Makita 1850 battery charger FIX. A friend asked me to check his charger unit which had failed after it had been connected to a portable petrol generator that incorrectly generated 317 Volts AC and not the usual 240 Volt AC. On the charger circuit board next to the transformer wire connection is a component marked F2; this is a 2.5Amp fuse covered with heat-shrink sleeving. This fuse had ruptured/blown. Also blown was Transistor Q1, a ''P'' Mosfet labelled IRF9Z24N and Schottky Diode D9 labelled SR560. Replacing these 3 items got the charger working again. NB Resistor R31 is only 0.1ohm - don't assume it's gone short circuit! NB. I'd presume that most other Makita chargers will have this heat-shrink sleeving ''camoflaged'' fuse on the input of the circuit board and it would definitely be worth checking if the charger has stopped working. Regards Roy

It sounds like there may be an issue with the charging circuitry on your Makita DC18RC charger. Unfortunately, without a schematic, it can be difficult to diagnose the problem. However, here are a few things you could try: Clean the battery contacts: Sometimes, a buildup of dirt or debris on the battery contacts can prevent the charger from properly detecting the battery. Try cleaning the contacts on both the battery and the charger with a clean, dry cloth. Check the power source: Make sure the charger is plugged into a working outlet and that there are no issues with the power source. Check the thermal sensor: The Makita DC18RC charger is equipped with a thermal sensor that prevents the battery from charging if it gets too hot. If the battery is too hot, let it cool down before trying to charge it again. Try a different charging mode: The Makita DC18RC charger has two charging modes - rapid and maintenance. Try switching to the other mode and see if that makes a difference. Check for loose connections: Inspect the charger and battery for any loose connections or damaged wires. If you find any, try repairing or replacing them. If none of these steps resolve the issue, you may need to take the charger to a professional repair shop or contact Makita customer service for further assistance.

I’m not sure if you can buy a new c/board .
The charger tests the battery before charging & if it picks up a fault it won’t charge the battery. At our repair shop we just replace the whole battery ( under makita warranty if it’s under two years old / depending on what warranty your country has )

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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.

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.

Smart chargers will fail to charge completely discharged battery. Simple charger w/o electronics will. Try connecting two batteries together with charger. ALL in parallel. + to +, and - to -.

This isn't true because I have a second charger and it works fine

If the charge count on the batteries is under 300, Makita will replace them. Makita has a known defect in this battery that causes the battery to shut down before it is dead. So as of now they are exchanging ones with low use.

If they are truly defective and makita won't replace, you have to open them, find the dead cell or blown fuse, and replace. Search youtube makita battery for a video on repairing this battery. But once the red and green lights on the charger flash, the the battery can't be charged on a Makita charger -- it's been locked. So use a third party charger.

Internal board fuse checked? This may/may not help?

Makita 1850 battery charger FIX. A friend asked me to check his charger unit which had failed after it had been connected to a portable petrol generator that incorrectly generated 317 Volts AC and not the usual 240 Volt AC. On the charger circuit board next to the transformer wire connection is a component marked F2; this is a 2.5Amp fuse covered with heat-shrink sleeving. This fuse had ruptured/blown. Also blown was Transistor Q1, a ''P'' Mosfet labelled IRF9Z24N and Schottky Diode D9 labelled SR560. Replacing these 3 items got the charger working again. NB Resistor R31 is only 0.1ohm - don't assume it's gone short circuit! NB. I'd presume that most other Makita chargers will have this heat-shrink sleeving ''camoflaged'' fuse on the input of the circuit board and it would definitely be worth checking if the charger has stopped working. Regards Roy

Sorry to give you my opinion, but these chargers are very delicate, I have 4 and can barely keep 2 going. My recommendation? Open it up and look for obvious shorts/loose wires, if no luck then buy another one and return the busted one as if it were the new one. You will end up with two working chargers. PS this is probably fraud...ha!
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