Do I need advanced charger or use DMM to know battery condition? (with pics!)

I have about 25 rechargeable AA and AAA NiMH batteries, mostly from Tenergy. Some are up to 5 years old, others maybe 1 to 2 years but I have lost track of which are new and which are old. They are charged using this v6280 smart charger which occasionally reports a bad cell and I discard it. I tend to use and recharge these cells about every 3 to 4 months in lights and other gadgets.


I also have 5 Li-Ion 18650 cells that are 2 to 4 years old (brands are Tenergy and KeepPower) which get used/recharged maybe once every 6 months with this charger.

Is a multimeter sufficient to determine the overall condition/capacity of these cells or do I need a more advanced charger to know when a cell is going bad? I want to avoid putting a recharged battery in a device if the battery isn’t going to last as long as long as a better cell.

It is possible to check the condition of a battery using only a dmm and a known resistance. But it takes a lot of work and time. It is much easier to use an analyzing charger.

Typically a battery will slowly loose capacity, each time it is used, and not suddenly fail. The exception is if you overcharge or discharge too much and the battery is heated. Or if the battery is stored discharged for a long time.

Thanks! What is a good yet budget analyzing charger? My v6280 model gets my cells warm/almost hot during charging which I think is not so good.

I have a MAHA C9000 for testing and charging my AA and AAA nimh-batteries. Not exactly budget, but very nice.

I have also sent for a Opus BT-C3100 V2.0 in a group buy here on this forum. Seems to be a good deal and a decent charger. Not perfect, but decent. It can analyze and charge both nimh and li-ion. And you can specify the charge current so the nimh batteries don’t get too warm.

I will mainly use it to monitor the capacity of my li-ion batteries, and to charge some 26650. I will most likely keep using my Pila IBC for charging 18650 and my MAHA C808M or the MAHA C9000 to charge nimh.

See this thread for more info on the Opus BT-C3100 V2.0: Opus BT-C3100 V2.0 "Dreamcharger" GROUP BUY Now @ $ 36. New coupon code - tatasal -(to close July 15) NOW CLOSED

I recommend the Accupower IQ-328 for a NiMH only charger/analyzer. They can be had for <$30 shipped from the US. I have a pair of them and they handle all my NiMH charging needs.

Note a “refresh” cycle can take upwards of 72 hours (thats at 350mA drain, 700mA charge rates) so if you want to refresh all your cells right away it’ll probably take close to a month to get threw your 25 cells. Last week I found 20 black top duracells in the recycling bin at home depot and I’m only on the second set of 4 but its worth it, they started at ~800-1000mAh capacity and ended up at >2.2Ah! That was the deal of the month!

I am not deterred by longer charge cycles. I like having enough cells that I have spares that can be charging.

Hmmm, the big Opus BT-C3100 thread has me concerned given the comments/issues/suspected issues. I am mostly concerned with my NiMH AA/AAAs so perhaps I will consider a cheaper Accupower IQ-328 or others if someone has a similar NiMH to consider…? I see the Accupower IQ-328 for $34 at Amazon and somebody named ‘rdana’ selling on eBay for $30.

Its good to have a Multi Meter :

Fully charge your batteries , note voltage ..

Test again the day after , and note voltage sag ..

If you store batteries , test again a few months latter and note voltage loss ..

I had a few AA that were 0.0v after 6 months ( Recycled )

A few others that were 0.9v , I recharged them ..

Some bad AA can come back after a few charges and discharges ( cycling )