Search found 70 matches

by isaac_alaska
May 27 2013 4:31pm
Forum: General Discussion
Topic: Hobbyking Customer Service.
Replies: 225
Views: 5248

Re: Is HobbyKing USA a piece of $#!7?? Two dead batteries

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 volts,...
by isaac_alaska
Mar 22 2013 1:01pm
Forum: Battery Technology
Topic: Zero-Draw, Solid State Contactor w/Precharge (Arduino)
Replies: 406
Views: 26376

Re: Zero-Draw, Solid State Contactor w/Precharge (Arduino)

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 it ...
by isaac_alaska
Mar 20 2013 1:57pm
Forum: Battery Technology
Topic: LTC3300-1 (High Efficiency Bidirectional Multicell Batter)
Replies: 13
Views: 2562

Re: LTC3300-1 (High Efficiency Bidirectional Multicell Bat

this looks like a dream-come-true active balancing chip. has anyone played with it yet?
by isaac_alaska
May 31 2012 3:49pm
Forum: Battery Technology
Topic: Absolute lowest lipo voltage?
Replies: 20
Views: 1262

Re: Absolute lowest lipo voltage?

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 little...
by isaac_alaska
May 27 2012 9:30am
Forum: Battery Technology
Topic: Absolute lowest lipo voltage?
Replies: 20
Views: 1262

Re: Absolute lowest lipo voltage?

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 will ...
by isaac_alaska
May 25 2012 6:24pm
Forum: Battery Technology
Topic: Absolute lowest lipo voltage?
Replies: 20
Views: 1262

Re: Absolute lowest lipo voltage?

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 the...
by isaac_alaska
May 23 2012 2:22pm
Forum: Battery Technology
Topic: Absolute lowest lipo voltage?
Replies: 20
Views: 1262

Re: Absolute lowest lipo voltage?

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 should ...
by isaac_alaska
May 23 2012 7:27am
Forum: Battery Technology
Topic: Absolute lowest lipo voltage?
Replies: 20
Views: 1262

Re: Absolute lowest lipo voltage?

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 communicate a...
by isaac_alaska
May 22 2012 8:13pm
Forum: Battery Technology
Topic: Absolute lowest lipo voltage?
Replies: 20
Views: 1262

Re: Absolute lowest lipo voltage?

on the order of one mA, with 45 Ah cells.
by isaac_alaska
May 22 2012 3:48pm
Forum: Battery Technology
Topic: Absolute lowest lipo voltage?
Replies: 20
Views: 1262

Re: Absolute lowest lipo voltage?

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 better idiot....
by isaac_alaska
May 22 2012 3:13pm
Forum: Battery Technology
Topic: Absolute lowest lipo voltage?
Replies: 20
Views: 1262

Absolute lowest lipo voltage?

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 doi...
by isaac_alaska
Mar 15 2012 4:00am
Forum: Battery Technology
Topic: 8 kWh Battery pack advice
Replies: 85
Views: 7320

Re: 8 kWh Battery pack advice

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 tha...
by isaac_alaska
Mar 14 2012 8:29pm
Forum: Battery Technology
Topic: 8 kWh Battery pack advice
Replies: 85
Views: 7320

Re: 8 kWh Battery pack advice

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 are ...
by isaac_alaska
Mar 14 2012 2:11pm
Forum: Battery Technology
Topic: 8 kWh Battery pack advice
Replies: 85
Views: 7320

Re: 8 kWh Battery pack advice

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
by isaac_alaska
Mar 14 2012 2:01pm
Forum: Battery Technology
Topic: 8 kWh Battery pack advice
Replies: 85
Views: 7320

Re: 8 kWh Battery pack advice

hey guys, little update here: we totally blew the competition away this year. first place in all but two of the nine categories. one of those was weight, which we lost by 30 lbs. but we had an 8kwh pack, and the lightest team only had 3.2kwh. we also "lost" the range event, because our motor decided...
by isaac_alaska
Jan 17 2012 9:00pm
Forum: E-Vehicles General Discussion
Topic: Bullet Connector Assembly Help
Replies: 15
Views: 2301

