chassis batteries failure

[rahangman]

Here we go again with chassis batteries.....parked 5 days at FMCA rally in Bowling Green, Oh, went to start bus this PM and ... dead...battery kill switches were off. Should not have happened, have recently left bus like this at home before trip up here. These are new Interstates installed at JAX Prevost in January this year. No previous troubles. Since I don't have a 24 volt charger, checked all 4 individually, 2 were at 12.5 and other 2 were at 1vdc or less. Used my 12 volt charger individually charging one, got it to 12.4 and charging the other lowest at this time to about the same. Will leave set overnight (warm here) and will check 1st thing in morning to see if there is a voltage drop. I do not have my load tester with me. If not one of the new batteries, I am puzzled. I guess I will leave the battery switch off and see if I have more than a few Ma's for phantoms, but perplexed about "why now?".
Could the Equallizer have blown a fuse? If so, where, etc. ? Appreciate any replies.

[hhoppe]

Double check the cable positions to make sure they exactly match the chart posted on the side battery compartment door. When they are that far out of balance one to the next as you indicate two dead, two with charge my guess cables are crossed or faulty. Any draw by a short somewhere should take them down equally. Good Luck.

[Jon Wehrenberg]

RA,

This is a perfect example of why owners really need to monitor their coaches and get to understand them. This is especially true on older coaches, not because they are trouble prone, but because as a coach ages different folks along the way put their hands all over them and through lack of understanding start making modifications. Yours may have experienced changes and now you have to figure out what is going on or have a repeat of what has happened.

Obviously the first step is to get the batteries back in good shape. From your limited description it seems you have a 12 volt phantom load pulling the batteries down. The connections likely have bypassed the master cut-off switches.

Restore the batteries, and then start looking to see if you have any loads, especially off the 12 volt side. Verify your chassis battery charging system is working. What you need to find is the reason for the problem. I do not turn the switches in my coach off, and I can sit for months and the batteries have the power to start the bus. You need to isolate the current draw.

If you solve the problem and decide to add a chassis battery charger that's fine, but to add one without curing the problem is like taking an aspirin for a brain tumor. You are treating the symptoms and not curing anything.

[Joe Cannarozzi]

I think 1 of those 2 batteries that were parralleled is bad and it is dragging the other one down with it.

Isolating, charging, waiting and then retesting will show 1 of the two very quickly way down again.

[truk4u]

They must be load tested individually with the cables unhooked. If they're only a year old and have been working fine, like Jon said, you have a 12 volt load somewhere taking them down in a hurry. Checking them with a meter while hooked up is useless, other than getting a general voltage while paralleled, you have to isolate them.

Once you get the batteries back up, check the 12 volt side of the equalizer and also the 24 volt side. The 24 volt should be within .5 volts of the 12 multiplied by 2.

Then be sure your alternator is putting out by checking the batteries with a meter with the bus running on high idle.

[Denny]

I can turn the switches off and in two or three days the bus will not start. There is enough draw on the chassis batteries to cause this. I have installed a 24 volt Battery Tender charger to prevent this from happening.

I just went thru the not starting drill. Started the bus to hookup the car and 10 minutes later it would not start. Big discrepancy in individual voltage; two batteries were bad. It is important to put a load test on the batteries and not just a volt meter. Mine were good under volt meter test but failed a load test.

After replacing 4 new batteries bus started but Battery Balance light was on. Truk's previous test is the correct way to test equalizer and Jon had a post on this a few weeks back. In my case the equalizer needed replaced.

I just got back from a 1,000 mile trip and everything worked great and the bus started every time. I wonder how many chassis batteries are replaced with failure caused by a bad equalizer?

[rahangman]

AHEM....(and this hurts) found the immediate problem. I had charged the 2 low batteries (individual of all others). My starting problem was (this hurts) I neglected to connect chassis ground back to battery bank. Did so, 25 volt reading and bus started right up! When closing the door to elec compartment below driver, bus died for a moment, opened door, kept running. Found a wire that was sticking out enough to touch door when closed that had a very very small wear spot and bare seemingly causing short. Taped wire and repositioned and checked rest of compartment. I think this may have caused the batteries to go down like they did. Murphy law at FMCA? Now, checking the other units will be done as instructed. Jon is right, and I am queesy about letting any "shade tree mechanic" work on the bus. I am working on elevating my knowledge of Elec Systems and trying to keep the ERS boys at home. Thanx much for all of your efforts and information, it was well received. (Is crow better with/without mustard?)

[phorner]

Always be thankful for an EASY fix..... no matter what

Hopefully you have identified the problem and are well on your way to correcting it.

Good job following through and getting to the bottom of it!

[Sid Tuls]

Rahangman: Don't eat that crow with that shirt I gave ya !!

[rahangman]

Sid, that shirt got "tight" after only 1 helping of crow.....I can't understand it, cause I cooked it in "Light" oil......