911 - Charger Death?

- All 120 volt equipment is working.

- Woke to a frigid rig this morning by the furnace fan coming on and sounding weird (pretty sure running on low voltage). I hit the thermo button and the light was dim but it did shut the fan off.

- Currently the thermo is still dim lit but nothing that needs it will work so no heat strip or furnace; brrrrr. I've got a 120v heater running the front with the divider curtain closed so we're warm and can cook breakfast and COFFEEEEEEE!! yay

- The (piece of crap MaxxFan) in the front was on too and definitely on low voltage. I had to pull the fuse to the front of the rig to shut it off as it ignored it's own power switch (something it's done since new).

- Some of the 12 volt lights would try to come on but those that will are dim.

- The batteries are old and need replacing. I put a battery charger on them on boost and that did raise the voltage some as more lights would come on but all are still dimmer than they should be.

- I haven't tested the voltage yet but it will just confirm something I already know.

- The inverter control panel isn't working. I checked it with no results but when I returned to it later it stopped when I pressed the power button.

- Recycling shore power had no effect.

- The 'use' button by the door has no effect. Note the red light is on and doesn't extinguish by pushing the button on/off as it should.

First task is I'll replace the batteries with known good or new and see if that helps or resolves the problem. The battery light/gauge behind the driver seat shows 50 percent but is dim.


Any clues folks??

Additionally.

Had to reset the external battery charger I put on the batteries and it has two gauges on it. One is reporting the batteries are good and the other says there is no charge being accepted/applied.

I've never trusted the good/bad indicator but I've never seen a battery on charge not indicate 'some' level of charge by the second gauge.

Possible charging to batteries in parallel could cause that? I'll have to pull them to know if one is bad and one not.

Will know the answer to the battery issue if any in a couple of hours.

Check the wiring near the metal connector to the battery posts. Years back ours had started to separate right at the connector/battery terminal clamp. It looked OK until you shifted it.

Take the negative cable off the batteries.  Does the shore power now work normally?  If so, one or both batteries are dead.

Batteries in parallel is generally not the best idea.  When the batteries are new, it's fine but overtime, one battery will start to lose it's capacity and it will drag the other battery down with it and cause the problem you are seeing.

The simple fix, is get a larger single battery. Also make sure the batteries are "deep cycle" batteries, nor "starting batteries"

Personally, I use 2 high capacity 6v AGM  batteries in series instead of a huge 12v or 2 12v batteries wired in parallel.  I use 2 Lifeline GPL-4CT 6v AGM batteries wired in series to get 12v output.

Check the wiring near the metal connector to the battery posts. Years back ours had started to separate right at the connector/battery terminal clamp. It looked OK until you shifted it.

Thanks. Will check them carefully when I replace the batteries. They're well overdue any way.

Take the negative cable off the batteries.  Does the shore power now work normally?  If so, one or both batteries are dead.

Shore power is working fine now. Only 12v systems are affected.

I use deep cycle. I'm not traveling much so not keen on the AGM expense.

These two are way over due for replacement so we'll see shortly if it's a battery issue.

Oky Dokey.

Volt meter applied to batteries while connected:
6.1v

Volt meter applied to each battery uninstalled:
11.8
1.0

I'm off to the battery store.

Pic of what's been in there and working since 2019 (yeah yeah I know  ).

Parallel or Serial????

This is how the rig came wired.

That's parallel. 2 12v batteries

Oky Dokey.

Volt meter applied to batteries while connected:
6.1v

Volt meter applied to each battery uninstalled:
11.8
1.0

I'm off to the battery store.

Pic of what's been in there and working since 2019 (yeah yeah I know  ).

And there is your problem.  One of the 12v (measuring 0 volts) is bringing the other battery down to 6v

As I noted in earlier post in a parallel setup, the weakest battery will drawn down the stronger battery

Bought the same model batteries. Installed.

The dead ones provided almost 5 years of full timer service. That's good enough for me and only $112 dollars each at Advanced Auto.

All is well.

Thanks for all the input!!!

Personally, I use 2 high capacity 6v AGM  batteries in series instead of a huge 12v or 2 12v batteries wired in parallel.  I use 2 Lifeline GPL-4CT 6v AGM batteries wired in series to get 12v output.

I have the same as donc13, two 6V AGM batteries, though I bought ours back in 2015 at Sam's CLub for about $183 each.  They remain in good service today.

Like donc13 says, a pair of 12V batteries will be only as good as the worse one as it brings down the better one.  In an emergency situation as you found yourself in, determine which battery is the worse of the two and take it off-line, then try to reawaken the better battery by itself and live with one battery until you can replace both.  That will get you through your difficult situation.

My experience with two different pairs of 12V wet acid batteries is that we got only 2 good years, one marginal year, and one problematic year.  Our pair of 6V AGM batteries is coming up on 10 good years.

One practice I have been doing for some years now is when not using our PC, I disconnect all the batteries from the house and chassis, charge them until full, then forget about them until it's time to use the motorhome.  When it's time to use our PC, I charge the batteries back to full which happens quickly, reconnect, and all is well.

I used to keep the batteries connected and maintained them on occasion but found that to be a lot of work with occasional gaps of forgetfulness.

My earliest years was keeping the rig plugged into 120V with the on-board inverter maintaining the batteries.  That was the worst.

I learned every wrong way on battery maintenance.

This has been a great learning experience for me.

Note I did say that I've been full-time on these two flooded batteries. There's been zero storage time on them since they were new in 2019. I can't fault them in any case. I might could have used the one that checked in at 11.8 volts a while longer but I'd be worried about the thing all the time.

I wasn't aware AGM batteries could be purchased for $183, my ignorance there, although Donc13 uses GPL-4CT 6v AGM batteries which a quick Google come in around $400 each.

My understanding of this 12v system has risen a bit. I didn't think battery death would affect the rig while on shore power since it has a charger outputting 12v 24/7. Can someone explain why that is? If I have a constant 12v source why do I even need batteries in the circuit?

I wasn't aware AGM batteries could be purchased for $183, my ignorance there, although Donc13 uses GPL-4CT 6v AGM batteries which a quick Google come in around $400 each.

Keep in-mind that I bought my pair of 6V AGM batteries nearly 10 years ago.  Prices go up on everything.  I have no idea what Sam's Club sells them for today.

Full-timing 5 years on a pair of 12V wet acid batteries?  You did great!  Maybe you broke some kind of record.

You should not run off 12V from the inverter/charger without at least one battery in the 12V circuit, whether it be a good one or one needing replacement.  I can only guess why.

The converter, not the inverter, is what charges the batteries.  You can disconnect the 12v batteries when plugged into shore power or running the Genset. 

As to why the bad battery caused problems when plugged in on shore power is because the converter/charger can not overcome the loss due to one of the batteries essentially being shorted out. Flooded cell batteries lose water when being charged.  Letting the water run below the top of the lead plates in the battery causes the plates accumulate corrosion and eventually short out.  Even if you keep the batteries always full of water, no chemical reaction is perfect inside a battery and the plates and the electrolyte eventually weaken and you lose battery capacity.