Block 9V rechargable failure due to lack of inter-cell balance, how often?

[Oiyuk Ti]

I used search function however didn't hit discussions matching addressed question.
In my life it is (since years) only digital multimeter for which I need block 9V battery. Other devices in household, car, hobby are satisfied with rechargeable cylindrical batteries AA, AAA, C-size.
Long time ago I purchased rechargeable block 9V as DMM doesn't seem to use low-energy mode, battery gets discharged very quickly. For its charging have got AccuPower charger without insights into battery health condition for user. So I am on search for a charger which provides me with more insights into block's actual health condition.

However I wonder if I shouldn't have following problem in my view too.
I wonder how often these rechargeables wear-out due to cells run out of balance before other aging factors kick in.
I wonder if for high quality block 9V batteries special yet additional measures are taken during production in order every block gets matched cells - at best possible level yet under economically reasonable effort.
I wonder for how long such a special additional measure during production can help as there is no guarantee cells do not run out of balance during usage.
Unfortunately I was not able to find block 9V rechargeables with port for cell balancing - I am not sure it is feasible to build such.
What are your opinions?

 

[HarryN]

The usual challenge with block type 9 volt rechargeable battery approaches is that they are usually made from 6 x NiMH, so really are 6 x 1.2 volts = 7.2 volts. A normal 9 volt alkaline battery is closer to 8.4 - 8.8 volt IIRC.

It might be possible to use 3.8 volt LiIon cells but that might be the upper end of the the DMM.

A pack made from 3.3 volt LiFe would be closer (or wired 3S2P)

It is quite fine detailed work to solder in the fine wires for balancing, but honestly I really wonder if that is the problem.

Other possible options for you:

1) Energizer Li 9 volt primary
https://www.batteryjunction.com/energizer-l522bp.html

2) Ultralife 9 volt primary
https://www.batteryjunction.com/ultralife-u9vl-bp-9v.html

3) Consider to replace the DMM with a newer model

The capabilities of the newer DMMs are quite impressive. I own 2 of these Extech DMM + clamp meters because I need to measure current a lot on wires without removing them.

http://www.extech.com/

I own 2 of them to cover the DC current ranges (one has a 4 amp and 80 amp setting, the other is higher)

http://www.extech.com/products/380950

I use it very often and change the battery so little that I just use standard AAA Li primary in it.