How To Fix A Flexvolt (not jump-start)

I received this 9ah flexvolt battery which was in a sub optimal condition upon inspection the voltage was low 2v in the 18v/ 20v range and 6v in the 54v/ 60v range. The issue with the battery was the voltage it was much to low for the charger to be able to charge it so I had 2 options. The first option was to attempt to jump start or boost the battery by connecting it to a good one. I choose option 2 which was to raise the voltage slower over about 5 hours in fact using a DC power supply. The method is as follows connect the power supply until the voltage reaches around 17v this should bring it into charger range then connect it to the charger if there are no other internal issues the charger will then charge the battery fully. I must say it worked a treat the battery recovered completely from its low voltage state it doesn't always work but it did this time.
How to test voltage on a Flexvolt is shown here too.
Dewalt Flexvolt battery won't charge on the Dewalt charger? This may be of help
the items used in this repair
Venlab Digital Multimeter
UK https://amzn.to/3KDi805
USA https://amzn.to/3MlEep8
DC power supplies
UK link https://amzn.to/3LMSO93
USA link https://amzn.to/42ya87A


The flexvolt battery is a dual voltage innovation from dewalt it is suitable for 18v and 54v tools 20v and 60v in USA. The 9ah flexvolt uses samsung 21700 cells as opposed to the 18650 cells used by the 6ah flexvolt and XR. I show how you can sometimes repair these by relatively low cost means. Can You repair your 54v/60v flexvolt battery if its not charging ? If I can you can
#repair #dewalt #powertools