But for D cell, I am not aware of anything at even 8000mAh for the price. Otherwise would agree.
not really, unfortunately, i’m in nyc
I got some of the Blues 10K -they were all over the place for consistency and capacity, plus bad IR. Can’t recommend them.
I have not used the Premium D 10K but based on their capacity claim I’d avoid them.
AFAIK, they can ‘claim’ 10K, but none will HAVE 10K capacity. I used a number of NiXX D-cells over 12 years for dive lights. They got a good workout. The overrated stuff doesn’t hold up. The most you can actually hope for is ~ 8K, functionally, not very very low discharge.
I have some Tenergy Centura 5K C-cells. They do live up to the capacity claim, are being cycled about every 2 weeks, and have been consistent for ~ 6 months now. These may be OK cells.
I have some Tenergy Centura 9 volt NiMH batteries (7 cells per battery). I’ve only had them a couple of years, and use them in smoke detectors and low-drain stuff like that. So far, they seem to be holding up fine. Of course, I’ve only charged them a few times.
I wouldn’t call them “low self discharge”, which is what they claim. They’re certainly not in the same class as Eneloops, but Eneloop don’t come in 9v. But they will hold about 75% after 12 months idle, which is reasonable. Most of the self-discharge seems to happen within the first 3 months.
Overall, I don’t think I’d buy them again, unless I had a high-drain application that needed 9v cells. For low-drain stuff, 9v alkalines are better value. I just bought these ones to try out. They’ll need to last 10 years to make it worth it, and I doubt they will. Other 9v rechargeable batteries I’ve bought in the past lasted maybe 3 or 4 years before internal cells started giving out.
9v - Seems the smaller the cell, the less effective the LSD capability is. My AAA Eneloops aren’t in the same class as the AA.
i had nothing but good experience with tenergy D cells, AA otoh, not so much.
Yes, that’s true. I notice my AAA Eneloops self-discharge a little more quickly than AA Eneloops. And, the AAA’s also show about 0.01v less voltage out of a fresh box. Although the AAA’s claim to hold 70% charge after 10 years (same as the AA), I rather doubt they really will.
A 9 volt NiMH battery is composed of 7 AAAA sized cells. So, quite a bit smaller.
I’ve also found there’s little difference in the 9 volt self-discharge rates between Tenergy Centura’s low-self-discharge batteries, and an Energizer 9v which does not claim to have low-self-discharge. They probably both use the same generic AAAA cells inside.
Hello again all,
I decided to buy 4 of the blue Tenergy 10,000mAh batteries. They arrive this week.
I would like to test the batteries when they arrive. I could either do so with an iMax B6 RC battery charger….or….by applying a known current drain to the fully charged battery and see how long it takes to get discharged to it’s minimum voltage point.
Would a 1 amp load be the best? Somehow I can’t see a D cell providing 1 amp for 1 hour.
Well, I certainly hope your cells can provide 1 amp for 1 hour. Hopefully, close to 10 hours. Anyway, it depends on your application how many mAh’s your going to get. At 1 amp, you should probably get close to 10,000 mAh, so it’s a good current to use that balances maximum capacity vs. time.
Do you have a device that will drain at a constant current? Most devices (like regulated flashlights) probably drain at a constant power, which will raise the amps as the voltage drops over time. If your charger does discharge tests, use that.
Capacity testing is done at 1/5C, so 2A in this case….theoretically. If they can’t do an amp, they ain’t much of a D-cell.
Ok,
Thanks for the info.
I just received the 4 Tenergy Blue lable 10,000mAh D cell batteries today and tested their resistance values before ever charging or using them.
The values were 73, 73, 77 and 79
Are these acceptable values for these batteries?
What are “optimal” resistance values for these batteries new ?
Thanks
those numbers represent what? Ohms, mOhms? you really need to charge them and discharge them to see how they really perform under load. also nimh need few cycles before they start working at full capacity.
if thats milliohms and the test is accurate they are lousy.
my honda insight hybrid d cells are around 6mohm.and they are from 1998!
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.