Inverter Issue #2

[bad99ram]

I have a 2016 Montana High Country with the residential fridge. While on the road while being towed the fridge is supposed to be able to run powered by the inverter. The inverter runs off the battery which is being charged by the tow vehicles charging circuit. The inverter keeps on kicking off. After a visit to the RV dealer who didn't know squat I contacted the manufacture of the inverter. I was told that if the tow vehicle exceeded 14.3 amps the inverter would shut off as there is a protection system built into it. I metered the charging circuit of my truck and at times it would get to 14.6 amps.
My question is Does anyone know of a way to regulate incoming power (12V) to the inverter. I have thought of disconnecting the charging circuit and just let it run off the battery. When I plug in to 120V at the end of the day the battery will recharge via the converter. Any advice would be appreciated

[cw3jason]

First I have heard of this issue. Most have the inverter cut out if they shut the truck off due to no charge and low battery, but once the truck is running, they can restart the inverter. your issue is the exact opposite. Seems to me your voltage regulator on your alternator may be faulty. If your alternator is designed to put out 14.6 volts, then you will need to put a resister down stream to lower the voltage or get a different inverter that can handle the higher voltage.

[bad99ram]

Originally Posted by cw3jason

First I have heard of this issue. Most have the inverter cut out if they shut the truck off due to no charge and low battery, but once the truck is running, they can restart the inverter. your issue is the exact opposite. Seems to me your voltage regulator on your alternator may be faulty. If your alternator is designed to put out 14.6 volts, then you will need to put a resister down stream to lower the voltage or get a different inverter that can handle the higher voltage.

Just to make sure that is the problem I am thinking of disconnecting the charging circuit before I take my next long trip in July ( about a 6 hr run). If the inverter keeps running then its a spike of voltage coming from the tow vehicle. If it kicks off again then that is not the problem.

[mhs4771]

Even if you have 14.6 Volts at the TV, the voltage loss in that charge line would drop several volts by the time it reaches the Monty.
Don't know what brand inverter is in your unit, but we have a Magnum in our SOB and it's never shut down like that and I've seen 15 volts at times in the TV, but I do have a bank of 4 Deep Cycle 12 Volt Batteries.

[cw3jason]

Originally Posted by bad99ram

Just to make sure that is the problem I am thinking of disconnecting the charging circuit before I take my next long trip in July ( about a 6 hr run). If the inverter keeps running then its a spike of voltage coming from the tow vehicle. If it kicks off again then that is not the problem.

sounds like a plan, like I said, mine will cut out if I stop and shut off the truck, usually on the second day of travel, because I have used more battery than the charger can put back in, but If I start the truck and energize that charging line again, I just reset the inverter and it will continue to run until I shut off the truck again. The inverter is meant to shut off before draining the battery fully, so when I shut off the truck it detects the drop in voltage and cuts out. this may be what is happening to you. I have since upgraded my batteries to two group 31 batteries and am hoping to get 3 days of travel out of them.

[DQDick]

One of the problems with all RV brands is that the parts are supplied by the low bidder. I'd look into a good inverter.

[bad99ram]

Originally Posted by DQDick

One of the problems with all RV brands is that the parts are supplied by the low bidder. I'd look into a good inverter.

That would be an option however trying to get at the root of the problem. Its still under warranty and they agreed (dealership and district manager) who happened to be in to extend warranty until after the next long trip. If I can narrow down whats wrong I would rather get it replaced for free.

[mjammersc]

