Thanks a lot FlashPilot. Yes C9000 does not use -dv/dt but I don’t think temperature is the major parameter for termination. I have two C9000s and will check whether they came with different power supplies. It is a great charger but you will need to press much more buttons to set up the charging. I totally forgot the rested voltage for the depleted cells. And I think C9000 does not take over-discharged batteries.
The Wizard One terminates at 1.47v, in addition to whatever other methods it might use.
It will reject batteries with an I.R. just over 2.04’v’.
Chris
How good or bad does a standard 4 bay lithium charger, charge aa’s? Most lithium chargers seem to charge nimh as well but do they do it as well as say a dedicated Maha charger?
BtW, the new Maha charger lineup seems cheaply made.
Not apples to apples exactly, but the Eneloop Lite sure beats the pants off of any others for cycle life.
I've honestly never had NiMH cells last a very long time but standard Eneloops have done the best and I have I think four of them that are going on about 7 years now, only about 30-40 cycles on them, maybe a bit more. Most of the earlier cells died way early for me, which I attribute to dumb chargers and the high self discharge at the time, plus some that I accidentally abused by allowing to discharge on the shelf rather than keeping them topped up. The better LSD cells from 2012-2013 forward do so much better and the last (2016-ish?) generation is such that there's hardly a good argument for alkalines anymore for almost anything except the most rudimentary lowest constant drain applications. I haven't tried the most recent Energizer NiMH or Duracell, but early ones from both pretty much sucked, and then Duracell got a leg up with some better cells (FDK I'm sure) but to me they still weren't as good as the Eneloop in either version, or the Imedion and Powerex...the older black Fujitsu were also pretty decent. I think on high cap cells I'm usually getting about 300-350 cycles from them on AA and seems like 200 or so on AAA (very rough estimates there...I don't keep track). Bottom line is it will still come down to cycle count with reasonable use/storage/charging current...and actually using them is much better than letting them sit idle at any state of charge although with the latest LSD that's much less of a concern.
I still tend to charge at 0.2C or 0.25C and once in awhile I'll give a zap with 0.5C or 1C depending on the cells. Rarely run a refresh cycle on them but my use case for almost all the cells doesn't seem to make that helpful. At this point having wasted a lot of time with those early cells that were dead, on their last legs, for whatever reason(s), I think it's a waste of time trying to save or rejuvenate them. Just pick up some new quality cells, feed and water them as prescribed, and recycle those old ones. That said, if you have cells in bad shape and maybe your smarter charger doesn't accept them, you can still get much longer life out of them (with the expected reduced capacity) by just using a dumb charger and trying to be smart about the time they spend in it. I don't know if very low voltage really damages them or not. The test standards call for 0.9 volts and that certainly doesn't seem to hurt anything (not positive but I assume that's an immediate measurement before resting bounceback). Maybe the combination of higher cycle count and low discharge is bad...? Doesn't sound like a good combo. I try to charge my NiMH that see appreciable current drain just as I do lithiums and not let them drain too far below that theoretical "empty" point...simplifies things if nothing else.
I still pull out the Maha for NiMH. It has more current settings than the C4-12 I otherwise use now. The combo chargers are usually fine but it doesn't hurt to check to see if HKJ has reviewed one you're interested in just to be sure it isn't a dud there. I would just suggest that you manually select your current instead of letting it pick an auto. Most do that by assessing the resistance/impedance but most are also notoriously inaccurate even if they are relatively consistent in reading it. Better to just use the C-rates wisely for what you're putting in the charger, imho. I think with the Maha, the CC/CV method is better long term for NiMH but it may not top up the voltage as high as -dV/dt that is used on most lithium chargers unless you happen to be charging cool cells in a chilly room. Also, pull them off the charger as soon as they're done...not all chargers do a long term trickle but you don't want that, and you don't want parasitic drain, either, which most do at least a little.
The new Maha seems like just a form change and some tweaks in the firmware. It'll be interesting to see if anyone gives it a solid test with teardown photos. They're well made and well designed, just limited. If Maha ever comes out with a do-all that handles lithiums I would almost buy one sight unseen.
I'd be very interested, but I would wait for a bunch of reviews.
It would also probably be above my budget.
If I am not wrong… Many soviet union submarines have NiCd batteries and they last 40 years with no problems.