Battery question

Jun 26, 2012 12 Replies

There's an old motor home on our property we want to get rid of. It was driven into place about three years ago. Apparently, no one checked the batteries, and they are all dried now, I would guess fried. Can one fill with electrolyte, charge, and hope for a Hail Mary? Or just go get new batteries........ three of them.



Steve


I don't see why you'd need 3 batteries just to start it and take it to a junk yard. I would think only 1 would be required for starting and the other 2 would be deep discharge type to run 12V loads when the RV is parked and the motor off.

Very unlikely you're going to revive a 3 year old battery that's just been sitting there and allowed to go dry. When they sit discharged, they sulfate and go kaput. Could you temporarily use a battery out of another vehicle? Or take an old one that's near replacement time from another vehicle and put a new battery in that one? Another possibility would be if there is a nearby junk yard that would sell a used battery for $20.

You don't need new electrolyte, what has dried out is H2O and that's what you should use as replacement fluid.

Ordinarily, the acid doesn't evaporate...just the water. Conventional wisdom is, "never add acid to a battery." I'd remove them. Add water. Wait a few days for things to diffuse around before trying to recharge.

Chance of recovery is slim and none, but the cost of the experiment is low.

I'd replace the cranking battery and make sure the thing runs. Remove the other two, verify that you won't blow up all the lights because of the way the charging circuit is implemented. Sometimes, you can put a jumper from the cranking battery to the rest of the system. Don't just short one of the isolation diodes, hook the cathode sides together. And verify what you're doing so you don't blow stuff up. They're not always wired the way you'd think reasonable.

Don't try to jump start it with the bad batteries. You never know what the open-circuit alternator voltage will do to the electronics the instant you remove the jumper cables.

And don't try to run the microwave from an inverter when using just the cranking battery. Wiring is often sized by the charge current, not the maximum discharge current.

Negotiate the price based on whether you replace the other two.

Get rid of, by selling, or junk ? Above good advice.

Greg

It should only take one battery to start it. The others are probably there to run the 12 accessory systems (lights, pumps, radio etc).

If it is just going to the salvage yard can you pull a battery out of an existing vehicle to get it there.

RonB

if you have freezing weather, then they're shot.

hell, just jump start it and go.

Be careful if you try to jump start. Dead batteries in similar circumstances have been known to explode.

If you want to donate it put an avert on Craig or freecycle.org were is as is.

Some charties will pay a tow company to haul it off and you can get a tax deduction.

You don't need new electrolyte, what has dried out is H2O and that's what you should use as replacement fluid.

H2O Yes but the water you use must not had contact with metal source rain water accumulated on plastic sheets would be Ideal. good luck!

SAY WHAT?!?! I've been filling them with tap water for decades.

In some parts of the country, the mineral content of tap water will kill batteries. It's a good idea to go buy distilled water, at the store, for auto battery top off. The buck a gallon or so is worth it, not to risk killing a $75 battery.

Christopher A. Young Learn more about Jesus

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SAY WHAT?!?! I've been filling them with tap water for decades.

You must live in an area with very low mineral content in your water. Distilled water is the best as it is (supposedly) pure water with nothing else dissolved in it. Anything dissolved in the water will upset the battery chemistry.

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