Mighty Mule gate system...battery keeps slowly dying

[Uncle Ben]

Hey folks, I wanted to see if anyone could offer any insight regarding my Mighty Mule 362 double gate system. It uses a 12v gate battery and a power transformer to keep the battery charged (no solar panel). The last month or so the battery is only lasting 1 or 2 weeks before it quits working, and then I have to remove the battery and fully recharge it with my car battery charger. Then it works great for a week or so, then the gate starts operating more slowly, then gets to the point where the control panel with beep with one long continuous beep when the gate is in the middle of operating and then stops completely, due to the battery being too low.

I have tested to see that the transformer is putting out the proper low voltage, and with a volt meter you can see the voltage of the battery drop as the gate is operated, but then when the gate is fully open or closed, you can watch the meter and see the voltage slowly climbing back up, indicating that the transformer is charging it...so I can't figure out why the battery will no longer last more than a week or two at the most before it goes dead.

Thanks for your input!

 

[Fixr]

Hey folks, I wanted to see if anyone could offer any insight regarding my Mighty Mule 362 double gate system. It uses a 12v gate battery and a power transformer to keep the battery charged (no solar panel). The last month or so the battery is only lasting 1 or 2 weeks before it quits working, and then I have to remove the battery and fully recharge it with my car battery charger. Then it works great for a week or so, then the gate starts operating more slowly, then gets to the point where the control panel with beep with one long continuous beep when the gate is in the middle of operating and then stops completely, due to the battery being too low.

I have tested to see that the transformer is putting out the proper low voltage, and with a volt meter you can see the voltage of the battery drop as the gate is operated, but then when the gate is fully open or closed, you can watch the meter and see the voltage slowly climbing back up, indicating that the transformer is charging it...so I can't figure out why the battery will no longer last more than a week or two at the most before it goes dead.

Thanks for your input!

Sure sounds like the charger isn't working properly, or maybe there's a bad connection in the charging circuit to the battery.

 

[Mike65]

Did you have the battery load tested; the battery might have a bad cell.

 

[WildBill]

Did you or can you pull the leads off the battery and measure voltage on them? It sounds like you might just be measuring what the battery puts out, it will drop under load and come back up again after. Unless I misunderstand what you said, if so disregard this.

 

[tyyost]

How old is the battery? May be time for a new one.

 

[BrandonV]

As someone else pointed out what does the transformer read in terms of output voltage and if you disconnect the battery what does the leads from the control box to the battery read (VDC)?

The Mighty Mule transformer puts out 14VAC and the control box itself handles the rectification and charging of the battery. To understand the full picture of what is going on you should have both numbers available.

Does your control box have a yellow LED? If so - that should give you an understanding of what the onboard charger is attempting to do.

 

[Youngandfree]

What kind and size battery is it?

 

[Uncle Ben]

Thanks so much for all the responses. To answer some of the questions above, the battery is part # FM150, which is the Mighty Mule 12V, 7 Amp hour battery. It is about 2-3 months old.

The transformer that I have had for the past 3 years is an 18V transformer, but it puts out around 20V. When measuring the voltage at the control board with the battery disconnected, it is only measuring about 4.5V. (the manual says it needs to be a 14V transformer, but I have had the 18V transformer on this gate for several years with no previous battery charging issues)

I actually got on the phone with Mighty Mule's tech support, and they said based on the fact that I am only getting 4.5V at the control board with the battery disconnected (the two blue connectors in the top left of the attached photo), that means the board is bad and needs to be replaced. Just the control board alone is $350, so I would like to figure out what component on the board has gone bad so I can repair it. I have experience soldering on a printed circuit board, so I am up to the task, but I don't know what part to replace...or perhaps a solder joint on a component is failing.

 

[BrandonV]

Thanks so much for all the responses. To answer some of the questions above, the battery is part # FM150, which is the Mighty Mule 12V, 7 Amp hour battery. It is about 2-3 months old.

The transformer that I have had for the past 3 years is an 18V transformer, but it puts out around 20V. When measuring the voltage at the control board with the battery disconnected, it is only measuring about 4.5V. (the manual says it needs to be a 14V transformer, but I have had the 18V transformer on this gate for several years with no previous battery charging issues)

I actually got on the phone with Mighty Mule's tech support, and they said based on the fact that I am only getting 4.5V at the control board with the battery disconnected (the two blue connectors in the top left of the attached photo), that means the board is bad and needs to be replaced. Just the control board alone is $350, so I would like to figure out what component on the board has gone bad so I can repair it. I have experience soldering on a printed circuit board, so I am up to the task, but I don't know what part to replace...or perhaps a solder joint on a component is failing.

Did support have any issues with the 18V supply? Running things a couple of volts hotter can cause things to burn out over time.

