Question about Makita Tools 18V 1/2" Lxt Lithium - Ion Hammer Driver - Drill Kit - BHP451

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Makita 24V UM401D cordless lawn mower

I was given this mower, but have no manual and cannot get it to work. The battery is new, but does not seem to charge. Where can I acquire this manual/information? Thank you, Charlotte

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  • Anonymous Mar 04, 2009

    I've got the same problem. I bought 2 new 12 volt batteries for the mower. When I charge the battery, the charger flashes a red light, indicating "recovery charging" doesn't want to switch out of this mode. I'm not sure what the problem might be. Do the batteries get hooked up negative to positive or positive to positive and negative to negative?


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I just repaired my mower with similar characteristics. My fix was determined by compressing and releasing the power cord that goes into the mower just in back of, before, the strain relief. When I compressed and release this power cord, I got the green light to stay constant on the charging transformer, which tells me that the conductors somewhere in the power cord had been compromised. I suspected end closest to the mower side due to it's continually being plugged in and out (without very robust strain relief.

I was able to confirm this fact by cutting the power cord an inch in back of the power plug that goes into the mower and then restripping the wires (paying close attention to the polarity) and soldering the now properly connected powercord wires. I put heat shrink tubing on each leg, then shrunk the tubing in place, then wrapped the who shebang with electrical tape. and... viola!!! she worky! Charges like a champ.

Note: Another situation that arose at one point that gave a me similar flashing red light was when the was a small bit of debrin down in the mower power plug in recepticle. This debris kept the plug from seating all the way down into the plug recepticle and prevented the charge/power from reaching the connector.

Hope this help!


Posted on Jun 28, 2010

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I am researching the same problem.
FYI is the relay is bad or the switch in the handle
then HOTWIRE the thing

Take the big White wire of the relay and put it in place of the Red on on the mower.

Posted on Sep 26, 2009

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I have the same problem with my Makita mower (not accepting the charge, flashing red). I've been unable to find a replacement battery(ies) for a reasonable price and Makita is no longer manufacturing that model. The batteries should be hooked in series, i.e., postive to neg. so that the 12v output of each is doubled to the 24 volt rating of the mower. Good Luck but I'd also start thinking about getting a new mower for the spring.

Posted on Mar 22, 2009

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Go to and under the heading Factory and authorized service centers type in your model number and you should be able to download a manual. I had a couple of these when I worked for Makita and when running they are great. Good Luck. Dave

Posted on Dec 24, 2008

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