Recent content by isaac_alaska

i ordered 80 turnigy 5ah 20C 6s packs from china, only 2 of them had cells that were out of balance and none of the cells were at zero volts or puffed. that was two years ago. one year ago i ordered 37 zippy flightmax 5.8ah 10s packs from usa warehouse, 2 of them arrived with one cell at zero...

on my electric snowmobile (running 250 volts and 250 amps, from an 8kwh pack of turnigy lipo) i have a latch circuit with a three-position automotive key. you turn the key from off to run and it connects all the low voltage stuff (12 volts). then clicking it once to "ignition" and then releasing...

i guess i will have to get on it then!

this looks like a dream-come-true active balancing chip. has anyone played with it yet?

Finally emailed me back, at least one cell is now at 0.0 volts... Th one that I made extremely easy to measure externally. Wonder if it will catch fire if it charged for an hour at 1/9th C. Guess we will find out. Maybe methods can build me a lvc circuit designed for one pack. To take up very...

haven't heard back in about 4 days now. hoping this one doesn't have to get written off as "lesson learned for next time" and have to scrap it. the least i can do is put the cells in my e-trike when they get back. i have it up to a sustained 45mph now, and it's scary fast at that speed. but it...

i'll keep that in mind and probably add it to the next version of the bms code...or at least change the cut offs a bit. i also need to add a hard cutoff (and a way to override it) so the contactors open if any cell drops below a certain voltage. that way no one can over discharge the pack unless...

it happened while they were using it but it wasn't under heavy load, the current was limited to 3C at the worst so it wasn't a huge spike...and the other cells being pretty good tells me that if there's a low cell it's probably not at zero. the mechanic says he was checking it when the cells...

sent instructions to the mechanic explaining how to turn the charger on without the bms, as well as instructions to charge it outside ;) the bms won't allow the charger to come on if it can't communicate with all the cells...and if one of the cells drops low enough then that cell can't...

on the order of one mA, with 45 Ah cells.

these are hobbyking RClipo, the 20-30C rated ones, in 6 cell packs. from the 25 (out of 48) cells that still show voltages on the bms, all 25 are between 2.78 and 3.36 volts. 2.78 is the lowest, most are still above 3 volts. try to make something idiot proof and the world will invent a...

i'm wondering what the absolute lowest voltage is on a lipo where it might still be an option to recharge it. The snowmachine with the battery pack in it is up in greenland, and the mechanic said that the bms isn't working....he sent me pics and for some reason one of the bms slave modules isn't...

You're right on all counts, the A123 are definitely a more bulky cell. Part of it depends on what numbers you go by though, at least from what i can see. because going by the numbers on the data sheet from their website, the A123 cells are only a little tiny bit bigger. i think the difference is...

thanks! that may be a good way to go about it, as it would reduce my series strings from 9 strings, to only 2. (it could be done in one string, and ideally it would be, but competition rules limit us to 300 volts nominal, 400 volts off the charger.) did a few calculations and the a123 batteries...

i really want to try to find a larger cell for next year, to reduce the number of parallel strings. probably going to run higher voltage, too, maybe 310 volts instead of 177. all in an effort to keep the wire count lower haha