1200 watt inverter shuts down while driving

[DrSmart]

For inquisitive minds. Please read to the end before suggesting a simple solution.

Just returned from a long trip. We have a residential fridge and 1200 watt inverter. I've set the inverter for low battery cut out at 12.1 volts and a 90 seconds delay before shut down. Once we're on the road we monitor the trailer voltage using the One Touch app on our cell phone. We can see the battery voltage charge up to 13 volts plus and drop slowly to 12.5 when the fridge is running. When the fridge meets temperature, the compressor shuts off and the trailer battery charges back up to 13 plus volts. Problem appears to be when I apply the trailer brakes long enough to exit the highway at a service center or fuel stop, the voltage drops very quickly and the inverter shuts down. At that point we don't even get a reading from One Touch since the voltage has dropped below it's operating parameters. Once we are stopped and the voltage has come back up, I must reset the inverter. So knowing that pin 4 on the 7 pin trailer connector is the auxiliary 12 volt charging line that goes to the house battery and pin 2 is the power to the trailer brakes, something is causing the steep drop when the brakes are applied. One theory I have is that the ground wire on pin 1 is too small a gauge to carry the current for the inverter and brakes at the same time. I noted that while traveling with the inverter off, the brakes had significantly more grab.

[Allen_C]

Not sure about the wiring but you didn't mention the age, condition or aH capacity of the battery. The inverter only operates as long as the battery can supply appropriate amps and volts. Also, stting the inverter cutoff to 12.1v is a too low for a lead acid or agm battery. At 12.1v a lead acid battery is considered at only 36% capacity. Drawing down the battery below 50%, 12.2v, routinely will drastically reduce the battery's life and capacity.

[RoadrunnerII]

How many batteries and what type are they? If you only have one 12 volt rv/marine battery its not going to have enough reserve for a days drive.
The battery charge line is too small a gauge on most trucks to bring that battery up and keep it up going down the road with an inverter with residential fridge load.
Our home residential fridge rated at 10 amps * 120volts is 1200watts A/C power.

Look at the tag on your inverter for its input rating. 12 volts DC but how many amps DC at full load.
You are pulling too many amps out of the battery for all the loads on it.
Think about the loads on that battery
Electric jacks... Did you leave trailer plugged into A/C power when you hooked up and retracked jacks?
The inverter and Fridge. Did it cycle before you moved but after you disconnected from pedistal.
Is your TV wired thru the inverter? Even when powered off it draws power unless you unplug it.
Propane/CO2detector draws 12volts
Your pump which should be off when travelling anyways
Your interior lights
Your Bathroom fan is it turned off
Lots to consider

RoadrunnerII

[DrSmart]

Hi RoadrunnerII. The trailer battery and inverter are handling the fridge and parasitic loads based on what I described. We can drive all day and the combination is maintained between 12.5 and 13.2 volts. The trailer brakes are on a separate line coming from the truck battery via the brake controller. The trailer battery should only be engaged with braking if the brake away switch is triggered.

I may have to contact Jayco support and see if they can shed some light on the two 12 volt circuits.

[RoadrunnerII]

Ok
Reread your original post.
Check the wiring to the trailer brakes. You may have a dead short on the brake wires from chaffing. If not the wires could be a bad magnet.
Something is sucking all the juice it can get.
My second thought is check the ground connections on trailer. Not just the one on the battery either.
Something to help isolate
Hooked up to truck with engine running. Engage the trailer brakes. Watch the engine rpm. If it drops revs and sounds like the motor loaded up its in the brake circuit likely. Make sure all the brake connection wire is solid.
It could be in the brake light circuit on trailer as well.

Any melting on the 7 pin plug plastic?
Plug loose in socket?


RoadrunnerII

[DrSmart]

Good idea. I'll get into it after our 14 day R&R. Thanks.

[DrSmart]

Originally Posted by Allen_C

Not sure about the wiring but you didn't mention the age, condition or aH capacity of the battery. The inverter only operates as long as the battery can supply appropriate amps and volts. Also, stting the inverter cutoff to 12.1v is a too low for a lead acid or agm battery. At 12.1v a lead acid battery is considered at only 36% capacity. Drawing down the battery below 50%, 12.2v, routinely will drastically reduce the battery's life and capacity.

Thanks Allen C. Understood. Had these settings temporarily to try to figure out what was happening. The drop below 12.1 was brief but at times longer than the 90 second delay before shutdown I had configured. Without the trailer brakes engaged, I wasn't going below 12.5.

[RoadrunnerII]

Originally Posted by DrSmart

Good idea. I'll get into it after our 14 day R&R. Thanks.

