[volt-nuts] volt-nuts Digest, Vol 24, Issue 19

[Chuck Harris]

On the contrary, the manufacturers of NiCd cells consider 0.1C to be the highest
rate that can be applied indefinitely to a NiCd cell.  It is by definition the
trickle charge rate.  At the 0.1C rate, the cell will be fully charged in 14 to 16
hours.... The extra 50% allows for losses in the process.

If you charge at a C/40 rate, it will take 64 hours to fully charge your pack,
which is too long for most applications.

C/250 to C/300, which are the maximum indefinite term charge rates that modern
NiMH cells can take are ridiculously long.  If you want to "trickle" charge at
that rate, you will need a charger that can boost the cell up to full charge
at a higher rate, and then drop down to the C/250 to C/300 rate as a maintenance
charge rate.

-Chuck Harris

shalimr9 at gmail.com wrote:
> 0.1C is not trickle charge, it is the normal charge rate for 14 hours recharge
> time. Most NiCad and NiMH batteries will not like that too much as a trickle
> charge rate and will get and stay warm, at least those that I have had experience
> with. The batteries in the HP 8116 function generator were trickle charged at that
> rate and cause extensive damage when they get tired of it. I have had better luck
>
>
> Trickle charge would be 1/10th or 1/20th of that.
>
> Didier KO4BB