I don’t yet use lithium cells, but am imagining that there have been firmware-tweaks and hardware-improvements over time within each charger line - including for NiMH cells.
For example looking at “Opus” type series, see NiMH-only C2000 and C2400 (v2.2) models still sold, and the lithium+NiMH C3400 (v3.1) seems to be the most recently introduced.
After a final (alkaline-leaking) straw broke this camel’s back, moved to mostly NiMH - and have been building up a collection of batteries with which a fine, but apparently selective, charger (Sony BCG-34HRE) will no longer deign to associate. (Don’t know what quick test it runs to reject them.)
So figure an analyzing charger may be worth it…not only could try a repair-refresh type sequence to get some extra life from the old rejects, but also could match batteries by capacities, and follow changes in internal resistance over time for individual cells, etc.
Thanks for any comments or suggestions.
PS Have been looking mostly at Opus and Xtar 4 slot models, as something like SkyRC NC2200 or Powerex MH-C9000PRO may be overkill price-wise for my relatively low usage. (The SkyRC NC1500 is well within range, but noticed negative comments regarding things like overheating and overly aggressive trickle charging.)
I’m not sure somebody could really make a blanket statement on this, it’d depend on the specific chargers.
People generally seem to not like the xstar 4 slot chargers like the VC4 plus/vc4sL for NiMH.
I find they can be made to charge ok-ish once you finally figure out how they think and watch it constantly but they’re frustrating and they definitely aren’t great NiMH chargers.
For one, they don’t go right into the proper charging speed when you insert a battery. They do a weird thing where charging starts in the mid-high 300mA’s for 5 seconds before dropping to the low-mid 200’s, and it bounces around in there for the first 3 minutes any time any nimh battery is inserted. It won’t terminate charging during this stage no matter how full the battery is.
Then, when it does switch to the proper charging speed its programmed to not terminate charging in the first like 5-6 minutes, no matter how charged the battery is. UNLESS a battery you had inserted earlier happens to be done charging in that time frame, because when one battery is finished charging usually the charger decides the other batteries are finished charging too, whether they actually are or not.
So if those batteries weren’t actually finished charging now you need to manually reset them and now you need to wait another 3 minutes before they start actually charging again. Usually. Or sometimes it decides 1 battery needs 2 hours more than all the others even though it actually was finished at the same time.
And the storage feature is almost useless, since it stops as soon as the battery is 1.2V under load, and unless it just came off the charger in the last hour all NiMH batteries drop to 1.2V under load pretty much instantly. So there’s not really a way to discharge NiMH with it unless you go through a full capacity test and let it fully discharge
Point is it’s not great. You can make it work if you watch it like a hawk but it’s a huge pain. That doesn’t mean all li-ion/nimh chargers are bad though. It depends on which charger.
Couple of points to be aware of.
As you have figured out, with use internal resistance goes up in all NiMh. It ‘tends’ to stay down better/longer in higher quality NiMh.
You can get a sense of that from these test and associated graphs: Why AA Cycler? · AA Cycler
Over discharge, or overheating with charging or use will tend to shorten life and increase IR.
Even good cells like Eneloop will tend to have a shorter life-span in the higher capacities. The really high capacity NiMh (this is ignoring the bogus 2800+mAh junk) tend to go bad way faster.
Any/all of the chargers can get cranky when the IR gets quite high. I have a number of well respected multi-chemistry analyzing chargers and a couple dedicated NiMh chargers. It can be an issue with any of them.
To complicate that, the IR reading you get from slider-type charges is a bit flaky. They are still useful, especially to get a relative sense of health and to watch trends. Keep the battery contacts and sliders clean. Do multiple tests and throw out the outliers.
Thanks much for the kind welcomes (Milla J. hangs out here too?), and for the useful links and comments for me to think about.
I had originally considered just a dedicated digital IR meter, to follow changes or figure out which rejects might be saved, but they seemed priced similarly to getting an entire analyzing charger which included some implementation of that feature.
If of interest, had looked first at Amazon, where the non-automobile-specific battery internal resistance testers were (to me) unknown generic brands, ranging from this temptingly priced one (sporting a classic rotary selection knob), to more expensive, and implied to be more accurate, “4-line” “handmade”??? “AC” models (with accessories) like this one.
XTAR really dropped the ball with the VC4SL. Inconsistent NiMH charging and sometimes thinks a NiMH is Li-ion. I would advise using the Vapcell S4 V3.0, or maybe the Nitecore UMS2/4. Also consider dedicated NiMH smart chargers such as Panasonic BQ-CC65, Panasonic BQ-CC63, Panasonic BQ-CC55, Ikea Stenkol, or Maha Powerex MH-C980 Turbo.
From suggestions I got from this forum I went for this:
It’s a couple years old now and there are probably far more options. It’s main features, for me, is it will discharge from O.1A>2.6A, and do so with a constant draw. Most of the ‘slider type’ analyzing chargers the current changes as the voltage drops. Most of those won’t handle over 1.0A, and many won’t do better than 0.5A. It’s pretty affordable even adding a cradle to the mix:
I have 2 of them in the basement that have been working almost continuously for 2 weeks as I check out some old batteries.
It also does IR in a consistent and repeatable manner, much better than the chargers. My [analyzing chargers] have become more [just good] chargers less for analyzers. If I have any serious concerns about particular cells they go to the ZB206+.
Seems like a useful device. Less-specific web searches kept coming up with a ZB2L3 version (apparently without the IR display option), but that ZB206 is still on eBay.
Thanks to all. Appreciate the additional observations. The range of options - from bare PCBs to all-in-ones to dedicated testers - is fascinating!
…I’m thinking this forum is the right place to get an education.
