Mighty Mule charger replacement

[ArTrvlr]

Mighty Mule battery charger replacement

I have a Mighty Mule FM500 single gate opener. It has worked fine since 2006, but recently quit at the half-way point on an open cycle. After doing all the tests on the Mighty Mule troubleshooting site, I determined that the battery charger (built into the control board) was dead. A replacement board is $240 to $250. I found this website, of a guy that repairs circuit boards, but an e-mail from him predicted that his repair charge could be as much as a new board.

Since all functions of the opener, except battery charging, still worked, I decided to try and by-pass the built in charger. I unpluged the MM transformer, disconnected the MM transformer wires from the circuit board and temporarily connected a Harbor Freight trickle charger (there are three HF #s, 42292, 69594, and 69955). I walked away, and when I went back a few hours later, the battery had went from about 11V to 12.9V. The opener then worked normally. I cycled it a few times to be sure all was OK. After each cycle the battery would drop to close to 12V, then quickly charge back up to close to 13V.

I then took the wires that previously came from the transformer to the circuit board (18V AC terminals) and connected them directly to the battery. I cut the battery clips off the HF charger and butt connected them to the other end of those wires (inside the garage) and plugged in the HF charger where the MM transformer had been. This eliminated the MM transformer and bypassed the built-in battery charger. It has been a few days and it is still working fine and the battery is staying charged. If you are skeptical of HF quality, you could use a Battery Tender charger. I got the HF charger on sale with a 25% coupon for about 6-7 dollars. Sure beats $250 for a new board!
jps

 

[davrow]

Thanks, ArTrvlr! No problems with mine, but good info to have.

I'm considering a solar panel from HF to keep mine charged. Ever considered that?

 

[Gary Fowler]

Thanks, ArTrvlr! No problems with mine, but good info to have.

I'm considering a solar panel from HF to keep mine charged. Ever considered that?[/QUOTE I think that is where my sister in law bought a solar panel that was supposed to be 12 volt but in reality puts out 20.5 volts. I don't know what this would do to a battery in long term operation. Test any panel you put up for solar charging to make sure you aren't getting more than 14v.

 

[ArTrvlr]

Thanks, ArTrvlr! No problems with mine, but good info to have.

I'm considering a solar panel from HF to keep mine charged. Ever considered that?

It crossed my mind, but I had a couple of new HF trickle chargers on hand, and I have had good luck with them keeping lawn mower batteries charged year round, so I went with what I had. Also, there is a place on the MM board to connect a solar charger, and that may be related to the battery charger that went bad, so I didn't want to experiment, not knowing if that part of the board was bad also.

 

[davrow]

Test any panel you put up for solar charging to make sure you aren't getting more than 14v.

Good point, I'll keep that in mind.

I have no power at my gate is why I'm considering solar.

 

[ArTrvlr]

Thanks, ArTrvlr! No problems with mine, but good info to have.

I'm considering a solar panel from HF to keep mine charged. Ever considered that?

Thanks, ArTrvlr! No problems with mine, but good info to have.

I'm considering a solar panel from HF to keep mine charged. Ever considered that?[/QUOTE I think that is where my sister in law bought a solar panel that was supposed to be 12 volt but in reality puts out 20.5 volts. I don't know what this would do to a battery in long term operation. Test any panel you put up for solar charging to make sure you aren't getting more than 14v.

Good point, I'll keep that in mind.

I have no power at my gate is why I'm considering solar.

The MM built-in battery charger uses 18V AC input from their "wall wart" transformer, or 18V DC from a solar panel. So if you use one of MMs solar kits the hook up is to the control board. If you go with any other solar panel (HF or otherwise) you would probably need a solar charge controller to regulate the voltage output. If I was going to try a HF setup I would use the 96418 15W panel and the 96728 charge controller and connect the output directly to the battery. Those two items can be bought for less than $100, plus some wire and you would have to build a mounting bracket for the panel. MM solar comes in a 5W for about $160 or a 10W for about $260. So for less money with HF you would have a higher wattage charging system than with a MM kit.

 

[Richmean66]

Mighty Mule battery charger replacement

I have a Mighty Mule FM500 single gate opener. It has worked fine since 2006, but recently quit at the half-way point on an open cycle. After doing all the tests on the Mighty Mule troubleshooting site, I determined that the battery charger (built into the control board) was dead. A replacement board is $240 to $250. I found this website, of a guy that repairs circuit boards, but an e-mail from him predicted that his repair charge could be as much as a new board.

Since all functions of the opener, except battery charging, still worked, I decided to try and by-pass the built in charger. I unpluged the MM transformer, disconnected the MM transformer wires from the circuit board and temporarily connected a Harbor Freight trickle charger (there are three HF #s, 42292, 69594, and 69955). I walked away, and when I went back a few hours later, the battery had went from about 11V to 12.9V. The opener then worked normally. I cycled it a few times to be sure all was OK. After each cycle the battery would drop to close to 12V, then quickly charge back up to close to 13V.

I then took the wires that previously came from the transformer to the circuit board (18V AC terminals) and connected them directly to the battery. I cut the battery clips off the HF charger and butt connected them to the other end of those wires (inside the garage) and plugged in the HF charger where the MM transformer had been. This eliminated the MM transformer and bypassed the built-in battery charger. It has been a few days and it is still working fine and the battery is staying charged. If you are skeptical of HF quality, you could use a Battery Tender charger. I got the HF charger on sale with a 25% coupon for about 6-7 dollars. Sure beats $250 for a new board!
jps

I just did the same thing and it works. The circuit board charging circuit quit charging the battery. So I went to harbor freight and bought their deluxe float charger that turns off when the battery is charged. I totally did away with the transformer and wires from the transformer to the mighty mule circuit board. I cut off the ringed ends on the float charger, and the battery tabs that were plugged into the battery. Strip them back half inch each. Twist the red wire together with the fused end of the float charger. Then the black with the other. Crimp on spade fittings on each pair of wires and plug them onto the battery spades. I taped them down seperate so the didn't move. Plug in the float charger and enjoy. The light will turn green and stop charging when battery is full. And will recharge as needed. You just saved hundreds !!!