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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: Thu, 26 Oct 2000 11:19:16 +0200
Hi Paul.

I was right then, the cause of the ever glowing test LED is the larger
number of cells. This will render the test LED useless in your case...

You can do your own test by using a cheap voltmeter and measure the
two most left connectors on your battery pack (seen from behind, with
the lettering on the pack in normal reading position). The switch on
the bottom of the pack must be on single or sequence.
Your meter reading in volts will give you an idea about the charge
condition of the pack.

The nominal voltage of the cells is 1.2V each. After charging they
will be 1.35V or slightly more. I am not certain, but I think that the
test LED (designed for the original 12-cell pack) goes off at 1.1V per
cell and lower. You can consider this as a safe limit for 'empty'
cells in your case too. I must add that some battery firms advise to
recharge when the voltage has dropped below 1.0V when they are
considered completely empty.

This all means that you may find it necessary to recharge when
metering your 14 cell pack gives less than 15.4 volts (14 x 1.1) - but
of course _because_ you have used 14 instead of 12 cells you will have
some capacity left to go on shooting, maybe until the cells are giving
less than 1 volt each!

BTW, the motor drive was designed to work also with 12 alkalines (in
the hand grip). 12 alkalines, when new, will give a voltage of 19
volt.
A pack of 14 NiMH cells, fully charged, may give a voltage of 19.6
volts for s short while (1.4V per cell). If you leave the pack alone
for a few hours after charging, the voltage will go down to 18.9
(1.35V per cell). This will be completely safe. 
Probably 19.6 volt will do no damage either, as Olympus will have
taken a safety marge when designing the thing.
The low voltage limit for proper working of the motor drive is 12 volt
(lead battery operation).

Frank van Lindert.



On Wed, 25 Oct 2000 18:39:23 EDT, P2CON@xxxxxxx wrote:

>Hi Frank,
>
>I couldn't remember what I did when changing to NiMH so I looked up the FAQ 
>info I used for the conversion. I remember spliting one of the Varta 
>batteries to fold it around the tripod thing so I did use all 14 cells. It 
>has been almost two years since the conversion and as I said the motor has 
>not been used more than once or twice, and that was back at the time of the 
>conversion. I have periodically used the red light test to see if it needed 
>recharging, but never used the motor. Just now I put it on an OM-4 without 
>film and ran it through a couple of simulated rolls of film on single and 
>sequence and it purrs like a new motor, easily 5fps.
>
>Is there a way to check the need for a recharge without tearing it apart to 
>check individual cells? I also have a M15V with the original NiCads and it 
>loses the ability to light the red light after just a few days of sitting 
>idle. I really don't use the motors but would like to keep the power supplies 
>in shape should the need arise.
>
>Thanks, and regards, -- Paul Connet
>
><< 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? >>


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