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Re: RE : [OM] M15V WITH MD2-now recharge time?

Subject: Re: RE : [OM] M15V WITH MD2-now recharge time?
From: Frank van Lindert <franklin@xxxxxxxxxx>
Date: Wed, 25 Oct 2000 23:23:59 +0200
Cc: P2CON@xxxxxxx
Hello Paul.

Do you really mean that you didn't recharge the NiMH's for half a
year, and that they still have hold their charge? Most remarkable...
Usually NiMH batteries empty themselves faster than NiCads.

Can it be that you have put in more cells (13 or 14) than the original
number of 12?  I know that other people have done so, to gain some
extra power from the batery, since it has been mentioned on the list.
It probably won't harm the motordrive with one or maybe even with two
extra cells, but the charge level can no longer be properly checked
with the LED test button. 
The LED will keep glowing red, even when the voltage _per cell_ has
dropped below the acceptable level. This is because there are now more
cells and the total voltage of the cells - even when needing a
recharge - is higher than the treshold set for the 12 old NiCad cells.

But if you did not put in more than the advised 12 cells, than you
have a remarkably good NiMH battery. I consider mine as empty after
4-6 weeks of self discharge without use, and I give them a full charge
after that period (when I think of it, of course - sometimes I just
forget...)

About the charge time: just behave like with the old NiCad battery,
with a correction for the new capacity. Roughly it is as follows:
The old NiCads had a capacity of about 125 mAh, and when empty they
needed charging during 5 hours with the charger giving a 35 mA
current. (5 x 35 = 175 mAh, compensating for loss during the charge
process).
When you have 150mAh cells, like I do, you will now need to charge
about 6 hours (6 x 35 = 210 mAh, allowing for the same proportional
loss during the charge process).
Olympus recommended for the NiCad not to exceed a charge time of 6
hours to prevent damage to the battery. I keep on the safe side, and
make sure that I never charge longer than 6 hours too.
I have also a battery which I fitted in the pre-NiMH era with fresh
NiCad cells, but with a 225 mAh capacity. These I charge for 9 hours.

You will have to make your own calculations, based upon the capacity
of the NiMH cells you used. If you don't know, 6 hours is a safe
charge time, IMHO.

Please let me know how many cells you used, and if it is 12 - then I
am very curious about the brand...

Frank van Lindert.




On Wed, 25 Oct 2000 14:35:51 EDT, P2CON@xxxxxxx wrote:

>Frank writes:
><< One of my older NiCads lasted for three rolls only. Its voltage after
> a charge read 16 volts (which is good) but it couldn't keep its
> charge... I have now replaced it with a 150mAh NiMH set, and it will
> probably do far more than 40 rolls. 
> Unfortunately (?) I will never know, because I recharge the battery
> after each shooting or even after a month of no use at all to keep it
> fit.
>  Frank van Lindert >>
>
>Frank, how long do you keep the NiMH M15V on the charger when you are 
>recharging simply because of no use?  I have an M15V that I refit with the 
>NiMH batteries about a year and a half ago and have not used it since. It 
>still lights the red light when the test button is pressed but I have no clue 
>how long it would last if put to service.
>
>Regards, Paul Connet
>
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