 

[gregs]

If your only problem is the battery charging side of the board and all the rest functions correctly? I would look for a separate rectifier/regulator and skip using the built in charging system. I had a similar issue but am using a solar panel. It was designed to attach to the main board but after a while stopped working correctly. I am assuming that the rectifier transistor / diodes failed from old age. Most of the components are surface mount so its not as easy to repair, even if you figure out whats bad and thats a whole different project. So I got a solar charger rectifier thats around $20 and wired the panel to it and then to the battery. I'm sure you can find a AC voltage regulator / DC rectifier fairly easily and do the same thing with your transformer.

I am guessing that you checked the output voltage of the transformer with everything connected. I have seen transformers that seem ok with no load on them but drop when a load is applied. Its pretty typical for them to read a little higher than the rating with no load. But should stay close to the rating with a load applied.

 

[BrandonV]

I have experience soldering on a printed circuit board, so I am up to the task, but I don't know what part to replace...or perhaps a solder joint on a component is failing.

FYI these boards have a thick conformal coating applied. It's not a DIY job.

 

[Uncle Ben]

Did support have any issues with the 18V supply? Running things a couple of volts hotter can cause things to burn out over time.

You make a good point. They did insist to me that the transformer needs to be 14V, but when you are on the mighty mule site and looking at the MM362 gate opener, it shows all the accessories for it and shows the 18V transformer, but in the manual it says 14V. Since the 18V transformer has been on the gate for quite a few years, I figured that was not the issue, but maybe it has caused an issue over time.

If your only problem is the battery charging side of the board and all the rest functions correctly? I would look for a separate rectifier/regulator and skip using the built in charging system. I had a similar issue but am using a solar panel. It was designed to attach to the main board but after a while stopped working correctly. I am assuming that the rectifier transistor / diodes failed from old age. Most of the components are surface mount so its not as easy to repair, even if you figure out whats bad and thats a whole different project. So I got a solar charger rectifier thats around $20 and wired the panel to it and then to the battery. I'm sure you can find a AC voltage regulator / DC rectifier fairly easily and do the same thing with your transformer.

I am guessing that you checked the output voltage of the transformer with everything connected. I have seen transformers that seem ok with no load on them but drop when a load is applied. Its pretty typical for them to read a little higher than the rating with no load. But should stay close to the rating with a load applied.

Yes, the board and all functions work properly, other than the battery discharge issue, so I might go the route that you are suggesting. I have a plug-in trickle charger that I was thinking about attaching directly to the battery and not using the transformer. I think the trickle charger puts out about 13.5V, last I checked. I would just have to figure out how to attach the blade terminals and the trickle charger claps to the blades on the battery...and hopefully that would work to keep the battery charged.

 

[gregs]

You make a good point. They did insist to me that the transformer needs to be 14V, but when you are on the mighty mule site and looking at the MM362 gate opener, it shows all the accessories for it and shows the 18V transformer, but in the manual it says 14V. Since the 18V transformer has been on the gate for quite a few years, I figured that was not the issue, but maybe it has caused an issue over time.


Yes, the board and all functions work properly, other than the battery discharge issue, so I might go the route that you are suggesting. I have a plug-in trickle charger that I was thinking about attaching directly to the battery and not using the transformer. I think the trickle charger puts out about 13.5V, last I checked. I would just have to figure out how to attach the blade terminals and the trickle charger claps to the blades on the battery...and hopefully that would work to keep the battery charged.

Thats an option. You could just get a battery tender and solve all the problems as long as you can keep it out of the weather. They usually have ring terminals on the ends.

I dont have power where my gate is thats why I went solar, but it has its problems to.

 

[Uncle Ben]

Would it be an option to run the transformer directly to the battery? That would bypass the board and allow the full transformer voltage to hit the battery without the voltage loss that the board seems to be introducing.

 

[BrandonV]

Would it be an option to run the transformer directly to the battery? That would bypass the board and allow the full transformer voltage to hit the battery without the voltage loss that the board seems to be introducing.

I would just buy one of these and call it a day.

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They're designed for VLRA batteries like the one the gate uses.

You can't tap off the transformer without rectifying and regulating the voltage.

 

[Uncle Ben]

I think that is what I will do. I hope the control board only needs to see the battery voltage, and hopefully does not need to see incoming voltage from the transformer in order to operate properly.

 

[BrandonV]

I think that is what I will do. I hope the control board only needs to see the battery voltage, and hopefully does not need to see incoming voltage from the transformer in order to operate properly.

I mean I'd leave the transformer going to the control board in place and just disconnect the leads going to the battery from the control board and connect the battery to the standalone charger.

Basically, the setup for a solar battery charger just with the solar panel replaced with the VRLA charger above.

 

[tarmy]

I am guessing you do not want to hear this…but get a new opener that is NOT Whimpy Mule.

