Battery Overcharged

[MattC]

Short Version:  Bus has 4 new batteries replaced by previous owner the day before I drove the bus from LA to East Texas.  The previous owner had issues with the batteries keeping a charge.  He replaced all four batteries before I hit the road.

Once home I noted the smell of 'fried' battery.  The bus started without issue a couple weeks later, but a month after that, no go.  I checked the batteries and the left bank were low, but the front left one was toast. 

Question:  Is this random stuff, or is it symptomatic of some larger issue, such as equalizer or alternator?

[Blacksheep]

What is the cable hanging down on the left side that is not connected?

Also, check your voltage regulator! Sounds as though they were OVER charging as you drove it home and held enough charge for the couple of weeks it sat.

Keep in mind that one bad battery will eventually cause you trouble in the other 3.

I found this out just recently and am still searching for physical answers!

Ace

[Highway Yacht]

I was in your shoes a couple years ago. The bus got to the point that it wouldn't start unless I put the charger on it before I attempted to start it if it set for longer than a couple days. I had older 8D batteries in it so I figured I had bad batteries. I went and purchased 2 brand new batteries...Not Blems.. I installed the batteries and she started up like a champ. Two weeks later, I went out to start the bus and it turned over but not enough juice to start. I then figured I had deeper problems with the charging system.. I started checking and cleaning wires, connections, etc.. Put the charger on the batteries on slow charge for a day and it started as usual. Next day,t would not start again. I took both new batteries back to the parts house and had them both checked. One battery had a short inside the casing and was replaced free of charge and they told me we were lucky it didn't destroy the good battery too since they were connected together. Its been over two years now and it has always cranked even after sitting for months. It is possible that maybe the previous owner purchased a bad battery with a short in it that caused it to fry.

[Lee Bradley]

I don't know how much difference it makes but it looks like you have a battery equalizer with three connections; 24 volt, 12 volt and ground. The 24 volt is connected to 24 volts and the 12 volts is connected to 12 volts but it looks like the 12 volt loads are connected to 12 volts but there is two cables between the two 12 volt taps. I would want the equalizer 12 volt connection at the same post as the 12 volt loads. The main battery connections have the batteries paralleled  and then series, which is fine I guess but I prefer series then parallel.

[MattC]

What is the cable hanging down on the left side that is not connected?

Also, check your voltage regulator! Sounds as though they were OVER charging as you drove it home and held enough charge for the couple of weeks it sat.

Keep in mind that one bad battery will eventually cause you trouble in the other 3.

I found this out just recently and am still searching for physical answers!

Ace

The big cable hanging on the left is residual non-functioning wiring for the chair-lift.  Haven't gotten around to cutting it and removing the rather beefy pump to which it's connected.

Thanks fer the advice, I'll check the ALT and toss the smoked battery.

[MattC]

I don't know how much difference it makes but it looks like you have a battery equalizer with three connections; 24 volt, 12 volt and ground. The 24 volt is connected to 24 volts and the 12 volts is connected to 12 volts but it looks like the 12 volt loads are connected to 12 volts but there is two cables between the two 12 volt taps. I would want the equalizer 12 volt connection at the same post as the 12 volt loads. The main battery connections have the batteries paralleled  and then series, which is fine I guess but I prefer series then parallel.

Lee,

Thanks.  The photo could have been at a better angle.  The 12v pos. and 12v neg. are to the same battery, the 24 neg is not connected to the back battery neg post, rather it's harnessed (maybe by DART?) to the 24neg. connection to the chassis.  I'm guessing it should be the same as 24neg should be 24neg wherever?

[buswarrior]

For busnut use, consideration should be given to moving all connections to after the battery switch.

Off will mean OFF.

Many coaches have parasites wired in that bypass the battery switch. Fine if the coach is run daily, but a killer for the weekly/monthly/whenever driving cycle of the busnut.

It also reduces the chances of accidentally putting wires back on the wrong battery post when messing with battery connections for maintenance, changing, whatever.... the only cables to deal with are the battery cables.

happy coaching!
buswarrior

[RTS/Daytona]

My Guess

#1 - Your front left "toasted" battery has a shorted cell - a battery with a shorted cell will drain the battery that it's in parallel with + as the left 12v set goes down the vanner will start taking power from the upper 12v set to charge the lower 12v set (that's it's job).

#2 - It great that you have a dual cutoff switch - This way you can move the vanner connections to the OTHER SIDE of the cutogg switch - vanner's have fairly large (about 1 amp) idle draw - enough to kill your batteries fairly quickly