Hyena said:
full-throttle said:
the volts were plummeting down - 42.. 41.. 40 then the LVC on the controller started to kick in.
Any thoughts guys?
If your voltage dropped suddenly in the order of 8 volts it sounds to me like more than one crook cell, either that or like cell_man suggested they were well out of balance and not full to start with.
I'd give the pack a full charge and then manually check each cell voltage with a multimeter. Yeah it's a bit tedious but i'll help you quickly diagnose what the problem is.
*Hyena says something under his breath about how good lipo is*
It could be.
Some cells were 3.6v and some were 3.3v when we measured them "charged" yesterday.
That could mean the 3.6v cells were topped off, and the 3.3v cells were at 99%.
Or it could mean that the 3.3v cells were at 50%....
There are pluses and minuses about the different chemistries.
Ask Kim how much fun Lipos can be...
Mine only lasted a year, but they were cheap.
They can catch fire if you overcharge, or over discharge - again this seems less of a risk these days.
(Although the Headway cell that Luke burned seemed to go pretty well, it won't burn if you abuse the cell, you have to blowtorch it).
My BMS screwed up due to a failed tab weld, and discharged a headway to 0v. It came back up to 2.5v overnight by itself, then I charged it as normal. They are pretty tough (although I did replace that cell). My brother's headways are over 2 years old now and still going strong, no noticeable degradation. My are 18 months old and same story, same capacity as new, same sag as new.
Lipos are made out of nasty stuff, LiFePO4 less so. Lipos are never going in cars, so you aren't helping that technology advance.
But lipos are lighter, and sag less (although my headways are good enough).
There's something wrong here, it's not normal.
I'd single cell charge all the cells. I have a single cell charger (but I'd need it back soon!!)
But, I am thinking about another bike, maybe RC, with lipos. It won't have enough energy to commute, it'd be just for fun.