Eric
10 mW
First off, let me just say that this is very embarassing. 
Hopefully you can all get a good laugh at my boneheaded move.
Four months after my previous company's RIF, I was finally able to finish purchasing the last major parts for my ebike - the batteries and chargers. I have 3 miles of hilly, winding, high-speed, shoulderless road to ride before getting to a safer, slower speed bike route where I can finish my 19 mile commute. With an X5304 & a 72V48A controller, I chose to start with a 16s5p pack from DeWalt scavenged A123 cells. Several new packs of batteries and my 48V 2A charger had arrived; I couldn't wait to test it all out!
View attachment 2
I removed a group of batteries from one tool pack and connected my new charger to verify it worked. I should have "connected" my brain first. The charger's green light at no-load turned red upon connection, so it was charging. I left the pack to charge resting on a ceramic plate in my kitchen.
About 10 minutes later, I heard the first "POP". I figured it was a power supply cap in the "cheap" charger I had purchased. I raced into my kitchen expecting to unplug a smoking charger only to find one of the cells had blown! A couple seconds later, "POP" went another cell, then another. Each depressurized cell spewed vapor and solvent. The remaining solvent could be seen boiling inside the cells. It was at that moment that I realized my boneheaded move.
48V (charger) >> 32V (battery pack)!
I tossed a towel over the steaming, boiling mess, unplugged the charger and set the pack outside on my snow covered patio table. I watched with horror as all 10 cells vented over the course of about 3 minutes. I left the cells outside in disgust (and to let the solvent evaporate). Each cell vented from their positive contacts as designed.
I'm sure glad I wasn't charging LiPo!
The cells sat outside all week in the cold, rain and snow until today. I could now stand to deal with the consequences of my mistake. I picked up the string of cells and thought I heard the characteristic snap of an arc as the unbound string of cells brushed against eachother. When I put the pack down, I heard it again. I couldn't believe what I was hearing, so I grabbed my ancient multimeter.
View attachment DSC07545s.jpg
View attachment DSC07544s.jpg
I'm curious how much capacity they have left? Doubtless their chargeability and high discharge rate are gone, but to have any voltage after this treatment is amazing to me. I wonder if I can recycle them anywhere?
So how do you kill an A123 cell?
Eric
Hopefully you can all get a good laugh at my boneheaded move.Four months after my previous company's RIF, I was finally able to finish purchasing the last major parts for my ebike - the batteries and chargers. I have 3 miles of hilly, winding, high-speed, shoulderless road to ride before getting to a safer, slower speed bike route where I can finish my 19 mile commute. With an X5304 & a 72V48A controller, I chose to start with a 16s5p pack from DeWalt scavenged A123 cells. Several new packs of batteries and my 48V 2A charger had arrived; I couldn't wait to test it all out!
View attachment 2
I removed a group of batteries from one tool pack and connected my new charger to verify it worked. I should have "connected" my brain first. The charger's green light at no-load turned red upon connection, so it was charging. I left the pack to charge resting on a ceramic plate in my kitchen.
About 10 minutes later, I heard the first "POP". I figured it was a power supply cap in the "cheap" charger I had purchased. I raced into my kitchen expecting to unplug a smoking charger only to find one of the cells had blown! A couple seconds later, "POP" went another cell, then another. Each depressurized cell spewed vapor and solvent. The remaining solvent could be seen boiling inside the cells. It was at that moment that I realized my boneheaded move.
48V (charger) >> 32V (battery pack)!
I tossed a towel over the steaming, boiling mess, unplugged the charger and set the pack outside on my snow covered patio table. I watched with horror as all 10 cells vented over the course of about 3 minutes. I left the cells outside in disgust (and to let the solvent evaporate). Each cell vented from their positive contacts as designed.
I'm sure glad I wasn't charging LiPo!
The cells sat outside all week in the cold, rain and snow until today. I could now stand to deal with the consequences of my mistake. I picked up the string of cells and thought I heard the characteristic snap of an arc as the unbound string of cells brushed against eachother. When I put the pack down, I heard it again. I couldn't believe what I was hearing, so I grabbed my ancient multimeter.
View attachment DSC07545s.jpg
View attachment DSC07544s.jpg
I'm curious how much capacity they have left? Doubtless their chargeability and high discharge rate are gone, but to have any voltage after this treatment is amazing to me. I wonder if I can recycle them anywhere?
So how do you kill an A123 cell?
Eric
