The Museum of HP Calculators

HP Forum Archive 13

[ Return to Index | Top of Index ]

How long should I charge the batteries
Message #1 Posted by Arnaud Amiel on 5 Nov 2003, 1:33 p.m.

I have rebuilt my 45 battery pack and used 650mAh NiCad. I believe the original was 450mAh and had to be charged for 14h. Am I right in thinking I should charge mine for 20h.

Thanks for your input

Arnaud

      
Re: How long should I charge the batteries
Message #2 Posted by Bill (Smithville, NJ) on 5 Nov 2003, 1:49 p.m.,
in response to message #1 by Arnaud Amiel

I've always used the following for NiCds:

(1.5) times (battery capacity) divided by (charger capacity) = hours

Assuming the HP-45 charger is 50 ma, then

1.5 x 450 / 50 = 13.5 hours

1.5 x 650 / 50 = 19.5 hours

So, 20 hours should be about right.

      
Re: How long should I charge the batteries
Message #3 Posted by David Smith on 5 Nov 2003, 3:42 p.m.,
in response to message #1 by Arnaud Amiel

Most of the original HP packs were 600 maH. Some very early ones were 500.

      
Re: How long should I charge the batteries
Message #4 Posted by JasonG on 8 Nov 2003, 2:55 p.m.,
in response to message #1 by Arnaud Amiel

Aha!

Charge them all the way to the end, right from one end to the other. Anything else leads to a big bulge at one end and then it won't fit into the battery compartment.

Wooooooooha!

JasonG...

PS: Sorry for the frivolity...it's just a wild reaction against a very crap week...


[ Return to Index | Top of Index ]

Go back to the main exhibit hall