Re: Bullet Connector Assembly Help

yeah, the ones i got from epbuddy are a very tight fit also. i just drilled them out and they work great. another option is to use teflon wire instead of silicone though, it has much thinner insulation. (but lots tougher) i'm using some wire from http://www.bulkwire.com/wire-cable/ptfe-high-temperat...
by isaac_alaska
Jan 16 2012 4:59am
Forum: E-Vehicles General Discussion
Topic: Bullet Connector Assembly Help
Replies: 15
Views: 2301

Re: Bullet Connector Assembly Help

tin the wires before you strip them, it will save you a LOT of time. you have to strip and tin the wires anyway, you might as well reverse the order (tin, then strip) and save yourself a trip to the bench grinder (:
by isaac_alaska
Jan 14 2012 6:22am
Forum: E-Vehicles General Discussion
Topic: Bullet Connector Assembly Help
Replies: 15
Views: 2301

Re: Bullet Connector Assembly Help

i actually learned the secret of how to solder "noodle" wire. (the type with silicone insulation, and super fine strands.) first, get a nice sharp pair of wire cutters (something with scissor action, instead of dikes) and cut the end of the wire off so the wire and insulation are flush with each oth...
by isaac_alaska
Jan 12 2012 1:32pm
Forum: Battery Technology
Topic: Good and Reliable Bms
Replies: 17
Views: 1343

Re: Good and Reliable Bms

have got the peter perkins BMS almost completely set up. was a bit of a learning curve but it's actually coming together very nicely now, it is capable of monitoring voltage, current, temperature, speed, time, energy used, power being consumed, and total distance/ trip distance. very very nice syste...
by isaac_alaska
Jan 10 2012 8:55am
Forum: E-Vehicles General Discussion
Topic: Bullet Connector Assembly Help
Replies: 15
Views: 2301

Re: Bullet Connector Assembly Help

the 10awg from turnigy is copper, or at least the stuff i have. it's shiny silvery colored because it's pre-tinned. I was just doing some connectors on my wires, and was having problems so i did a search and found this thread. the connectors i'm using are the 4mm bullet connectors from epbuddy: http...
by isaac_alaska
Nov 15 2011 5:10am
Forum: Battery Technology
Topic: Perkins BMS
Replies: 5
Views: 905

Re: Perkins BMS

thanks Peter! i didn't really want to burden you with tons of questions as i know you're busy. but, i've ordered the pic programmer you linked to on BVS, as well as both bare pics and picaxe chips for the master. I figure if i can't get one of them working, maybe i can get the other working :) i'm c...
by isaac_alaska
Nov 14 2011 4:48am
Forum: Battery Technology
Topic: Can any1 recommend a headway US distributor
Replies: 11
Views: 774

Re: Can any1 recommend a headway US distributor

How many do you need, and what size? i have a few kwh of the 10 aH cells sitting on the shelf, don't have anything to use them in right now. need to keep a few spares for when the packs in the other snowmachine and the four-wheeler need new cells (packs weren't built very well so they sometimes get ...
by isaac_alaska
Nov 14 2011 4:43am
Forum: Battery Technology
Topic: Perkins BMS
Replies: 5
Views: 905

Re: Perkins BMS

Thanks for the link! Peter is actually on my Gmail chat bar, and has been great at answering specific questions, but i get the feeling he has other more important things to do than walk a noob through simple stuff :) on the other hand, i think i have the parts ordered that i need for getting started...
by isaac_alaska
Nov 09 2011 7:31am
Forum: Battery Technology
Topic: Perkins BMS
Replies: 5
Views: 905

Perkins BMS

Hey guys, I'm building the Peter Perkins BMS, i think i might have mentioned it earlier. But i have NO idea how to go about getting the code onto the chips. Does anyone have any experience with it? Peter has changed his design a few times, but i think the latest one uses bare pic chips instead of pi...