Battery questions

Thanks for the advice everyone, gives me a good deal to ponder. Unfortunately, I don't have time in the two days before our camping trip to do much of what has been suggested. I think I'm just going to roll with what I have and use the generator when I need to. Sometime down the road I'll look into investing in a pair of new batteries, charger, etc. Might as well just add a Honda eu3000 to the list as well ;)

Hi,

You could use the better one to 12.45 volts and then switch to a balanced wiring parallel configuration.

Or you could *work* on the weaker battery doing reconditioning and equalizing until the specific gravity of both batteries is the same.

Voltage is generally a poor indicator of state of charge.

I will reinforce run separately as the weaker will pull down the stronger. Invest in a battery monitor Victron or Trimetric it is the only way to accurately know the battery(s) state of charge.

From reading between the lines on your battery use, I'd suggest to buy two new 6v GC2 batteries and hook them up with fresh wire and new connectors. The 6V batteries will be more tolerant of your use and will last longer than another pair of Walmart Grp 24's. The 6V are about the same price, if bought at a discount outlet like Costco or Sam's.

After the new batteries are in, you should look at your charging regimen and figure out why you are not getting a full charge to the batteries. Usually, an owner drives a few hundred miles back from the campgrounds and calls it a day without knowing, fully, what state of charge his battery is at. The battery may be disconnected or it may be allowed to run to nothing from the parasitic loads and recharged when another use is anticipated. Using two batteries and changing them out when one gets low, only adds complexity.

You could try to equalize both of the Grp 24 batteries you have and then put them on a trickle charger for a few days. That may get some more use out of them but batteries are kind of like elephants, they have a long memory.

AFAIK, the 12V charger output of a Honda 1000 is about 8 amps. Your stock converter should be better than that by a factor of 4X.

Read this, it may answer some of your questions.

The 12 Volt Side of Life

phishheadmi wrote:
Thanks for the info. If I were to use them separately, at what reading would I want to stop using one battery and switch to the other?

As a rule you should not draw a battery down lower than 50%. That corresponds to a voltage of 12.06v.

Pianotuna has it right... Pull them both from rig... Run each thru a desulfate/recondition mode then charge. Let sit... Read voltage...

Then I'd wiire them together as depicted above and run through a charge cycle at max AMP... I use a black and decker vec1093dbd... By far the best I've owned...

I would use the weaker one first. You will have a good idea how long the better one will last then.

With your voltmeter, and when you are not using loads for 30 minutes or so (like pumps or fridges or lights), measure and record the battery voltage and hours used. It's very useful to have a chart and then you will be able to judge how long it will take to use up each .1 of a volt. I use up about .15 from two 6V batteries each day, so get 4 days from 12.6 to 12.0

Plug your camper into the generator through a 15 Amp dogleg, and let the converter charge the battery.

Also thank you pianotuna. That's the way I had planned to wire the two batteries. I'm sure I'm over thinking this, I'm running all led lights and an efficient water pump which, along with a small draw from the fridge is really all I'll be running. We've gone three or four days on a single battery with no problem. I like wiring them together because it saves switching them around while we're there.

Thanks for the info. If I were to use them separately, at what reading would I want to stop using one battery and switch to the other?

I'll have to look into some more detailed specs on my generator 12v line as well as the converter charger.