I need battery basics

[Stefrobrts]

Ok, I've been reading the battery info on the forum all morning, and my head is spinning. I need just the basic info. I'm not very electrically inclined, thinking about this stuff makes my head hurt!

I have one type 27 deep cycle battery in the Caravel, purchased May '98. It gets charged with the original Univolt. I checked it with an analog multimeter, and it says it has 12v on it now. I plugged it in and the guage swung up to about 13v (I'm wishing I'd bought a digital one now). The label on the Univolt says it charges at 13.5v.

So I'm wondering what do I need to do to maintain the battery - anything? How will I know when it's going bad and needs to be replaced? The only 12v items in my trailer are the lights, everything else runs on propane, so battery usage is pretty light, and while at home I keep it plugged in most of the time so it will be ready to go. I was surprised when we had to plug in on our last trip because the battery was now sufficient to keep the lights on bright.

How many years can I expect to get out of a battery, and is there something I should be doing to help it last longer?

[robandzoe]

Stephanie,

Is the Type 27 the size of battery made for the Caravel. I pick my Caravel up in a few weeks, and it needs a battery. Looks like a small place to get a big one in, like in my '85 Limited (it takes two) and I want to know the size required? Thanks.

Rob

[thenewkid64]

Stephanie,

Voltage is only one of the possible ways to test a battery.

If you have been maintaining the water level properly the battery could just be wore out. 7 years on a battery is actually really good. depending on use, and maintenance 3-5 is the normal life span.

There are 2 other test that you can run or have run. One is a load test. I will bet that it will fail this one. The local auto parts store will have a tester for that. Most do it for free. They want you to buy a new battery.

The other is to check the specific gravity of the electrolyte in the cells. This requires one of those testers that looks like a turkey baster with little colored floats in it. You draw out some of the water/acid mix from each cell and the floats tell you the gravity. These normally run 5-10 bucks. There is also one with a needle/float. This is the most accurate way to check the health of a battery.

Let us know what you find!

[Stefrobrts]

RobandZoe, I don't know if the group 27 is original to the trailer or not. The area it is in is large (it's the street-side compartment under the gaucho), and there is pleanty of room to pull it in and out - it's a little awkward and hard on the back, but what else is new?

Thanks Brett, I'll go swing it by the local autoparts store and see what they find. I have a feeling it might not be holding it's charge.

[Stefrobrts]

Well, I tested it a little more at home before going to the autoparts store. My hubby was skeptical that they would tell us anything but 'it's bad', since they're only helping so they can sell you a new one. So I charged it up, and the Univolt shut off when the battery was at approx 13.5v. I turned on the three main interior lights and went about my business. When I came back an hour later the battery was at 9v. That seemed like a pretty severe drop for only having a few lights on.

So I took it to the auto parts store and the first test they did said it was ok, and to proceed to 'recharge and test'. I felt this would be the equivalent of what I'd already done at home. So I went ahead and bought a new battery. The guy was amazed that my 1998 battery was still working for us anyway, so it was probably time.

[JanP]

Stephanie, At an International Rally, the "full timer" meeting moderator said that he had given up on batteries and bought a new set every 2 years. Never had a problem after that. I think that Sears deep cycle batteries have a 3 year warrantee now. I use Sears because they are in most every town. They run a full battery of tests and say good or bad. no hassles. Some Univolts do not turn off and boil batteries dry. When at home, I use the best battery charger available- one that automatically tapers off when full charge is reached. No overcharging that way.

Ernie and Jan

[74Argosy24MH]

Originally Posted by JanP

Stephanie, At an International Rally, the "full timer" meeting moderator said that he had given up on batteries and bought a new set every 2 years. Never had a problem after that.

Ernie and Jan

That's one way to keep the meeting short.

John

[ALANSD]

It seems for me a big helpo on battery life has been disconnecting the batteries when not in use with a blade switch. Cheap and effective. Then if you do see a slight drop in voltage, charge them back up, or use a battery minder to do so.

[jaco]

Managing Twelve Volts by Harold Barre

I have yet to read this book.

but it comes highly reccomended in and on many RV sites.
My Library doesnt have it. Think I'll call and arrange an inter-library loan search.

Don't know if it is Current enough to address today's batteries or how much it addresses battery life expectancy at all. Nor do I know if today's batteries are much or any improved over those 20 years ago?

Perhaps someone could advise. Preferably someone who has actually read the book.

[nickcrowhurst]

Jaco, yes, I've read, learnt, and inwardly digested this book, and it sits on the bookshelf in my trailer. It's a useful reference book, rather than a one time read, as there are various charts of data that are useful. e.g wire sizes, % charge at various voltages. Recommended. Nick.