Battery Troubles.

Flyboy · July 10, 2007, 12:05:05 PM

Hi ALL,

Having trouble with my batteries. Have a 12V system with two CAT batteries wired in series. Left the bus unplugged from shorepower for about two weeks and to top it off a friend of the wifes stayed in it and used lights etc while I was away. Batteries flatlined. I noticed this AM when I went to fire up bus.

I plugged it into shorepower for about 4 hours and was able to get a start out of it. Left it running for 30 minutes and then drove for an hour or so to go pump de pooper.

While driving I noticed that when at idle at stoplights the voltage would show below 12 and then spike to the normal range while driving.

When I got home, tried to start and it's dead to the point where it won't turn over.

Are my batteries going to be toast after one discharge like this or should I try hooking up to charger? How long would it take driving to charge back up?

I also have a solar panel but I guess it doesn't actually charge the batts...just tops 'em off??

Any help appreciated.

Aron.

Flyboy · July 10, 2007, 12:07:54 PM

P.S. I checked the water level in the cells...all good.

FloridaCliff · July 10, 2007, 12:19:43 PM

Aron,

Put them on a charger and get them fully charged before using again.

It didn't do them any good to be discharged that far, but I would charge and test first.

My advice is never use the bus to charge them up from dead.

Cliff

Flyboy · July 10, 2007, 12:24:11 PM

Hi Cliff,

Thanks for the response. My shorepower is set up to charge the batteries (able to get a start after half an hour) could I just let it re-charge this way or should I disconnect and charge with a charger. What's the difference btw the two as far as the batt is concerned?

Aron.

FloridaCliff · July 10, 2007, 12:31:01 PM

Aron,

Your good to go with the shore power hookup.

Does it show you the "state of charge" ?

If not I would let it go 24 hours.

I should have said using the bus alternator/generator while the engine is running.

Do you have a battery load tester?

Cliff

Flyboy · July 10, 2007, 01:02:05 PM

Hi Cliff,

I'll leave it plugged in for a while b4 I run again. As far as a "state of charge" I don't know. I have a voltmeter overhead of the driver's station but that's as much as I know.

I have a 10 Amp marine deep cycle charger as a backup.

How do I test the battery?

Aron.

Busted Knuckle · July 10, 2007, 01:33:26 PM

Hey Aron first off Cliff is absolutly correct on recharging it from your shore power instead of using the coaches gen/alt. And he's also correct at 24 hrs. Now I'll take it a little farther, if your shore power charger does not have a way to be sure it's not fast charging I'd unhook them and use your back up charger. It does have a low amp setting doesn't it? charge them for 24 hrs each (seperately) on about a 2 amp charge! Then use a load tester to test each one seperately. I believe you'll be alright, and they should both bounce back as long as they weren't already in bad shape. an ol' guy I used to buy batteries off from (he had a service rte like Interstate Batteries Drivers do) taught me that this is the proper way to do it.
Here's his explanation "Charging batteries is like baking a cake, if ya wanta battery to charge fully and last it's proper life span. Ya gotta charge them on slow charge for 24 hrs to fully charge it completely thru the whole battery! If ya cook a cake a hotter temps and shorter time it's gonna be done on the outsides and messy on the inside, right? Ok well if you fast charge a battery it'll have a surface charge but still be lacking that good solid charge it needs to hold up! And will eventually fail prematurely because of being used at less than 100% capacity!"
Now that is the way it was explained to me many yrs ago, and I've always used that system and I've have very good luck with batteries and have rarely had a battery fail that didn't give me several warnings first before having to be replaced. FWIW BK

DavidInWilmNC · July 10, 2007, 01:44:45 PM

I'll leave the charging recommendations to those with more experience! If you don't have a load tester, Harbor Freight has a couple that are fairly cheap. I have the 100 amp version, but they also have a 500 amp model, too http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91129. Note that this tester is for 12 volts; you'll have to check each battery separately (disconnected from any chargers or loads, of course). If you have a Harbor Freight store nearby, check their website price before you buy anything there. If it's cheaper on the web, print the page and take it with you. They'll honor the web price at the retail store (as long as it's a stock item).

David

Stan · July 10, 2007, 01:48:39 PM

Usually when people refer to CAT batteries they are talking about large heavy equipment 12 volt batteries. You say you have two of them in series which would be 24 volts, so are they 6 volt batteries or did you mean that they are 12 volt batteries in parallel.

The proper slow charge rate is determined by the amp hour capacity of the battery. 2 amps for 24 hours is only 48 amp hours which would be about 30+ amp hours of charge or suitable for a very small battery. Do you have the size number of the battery or the physical dimensions of the battery?

Flyboy · July 10, 2007, 02:04:35 PM

Hi Stan,

11x19x9" are the dimensions. 2 12 volts wired to the same system. The manufacturer is Northern Energy, they each have 6 removable maintenance caps and are fillable.

My voltmeter always reads 12 volts. I assume that means they are wired in parrallel as opposed to wired in series.

Aron.

DrivingMissLazy · July 10, 2007, 02:30:59 PM

Gonna take a lot longer than 24 hours to re-charge those babies at a 2 amp rate.

Just hook up your shore power and let them re-charge a day or two. You really did not hurt them by discharging them. You really need to get some way of telling what your charge rate is if you do not have anything.

Stan · July 10, 2007, 03:42:36 PM

Flyboy: Those are typical dimensions of a size 4D battery which is a nominal 330 amp hour (reserve capacity) battery. A slow charge rate of 15 amps for 24 hours should get you close to full charge on one battery from dead. If you use a 10 amp charger, leave it on for a couple of days because the charge rate will fall off as the voltage comes up on the battery.

Tony LEE · July 10, 2007, 04:05:18 PM

All this advice assumes that your shore power setup included a decent 3-stage charger that will bring the batteries up to 100% more reliably than cheap taper chargers.
Still, either will probably be better than the bus alternator which is usually set a little low to get batteries up to full charge.

Buffalo SpaceShip · July 10, 2007, 04:14:49 PM

Aron, when you said wife's friend discharged the batts when she "used the lights, etc." do you mean that your coach batts and house batts are the same batts? Or did she use the coach lights (headlights, etc.)? If coach and house are the same, I'd suggest getting a house batt system in place ASAP. Starting batts are not designed to be discharged much nor discharged slowly. You can parallel the charging of house and coach batts (on your alt. and shore power), yet isolate the discharging to prevent what happened to you from happening again.

HTH,
Brian B.