This jump starter battery had one of its terminals badly burnt due to a slack connection. The female terminal has the surrounding plastic melted and now the battery can't be used to jump start a car! Mind you the battery itself is fully functional but the high current jack is useless.
Read on for how I fixed it!
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Step 1: Exploratory Surgery.
Not the kind of thing you want mentioned by a doctor but for this battery it is necessary. Precise and shallow cuts with my vibrating saw allowed me to expose the burnt jack and circuit board. I used a small flatblade screwdriver to pry out pieces of the cut plastic enclosure.
Step 2: Analyzing the Guts.
Here is the charger board and terminals of the LiFePO4 battery. Using a sharp knife I carefully cut away the plastic wrapping on the energized electronics without causing a fault. The high current jack has pretty short leads to the battery terminals.
Step 3: Preparing the Battery.
Here I cut away the melted connector jack to expose the thick gauge wires for positive and negative.
Step 4: The Replacement Connector Jack!
Luckily I had a spare male connector jack from a salvaged jump starter. This I soldered to the exposed terminal wires. I had to bring out my 100Watt soldering iron to get a proper joint made for the large gauge wires.
Step 5: Insulation!
Ah, the unsung hero: Silicone adhesive. I used copious amounts to insulate and bind the components.
Step 6: Securing the New Connector Jack.
A plastic cable tie I used to secure the jack leads to provide a robust solution.
Step 7: Finishing Touches and Completion!
Using more black silicone adhesive, I coated the entire charger board and let it cure for 48 hours. Now the jump starter battery pack has a second life and works the same as before!