Finished ours last Wednesday officially. We are staying put on our property for the foreseeable future. Our son will bring us out groceries when he shops for his family. Be safe be smart.... Stay home.
This is not going anytime soon from the look of it! Corona crap
RoadrunnerII

[Jay2504]

DrSmart the very first thing to do is get the battery or batteries load tested. If you don’t have the equipment to do that, places like Auto Zone or Advanced Auto will gladly test them for you. Because the trailer brakes and the Inverter are not connected in any way, here is what could be happening. The battery or batteries are junk, (one being junk is enough if you are running 2 6volts) but the truck is putting out enough to cover the load until you come to a stop. Then 2 things happen. 1. The truck engine goes to idle slowing down the alternator, making it put out less electricity. 2. You engage the ELECTRIC trailer brakes, pulling the truck voltage down even further. Now the junk trailer batteries can’t run the Inverter. If you don’t want to go out right now because of the virus, just plug in the camper, turn on the fridge, then unplug the camper and see how the batteries do. Please let us know how many batteries and what type you have and what happens when either they are tested or you do it with with the refrigerator. Jay

[RetiredOne]

Originally Posted by Allen_C

Not sure about the wiring but you didn't mention the age, condition or aH capacity of the battery. The inverter only operates as long as the battery can supply appropriate amps and volts. Also, stting the inverter cutoff to 12.1v is a too low for a lead acid or agm battery. At 12.1v a lead acid battery is considered at only 36% capacity. Drawing down the battery below 50%, 12.2v, routinely will drastically reduce the battery's life and capacity.

Maybe that depends on how long it stays at that voltage level. If I run my coffee maker off the inverter, it can run down to the upper 11s on voltage during the perk cycle (for like 9 minutes), then comes back up into the 12s when that cycle ends. My inverter shuts down, I think, in the upper 10s 10.9?) on voltage.

Also, I think it probably be OK to run a battery down to 12.1 (which is 50% state of charge). Just don't let it stay in the upper 11s for an extended period.

[RetiredOne]

Originally Posted by Jay2504

DrSmart the very first thing to do is get the battery or batteries load tested. If you don’t have the equipment to do that, places like Auto Zone or Advanced Auto will gladly test them for you. Because the trailer brakes and the Inverter are not connected in any way, here is what could be happening. The battery or batteries are junk, (one being junk is enough if you are running 2 6volts) but the truck is putting out enough to cover the load until you come to a stop.

I agree with getting them load tested. Just because the rig is new doesn't mean the batteries are good. Many times these batteries are killed or flat lined during manufacture and sitting in the dealer's lot or at Jayco, so this will damage them. When sitting idle, it may look like they hold voltage, but under load, the voltage drops off. A load test will give a better idea on their health.

When I bought my rig last year, both my chassis battery and coach batteries wouldn't hold a charge, so they were both allowed to run down or were killed either at Ford, Jayco or the dealer multiple times. I ended up having to replace both batteries, and add a second coach battery.

1. The truck engine goes to idle slowing down the alternator, making it put out less electricity. 2. You engage the ELECTRIC trailer brakes, pulling the truck voltage down even further. Now the junk trailer batteries can’t run the Inverter.

I've seen it posted here that the wire feeding that 12 volt power to the trailer is a small gauge, and can't supply the amperage needed to power the fixtures and charge the battery at the same time. It's like only having a trickle charger instead of a true battery charger, so this could be why the truck isn't keeping the battery charged. The inverter and fridge is drawing off more than what's being put into the battery. Some people have said they ran heavier gauge wires from the alternator directly to the trailer, so they can get the higher amperage to the trailer, and bypass the smaller trailer hitch wiring.

[DrSmart]

From the Xantrexinstallation manual:
"The Freedom X uses 12-volt battery banks. Every Freedom X system is recommended to have a deep-cycle battery or group of batteries with a total capacity of 100 Ah or more which provides the DC current that the Freedom X converts to AC."

We only run the inverter while driving to power the residential fridge. I replaced the dealer's battery in December with a US 31DC XC2 rated at 130AH.


https://www.usbattery.com/products/1...s/us-31dc-xc2/


It is handling the load nicely. The problem occurs when the trailer brakes are activated. I will be checking grounds, connections and 12 volt cable gauge feeding the Xantrex. Manual recommends #2 cable from the trailer battery to the inverter.

[DrSmart]

Hi Retired One. I am considering running a heavier gauge from the truck batteries with an inline fuse.

[DrSmart]

Just ordered this meter:


https://www.kleintools.com/catalog/c...anging-400-amp


I'll finally be able to measure 12 volt DC parasitic draw and inverter draw with fridge running. It should arrive by the time our 14 days is up and we can go back to the trailer and do some testing. Should be interesting.
Also thinking of disconnecting the inverter 120 VAC output and running a cord from the inverter to the fridge, since I don't know what else Jayco has wired to the inverter output. This should prove if the inverter is functioning properly.

[RetiredOne]

Great choice on that meter. I have one like it, and you'll be able to test a bunch of different things with it. One of the best tools in the toolbox!