Intro: Post Mortem of a Lithium Jump Starter.
Last week the maxmade lithium jump starter for my wife had stopped working. No more charging of cell phones and the output voltage on the jump start cable was around 8.3v compared to 11.4v originally. I suspected a faulty cell and as part of a bet with my wife, I opened up this device to prove my Point.
Step 1: Opening by Force!
There are no screws in this jump starter. Using my pen knife I set to work, while at work!
Before the jump starter quit working, there was a rattle inside of it. Apparently piece of a ferrite choke get broken and made the rattling. I am not sure if these pieces caused a fault internally.
Step 2: Checking Out the Insides.
What we have inside is a lithium iron phosphate pouch cell battery (actually 3 cells in series) and a circuit board for charging, balancing and bucking to 5volt. Also a high power led is part of the package for providing light.
Step 3: Investigation and Salvaging.
OK here is the pouch cell battery. Taking off the wrapping shows a damaged cell caused most likely by heat or manufacturer defect. These cells are lithium polymer and are not rated for high current use. If they were lithium iron phosphate then definitely they would last as a jump starter battery.
As a result of this post mortem, I have an extra led to play with now!
So, the bet is won and I'm looking forward to wifey jobs.