Question about Makita 2 Bl1830 18v Battery,dc18ra Charger Lxt Fr Drill

2 Answers

Is it possible to repair a defective lithium ion battery? I have 3 batteries that won't charge (red & green flashing lights). I opened them up and found that 9 out of 10 cells are good in each battery, showing about 3.5 volts when tested. I tried swapping out the bad cell in one battery pack with one of the good ones in another battery pack and my "new" battery with all 10 good cells still reads defective on my charger. Is there something I can do with the circuit board to make it stop reading as defective on the charger? I've soldered on circuit boards before but I don't want to start messing with this if I don't know what needs to be fixed. Like zzfiremanzz commented, $100 per battery is a lot when the battery pack fails immediately after the warranty is up and I'd like to be able to steal the good parts of my 3 bad batteries to make (at least) one good one.

Posted by bjones004 on

  • bjones004 Mar 19, 2011

    Not a problem with the charger. I actually have 3 chargers and 7 batteries (3 of which are currently showing as defective on each charger) My remaining 4 batteries charge fine on all of my chargers. Thank you for the suggestion though, tvenetis.



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Steve Hockey

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This is a known problem with BL18XX batteries. Makita designed the battery supervisory circuit to run off only one of the 10 cells, so leaving your battery uncharged for a long time eventually discharges one cell much more than the others. When you put this battery in the charger, it reports that the battery is defective. Another Makita fault is that the intelligent (DC 18XX) chargers will only attempt to charge a 'faulty' battery 3 times, then they will re program the micro in the battery to lock out charging for good. The only solution is to buy 3rd party replacement battereis that don't have the faulty Makita supervisory circuit.

Posted on Sep 05, 2012


Tim Venetis

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Maybe there is something wrong with the charger itself. If you have a friend that has the same drill try to charge the battery on his charger.

Posted on Mar 19, 2011


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