I had a couple of their products (gate opener and side gate opener) and they were just crappy the entire time I had them. Then the expensive stuff started failing, like a mother board on one. Then they quit supporting replacement parts…finally out of total frustration I made the decision to replace both.

My research led me to LiftMaster openers. They are built better, never give me any trouble and have been great. Money well spent. Oh, not one issue in years of use.

Good Luck OP.

 

[Uncle Ben]

I am guessing you do not want to hear this…but get a new opener that is NOT Whimpy Mule.

I had a couple of their products (gate opener and side gate opener) and they were just crappy the entire time I had them. Then the expensive stuff started failing, like a mother board on one. Then they quit supporting replacement parts…finally out of total frustration I made the decision to replace both.

My research led me to LiftMaster openers. They are built better, never give me any trouble and have been great. Money well spent. Oh, not one issue in years of use.

Good Luck OP.

I'm definitely not in a position to change my whole gate system right now, but I will keep LiftMaster in mind when I do have to replace the system some day.

 

[gregs]

I mean I'd leave the transformer going to the control board in place and just disconnect the leads going to the battery from the control board and connect the battery to the standalone charger.

Basically, the setup for a solar battery charger just with the solar panel replaced with the VRLA charger above.

I dont think he can do that. The leads coming from the control board to the battery is what also powers the opener portion.

It will work just fine without the transformer connected to it. No different than loosing power and the gate still works, or my solar system not producing electricity at night. Dont over think it to much. The simple solutions are the best.

 

[Fixr]

I'm definitely not in a position to change my whole gate system right now, but I will keep LiftMaster in mind when I do have to replace the system some day.

I'll second the recommendation not to sink major money into the MM. I went through two in just over a year when the boards failed and the cost for the board was about the same as the whole opener kit. The next time it happened, I got a US Automatic, which has been working well for 10 or 15 years. I understand not having the wherewithal to replace the MM now, but I suggest saving up for a major brand opener instead of dumping any real money into what you have now. I would have been way better off to have bought a major brand first instead of throwing away too many hundreds of dollars in the MM garbage.

 

[BrandonV]

I dont think he can do that. The leads coming from the control board to the battery is what also powers the opener portion.

It will work just fine without the transformer connected to it. No different than loosing power and the gate still works, or my solar system not producing electricity at night. Dont over think it to much. The simple solutions are the best.

Been a while since I've looked at one of these but yeah... if it can work off solar... yup just ditch the transformer.

 

[drmarkr]

The damn opener is working fine.... why should he replace it? You have power right there just add a trickle charger to the battery and you're finished with this. That is exactly what I have on my Liftmaster!

 

[Duke957]

I'll agree that the mules charging system *****, I use a car battery, or larger mower battery. If it's winter you're screwed anyway. My battery is in a semi heated room ,I'll bet most are mounted on a frozen outside pole. This can be thought out to make sense.

 

[38Chevy454]

At my old place I had a MM swing gate opener. I put a second battery in mine and charged it with a 10w solar panel. The second battery was to help on overcast or snow days. Besides the already mentioned crappy MM opener, the solar panel and second battery never gave any troubles. I agree if you have 120vac coming in, just get a small trickle charger.

 

[Uncle Ben]

One question to add on to this...what is the best way to go about connecting the small ring terminals from the trickle charger to the battery, while still being connected to the wires that go from the control panel to the battery? The battery itself has male quick disconnect (spade) terminals, so that is the type of connection that goes from the battery to the control panel, and I just need to add in the trickle charger to the equation.

Basically, I have a female battery ring connector on my trickle charger and a female quick disconnect wire from the controller, and those both need to connect to the male quick disconnect (spade) terminal on the gate battery.

Thanks!

 

[gregs]

This is the easiest way I can think of. You can get multi tap terminals used for capacitors in starter boxes that will allow you to have 2 male terminals at the battery with no modifications. Then cutoff and replace the ring terminals on the charger with 1/4" female terminals.

 

[Uncle Ben]

Simple and perfect. Thank you very much!

 

[dcg9381]

I actually got on the phone with Mighty Mule's tech support, and they said based on the fact that I am only getting 4.5V at the control board with the battery disconnected (the two blue connectors in the top left of the attached photo), that means the board is bad and needs to be replaced. Just the control board alone is $350, so I would like to figure out what component on the board has gone bad so I can repair it. I have experience soldering on a printed circuit board, so I am up to the task, but I don't know what part to replace...or perhaps a solder joint on a component is failing.

You're a MM customer. Better get used to the "board tax"....
These damn things are expensive... Over time..... You don't want to know my cost of ownership over 5 years.

Sounds like you've got 120V around that gate, just throw a real charger on the battery.

I moved to "real" lead acid deep cycle batteries pretty quickly.. Just had to add an enclosure.