Hi, I have repaired 3 Makita 18V 3Ah Li-Ion batteries recently by removing good cells from other faulty batteries. The Voltages are good now on all 3 and they charge/discharge OK on my own charger but flash as faulty on the Makita charger. Have received info stating the circuits on the batteries lock-up when more than 3 attempts to charge them when they were faulty. is this correct? Does anyone know how to reset them?? Cheers Mike

SOURCE: Makita DC18RA Li-Ion 18V Battery Charger

Most likely, but unless the transformer blew, which is somewhat unlikely, a good repair shop should be able to fix it. Basically the charger unit is a transformer, some diodes to convert ac into dc, and some sensing circuitry to tell you when the battery is done charging. Diodes and sensing cisrcuitry are commonly available parts and not expensive. Transformers are expensive. Even if you get it repaired youll still need an adaptor to convert from the mains 240 to the 120 that the charger wants to see. Get one with a high enough wattage for the charger. Wattage is printed on charger base.

SOURCE: 18v Lithuim Ion battery will not charge

If you have been a bad boy and managed to short the battery by using it for non-proscribed purposes, the fusible link will blow (kind of like a fuse) To fix it, open up the battery (use a Torx 10 security bit, or a small flathead in a pinch) On the battery connection nearest the spring-loaded white catch there is a small bridge of metal with a hole in the center. If this is melted you can solder it back together by sanding the two pieces and putting a glob of solder on them. This will void your warranty (duh!) and remove the battery's fuse protection, but it WILL work again. If the link is intact and nothing else is obviously wrong, you almost certainly have a bad cell. I recommend pulling out the bad cell ( it will be the one that does not read between 2.5 - 4 vdc) and replacing it with one from another dud battery- this requires some fudging and re-soldering. Or do what I did, pull the cell, toss the electronics and the short pink wire, add a cigarette lighter socket and voila! you have a portable power supply giving around 14 volts. Charge it up by wiring two cigarette lighter male ends together (check polarity , + to + (tip end) and - to -) and plug it into your car, but only while it is running or you will be charging your car battery with it! Hope that helps.
Matt Binns GiantGlobes.com

SOURCE: my makita 18v li-lon impact driver has only 70%

Worn brushes or wrong trigger.

SOURCE: One question please, I have makita cordlless

according to the schematic I saw yes you can and I think that you will be pleased with its performance, their operator manual even lists the weight of tool with this battery. Makita has a 1 year limited warranty on the Li-Ion battery that you might want to consider if you have the receipt.

Testimonial: "thanks"