thenewguy821 wrote:
I've always heard that continually charging at a High amperage wears out the batteries. The extra heat involved is enough to cut down the battery life. Maybe things have changed with the much higher Mah today's batteries can handle.
that is correct.... the higher the charge rate, the less cycles you will get out of your cells... this applies to any type of cells- ni-cad, ni-mh, li-ion, and li-polymer...
for any of the newer people out there- there are typically three reasons your cells get extremely hot during charging for ni-mh-
1. too high of a cut off voltage.... the higher the cut off voltage, the further past peak the packs are charged.... if you lower the cut off voltage like Paul did, this will reduce the amount of charge time past peak, and help reduce temps....
2. too high of a charge rate..... when the engineers design the cells initially, they are nearly always designed for a 1C charge... this applies to all types of cells... if you are running IB4200's, chances are nearly 100% that the sizes of the cathodes, anodes and chemical mixtures were calculated for 1C charge rates during the design stage... if you charge at a higher rate than this, the electrons are not very efficiently transferred, resulting in more heat, and more "wear" on the cell..... of course, a higher rate will typically yield in higher voltage under load during discharge, but at the cost of cell life...
3. cell damage.... if the internals get damaged in a pack, charge temps can skyrocket.... high spike, or continuous discharge load is probably the number one reason for major cell damage.... with overcharge perhaps being the second most common...
chances are very likely that if your packs are peaking at 140+ degrees that the pack is ruined.. and while it might actually work, it's very likely it's voltage under load during discharge is very poor (more so at higher discharge loads, 20-30C, less so at 1-5C)....
T.
I am surprised it didn't blow up!
