Nimh charging with Bantam BC6

[Steve-O]

Is there a special way to charge Nimhs with the Bantam BC6?? I set it Nimh, entered the amps I wanted (I went with 1C, it was a 3300 pack so 3.3amp) and it reached 3300mah but didnt seem to want to stop charging it :eh?:. The pack was at 3550mah when I decided to turn it off, glad I did as I started to hear the venting sound cells make when over charged.



I charged a RC18T 7 Cell 1100mah pack at 1.1amp and it cut off at 1400mah


Should I have changed a setting somewhere? Should the charger not have detected the pack was full??? They hadn't been charged for a while since moving to Lipo.

Thanks

[D20MCK]

Sounds like you have your fall back (delta peak) voltage set to high. I can't remember off the top of my head what it should be but I'm sure someone will know.

[terry.sc]

When battery charging the process is fairly inefficient so to put 3300mah into a pack of cells could mean the charger has to pump out 4500mah to reach that amount in the cells. All a charger measures is what it is putting out, not what is actually in the cells.

The cell rating legally has be a minimum capacity, so a pack of 3300mah cells should have at least 3300mah of capacity to be able to be sold. The worst 3300mah cells you can buy must have at least 3300mah in them, but many top spec packs of 3300mah cells would have a capacity of 4000mah or more which is why they were more expensive.

The 3300mah cells sounds more like the cells were out of balance, especially if left for some time. If one cell has more charge than the rest it will be fully charged first, but the voltage drop on that one cell when charged won't be noticed by the charger which only sees the rising voltage from all the other cells. To prevent this you have to discharge the cells first to equalise them out, or if you haven't got a cell discharger then trickle charging them all first will do much the same.

[Steve-O]

thanks, I will try discharging the next pack first and see.

The Delta peak is set to default, which is apparently 7mv. I might lower it to 6 or 5 if the discharge option doesnt work first.

thanks

[bodgit]

Have a read of this
http://www.oople.com/forums/showpost.php?p=71162&postcount=1
it recommends
4. Use a maximum Delta-Peak setting of 3mV per cell (6-cell pack = 3mV x 6 =0.018V).