How long should I charge the batteries


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



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.


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



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.



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

Possibly Related Threads...
Thread Author Replies Views Last Post
  HP Prime: Long integers (continued) Helge Gabert 2 806 11-07-2013, 11:24 AM
Last Post: Helge Gabert
  HP Prime: Pass "Long" Integers to a Program Helge Gabert 6 1,350 11-03-2013, 01:12 PM
Last Post: Helge Gabert
  HP Prime polynomial long division bluesun08 13 1,975 10-30-2013, 03:29 AM
Last Post: parisse
  A very long HP-17BII equation Gerson W. Barbosa 22 3,052 04-19-2013, 12:37 AM
Last Post: Gerson W. Barbosa
  A long WP-34S night Siegfried (Austria) 10 1,657 04-16-2013, 02:11 AM
Last Post: Siegfried (Austria)
  HP-25 left on for a long, long, while Matt Agajanian 12 1,811 04-10-2013, 11:33 PM
Last Post: Steve Leibson
  RPL long vs. short names peacecalc 5 1,085 10-30-2012, 01:25 PM
Last Post: peacecalc
  HP41 Long term storage Steve Hunt 6 1,052 09-27-2012, 11:08 PM
Last Post: db (martinez, ca.)
  Long term storage question on 15C LE nick lidakis 4 894 09-12-2011, 01:35 AM
Last Post: Peter Murphy (Livermore)
  Too Long With No New Calculators! Jeff 12 1,634 05-13-2011, 10:28 AM
Last Post: Marcus von Cube, Germany

Forum Jump: