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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!

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!

<p>Thank you for sharing this. I just bought an Instaboost 400 battery charger from a clearance of a warehouse and is nonreturnable. The instaboost just doesn't charge not hold any charge. After reading a lot of reviews, I conclude the batteries may have gone bad and called the company but no response. Any suggestions where I may find the batteries to replace and how to replace them would be much appreciated. </p>
<p>mine failed recently. The best advice is to do as I did:</p><p><a href="https://www.instructables.com/id/My-DIY-Portable-Jump-Starter/">https://www.instructables.com/id/My-DIY-Portable-Ju...</a></p>
<p>useful info...thanks :)</p>
Aww thanks!

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Bio: I'm a Trini hobbyist who enjoys making new projects, doing repairs at home, exercise and improving existing systems. I relish publishing my projects on ... More »
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