Re: NiMH Chargers that I May Have Missed

Wayne <nospam@xxxxxxxxxxx> wrote:
In article <Tr8ji.628$vq6.351@xxxxxxxxxxxxxxxxxxxxxxx>, veldy71@xxxxxxxxx
says...

Of course, that is ludicrous. Especially if you program several cycles or do
a refresh analyze. There are already 2900mAh batteries available and such a
battery is already brushing up against the 4000mAh charging capacity limit.


I think you may be worrying about imagined problems instead of actual
problems. It does not seem to be any problem for AA cells, and of course, it
does not support larger cells. For example, the competitive Lacrosse BC-900
only allows 3000 mah. The Maha costs more, but runs circles around it in
several ways, doesnt seem to burn up for one. :)


3000 mAh charging capacity or 3000 mAh battery capacity? I say the latter.
To charge a battery, you need more charging capacity than there is battery
capacity due to heat losses. I believe those losses are in excess of 30%.
Assuming such, it is therefor not going to be possible to charge a battery
with greater than about 3000 mAh with a single charge cycle due to the fact
that it cuts off at 4000 mAh charging capacity.

I bought this charger as a future proof charger and since there are already
batteries at 2900mAh available [granted, they are a real stretch on capacity]
that threshold may be quickly exceeded.



"Question: Does the MH-C9000 battery charger have any limit on rechargeable
battery capacity ?

Answer: Answered by: William Chueh of Maha Energy : The micro controller can
support higher capacity batteries without any problem (however the capacity
calculation limit is 20,000mAh)."


20,000 mah was true then about the first two revisions, 0FAB01 or 0FAB02.
But the updated 0G0B01 version has been sold after March, and it cuts off at
4000 mah now. There were a few NiMh termination problems in the first two (at
lower charge rates), and Maha is replacing those with the newer one. The delta
V termination parameters were changed, and also this 4000 mah safety
termination was added. I see it as a good thing.


I see it as too low. Perhaps a better solution is something like 1.5x
capacity and have the user select capacity. I can assure you that if there
are ever 3200mAh NiMH batteries available and the charger hits the 4000mAh
charge limit ... this baby will be going back to Maha ... even three years
from now.

The manual also says 1 hour delay between discharge and recharge in the
Recycle mode, which was true then, but the 0G0B01 is two hours now. The
manual was only revised about the 0.5 to 1.0 C recommended charge rate.


I noticed that. The two hours were a surprise to me that prompted an email to
Thomas Distributing, but it isn't a real issue so I never followed up with
Maha.

--
Thomas T. Veldhouse

We have more to fear from the bungling of the incompetent than from the
machinations of the wicked.

.

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