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Batteries: to flatten or not to flatten

Subject: Batteries: to flatten or not to flatten
From: Vicki Powys <>
Date: Fri, 07 Jun 2002 13:57:16 +1000
Syd, Walt, Suzanne and all,

It's a bit of a trap to think that all batteries should be fully discharged
before recharging.  My Sony TCD D10 DAT takes a rechargeable 6V 1800 ah
NP-22H.  Nowhere in the documentation can I find the words "Ni-cad" but I
suppose it is?  Sony told me that for best battery life I should run the
batteries in the machine until the tape stopped running (inconvenient for
field use though).

So I made a discharging gadget with torch globes that discharged the batter=
y
at about the same rate that the DAT did.  My mistake was in running the
battery down DEAD FLAT before recharging.  My batteries soon died and could
not be revived.  Syd will know of Dave Stewart who also uses a Sony DAT.
Dave was HORRIFIED when I told him I ran my batteries right flat.  He said
you should never do that, and additionally you should measure the voltage i=
n
the batteries with a voltage meter, before recharging.

So I measured what the battery voltage was "when the tape stopped running" =
-
it was 5.5V.  Now when I'm discharging a part-used battery, I am careful to
take it down ONLY to 5.5V, before recharging.  I've had no battery problems
since then.=20

I can also recharge the batteries from a car cig-lighter and adapter, no
problems, engine not running, but like Walt I make sure I've got a good
heavy duty car battery before I go off on a long recording trip.

Vicki Powys
Australia


>
> Syd wrote:
>> I have a couple of rechargeables - "Nicad SC 1600 MAH 7.2V" labelled for
>> "Model Engines" bought from a hobby shop that sells them for radio
>> controlled model racing cars.  These I use externally with the Tascam.
>> Before recharging, I use an incandescent lamp to fully discharge them.
>>
>> Can anyone advise me whether it is likely to be OK to discharge the Tasc=
am's
>> rechargeable that way?
>
> Walt wrote:
> Should be ok. The test is how warm they get. If they are getting too
> warm to handle it's too fast a discharge rate. If they are not fast
> charge types then you should not even get them that warm.
>
> Marty wrote:
> I have used NiCd since 1962 and am familiar with their tricks, so I alway=
s
> leave them shorted with a 100 ohm resistor in storage then fully rapidly
> charge them before a field session.  But the NiMH were supposed to be so
> much better . . .
>
>
>














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