Hyena
10 GW
I'm almost reluctant to post these photos as I think lipo is the greatest battery chemistry around and that anyone too scared to use it are a bunch of sissies and deserve bad backs or poor handling from lugging around heavier chemistries
However this does serve as a reminder of the do's and don't of lipo. This is a long post with alot of probably excess details, but think of it as case study
The back story is, I built a kit for a guy last year with an 18S lipo pack. I set up my batteries with pretty foolproof anderson connector blocks for parallel bulk charging in banks of 6S (with manual balancing when occasionally required) At worst if a cell does go bad it's potentially going to overcharge only one parallel group. And even then with the voltage set conservatively to 4.16v/cell things have to go along way south before the others end up dangerously overcharged.
So around 6 months later I got an email from the guy with the following:
Fortunately the fire was fairly well contained butI felt pretty bad for the guy and wondered how things went so wrong so quickly.
My first thought was that something must have gone wrong with the charger and a failed component ended up passing though a higher voltage to the battery - maybe even 240v AC some how.
Then I got some more info about the events leading up to it and quickly realised the problem. Just like in the early days of poor quality RC lipo packs, many of the fires were caused by using the wrong chargers. And this is what happened here, in a big way.
The first issue, which I doubt is actually related to the fire:
But what really caused the problem is what came next:
Each cell would have exceeded 4.5v. Ouch. Lucky it didn't blow up there and then. This would have damaged all the cells, greatly reducing their life. I imagine they were quite puffy after this but he probably didn't notice inside the enclosure he'd built. He continued to ride it for another 3 weeks during which time I imagine the cells rapidly deteriorated from being heavily overcharged.
So, in summary the problems that lead to this failure.
* Used wrong charger
* Way overcharged cells with high voltage
* Ignored LVC and over discharged cells
* Ignored continued under voltage cell warning after charging, then left to charge unattended.
So basically everything you're NOT supposed to do with lipo!
1 simple email to me when looking for a second charger would have prevented all these problems.
But the other issue was ignoring the HVC and LVC buzzers.
Yes, you could argue a LVC that hard cut the throttle would have prevented over discharge and a more expensive / complex charger would have prevented over charge - but basic LVC buzzers are perfectly adequate if you actually heed their warnings, which I instruct people they must do. And with an ounce of common sense, these are the cheapest and easiest solution. If you think this leaves too much to chance remember that for nearly 100 years cars have used oil or check engine warning lights and beepers and everyone knows that if that comes on then you have to stop the engine or risk damaging it (in this case the battery)
So yeah I just thought I'd share this story, not to scare away the noobs or further propogate unsubstantiated hysteria around lipo use, but to serve as a reminder to follow the basic rules and don't be a stooge.
However this does serve as a reminder of the do's and don't of lipo. This is a long post with alot of probably excess details, but think of it as case study
The back story is, I built a kit for a guy last year with an 18S lipo pack. I set up my batteries with pretty foolproof anderson connector blocks for parallel bulk charging in banks of 6S (with manual balancing when occasionally required) At worst if a cell does go bad it's potentially going to overcharge only one parallel group. And even then with the voltage set conservatively to 4.16v/cell things have to go along way south before the others end up dangerously overcharged.
So around 6 months later I got an email from the guy with the following:
Left it on charge the other night after work and was woken by panicking neighbours reporting a loud popping sound.
Opened the garage to find flames up to the roof! Luckily we extinguished it in time to cause only minimal damage to the house and a layer of black
soot over my brother's car is all that it sustained... not so lucky for my toasted bike.
Fortunately the fire was fairly well contained butI felt pretty bad for the guy and wondered how things went so wrong so quickly.
My first thought was that something must have gone wrong with the charger and a failed component ended up passing though a higher voltage to the battery - maybe even 240v AC some how.
Then I got some more info about the events leading up to it and quickly realised the problem. Just like in the early days of poor quality RC lipo packs, many of the fires were caused by using the wrong chargers. And this is what happened here, in a big way.
The first issue, which I doubt is actually related to the fire:
In my rush to attach my half finished enclosure to the frame at midnight so that I can ride to work at 6am, a single wire found its way wedged between a pack and the frame. This stripped the wire and as I had my key switch temporarily just hanging, when I hit a bump the bolts bumped against the frame causing it to arc. Bright flash and loss of power, and nice weld spot on the frame and lovely smell After pulling up and inspecting, disconnecting and reconnecting the battery... taping up with electrical tape... I continued as I still needed to get to work. Was working ok but not as much power. charged up at work ok and was ok on the way home. Checked it out and discovered the above mentioned stripped wire, mended, balanced battery, sorted enclosure and mounted switch. Had no more troubles with it using it daily (about 2 weeks before fire).
But what really caused the problem is what came next:
ACK - wrong charger used, WAY over voltage.I bought a 600W charger, same brand as the one you supplied. It arrived with just the double red and black connector on it where I needed the six pole plug. After trying a few places (including Jaycar) no one had ever seen these types of connectors. I realised there was a double connector on the bike that connects the controller to the isolator switch. So I figured I'd give it a go charging that way (disconnecting controller and replacing with charger). It seemed to work ok except the charger did not automatically cut out when charging was complete. When I finally pulled it off and powered up the bike the battery was reading 81.6V! Ooops...At least it took off like a rocket for a bit! I didn't use that charger again and had no noticeable problems. (I think about 3 weeks before fire)
Each cell would have exceeded 4.5v. Ouch. Lucky it didn't blow up there and then. This would have damaged all the cells, greatly reducing their life. I imagine they were quite puffy after this but he probably didn't notice inside the enclosure he'd built. He continued to ride it for another 3 weeks during which time I imagine the cells rapidly deteriorated from being heavily overcharged.
I got home from work riding pretty flat out and battery warning was beeping and flashing at me. (which he ignored apparently, driving the cells probably well below 3v) I wanted to go out and get some food so I decided to give the fast charger another go and hooked it up again. Charging with that annoying beeping still going. After about 30 - 40mins I went out and checked it and the beeping was still going. (these cells obviously failed to recover above 3v after high current charging so they're officially dead by this stage) I hooked up the battery and it still showed 66V (multiple cells must have been well under voltage and presumably others were taking some of the charge) . I hooked up the charger and decided to raid the cupboard and fridge for scraps and went to bed. Next thing I know the neighbours are knocking on the door and well you know the rest.(I'm guessing the cells that DID take a charge would have ended up over 5v/cell based on the charge voltage last time when the cells were still good)
So, in summary the problems that lead to this failure.
* Used wrong charger
* Way overcharged cells with high voltage
* Ignored LVC and over discharged cells
* Ignored continued under voltage cell warning after charging, then left to charge unattended.
So basically everything you're NOT supposed to do with lipo!
1 simple email to me when looking for a second charger would have prevented all these problems.
But the other issue was ignoring the HVC and LVC buzzers.
Yes, you could argue a LVC that hard cut the throttle would have prevented over discharge and a more expensive / complex charger would have prevented over charge - but basic LVC buzzers are perfectly adequate if you actually heed their warnings, which I instruct people they must do. And with an ounce of common sense, these are the cheapest and easiest solution. If you think this leaves too much to chance remember that for nearly 100 years cars have used oil or check engine warning lights and beepers and everyone knows that if that comes on then you have to stop the engine or risk damaging it (in this case the battery)
So yeah I just thought I'd share this story, not to scare away the noobs or further propogate unsubstantiated hysteria around lipo use, but to serve as a reminder to follow the basic rules and don't be a stooge.