Solar inverter overheating - Montana Owners Club

DonandBonnie · 12-10-2015, 01:33 AM

With our recently installed solar the new larger inverter is mounted on the back wall of the battery compartment in the vacant space above the metal generator case. When we run the generator we get a "heat sink overheat" warning on the inverter display which shuts down our 110 in the unit until the inverter cools down. With compartment doors closed the warning comes on in about 20 minutes, about 40 minutes with the battery compartment door open and about an hour with both the battery door and generator compartment doors open. Outside ambient temperatures at the time of these runs was around 50 degrees F. This is indicating to us that the heat from the generator is causing the issue.

Has anyone encountered such an issue with an overheated inverter? We are exploring three possible solutions: 1. Add insulation within the battery compartment to block heat from the generator. 2. Try to find an after market fan that can be wired to operate when the generator is running to draw the heat out of the battery compartment. 3. If the first two solutions don't work, move the inverter to another location away from the generator heat. Any thoughts on these possible solutions?

Ozz · 12-10-2015, 02:18 AM

Could you post pictures of the install?

DonandBonnie · 12-10-2015, 02:32 AM

I could try, Ozz. I've not had much luck in figuring how to post pics on the forum. I could email them to you, if you PM your email address to me.

Drifty1 · 12-10-2015, 03:51 AM

If you had the inverter installed by someone that does installs for a living I would try get them to move it to another area. They should know not to put it in a warm spot. Is the solar charge controller located in the same area? If it is any excess power output from the solar panels that is not needed to supply to the battery's is just dumped as wasted heat by the charge controller. So this would not help with your problem..

Ozz · 12-10-2015, 04:40 AM

No problem on he email address, but after I read your post again) I need to learn to actually read and understand before I post..)
You need to change the location to the other side of the bulkhead if at all possible. That is where mine is, it would not overheat there. (As Drifty said...)
HVAC.repairs@yahoo.com
Jim Osbern

jcurtis934 · 12-10-2015, 10:31 AM

Truth spoken in those replies. Never mount in its current location. Anything you do to try to do in the genset area is just bandaids that you won't be happy with and you will still dramatically shorten the lifespan of the inverter. John

DonandBonnie · 12-10-2015, 11:10 AM

Thanks all for the input. It does not appear that moving the inverter will be a complicated project, but it will require longer wiring to reach the new location. We will be boondocking until after Christmas, then probably in campgrounds for the rest of the winter. After that we should be able to return to Indiana and have the installer make the correction. In the short term we have access to a piece of blanket insulation that we can just lay in the compartment temporarily and will run the generator in short bursts to avoid the overheating. Once this is resolved, the solar interlock will start and stop the generator to charge the battery as needed.

DonandBonnie · 12-15-2015, 03:21 AM

Just an update! The solar company has agreed to relocate the inverter away from the battery compartment. Looking at the weather, there is a beautiful window next week in Indiana with lows in the 40's, well above freeing. This is going to work well. We get the solar work done in Nappanee on Tuesday, then swing over to southern Ohio for Christmas with the kids and then head south all before freezing temps hit.

Still wondering about the heat in the battery compartment which we understand is normal. Does anybody see a problem with insulating the generator cover in the battery compartment?

Ozz · 12-15-2015, 03:29 AM

I would contact Onan, or, whoever makes it and ask them, that would be the safest way IMO
And congrats!!!

DonandBonnie · 12-15-2015, 04:38 AM

Thanks for your advice, Ozz.

mhs4771 · 12-15-2015, 05:05 AM

Deleted

DonandBonnie · 12-22-2015, 11:24 PM

Hopefully this is the last chapter to this saga. Last week we moved from a boondocking site to where we had shore power. Within 15 minutes of plugging in we again got the inverter overheat warning. No generator heat this time. After a quick call and discussion with the solar folks, they determined that the charging rate may be the problem. They had it set for 90Hz (whatever that is). They talked us through cranking it down to 40Hz. OVERHEAT PROBLEM SOLVED!

Now comes the tweaking. The lower the charge rate the longer it takes for the generator to recharge the battery. At 40Hz it takes 2-1/2 hours to charge the battery from 11.5v to 14.6v. At 90Hz it took less than an hour to recharge. The bad news with this is that it takes a lot more propane to run the generator for 2-1/2 vs 1 hour. The good news is that the generator wasn't running as fast resulting in the areas within the battery box being almost cold to touch. At the higher rate they were almost too hot to touch. We have now cranked the charge rate up to 60Hz. That works well in cooler temps and has shortened the recharge time. We will let that go for a while and see what happens in warmer temps. If all goes well we might experiment with higher rates until we reach what works.

Drifty1 · 12-23-2015, 12:44 AM

I think you are referring to charging amps not Hz. Yes the inverter/ charger should run cooler at the lower amp rate but it still does not cure the problem of overheating. The charging side should be able to run at the 90 amp rate if your battery's can take that charge rate. To me it sounds like they are trying to get out of moving your unit by derating the equipment and lowering its heat output. Just my thought as I can change the charge rate on mine unit up to 125 amps but have never set it up to that. My unit adjusts the charge rate to corespond to the amps I set the shore power input at. Meaning if I am hooked up to a camp site that has a 15 amp breaker at the post I can set my inverter/charger so I take say a max of 14 amps from the shore power cable and it will lower the charge rate down to say 10 amps so I will not trip the breaker. Sorry for the round about way of saying I think you still have a problem.

DonandBonnie · 12-24-2015, 03:05 AM

The Hz came from the display screen that shows the charge rate. Certainly the generator runs significantly cooler (and longer) at the lower charge rate. If the heat from the generator was the only issue we could agree with you, Drifty. What we don't understand is why we got the heat sink overheat when plugged into shore power. When that happened there was no heat from the generator and the inverter itself was cool to touch.

Mudchief · 12-24-2015, 01:26 PM

Sounds like you have a bad inverter. My unit is set for 125 amps and when the batteries are down it will put out 125 then taper down as the batteries come up. I have never had a problem even when the temp is high. I have been to the solar shop in Nappanee and I was not impressed when it came to the RV side of the business.

davidaf · 12-24-2015, 06:06 PM

My Magnum inverter/charger had to be serviced at 6 months due to a thermal sensor flaking out. They replaced some circuit board under warranty and it's been good ever since. I could avoid it by dropping the charge amperage to around 15 but after a couple weeks it just failed whenever it felt like it.

"Internal NTC - This fault message displays and the inverter shuts down
because the internal NTC (temperature sensor) circuit has been activated."

DonandBonnie · 12-29-2015, 11:47 AM

With the charging rate at 60, the generator runs for about 1'45", vs. 2'30" at the 40 charge rate. The inverter and generator both ran slightly warmer at the higher rate but not enough to trip any alarms. Going to let this rate go for a while to make sure nothing acts up. If all remains well, we'll try another higher rate at some future date.

Bigboomer · 12-29-2015, 02:03 PM

As Drifty1 and others have said, something does not sound just quite right. IMHO I believe your inverter is fried (circuit board). You should check on your panel readout the tech area and scroll thru the until you see what the temps for the various components read and note them and call the Magnum repair place back. More than likely the FET's (Field Effect Transitors) are cooked.
There are a number of possible reasons, including bad, loose or undersized wiring, etc. Could be you just got the unit that was built on Friday at 4 pm!

A thorough check of all the wiring and connections should be made before you put the unit back in service.

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