GRiDPAD 1910 battery

From: Joe <rigdonj_at_intellistar.net>
Date: Wed Apr 11 18:29:18 2001

At 08:00 PM 4/11/01 +0100, you wrote:
>>
>> Bill,
>>
>> It will probably work since the charging voltage of the battery is
>> certainly higher than the 15 volts that you would get from using alkaline
>> or carbon-zinc batteries.
>
>Some machines use the battery as a shunt regulator -- that is to say they
>rely on the fact that the voltage across the battery pack, even when
>charged from a supply _capable_ of giving out a higher voltage, will be
>limited. This is one reason why many HP and TI calculators may be damaged
>if you connect the charger without a battery pack in place.

   Tony's right. You should have the battery in place when trying this.
You'd probably be safe leaving the battery out if you used a power supply
with the output set at a safe voltage (~ 1.2 to 1.5 Volts/cell) but don't
try this with a standard charger. They're seldom regulated and you could
fry something. Leaving the dead battery out and trying to run a HP 2xC
calcualtor on the charger alone is THE biggest cause of dead HP 2xC
caculators.


>
>For the original poster, if you insist on using normal primary batteries
>(1.5V each), I would start with only 8 of them in series, which should
>give you 12V. I would not put 10 in. I have seen devices made with a
>battery holder that will take 10 AA cells, and which are supplied with 2
>dummy batteries (plastic rods the size of a AA cell, with metal contacts
>at the end that are shorted togehter). If you use primary batteries you
>use 8, and the 2 dummy batteries to fill up the empty slots. If you use
>NiCds, you use 10 of them.
>
>I am told that some HP calculators (the Woodstock HP21 series, for
>example) can be damaged if you put primary batteries into the battery
>pack. Now, I know how the Woodstock PSU should work (it's a little
>transformer-based transistor oscillator with regulation taken from one of
>the outputs), and I don't see why it wouldn't regulate properly at 3V
>input rather than 2.4V input. But I certainly am not going to risk it :-)

  FWIW I don't recommend it but I've run Woodstocks at 3 VDC and even a
little above. A FULLY CHARGED GOOD NiCad will often put out up to 1.55
volts/cell when they're new therefore a new Woodstock battery pack can have
up to 3.1 VDC.

    Joe

>
>-tony
>
>
Received on Wed Apr 11 2001 - 18:29:18 BST