House Batteries not holding a charge, new batteries

[coachrb]

My House batteries are not holding their charge for some reason.
Even though I am using it frequently I still turn the power off when I'm not using it for a few days.
Still, when I enter the RV the lights are dim with a little flicker. I'm not able to start my generator as the lights will all but go out when I try
1. If something is constantly pulling juice from the batteries, what could it be?
2. Could the house batteries be connected improperly?
3. When I turn the house batteries off when not using for couple days, is it really killing the power?

Now, when I turn on the ignition and let the engine run, in a minute or so, the lights will come on bright like they are suppose to. If I turn the engine off, it's about 15 minutes and the house lights will dim with a little flicker.

I've attached to pics showing the difference in V total with and without the engine running.
Thanks for any help you can provide.
Randy

[Morich]

This is one of those frequent problems but somewhat easy to explain.
When speaking of the coach batteries which feed both the inside lights as well as start the generator, there are "parasitic drains" which do use power ----even when we turn the disconnect switch off!
The designers are worried about us to the point that they do not turn off some safety items, like the porpane and CO detectors! It is common for them to be left on, so a small check may verify this.
Check to see if they have small led lights on them and it stays on when you disconnect at the switch? Suspect that to be true.
So when you buy an RV off a lot, there is an almost 100% chance the batteries are damaged as they do not go around and put a charger on everything on the lot and all batteries go down ---until they want to show the RV and THEN they jump start it enough to show it!

Parasitic drains on the start battey are ignition and radio presets, etc! Not a lot on either but enough to run down over time.

The natural state of a fully charged good lead acid battery is near 12.8 and anything above that is just showing that there has been recent charging as lead acid will not support any higher for long.

[DavidM]

Randy:

Parasitic RV loads are the bane of all of us who store our RV in a place where AC power is not available to keep the batteries charged up fully. My Thor Axis motorhome draws 0.05-0.10 amps while sitting with the battery switch disconnected. As creativepart notes above, these loads are for things like CO detectors which stay connected whether the battery switch is in or off.

You could try tracking down these obnoxious tiny loads. You will need an accurate DC clamp on ammeter to trace wire and measure the DC drawn. These can be bought on Amazon for about $80 for a decent one. See https://www.amazon.com/Klein-Tools-C...%2C705&sr=8-20

Or you can install a 50-100 watt solar panel and pretty well forget about it. My Thor Axis came with a 100 watt roof mounted panel, but in wintertime snow can cover the panel. So I temporarily hook up a 50 watt panel that I set on the south facing bumper and run cable to the installed solar controller. You could do the same with a solar panel kit. Renogy and others sell them on Amazon.

BTW, your batteries are probably toast after sitting for a few days fully discharged.

David

[creativepart]

The sad truth is if your house batteries truly are below 9 to 10 volts then they are ruined. No need to mess with them further.

The 14v reading is just the charge voltage and it's what you'll see with the engine running, the generator on or plugged into shore power.

We don't know what RV you have (year, model, floorplan) and we don't know what kind of batteries you have and how many. Could you please provide that info?

About what might be the cause for the issue we need to know a few more things. Like: how old are those batteries? How long have they been drained like that. How long was the RV in storage? And, are you turning off the battery disconnect (switch or solenoid) when you park the RV? If you have an inverter are you sure that you have it turned off when you put the RV into storage? Even 24-36 hours of leaving the inverter turned on will totally deplete your batteries.

If you want to try to resurrect those batteries then be sure that the cable connections are clean and tight. If they are Flooded make sure they are all topped up with distilled water. And, then leave the RV plugged in to shore power for a day or more to let the converter or inverter/charger fully charge them back up.

Then even if they display the correct voltage, 12.7v would be fully charged, unplug the RV from shore power. Turn off everything including battery disconnect and inverter and see how much the voltage drops over the next 24 hours.

That will give you a clear indication of how damaged the batteries are. If they fail to hold a charge just pull them out and put in brand new batteries and keep them in better shape.

[Morich]

For any newish folks who might read this later, there is a big note to keep in mind when shopping. If the person wants to start the engine and leave it running while you look it over, that may look like he is justletting you see the engine runs good.

Or he may know that the engine running will connect the start and coach batteries together and that lets the engine alternator cover up the fact that the coach batteries are probably bad!

If you want to get good coach batteries, try turning on a few things like lights and vent fans BEFORE the engine is started and then if the batteries are dead, talk trade from a point of knowing what's up?

[DavidM]

Morich:

You are absolutely right. Even RV mechanics will try to cover up bad batteries while doing a PDI. Last year I was doing a PDI of a 2012 Winnebago Via. Several problems were building up and it was obvious that the dealer had done nothing to prep the MH for sale.

The batteries were reading 12.4 when I turned on a few lights and fans. The voltage dropped to about 12.1. The mechanic conducting the PDI said that anything more than 12.0 was ok.

After that BS statement, I didn't pay any attention to him. He tried to cover up the bad batteries by starting the engine and noting that the coach battery voltage jumped up to the 13s.

I didn't buy that MH. Too many problems. Little did I know that a new MH would have even more problems!!!

David

[creativepart]

Originally Posted by DavidM

Several problems were building up and it was obvious that the dealer had done nothing to prep the MH for sale.

I have come to the opinion that dealers do nothing to review nor correct any known problems when a new "unit" comes in. To us, these are RVs but to sales people they are "units" to be passed off to some sucker.

I don't know this to be the case, but I suspect they cannot get reimbursed by the manufacturer for time and parts used to get a RV ready for sale. That they only get reimbursed for warranty work done for a customer that owns the RV.

In 2020 we were in Tucson for the winter. We went to the La Mesa dealership that's across the street from out campground entrance to look at Class A diesel pushers. They had two brand new Winnebago Horizons there. They were very anxious to sell these and even offered to take our Adventurer in trade at our full purchase price from 2017. Anyway, the two Horizons both had the exact same piece of wood trim missing from the valance and sitting on a sofa. When the salesman showed it to us he said they had just arrived and he was going to get that fixed ASAP. As a FYI, the trim in the Horizon is glossy bent wood from a manufacturer in Italy.

Then last year, we had a member join here with a new Horizon. I mentioned this story and he said, "Small world, I bought one of those Horizon's and that piece of wood trim was still sitting on the sofa when I viewed the one I purchased.

So, a $380,000 RV comes in with a piece of wood missing and they have the missing piece and all they have to do is reinstall it. And, even though it makes the RV look horrible with a gaping hole in a beautiful section of sweeping Italian cabinetry they just leave it that way.

Trouble is, I don't think this is unique to any dealer or manufacturer.

[puttin]

After the o.p. gets his new batteries he should install a manual disconnect at the batteries.