Full Chassis Batteries until unplugged

[BaldDaddy]

Good afternoon. Sitting here at a campground in Savannah having a problem that I am hoping someone can shed some light. House batteries showing 14.3v, on an absorb charge, when plugged into 50a shore power. Within 3-5 minutes of unplugging voltage drops to 12.5v quickly on the way down to the high 11’s not even able to engage the charger nor turn over the generator. Doesn’t seem like roof solar is doing much of anything. Batteries worked fine on the trip up here but wife unknowingly ran the microwave without the generator and drained the batteries. Electrical is not my fortè. . Any help is appreciated.

[brobox]

It sounds like one or more of the batteries have shorted out. Take a volt meter and check each battery. Check them while plugged in, then again 10 minutes after unplugging. If there is a big difference on each battery, it has a problem.

[LWBAZ]

Eric, you wrote “chassis batteries” but the battery voltage displayed on the Vegatouch screen in your photo is from the “house” batteries. Chassis batteries are the ones that start your engine. House batteries are the ones that provide power to your water pump, interior lights and other 12 volt DC loads, and they also provide power to your inverters.

On your coach, the chassis batteries are located in the last basement compartment on the passenger side of the coach, while the house batteries are located in an enclosed compartment just behind the second of your two basement storage trays.

Regarding what you’re seeing, a couple of questions:

1) How long was the microwave running? If only a few minutes, that shouldn’t be a problem for healthy house batteries.

2) How long were you plugged into shore power when you unplugged and noticed the batteries dropping to 12.5 volts? I’m asking this question because…

If we assume your house batteries were deeply discharged by, for example, running the microwave off of the house batteries (via the inverters) for an extended period of time, it will take several hours of charging to bring the house batteries back up to full charge.

Lastly, with your coach being a 2018, it could well be that your factory-installed made-in-China Discover house batteries are shot or very nearly so. Like you, I have a 2018 Cornerstone. Ours was built in mid-2017 and delivered in October 2017. My Discover house batteries needed to be replaced in mid-2019, so they didn’t even make it two years. I replaced them with higher-quality Lifeline batteries, which I expect will last significantly longer.

[BaldDaddy]

My apologies. Stressful morning. You are correct that I misspoke. Referring to the house batteries.

[wolfe10]

One or more batteries are bad.


If over a couple of years old, replace all of them.


If newer, fully charge, separate and load test them individually. If they are wet cell, you can also fully charge and with a battery hydrometer (under $10) check their Specific Gravity.


What is happening is that the charger is providing the voltage when there is a source of 120 VAC. When no source, it is normal for the batteries to fall from low to mid 13's to 12.7- 12.8 and stay there as that is voltage for a fully charged battery AT REST.

[LWBAZ]

The house batteries in a 2018 Entegra Cornerstone are sealed AGM batteries.

Below are some photos of what mine looked like after less than two years. Not good!

[BaldDaddy]

Originally Posted by LWBAZ

1) How long was the microwave running? If only a few minutes, that shouldn’t be a problem for healthy house batteries.

2) How long were you plugged into shore power when you unplugged and noticed the batteries dropping to 12.5 volts? I’m asking this question because…

If we assume your house batteries were deeply discharged by, for example, running the microwave off of the house batteries (via the inverters) for an extended period of time, it will take several hours of charging to bring the house batteries back up to full charge.

That is what was odd. She only ran the microwave for 3 minutes before everything on the coach's electrics went wonky. I was on 50A since Friday and unplugged this morning to head out when I noticed the immediate cave. I guess its possible that this quick discharge fried the battery that was otherwise working fine?

Larry - Did you change out the house batteries yourself? I know they are rather heavy and in a very inconvenient location but am not averse to some heavy lifting to get the job done. Just don't want to fry myself nor any components.

Thanks!

[BaldDaddy]

Looks like I have 4 of these in the basement.

[MRUSA14]

Originally Posted by BaldDaddy

She only ran the microwave for 3 minutes before everything on the coach's electrics went wonky. I was on 50A since Friday and unplugged this morning to head out when I noticed the immediate cave. I guess its possible that this quick discharge fried the battery that was otherwise working fine?

Three minutes of microwave would not harm a good set of batteries. Most likely your batteries were barely functional and this pushed them over the edge. If you replace them, I strongly suggest Lifelines. They cost a bit more but they go and go and go for many years.

