How to test the voltage on a Casita battery

[Lisle]

I'm having some issues with the gel battery in my very new 2018 Casita. Gel battery was installed by previous owner. Camper was only taken out 3 time prior to my buying it. A couple weeks ago i was camping in Maine, temps were cold at night, I wasn't plugged in to shore power and ran my heater a fair amount for 3 days. Apparently I completely discharged the battery because even the LED lights wouldn't come on. Had frig on propane. When I lost power, I paid extra and moved to a campsite that had electrical hook up and plugged in overnight. Since then have stayed with friends at two locations where I could plug in while in their driveways. Have used power to run LED lights, a little bit of the heater, charged computer and phone and run frig on 120V, no problem.

Today I thought I'd check the voltage in the camper by testing the television outlet over the bed/back booth, which was mentioned as one way to test the voltage. I tried testing it while connected to shore power. Had my tester turned to 20V DC and it tested at 12.15V. So:

1) Am I using the tester correctly? I assume I should touch the red (positive) lead to the bottom of the outlet? And the black (negative) lead to the side?

2) Is 12.15V the right reading if the camper is plugged into shore power?

Then I disconnected shore power and retested. Meter read 11.56. What does this mean?

[Raspy]

A true battery reading of 12.15 would indicate a battery that was about 50% discharged.

You test doesn't give enough information to say for sure. If there were other loads on the battery, or on the circuit you were measuring, you would not know the true state of charge.

With all loads turned off and the battery charging, it should come up to 14.1, or so, over some time. After turning off the charger and letting the battery rest for an hour or so, it should be settled down to about 12.65-12.7. If you have a smart charger, after reaching the full 14.1, it will settle to a float charge at about 13.2 and stay there while still plugged in.

Test your battery with no loads on it. Best to test it with your volt/ohm meter right on the battery terminals, but in a remote plug.

If you have been plugged in a for a few days as you say, and the voltage is 12.15 at the battery terminals, it means you are not charging, or charging very little, and the battery is at 50%.

I suggest getting a plug in digital meter that goes into you cigarette lighter socket and stays on. You can get a lot of info from these and constantly monitor your battery. They are cheap on Amazon.

[Steve L.]

Assuming you are a new to RV-ing I'll ask a simple question; Is/was the charger turned on while testing? I'm doubting it because the reading should be over 13 volts anywhere in the 12vdc system, regardless of the state of the battery, if it is being charged. The number you're getting seems more like a battery not being charged.

I wonder if it ever was turned on.

There is a circuit on the AC side of things for the charger.

Flip the breaker off, then press it "more" off. This resets the breaker, then flip it back up (on).

[Byron Kinnaman]

I agree with Steve.

Another point. All electronic test equipment and products have tolerances. The first one is easy any and digital measuring equipment only good to ±1 in the least signifiant digit position (the one farthest to right). Then there's another tolerance usually listed at ± a percentage of either full scale or of reading. When look at the tolerances the result can be pretty big. Meaning the reading could be a long ways from the actual.

[Lisle]

Thanks for the advice above. I also called Casita and talked to a nice guy in the service dept. He confirmed that the easiest way to test the charge on the battery when not plugged into shore power is the "cigarette lighter" type of tester, which can be inserted into the television outlet over the bed (back booth). He also said the best way to test if the converter is working is within the electrical panel. (By the way for us newbies -- you have to turn the little outer part of the lock on the electrical panel cover to get it to open. No one told me that and it took awhile to figure it out.) So when the panel is open, you can see a blue wire coming over the top of the panel from the converter which is what the positive lead of your tester should touch, and two white wires coming up from the bottom, which is what the negative lead should touch. You can either touch your tester leads to the actual metal of the wires, or to metal wires where they are attached to little metal posts. Just be sure you're touching something that has electricity in it. When I did that, the reading was 13.88, which is what it should be (between 13.5 and 14 or so). Whew!

Learning what you need to know about these little campers is going to take time.

[Jann Todd]

Originally Posted by Raspy

A true battery reading of 12.15 would indicate a battery that was about 50% discharged.

You test doesn't give enough information to say for sure. If there were other loads on the battery, or on the circuit you were measuring, you would not know the true state of charge.

With all loads turned off and the battery charging, it should come up to 14.1, or so, over some time. After turning off the charger and letting the battery rest for an hour or so, it should be settled down to about 12.65-12.7. If you have a smart charger, after reaching the full 14.1, it will settle to a float charge at about 13.2 and stay there while still plugged in.

Test your battery with no loads on it. Best to test it with your volt/ohm meter right on the battery terminals, but in a remote plug.

If you have been plugged in a for a few days as you say, and the voltage is 12.15 at the battery terminals, it means you are not charging, or charging very little, and the battery is at 50%.

