
These are generic cheap chinese cells rewrapped by tenergy.
So expect good and bad lots as well as inconsistency.
we do not know what range dmm was in, it could be 0,7, or 0,07.
the only way to really see how good batteries are is to cycle them.
i’d defiantly try to do that before claiming cells are garbage, maybe they are, than he could contact seller and ask for refund.
also what i found out the hard way, some tenergy cells (i had that happen with blue and white cells) they do not really work good with smart chargers when in series, i always use dumb charger and timer for them…
I got the reading off of a SkyRC B6 mini
The charge on the batteries was 1.25v on all 4 of them.
They have never been used yet (neither used, charged or discharged)
so that is not even dmm, it is a charger, that can cycle the cells, now i do not even phantom what those numbers are, but voltage seems healthy, charge\drain them few times, but do not discharged them below 1v per cell.
there is a chance they may terminate charge early, do few cycles, but it may take up to 10 to get them to perform as much as they can.
if they keep only getting 1\3-1\2 of the rated capacity before terminating charge, do not throw them away just yet, charge them with dumb charger and timer, (ac wall adapter with appropiate voltage output, (1,4-1,5v per cell, for charging) than discharge using your charger, and see how much mah they put out.
also blue cells are not lsd, so they will self discharge 1-2% a day. they are good if you charge them and use shorty after. for something on standby, and used as needed they may not be ideal.
It does say milliohms on the charger so that would be 77 milliohms etc.
I have lipo batteries also and they read like 5 - 7 milliohms so these batteries have a LOT more resistance than my Lipos apparently
But are NiMh batteries naturally more internally resistive or should they also be under 10 milliohms ?
Here’s a fantastic PDF document from Tenergy that lists all the specs and characteristics of this bettery.
Good NiMH AA cells will usually have internal resistance of around 50 milliohms. But D cells should be lower. It’s difficult to get an accurate measurement from a charger, so your cells may 77 milliohms or they may not. In any case, unless you’re running the cells hard, the internal resistance shouldn’t be a big deal.
— Tenergy Blue Label 10000mAh D cell —
Brand new, never cycled, not yet used.
Thanks for that. 50 milli-ohms is good? Ok, I thought others were saying it should be a lot less, like under 10 milli-ohms?
The other odd issue is that it seems no matter how long they stay on charge they will not charge above 1.43v and the charger never indicates the battery has reached peak charge. I just finally take it off the charger. I only charge at 1 amp or less so it’s not getting hot….just slightly warm.
I thought that 1.45 was peak charge for a NiMh cell. Is 1.43 “close enough” ?
But once OFF the charger, it begins to fall back down. It is back at 1.40v within 10 minutes. But the resistance now reads 58 milli-ohms.
How do I know for sure if I’ve left it on the charger long enough? 1amp for 10 hours?
Could this simply be because they are new and have not been “conditioned” yet?
By the way, thanks to everyone for your good help and advice. It’s appreciated 
50 milliohms is good for AA. But, yes, D cells should be quite a bit lower.
That doesn’t sound good. I have D cells, and they don’t charge up to as high a voltage as AA or AAA, but they will usually finish around 1.47v. And, yes, they should properly finish. If you’re only getting up to 1.43v and not detecting a -dV signal, then they may not be very good.
1 amp should be enough to charge D cells. I charge mine at 700mA, and they almost always give a proper -dV end of charge termination. Occasionally the charger will miss the end of charge signal, but that’s probably because 700mA isn’t very much to give a good signal. It’s less than 0.1C.
Even so, you should be charging them up higher than 1.43v.
Smaller cells, like AA and AAA Eneloops will often max out around 1.55v, especially if I charge them fast. D cells, like I said earlier, will be lower. But 1.43v isn’t high enough for a full charge.
That’s normal. Cells will drop off to 1.40v in about a day if left alone. You’re seeing it quicker because they never got a full charge.
1 amp for 16 hours (starting from fully drained) should give them a full charge and fully balance them. Don’t do that every time, but perhaps that will condition them so they’ll start charging normally after that. You can repeat it a couple of times if necessary.
Thank you VERY much for that detailed answer WalkIntoTheLight !
1A on a (supposedly) 10k A battery IS a conditioning charge (1/10C). Many/most smart chargers will not terminate much below 1/3C so I’m not surprised. Essentially the cell is full. It warms up as it gets full, stays cool when not yet full as long as the charge rate is not excessive.
These are not LSD cells, they will drop like that almost immediately. It will lose about 10% of it’s charge in the first 24 hours. This is normal for that type of cell.
The cells may do better after half dozen cycles. I’d put them to work. You may as well get some benefit while you are breaking them in. Using them won’t hurt anything, ABUSING them does.
I used my SkyRC B6 mini to discharge the battery and it reported 9,773 mAh to reach fullly discharged….0.9v
Not bad. Only 227mAh away from the claimed 10,000mAh rating and that was the very first cycle ever for this battery. I can live with 9,773 mAh
I’m now recharging it to see how it does. At the moment it’s at about 8,000mAh and 1.31v so looking good.