Dead Battery: Please help!

[Julie and Jose]

Hello. I am hoping you can help me solve this problem. We took our relatively new-to-us 2008 Scamp 13 for our first longer-than-a-weekend trip. The battery died after the 3rd day. When we returned home, we took the battery to a shop to get it charged. We were told the battery was old and should be replaced. We brought a brand new fully charged battery home and put it in the trailer. Now, just two days later, that battery is also dead. What could be going on? What should we be checking? Thanks in advanced for any help you can provide.

[sokhapkin]

Check if your tow vehicle has 12V on the trailer connector when the engine is on. Also there could be a burnt fuse in the battery wiring.

[Darwin Maring]

If that first battery lasted 3 days, then I think you had a good battery.

If it had removable access to the cells, you could have checked it with a hydrometer that costs less than $10 at places like Northern tools and auto parts stores like Advance Auto. You charge the battery then check each cell with the hydrometer and it will tell you the condition of each cell. That is one way to determine the condition of the battery regardless of the age.

Suggestion: Purchase a battery charger at places like Sears, Advance Auto. You don't need the most expensive one either.

[tractors1]

Sure the fridge isn't on using 12V?

[The Minimalist]

Question: Are you trying to run an AC/DC/LP refrigerator on DC. If so, that is probably the issue. They run on resistance heat in AC and DC mode. DC mode is a battery killer, even if the TV is providing charge voltage to the battery while traveling.

You would do well to buy a few pieces of basic electrical test equipment. As a trailer owner you will find many uses for them over the years and likely save yourself some money over time.

You at least need the battery hydrometer to test cell condition, but you should also invest in an inexpensive digital volt-ohm meter. You might also consider a basic 12 volt test light, the kind with an alligator clip on one end and a wire probe (read ice pick thingey) on the other.

The first thing you want to do is check for parasitic loads. With all the switches in the trailer off and disconnected from AC, disconnect the negative post of the battery and put that volt meter between the cable clamp and the post. With everything off, you should read no voltage, with one caveat. Safety equipment, such as CO, Propane, smoke detectors that run off of the battery are constant voltage drains. Disable these first. If you do have voltage on the negative side of the battery, you have something drawing power somewhere. Start pulling 12 volt fuses, one at a time, until the voltage goes away. That will be the leg where the leakage is, and will localize the problem or further testing.

Some folks try to do this with a 12 volt test light, but most come with a bulb too strong to find smaller leakages.

Does your trailer have CO, propane, smoke detectors etc. that are powered by the battery. These are constant drains.

What have you been doing the charge the battery?

[Julie and Jose]

Thanks all for helping.

We are not running the refrigerator on battery.
We do not have any detectors running off the battery. They each have their own 9v battery.
We charge the battery when we drive or when we are connected to shore power.
We have a meter to check the voltage.

Here's what happened:
1. A brand new battery that was fully charged was purchased on Tuesday and installed late afternoon Tuesday.
2. The 12 volt lights were tested. They worked. We turned them off. Nothing in the trailer was turned on.
3. Then the trailer was plugged into the 110 power (regular outlet) from my garage.
4. By Thursday morning, the brand new battery was was dead.

When we connect the car to the battery with the engine running it reads 13.5. Drops when the engine is turned off and still connected.

So...could this be a bad converter?

We had torrential downpours this afternoon and evening so my husband could not follow all your debugging recommendations. Hoping to do some more debugging tomorrow!

[sokhapkin]

13.5 volts at which point? On battery terminals?

[Julie and Jose]

We read it on a meter plugged into the 12V socket. (we also have a multimeter)

[sokhapkin]

Check the voltage on the battery instead of 12v socket.

[Julie and Jose]

What's the difference? Wouldn't the drop be tiny?

[sokhapkin]

There should be no difference, that's why I suggest to check.

[Julie and Jose]

ah! got it!

[Carl Pa]

Is your converter plugged in ?

[Julie and Jose]

Thank you. Certainly going to check first thing in the morning. We got 5 inches of rain in 1-2 hours tonight! That put a stop to our troubleshooting.

[Gerry Kiernan]

Did you have your fridge operating off either propane or 120 volts? Just a shot, but many newer fridges have a heater element in the frame of the freezer compartment. This element is operating all of the time the fridge is running, unless it is switched off. The switch is in the frame above the freezer compartment door.

[dkas]

Unless you actually ENJOY "the hunt", just take your trailer to a good RV shop and pay them to check this out. After all, you've already spent a fairly large bill on a NEW battery. Get it over with, and learn from what they tell you.

[Julie and Jose]

We didn't use the fridge. We still can't get it to work on propane. LOL. It used to light but not get cold. We cleaned the jet and now it doesn't even light! Oy vey.

Don't have a freezer either.

[Darwin Maring]

Go to Advance Auto where they do FREE battery testing and get it tested.

[Larry G.]

Originally Posted by Julie and Jose

Thanks all for helping.

When we connect the car to the battery with the engine running it reads 13.5. Drops when the engine is turned off and still connected.

So...could this be a bad converter?

When you check the battery with a charge source connected (either the tow vehicle or shore power/garage), your reading will reflect the voltage being SENT TO the battery, NOT the actual charge state of the battery. Only way to accurately check the charge state of the battery is to disconnect all cables and check with a meter at the posts.

This, of course, means that the readings taken while connected to a running tow vehicle and those taken while disconnected from any charge source SHOULD be different.

[Julie and Jose]

Well, it looks like we might have found problem #1 thanks to Carl Pa. The converter plugged had wormed its way partially out of the outlet, probably due to all the bumps on the road during our extended trip. It is now seated firmly in the outlet and we have 12v lights when plugged into shore power. Yay! The converter is still working...maybe....

We think we may still have a drain on the battery, though. So we will charge the battery and then disconnect from shore power to see what happens.

And yes, we have a multimeter. And yes, we know the battery is good. (Took the old one to the battery store to be tested. It was on its last legs. Replaced with a shiny new one.)

Appreciate all the help! We learn new things every day thanks to this great community.