On 11:36 17 Nov 2020, T i m said:

I was going through my collection of rechargeable batteries,
sorting the wheat from the chaff and because many seemed to be
pretty low on capacity / dead (or waiting for attempted
resurrection), I ordered some Amazon Basics 'Ready to use' NiMh
AA's (2000mAh) and AAA's (800mAh).

Now, on the AAA's it states the 'Standard charge is 80mA for 16
hours' and I presume by that they mean '... to get the best life /
cycles out of the cell'.

Now, the lowest current charger I have here is 200mA (apart from
my fully configurable one that goes down to 10mA but is only
single cell (for Ni-Mh per cell monitoring)) and I think the
charger they often sell with the cells is 375mA for AAA?

Surely that has been incorrectly taken from the standard advice to
slow charge a new battery for a long time (say 8 hours) to ensure
all cells reach max charge. Hard to see why it's applied to single
cells.

Now, we know one of the biggest killer of most rechargeable
battery chemistry's is heat so I'm very conscious of that with any
charging solution.

I 'get' that some people need their batteries re-charged asap (I
knew a wedding photographer who really cained his and treated his
high-capacity rechargeables as consumables) but for most of us,
wouldn't 'overnight' be ok [1]?

Does anyone know of a multi-cell / intelligent NiMh ( NiMH only
would be ok) charger that would take a minimum of 1 to 4 cells
(not in pairs as some torches and the like have 3 cells) and with
either 100mA charge option for AAA's or user setable down that low
please?

The default minimum charge rate of 200mA is fine for the 2000mAh
AA's and my Youshiko YC4000 does that very well. [2]

Cheers, T i m

[1] No battery should be left 'Unattended' whilst on charge but if
charging at a low rate (C/10 or greater etc) the risk should be
pretty low.

[2] It has a refresh option that repeatedly charges and discharges
the cell(s) until it hits the peak capacity and then reports it,
It take any mix of 4 x AA/AAA, NiCd/ NiMh, charges at 200
(default), 500, 700, or 1000mA (and discharges at 50% of each of
those values) and (each slot) any one of 4 programs (Charge,
Discharge, Refresh or Test).

That Youshiko YC4000 looks like a clone of the original La Crosse
BC-700, which is a nice charger.

NiMH has a faint "negative delta V" voltage drop at low charge
rates. If a charger uses that method (and no others) to determine
termination then the charger may miss it and overcharge the cell
causing vented gas that reduces capacity. For that reason some
people prefer to charge at no less than 0.5C (which is 400mA for the
AAAs).

There used to be a forum on charging at CandlePower which was quite
active. Here's a thread which goes into more detail than I have
time to read but seems to discuss this.

https://www.candlepowerforums.com/vb...178667-A-look-
at-slow-charging