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[OM] Re: T-45 Battery?

Subject: [OM] Re: T-45 Battery?
From: vonstahl@xxxxxxxxxxxxxxx
Date: Tue, 21 Jul 1998 10:22:11 +0100
I have converted a T-45 battery charger from 110/120 V operation to 220/230
V operation once and in order to gain better understanding of how it worked
I reverse-engineered the construction. The charger is very simple indeed, no
intelligence at all. There is a transformer with a simple rectrifier in it,
the accumulators in the battery-pack is divided into 5 branches and each
branch is charged via a 56 ohm power resistor in series with a diode. 

The voltage drop over each resistor was about 4 V when I measured it with an
empty battery pack, indicating that the accumulators in the battery pack
would be charged with approximately 70 mA when empty and that this current
will slowly decrease as the battery pack gets more charged, however, the
current won´t drop very much when the battery pack is fully charged and it
is thus possibly to over-charge it if not paying attention to how long one
charges it.

There is also one transistor in the charger but its only purpose is to let
the LED go on when the charger is charging the battery-pack. When the
voltage-drop over all 56 ohm power resistors are higher than a certain level
the LED will go on. As there are diodes in series with each branch of the
accumulators in the battery pack, it will not be drained if left in the
charger when the power to the charger is turned off. 

Additionally it could be mentioned that the transformer in my particular
charger was not possible to strap to operate on any other voltage than
110/120 VAC. I had to replace the transformer with another one intended for
220/230 VAC operation. I have no idea of if the battery pack itself may
accomodate any electronics to better regulate the charging or eliminate any
risks for over-charging but from the outlook of the battery pack I highly
doubt that there are anything but accumulator-cells in it. 

I do not know if every T-45 battery charger is built exactly like mine,
perhaps Olympus might have changed the construction of it some time.

Boris von Stahl
Stockholm, Sweden 


At 98/07/20, Brian E. Robinson wrote:
>Is the T-45 battery supposed to be placed in the charger when not in
>use? Does the charger have a brain or will it keep charging the battery
>past the point of being charged?


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