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Re: Batteries: to flatten or not to flatten

Subject: Re: Batteries: to flatten or not to flatten
From: Vicki Powys <>
Date: Sat, 08 Jun 2002 13:17:47 +1000
on 7/6/02 4:29 PM, Walter Knapp at  wrote:

> >
> Rechargable batteries should not be discharged below 1 volt per cell.
snip
>
> If it's a nicad pac, fully charge it, let it set a hour or so and
> measure it's voltage. Divide that by 1.35 volts/cell and it should give
> you a good idea how many cells are in it.

Walt and all,

Those maths work out just fine with my home-made discharging system.  My
fully charged battery is around 6.3 to 6.9 volts (depending on the age of
the battery).  Divided by 1.35 equals about 5, so maybe there's five cells
in the battery.  Don't discharge below 1 volt per cell?  No problem, if
there's 5 cells, that's 5 volts, and I'm discharging the battery only down
to 5.5 volts under load (or 5.9 unloaded).

(And to answer one of Syd Curtis's questions, I check the battery under loa=
d
when it is hooked up to the torch globes, just by touching the pins of the
voltage meter onto the battery terminals.)

If Sony ever stop making their DAT batteries, I'll make up a multi-cell
external battery, as described by Klas, and connect the terminals with a
dummy battery made from a wood block, as described some time ago by someone
on this list.

By the way, the Sony mains charger does the job in two hours, and the car
battery charger in one and a half hours.  There is no slow-charge option fo=
r
either.=20

Vicki Powys
Australia




>
>> Syd, Walt, Suzanne and all,
>>
>> It's a bit of a trap to think that all batteries should be fully dischar=
ged
>> 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?
>
>>> That supposition is correct.  It is a nickel-cadmium battery.> John Cam=
pbell

>>  Sony told me that for best battery life I should run the
>> batteries in the machine until the tape stopped running (inconvenient fo=
r
>> field use though).
>>
>> So I made a discharging gadget with torch globes that discharged the bat=
tery
>> 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 co=
uld
>> 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 yo=
u
>> should never do that, and additionally you should measure the voltage in=
 the
>> batteries with a voltage meter, before recharging.
>>
>> So I measured what the battery voltage was "when the tape stopped runnin=
g" -
>> 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 probl=
ems
>> 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

> Klas wrote:
> snip
> The solution: All high-current consuming aparatus, such as DAT's, MD's  a=
nd
> videos should - of course!! - run on single, regular 1,2 or 1,5 v cells.
> Then you could choose to run it on alkaline or NiCad's or whatever, and y=
ou
> could choose to charge each cell individually, and in 14 hours, and save
> yourselves a lot of money and trouble.

>>
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