Velocity Reviews > How to calculate Energizer NiMH Charging Times

# How to calculate Energizer NiMH Charging Times

newsgroup2003@gmail.com
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 04-29-2006
I have the Energizer CHDC charger and I checked online and I cant
figure out how htye are calculating the charging times:
http://data.energizer.com/PDFs/chdc.pdf

I have a set of 2300 mAH Energizer batteries and I don't want to charge
them too long.

Anyone know what "math" Energizer seems to be using?

Thanks

Bob Salomon
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 04-29-2006
In article <(E-Mail Removed) .com>,
http://www.velocityreviews.com/forums/(E-Mail Removed) wrote:

> http://data.energizer.com/PDFs/chdc.pdf

2500 x 1.25/360 will get you close.

--

ASAAR
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 04-30-2006
On 29 Apr 2006 15:25:02 -0700, (E-Mail Removed) wrote:

> I have a set of 2300 mAH Energizer batteries and I don't want to charge
> them too long.
>
> Anyone know what "math" Energizer seems to be using?

For AAA cells, dividing the mAh rating by 100 will give you the
identical results shown in Energizer's charging time table. Their
math wasn't quite as precise for AA batteries, but if you divide the
mAh rating by 300 you'll get very close. So for your 2,300 mAh AA
cells, 2,300 / 300 == 7.7 hours.

But you might want to do yourself and your batteries a favor.
Get a better charger, one that stops when the batteries are fully
charged, and use this CHDC charger only as a backup. These are
called "Smart" chargers. The problem is that to calculate the
correct CHDC charge times you'll need to use a more complex formula
that will reduce the 7.7 hours based on two factors.

The first is that your battery's capacities will progressively
diminish as they age, so while using 2,300 when they're new will
work, a year from now they might have dropped to 1,900, and that
would mean that the batteries would now only need 6.3 hours to reach
a full charge. Keeping them in the charger for the full 7.7 hours
that new 2,300 mAh batteries need would only help to further shorten
their lives.

The second factor is the charge state of the batteries when you
put them in the charger. If they're fully discharged, then 7.7
hours would be an appropriate amount of time to leave them in the
charger. But you'll often be putting the batteries back in the
charger before they've been fully discharged. Just because a camera
or other device says that the batteries need to be recharged, that
doesn't mean that the batteries are fully discharged. Put them in
some other devices and they may continue operating for hours!

Another example. Suppose that you fully charge a set of batteries
and don't use them for a month or two. Due to self discharge, they
might have lost 1/2 of their charge. Put these back in the CHDC
charger and they'd only need 3 or 4 hours to reach a full charge, so
if you let them charge for 7.7 hours they'd be "overcooking" in the
charger for several hours, and that would also shorten their lives.

That's the bad news. The good news is that this is a very slow
charger, faster than a trickle charger but not by a lot. So the
batteries won't be severely overheated, and the amount of their life
that's lost by overcharging will probably not be a lot. Instead of
them lasting for 3 or 4 years, they might only last 2 or 3, and
after a couple of years, even if they're still performing fairly
well, you might want to replace them with a new set of 3,300 mAh
batteries.

Joseph Meehan
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 04-30-2006
(E-Mail Removed) wrote:
>I have the Energizer CHDC charger and I checked online and I cant
> figure out how htye are calculating the charging times:
> http://data.energizer.com/PDFs/chdc.pdf
>
> I have a set of 2300 mAH Energizer batteries and I don't want to
> charge them too long.
>
> Anyone know what "math" Energizer seems to be using?
>
> Thanks

Too many variables to have an accurate answer. Get a good charger and
don't worry.

--
Joseph Meehan

Dia duit

newsgroup2003@gmail.com
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Posts: n/a

 04-30-2006
Thanks everyone. What's a good charger that can keep up with
increasing capacity of the batteries? I recall the Energizer has (at
least in the past) capped the maximum mAh in their larger chargers.

Guest
Posts: n/a

 05-02-2006
Thanks everyone. What's a good charger that can keep up with
increasing capacity of the batteries? I recall the Energizer has (at
least in the past) capped the maximum mAh in their larger chargers?

Bob Salomon
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Posts: n/a

 05-02-2006
In article <dRC5g.105075\$P01.77643@pd7tw3no>, <(E-Mail Removed)>
wrote:

> Thanks everyone. What's a good charger that can keep up with
> increasing capacity of the batteries? I recall the Energizer has (at
> least in the past) capped the maximum mAh in their larger chargers?

The new Ansmann Energy 8 Pro is rated for AA NiMh up to 6400 mAh.

--

Thomas T. Veldhouse
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 05-02-2006
(E-Mail Removed) wrote:
> Thanks everyone. What's a good charger that can keep up with
> increasing capacity of the batteries? I recall the Energizer has (at
> least in the past) capped the maximum mAh in their larger chargers?

Maha C401FS .... it is an awesome little piece of equipment.

--
Thomas T. Veldhouse
Key Fingerprint: 2DB9 813F F510 82C2 E1AE 34D0 D69D 1EDC D5EC AED1

newsgroup2003@gmail.com
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Posts: n/a

 05-03-2006

Thanks again. Curious though, quick or rapid chargers are recommended.
I was under the impression it's better for the batteries to be slow
charged?

SMS
Guest
Posts: n/a

 05-03-2006
(E-Mail Removed) wrote:
> Thanks again. Curious though, quick or rapid chargers are recommended.
> I was under the impression it's better for the batteries to be slow
> charged?

The batteries will have a larger number of cycles if they aren't charged
with a very high current. Probably not worth worrying much about, but
the better chargers don't charge at a high rate.