Charging batteries
I often have problems charging my Sanyo NiCd 2400 cells starter pack: charging stops
at only 400mAh or so, and doing another cycle (discharge+charge again) does not help.
It seems that the voltage is fluctuating during charging.
This problem is solved by waiting longer between discharging and charging,
the simprop charger waits only a few minutes but if you wait 20 minutes or longer
this problem does not occur.
I dont have this problem with my Sanyo NiCd 1700 receiver battery. The differences
are that the receiver battery is usually discharged up to 50% while the starter pack
is rarely discharged further than 75% from full. Furthermore the starter pack
are racing cells, the receiver pack are normal cells.
And of course their
pattern of use is very different: the starter pack has to deliver short bursts
of up to 60 Amps, while the receiver battery seldom will deliver more than 2 Amps.
Another problem is when charging 4-cell NiMH batteries. When you charge below 0.8A, the charger stops charging when the voltage per battery goes past 1.5V. Unfortunately this happens quite soon. Typically, 1100mAh NiMH batteries pass the 1.5V already when 180mAh has been charged. The only way I know to avoid this is to charge at higher rates. However, with that rate my 1500mAh 4-pack gets way too hot when it is nearly full, so hot that I aborted the charging when I tested this. Apparently the voltage 'bump' at the end of the charge cycle is too low to detect. This is a known problem with NiMH's, but in general 0.5 to 1 C charging (so that the battery is filled up in 1 to 2 hours) is recommended so above values should be about right. Also I charged my NiMH receiver pack with this charger. Pack is 8 cell 1400mAh and I charged with 0.6A (which is on the low side, recommended is 700 to 1400 mA). Here the charger stopped charging correctly, but it seems that much less goes in as compared to dumb 10 hours at 150mAh charging: I have the impression that the voltage drops much quicker when charged with the simprop.