HP97 battery pack rebuild

[Hans Brueggemann]

(02-11-2016 12:12 AM)rprosperi Wrote:  I agree with Den, it will work, but with these relatively large NiMH cells, it would probably take 3-4 DAYS to fully charge (assuming using the normal HP-97 charger.

The DC charge current into the battery pack is approx. Ich = 170 mA (measured on my HP-97) when using the standard HP-97 charger. for minimum overcharge of the battery pack with a given amp-hours of a single cell, you calculate the charging time as

Tch = 1.1 * Qcell / Ich (assuming a fully discharged pack!)

example: for the battery pack containing cells with 2400 mAh each, your time to fully charge the pack is
Tch = 1.1 * 2400 mAh / 170mA = 14.12 hours
(using HMS on your trusty HP-41C gives 14 hours, 7 minutes, 4 seconds)