Maybe you need to look at this from a different approach, especially as your dealer didn't provide much help. When you said you checked your trucks charging circuit you measured more than 14.6 volts (I assume you meant volts vs amps). What that at the input to the RV battery or somewhere on the truck. As was mentioned earlier, there will be substantial voltage drop between the alternator and the trailer battery. I did a quick check on a voltage drop calculator and for ~25' of 14 gauge wire you will be close to 1V drop so it probably isn't an over voltage unless you saw that right at the battery. The inverters will also shut down when the battery voltage is too low to protect over draw on the battery and also the inverter needs a min voltage to run. It may be your battery system can't keep up with the length of the trip and the draw from the fridge/inverter. Is the fridge fully at temp before the trip so it will only be periodically cycling or is it still trying to get to temp. The residential fridges are in the 700-750W range from what I have seen which converts to a 6-7A AC draw or 60-70A DC draw off the batteries. If the fridge is pulling this level of power for any length of time on typical RV batteries, you only can sustain that for a couple hours before it will low voltage cut out. Also the RV charger is a decent charger but they don't get the batteries to their ideal charge state so this limits the available usage time more. If the fridge is cold, it will only draw the power for short cycles (20% of the time as a guess) which allows the battery to sustain it more. Just some other ramblings for thought

[bad99ram]

Originally Posted by mjammersc

Maybe you need to look at this from a different approach, especially as your dealer didn't provide much help. When you said you checked your trucks charging circuit you measured more than 14.6 volts (I assume you meant volts vs amps). What that at the input to the RV battery or somewhere on the truck. As was mentioned earlier, there will be substantial voltage drop between the alternator and the trailer battery. I did a quick check on a voltage drop calculator and for ~25' of 14 gauge wire you will be close to 1V drop so it probably isn't an over voltage unless you saw that right at the battery. The inverters will also shut down when the battery voltage is too low to protect over draw on the battery and also the inverter needs a min voltage to run. It may be your battery system can't keep up with the length of the trip and the draw from the fridge/inverter. Is the fridge fully at temp before the trip so it will only be periodically cycling or is it still trying to get to temp. The residential fridges are in the 700-750W range from what I have seen which converts to a 6-7A AC draw or 60-70A DC draw off the batteries. If the fridge is pulling this level of power for any length of time on typical RV batteries, you only can sustain that for a couple hours before it will low voltage cut out. Also the RV charger is a decent charger but they don't get the batteries to their ideal charge state so this limits the available usage time more. If the fridge is cold, it will only draw the power for short cycles (20% of the time as a guess) which allows the battery to sustain it more. Just some other ramblings for thought

Thank you for your input. To clarify further , the Fridge is fully cooled down and was plugged in a 120V the entire night before. When we hit the road after we hit the first rest area usually within a 1 1/2 hr the inverter has kicked off. On our way to Florida last Oct , about a 1850 mile trip it worked just fine. On the way home is when we started to have problems. I think I will have the battery load tested to see if it is good.

[mjammersc]

Yep getting the battery tested isn't a bad idea. Also most dealers and RVs usually have dual batteries if they are using the inverter and residential fridge.

[boat391]

This is a great tread. I have solar up top and 6 6 volts and don't charge off the tow vehicle. That said I've never had a problem traveling with my inverter running. I'm very interested in hearing what may be the problem. As always everybody has given great advice. Good luck and keep us posted.

[jcurtis934]

Have to agree regarding running an inverter off of one battery...impossible unless you only wish minutes of runtime. Try two group 31 or four 6vdc battery bank.

[mhs4771]

To add to my post above, depending on make of Fridge and age, the new breed of Res Fridges are every energy efficient. Ours is a Whirlpool 20 cuft Three door and only draws 11 amps from the batteries when running.

[bad99ram]

Originally Posted by boat391

This is a great tread. I have solar up top and 6 6 volts and don't charge off the tow vehicle. That said I've never had a problem traveling with my inverter running. I'm very interested in hearing what may be the problem. As always everybody has given great advice. Good luck and keep us posted.

Did you disconnect the TV charge circuit?

[bad99ram]

Originally Posted by jcurtis934

Have to agree regarding running an inverter off of one battery...impossible unless you only wish minutes of runtime. Try two group 31 or four 6vdc battery bank.

The book states that it can run up to 12 hours off 1 battery depending on load of other things. I have ran it parked in my yard on 1 battery for 6hrs. The fridge was already cooled down prior to trying it out.

[boat391]

I do trip the breaker to the tv and satellite receiver only because when I take the dish down and reset at my next stop I have to do a full reset. I figured it isn't good on the receiver to travel without the dish hooked up.