[LWBAZ]

Originally Posted by BaldDaddy

Looks like I have 4 of these in the basement. Attachment 309142

Your coach was probably built a little after mine. In that time frame, Entrega switched from the Discover brand of batteries to the Relion brand. Not much difference as both brands are made by the same company, probably in the same factory.

P.J. Clanton (long-time Entegra employee & Travel Supreme before that) told me the two brands are virtually equivalent and the only reason Entegra changed brands was that they were able to get slightly better pricing on the Relion brand.

Your batteries don't appear to be swollen up like mine were, but that alone doesn't guarantee that one or more of them isn't bad.

[BaldDaddy]

The story gets more convoluted. Just tested both 12v sets. 12.5v, and 12.4v after a few minutes disconnected from shore power. I am unable to press the charger buttons on the Vegatouch as both go ghosted when disconnected and engine running saying “not charging”. Battery set 2 goes from 12.4v to 10.5v in the blink of an eye while set 1 is holding at 12.5v. The Battery Boost does nothing to assist in jumping the generator. Shouldn’t the inverters charge the house batteries when disconnected and engine running?

[LWBAZ]

Originally Posted by BaldDaddy

Larry - Did you change out the house batteries yourself? I know they are rather heavy and in a very inconvenient location but am not averse to some heavy lifting to get the job done. Just don't want to fry myself nor any components.

Eric, yes, I did change out the batteries myself. And yes, they're heavy and the location is inconvenient. It's a do-able job, but not a lot of fun.

If you decide to do your own battery replacement, start by turning off the big rotary disconnect switches on the passenger side of the coach, outboard from the battery compartment.

As you’ll see, there isn't a lot of "headroom" in the battery compartment, so it’s not possible to take a viable photo of all the cabling before you start removing cables. The best approach I could come up with was to draw a diagram of the four batteries, as if you were looking down on them from above. On your diagram, label the four batteries: #1, #2, #3 & #4. From there, each time you detach a cable, label it to indicate which battery and which terminal of that battery (positive or negative) it was attached to. For example 1+ or 1P = Battery #1, Positive terminal. 1- or 1N = Battery #1, Negative Terminal. And so on.

Rather than try to write on each cable, I used small 4” nylon ties like those in the photos below. Black ones were easy to come by; red not so much. So I used white in place of red. The idea being that if I removed a cable from the negative terminal of Battery #3, I attached three black zip ties to the end of that cable. And if I removed a cable from the positive terminal of Battery #2, I attached two white zip ties to the end of that cable. I’m not saying you need to label your cables any particular way; just be sure to label each & every one of them to avoid confusion when you reconnect the cables to the new batteries.

Because of the limited headroom in the battery compartment, you’ll have to disconnect the cables from the two forward batteries first, then remove those two batteries to gain access to the cables on top of the two aft batteries. Same thing when installing the new batteries – put the two aft batteries in place and connect their cables, then put the two forward batteries in place and connect their cables.

Any questions or confusion, feel free to ask.

[LWBAZ]

Originally Posted by BaldDaddy

The story gets more convoluted. Just tested both 12v sets. 12.5v, and 12.4v after a few minutes disconnected from shore power. I am unable to press the charger buttons on the Vegatouch as both go ghosted when disconnected and engine running saying “not charging”. Battery set 2 goes from 12.4v to 10.5v in the blink of an eye while set 1 is holding at 12.5v. The Battery Boost does nothing to assist in jumping the generator. Shouldn’t the inverters charge the house batteries when disconnected and engine running?

No,the inverters can only charge your house batteries when shore power or generator power is present.

When the engine is running, the house batteries can receive charge voltage from the engine's alternator, but only after a device called a Battery Isolation Manager (BIM) makes a connection between the chassis battery bank and the house battery bank.

[LWBAZ]

Originally Posted by BaldDaddy

The story gets more convoluted. Just tested both 12v sets. 12.5v, and 12.4v after a few minutes disconnected from shore power. I am unable to press the charger buttons on the Vegatouch as both go ghosted when disconnected and engine running saying “not charging”. Battery set 2 goes from 12.4v to 10.5v in the blink of an eye while set 1 is holding at 12.5v. The Battery Boost does nothing to assist in jumping the generator. Shouldn’t the inverters charge the house batteries when disconnected and engine running?

Sounds pretty definite that you have at least one bad battery among the two you're referring to as Battery Set 2.