I rang a few friends who are still involved with model care racing on a national basis ad they said they have not heard any the problems and they are normally in the know as one is linked to a battery manufacturer . the info for charging cells is from some one what has suppled cells in the uk for racing since the late 70s and was the main supplier of cells for a long time. Peter
Charge at 5 to 6.5 amps. Cutoff of 20mV for 6 cell pack. They should be quite warm at end of charge. (if not then set the mV up by 5mV until the pack fully charges with your charger). Always race with warm cells. Always charge on day from flat for max performance. You can let cool after a race and recharge when cool for a later race without any loss of performance. No need to discharge after 1st race. At end of day discharge batteries on an equaliser, even to flat (0V). But then , put a little charge back in, say 25%, before storing. The cells tend to discharge when nearly flat.
If you get a cell that has flat lined to 0.0volts and will not charge, it can be bump started back to life by flashing it with 12volts. Use a couple of wires and spark the +ve 12volt to the +ve of the cell.
NOTE: Do not precharge the night before and repeak on day of race. This may cause the vent to fail, and subsequent loss of fluid. If you repeak after a long wait, the peak voltage will remain flat and the cell may overcharge, especially if they were already fully charged. I suggest you only charge prior to the race, (this gives best performance) since the peak voltage will fold over correctly, and the charger will switch off. Also: do not temperature charge, since the cell temperature will vary considerably depending on the ambient temp, and the charge rate, and how much charge was already in the cell. This will result in either undercharging, or worse overcharging with subsequent venting, and reduced life . A temperature probe can be used as a safety cutoff.
It is not necessary to charge until the cells are absolutely maxed, unless you are critical for runtime with modified. In fact it is better to stop the charge at 90% since charging to absolute full may cause the cells to get too hot and develop a higher resistance.
It is best to race with cells that have just been charged and are warm. Cold cells will lose some performance. As will ones that have been standing around for an hour or so.
Normally a pack will peak in the low 9 volts at about 5 amps, and this will give maximum punch if you stop the charge rather than force the last few milliamps in, causing the voltage to rise as the cell develops more resistance.
The top numbers give the run time in seconds at the 5.0 amp discharge to 0.9 volts. The top voltage is the average over the 0300 seconds of discharge at 20 amps. The lower left large figure is the time tocharge, and will vary a lot depending on which cycle I am on and when the last charge was, so is only an indication that the pack charged. The small number on right is the internal resistance and should be as low as possible, but 10 is as low as feasible, and anything up to 15 is ok. The peak voltage of cell is the voltage at full charge and should be about 1.55. If too high then cell is poor or worn out. The peak will always go hand in hand with the internal resistance.
