Low Battery Mystery

[Machine99]

I went to turn my inverter on for a couple hours to get the refrigerator chilling before we head out today, but when I went to turn on the inverter there was a "Low Battery" message and fault light on.

We were just at a full hookup campground last weekend and were plugged in the whole time. It was only a 30 minute drive home. I always use the mechanical disconnect on both the house and chassis batteries and they were definitely disconnected. The panel said the house were down to 10.6 volts.

Also, the batteries are only 6 weeks old.

What could cause this? Am I doing something wrong? Could there be something connected to the batteries before the disconnect drawing current?

Many thanks!

[jacwjames]

Did you happen to notice what the state of charge was when you isolated the batteries. Are you sure they were fully charged.

Probably time to get out the voltmeter and check readings to make sure your charging system is working as it should.
If you have an amp meter it might be worth checking what the parasitic draws are both with the disconnect open and closed.

I have 325 watt solar charging and found that I have to turn off the salesman switch for me to maintain charged batteries. I can leave the disconnect switch on though.

[Machine99]

Originally Posted by jacwjames

Did you happen to notice what the state of charge was when you isolated the batteries. Are you sure they were fully charged.

I did not check the voltage when I isolated the batteries. They should automatically be charging when I plug into shore power correct? I shouldn't need to do anything?

I will keep an eye on it this weekend and see if they are charging when plugged in, check the voltage when I disconnect the batteries, then if they still drain in a week, whip out the amp meter.

Another question, does running the engine charge the house, or just the chassis batteries? And does the generator charge the chassis or just the house batteries?

[jacwjames]

Time to pull out a wiring diagram. I am not familiar with your coach so can't comment.

In my case my alternator will charge the chassis battery until it gets to ~13.4 volt and then start charging the house batteries. If plugged both my batteries stay charged but I have to leave the disconnects on since my inverter also charges the batteries and would be isolated if I closed both disconnects. My solar charger charges both batteries independent of the rest of the system.


I have a complete set of wiring diagrams for both the house and chassis. I still have to pull them out to check specific issues. Just did that now to respond to your question.

[YC1]

Both banks should charge from the alternator.

Even though most circuits are shut off by the cutoff switches in the battery compartment not all are. However, in a week you should have had plenty of power.

That said, running the fridge on AC power via an inverter could take quite an initial surge of power and may pull the batteries down for a a few seconds.

As mentioned, you do not know for sure what the battery state was when you shut them off..

If you have a problem with the alternator path charging them and you arrived home with a less than full bank you could have a problem.

It is time for you to become extremely familiar with how your systems work when they are running properly. Take pictures and write voltage readings on them after printing. Put the pictures in page protectors and keep in a handy place.

Post some pictures of your battery compartment when you can.

Your charging system is programmable so did you have it set up correctly? You could have set it at say 10% and then your batteries may never have been fully charged.

Lots of variables here. You need voltage measurements across the batteries before and after charging.

Your engine batteries should charge while on shoreline as well.

[txcpl]

You mentioned that the batteries are only 6 weeks old. That is the first variable I would be checking. Check each connection for cleanliness and properly tightened as well as battery water level and voltage check on each battery as there could be a bad cell.
Good luck and keep us posted.

[twinboat]

When did you switch the disconnects to off ?
While on shore power and driving or when you left it in storage ?

Why did you replace your house batteries ? A 2017 is not that old, unless batteries are mistreated.

All disconnects stay on at campgrounds and driving. The only time to switch them is while being left in storage.

Shore power and generator power are the same to the RV. What one does, the other does. The RV doesn't know the difference.

While driving, the alternator charges all batteries. If the house isn't being charged, something is wrong.

In a 2017 RV, the inverter/charger should be charging both the house and chassis battery, while on shore or generator power.

[Tha_Rooster]

If I understand you have been running MH just off batteries for a week? Do you have original fridge if so why not use gas? What was voltage when you unplugged? Why not run generator?

[hohenwald48]

Originally Posted by Tha_Rooster

If I understand you have been running MH just off batteries for a week? Do you have original fridge if so why not use gas? What was voltage when you unplugged? Why not run generator?

2017 Phaeton comes standard with a 3 door residential refer. The Phaeton 44OH doesn't even come with a propane tank.

[Machine99]

Originally Posted by twinboat

When did you switch the disconnects to off ?
While on shore power and driving or when you left it in storage ?

Why did you replace your house batteries ? A 2017 is not that old, unless batteries are mistreated.

All disconnects stay on at campgrounds and driving. The only time to switch them is while being left in storage.

Shore power and generator power are the same to the RV. What one does, the other does. The RV doesn't know the difference.

While driving, the alternator charges all batteries. If the house isn't being charged, something is wrong.

In a 2017 RV, the inverter/charger should be charging both the house and chassis battery, while on shore or generator power.

I had the dealer replace them when I purchased the rig. I didn't know their condition or how long they sat unused. They tested them and said they were borderline. So I had them replaced.

I only disconnected when I got back to the storage facility. We were plugged into 50 AMP all weekend. I did not run the generator on the way back to storage, but it was only 30 minute drive.

After camping the past weekend (also plugged into 50 AMP all weekend) i disconnected after parking at the storage lot again. The panel indicated house at 13.0 and chassis at 14.1 before I disconnected. I'll be back up there Thursday. Hopefully they wont be dead again.

[Machine99]

Originally Posted by Tha_Rooster

If I understand you have been running MH just off batteries for a week? Do you have original fridge if so why not use gas? What was voltage when you unplugged? Why not run generator?

We were at a campground for 2.5 days plugged in the whole time. Drove back to the storage facility, parked, disconnected batteries with mechanical disconnect, came back 5 days later and they were dead. Its a residential fridge.

[Ljwt330]

Originally Posted by Machine99

We were at a campground for 2.5 days plugged in the whole time. Drove back to the storage facility, parked, disconnected batteries with mechanical disconnect, came back 5 days later and they were dead. Its a residential fridge.

Just a question because I am not familiar with inverter use, but is the inverter also disabled when the battery disconnect is OFF? If not, could you have left the refrigerator ON and that drained the batteries through the inverter?

[Machine99]

Originally Posted by Ljwt330

Just a question because I am not familiar with inverter use, but is the inverter also disabled when the battery disconnect is OFF? If not, could you have left the refrigerator ON and that drained the batteries through the inverter?

That is a good question. I just assumed when I kill all the batteries it turns off everything including the inverter?

[bigchick]

many, many inverters are wired directly to the batteries and are not disconnected when the battery disconnect switch disconnects the batteries from the house loads. it is easy to check if this is the case.