Suzanne Gibson had written:
> I regularly read your groups as you have the best technical/tecnhique
> discussions and seem to be the only people who use the pro HHB Portadisc that
> I do.
I don't have a HHB, but I sure endorse the first part of Suzanne's comment.
And Paul Isaacs in answering Suzanne's questions on batteries has helped me
a lot.
Things start to fall into place. I use a Tascam DAT recorder, and the
advice in the manual is that the light on the charger changes from red to
green to indicate that about 30 minutes later you can stop charging. This
has annoyed me ever since I got the Tascam: I don't wish to sit watching
for the light to change so that I know when to start counting the extra 30
minutes! Why couldn't an apparently excellent piece of equipment indicate
when the 30 minutes is up.
Paul's advice to Suzanne was:
> The green charge led (on the front panel) is not an accurate indication of
> charge status of the batteries. It should be noted that re-chargeable
> batteries do not have a linear charge and discharge characteristic,
> therefore it is quite complex to calibrate battery level status for a wide
> range of AA battery types as they all have different characteristics. To
> include an accurate charge monitor status circuit for the Portadisc would
> have added quite considerably to the cost of the machine, so instead we
> decided to provide a basic system which would give an approximate indication
> of charge status for a wide range of batteries.
Seems likely much the same applies to Tascam. And leaving it to charge for
12 hours to ensure a full charge seems indicated.
Also Paul's advice:
> Another characteristic of NiMH re-chargeable batteries: if fully
> discharged and left for a period of time, the charge will partially recover
> as the ions migrate to the terminals - this will appear as a partial
> increase in the terminal voltage of the batteries which may cause the
> battery level indicator in the Portadisc to show a high percentage and fool
> the user into thinking that the batteries have sufficient charge. However
> this partial recovery has 'no depth' and thus once Portadisc is powered up
> the terminal voltage will drop quite quickly. e.g. on initial power up,
> might read 99%, then within several minutes of recording drop to 40%.
>
I've had just that happen with the Tascam and wondered what was going on,
fortunately only at home when editing tapes. Now I know.
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 Tascam's
rechargeable that way?
The hobby shop supplied a charger that works from a 12V car battery. Can I
safely use that to charge the Tascam battery - "NiCd BP-D1 (7.2V, 1.4 Ah)" ?
TIA
Thanks Paul for the so useful advice. And thanks Suzanne for asking.
Syd Curtis (in Brisbane, Australia)
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