I suggest getting a plug in digital meter that goes into you cigarette lighter socket and stays on. You can get a lot of info from these and constantly monitor your battery. They are cheap on Amazon.

With the Casita's to my knowledge you don't turn on and off the charger. It automatically charges when plugged into shore power. We've never had to turn anything on or off to charge the battery. My question would be is there a fuse possibly blown or maybe the circuit breaker not engaged good? We plug in our Casita every few weeks to keep the battery charged during the winter and times it is not in use. So maybe the battery is shot also and won't accept a charge.

[currinh]

This may still be a valid comment. With our trailers (Bigfoot and Escape) the converter (battery charger) comes on when plugged in. I'd suggest you test the battery while not plugged into 110V and with all loads in the trailer off.

You can take the battery into a service center (probably anywhere that sells batteries) and they can test it, usually for free. If the battery was fully discharged I'd test it.

[QUOTE=Steve L.;757058]Assuming you are a new to RV-ing I'll ask a simple question; Is/was the charger turned on while testing?/QUOTE]

[Raspy]

The "switch", is the circuit breaker that Steve is talking about, in the electrical panel. I don't have a Scamp, but isn't there a circuit breaker, as Steve describes, in the electrical panel that is for the converter/charger? It is one of the switches in the panel.

The most basic trouble shooting there is, is simply making sure you have power to the trailer and that the circuit breakers are on and not tripped. They can look like they are on, so turn each one off and then back on, as Steve describes.

The fuses in that panel are for the 12 volt system. The switches, or circuit breakers, are for the 120 volt system. The converter/charger runs on shore power and is on the 120 volt side. Do as Steve describes to make sure they are set properly.

It's hard to help you get beyond that point. But the next step, if the power is on and getting to the charger, is that the battery will charge. This is where it starts to get more complicated. No charging at that point, can be caused by a number of things, but make sure the charger is getting 120 volt shore power first.

[Jann Todd]

Originally Posted by Raspy

The "switch", is the circuit breaker that Steve is talking about, in the electrical panel. I don't have a Scamp, but isn't there a circuit breaker, as Steve describes, in the electrical panel that is for the converter/charger? It is one of the switches in the panel.

The most basic trouble shooting there is, is simply making sure you have power to the trailer and that the circuit breakers are on and not tripped. They can look like they are on, so turn each one off and then back on, as Steve describes.

The fuses in that panel are for the 12 volt system. The switches, or circuit breakers, are for the 120 volt system. The converter/charger runs on shore power and is on the 120 volt side. Do as Steve describes to make sure they are set properly.

It's hard to help you get beyond that point. But the next step, if the power is on and getting to the charger, is that the battery will charge. This is where it starts to get more complicated. No charging at that point, can be caused by a number of things, but make sure the charger is getting 120 volt shore power first.

This post is about Casita's which is what that person was asking about and that is also what I have. Scamps may be totally different. I've never had electric problems and didn't think about the switch being a circuit breaker. It sounded like Steve meant it was a switch that you turned on and off to charge the battery. Some RV's have on and off switches to turn the 12V on and off like in my motor home.

[Steve L.]

On my Casita, the charger circuit of the converter is on an AC circuit breaker. I leave it on all the time so that the battery is charged (if necessary) whenever I plug in. There is no reason to flip off the breaker unless you're working in that area

But, breakers trip sometimes. Since he said he was plugged in and only reading 12 something volts there was a chance the breaker was off (or tripped) and no charging was going on. (There is also the chance he wasn't measuring correctly but I gave him the benefit of the doubt.)

Whether the charger is on or off there should be some DC in the trailer unless the one or both of the 30a fuses have blown. (The two green fuses above the others in the box, bottom photo of the DC portion of the box).

Top photo is of my AC breakers. In this case, the last position, A.C is the air conditioner circuit.

[Lisle]

Thanks for all this information. I did check the circuit breakers and the one for the converter was on. Further testing of the converter wires per Casita service guy showed adequate charge. I have ordered one of those 12V testers that plugs into a cigarette lighter. From now on I hope to test the level of the battery's charge by plugging in that tester into the television plug over the back booth.

[Raspy]

Originally Posted by Lisle

Thanks for all this information. I did check the circuit breakers and the one for the converter was on. Further testing of the converter wires per Casita service guy showed adequate charge. I have ordered one of those 12V testers that plugs into a cigarette lighter. From now on I hope to test the level of the battery's charge by plugging in that tester into the television plug over the back booth.

Good plan.

If you have two cigarette lighter sockets, you could just leave it plugged into one of them all the time. Or get a splitter and leave it plugged in all the time. They use very little power and give you a constant reading that provides a lot of information.