Batteries Again?

[Richard Barnes]

Back in early February, I posted a call for help when both a check engine and stop engine light came on in the coach. To shorten this story, you helped me discover that Interstate had not connected my four new batteries correctly and I had one get very low on a trip from Atlanta to LA. That was the code that flashed and after moving one wire, the coach started and ran perfectly, the check engine light and stop engine light went out and everything appeared back to normal. I haven't moved the coach since then but today when I returned to LA, the coach would not start. Nothing on the dash lights up with the ignition switch on and no engine start.

I checked each battery and all were around 12.3 to 12.6volts. The problem is no 24volts. I checked for corrosion and found none on any battery nor on the ground to the chassis. No wires have been moved since I last started and operated the coach. I've compared the wiring to a template I found in my manuals (traced each one) and it appears to me to be correct. I put a meter on the battery equalizer and on the 12 volt side I get 11.96 volts and on the 24 volt side I get 11.96 volts.

I tested the two jump studs and I get 11.9 volts there as well. Also, both 12 volt and 24 volts cut off switches are on. Any help will be appreciated guys. The lovely Mrs. Barnes is on her way to California and I need to get started. Thanks!

[garyde]

Hi Richard. If you have a 24 volt charger, you should charge the batteries. It is very weird you are getting a good reading individually but not when grouped. I think you probably have some load drawing the batteries when connected. I had to buy a Guest charger to keep my batteries up when parked.

[gmcbuffalo]

Richard have you tried getting 24v off the battery bank by measuring ground to different battery terminals. Sound like you are not getting 24v to the 24v side of the equalizer. I would expect at least 21v on the 24v equalizer post. Moving that one wire you may have lost your 24v output from the batteries.
Greg

[Jon Wehrenberg]

Richard,

Knowing someone has messed up the battery cables the first place to look for issues is with the battery connections to verify they are exactly as Prevost intended for them to be.

On the RH engine side door there should be a battery wiring diagram. Step one should be to verify every battery cable is connected exactly as depicted in that diagram. While you are checking, disconnect each battery and get a reading of the battery voltage with each battery disconnected from the group.

This will take less than an hour and will tell you if you are wired correctly and the charge status of each battery. While you are doing this wire brush the cable clamps and battery posts.

If the batteries are charged, the wiring is correct, and the connections are clean and tight your problem will be solved. (note that you will likely have some small wires connected to the batteries. They are for the 3 DDEC circuits. If they are not connected you will get lights and the motor will spin, but it will not start. Make sure they are in place also.)

[JIM CHALOUPKA]

Richard, port side engine compartment door, upper left corner, there should be a decal of the start battery system wiring diagram.

If you have it, compare your wiring to it.

You might try to switch to the rear start button so you can listen for any sounds when a start is attempted. As in an automobile listen for the starter solenoid to click to engage the starter. If you hear a weak click or rapid weak clicking suspect the voltage/current to the starter. Any number of things can cause the deficiency.

Note: tight and clean terminal connections do not mean the cables are properly connected in the terminal on the end of the cable/wire.

Look for any small wire that may have broken off due to ??? and that has been overlooked due to your focus on big items.


JIM

[Ray Davis]

Richard, would you like me to drive out and give you a hand with this. I could be free this evening, if that works.

Ray

[Richard Barnes]

Thanks Ray but I'm leaving this afternon for a meeting in Bakersfield. I'll have to work on this tomorrow when I return. I'll try again to look at the recommendations made so far and if that fails I'll call you. I appreciate your offer very much.

[Richard Barnes]

Thanks Jon,

I'll do this again but, according to the diagram on the door, everything is connected correctly. I'm going to test each battery again tomorrow and see if they are still charged as they were last night. This is baffling to have them showing individual charges 11.96 to 12.66 last night but no 24 volts. I'm also going to check and clean every connection although they look as clean as a whistle. Thanks for your help.

[Jon Wehrenberg]

Richard, if Prevost situated the batteries on your chassis like mine are the positive terminal on the battery nearest the door and the chassis ground should give you 24 volts.

If the voltages are spread as far apart as 11.96 to 12.66 it sounds like a battery or equalizer issue. I'm guessing battery assuming the battery cables are correct.

Check voltages at the bottom of the equalizer. Connect to ground at the equalizer, and then compare the 24V reading to the 12V reading. The lower reading should be 50% of the higher reading within 1/2 volt.

[Ray Davis]

Richard,

Give me a buzz. I can be available Thursday or Friday night. Also could make time this weekend.

If you don't have one, I'd suggest picking up a 24V battery charger. I got one from Napa for about $80, but I'm sure they are available elsewhere. Before hooking it up, let me go over the stuff with you to make sure connections are correct.

Ray