More strange happenings and new info
Tom and Jon, I checked this out last night and, with your new suggestions,again this morning. The maximum reading I got was 12.8V. The breakers are OK but I only get the same 12.8V across them. Same with the master and from battery to negative on jumper lug. The main check that I think I should have been making (and stupidly didn't check earlier)is simply to see is I am getting 28V out of my battery bank. This is also 12.8V. There is an equalizer that has a 28V lug, a -lug, and a 12V lug. 12V measures 12.8 but the 28V yields a .59. One cable from the equalizer was placed on a negative battery post. When changed to a positive battery post the equalizer read properly except no 28V. I still do not have 28V anywhere in the engine/battery compartment, including the starter. Tom, I think you are on to something when you wrote about the battery cable issues. When this problem 1st occurred the road service company sent out a guy with a 1976 Chev 1/2 ton PU with a battery jumper connection hanging out of the grill. I told him there was no way this was going to get the bus started and I had ordered a commercial truck service truck. He insisted that he could get me started. When it didn't work he called back to his boss who had him remove the battery cables and charge each battery separately. Of course this didn't work either. The second company, with a similar setup but with 4 12V batteries was unable to jump start with the batteries so he jumped it from the starter.
Other than the cable I described above that was apparently mistakenly placed on a - post there is nothing obviously wrong with the cables. Of course there has to be if the batteries are fully charged and connected properly and only check out a 12.8V.
As it stands right now I may not be able to get back on this until Saturday. My whole family, wife, kids, and grandkids are leaving about 4:30am tomorrow for 2 weeks in Puerto Vallarta. Saying everything is in disarray is an understatement!
I am going to get into my Prevost schematics and thoroughly check out the cable configuration on the batteries. I suspect everyone that has helped me on this has wondered if I did something wrong. At this point I think I amy have overlooked the obvious. More to come. Thanks everyone! I'll keep you updated.
Guest Charger and Block heater connection
Since Darl is taking a break from his agony I have several questions. I now have the 2611A Guest Battery charger. Truk, I believe you said You may could send me a diagram on how to hookup. Also what is approx. location of the plug for the block heater which I believe I can plug charger into (not sure I understand this) I know as much about electricity as I do Brain surgery, so please be gentle with me. Thanks, Dan
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More than one way to skin a ...
Attachment 1911
I have the same Guest charger on the '97 Liberty and this is how I wired it.
Based on your battery cableing configuration you just have to find the primary postive terminal and the primary Negative directly to the ground.
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Good News! The coach is running.
Quote:
Originally Posted by
Jon Wehrenberg
Darl....the following is a direct quote from post #34....
"Here is the procedure I would use to check this, and why.....
I assume your batteries are up to their desired voltage and are connected according to the Prevost diagram. Obviously this is essential to insure you get the right voltages to the 12V and 24V circuits....."
Perhaps rule number one should be to never leave anyone without Prevost specific experience and knowledge alone with your coach, and after anyone touches your coach verify what they did and if it was right.
To; Jon John, Joe, Tom, all the Jims, and everyone else that helped me solve this problem. It was one battery cable that caused all this starting problem. The center battery of the rear three had the - cable going to the right rear battery - instead of going to the negative on the single forward battery. I am now sure that the 1st company that tried to jump the batteries did this but it could have been the second. I tried watching them but it is a bit difficult getting two people into that space. I also went inside the house and the cab while they were working. Still no excuse for not double checking their work. Yesterday it got 2 degrees above freezing and the snow slowed to a shower so I went out and took pictures of the batteries and of the battery schematic on the door (thanks for pointing that out also) and then retreated to the house and my computer. Upon examination it became very clear that one cable was misplaced. Since it was 15 degrees this morning I waited until the temp got up to 33 and went out and made the change. I checked for the 24V at the shut-off switch and knew it would be OK. Needless to say the coach fired right up.
My only issue right now is why the yellow wire at the negative pole on the inside rear battery sparks when I attach it. It does that regardless of the position of of the shut-off switches. I am going to see if I can find something that identifies that wire and where it goes after leaving the battery. See attached pic. The unattached yellow wire is at the top right of the picture and the offending cable is on the bottom right, before it was moved.
I want to sincerely apologize to all, especially Jon, who spent so many hours helping me solve something that should have been obvious. :oThis was real stupidity on my part and I caused a lot of work that shouldn't have been necessary. The good thing, for me, is that you great POGers helped me find the problem. I guess I thought it couldn't be the cables since they seemed to fit like a jig puzzle. Wrong!! Thanks, Darl:)
Eureka.....Thanks to Ben of Parliament
I am in the process of doing an article that should help with a basic understanding of the coach electrical systems. With help from Jeff (as in JPJ) and Ben of Parliament Coach the article is being done in a question and answer format. As we were discussing chassis batteries Ben revealed something I have never heard before, nor have I ever seen it in a service bulletin, or in a shop manual. The information Ben provided goes right to the heart of two of the very important threads recently covered here.
As I learned (to my chagrin) and posted previously Prevost does wire from the batteries directly to the rear electrical box without going through the chassis battery disconnect switches. I now think I fully understand why, and I also understand why some coaches experience drained chassis batteries and require a battery charger or maintainer.
First a reminder of what wires bypass the battery disconnect switches. Those wires such as on Paul's, or Truks or any coach in that vintage power circuit breakers 19, 20, and 21 in the rear electrical box. Two relate to the DDEC and one relates to the transmission computer.
Ben indicated that they experienced random instances of dead chassis batteries on coaches being converted and found that it relates to how Detroit Diesel set up their DDEC and/or engine. On some, (Ben estimates 50%) of the coaches the power from the batteries is going to the fuel injector solenoids. On others the circuit was open. This explains why some of us could go months and the batteries were still charged, yet others of us would have dead batteries if an auxiliary charger was not used. Remember, these circuits completely bypass the main battery disconnect and the 12 volt disconnect.
On coaches with this characteristic the battery drain can be stopped by tripping the DDEC circuit breakers. The downside to doing this in addition to it being a pain to have to do, is that some memory logging in the DDEC will be lost, and some items in the volatile memory are erased.
So we can all breathe a little easier thanks to Ben because a problem we here could not quite get our arms around, we now have a logical explanation for why some of us need an auxiliary charger and why those with the problem of battery drainage see that spark when reconnecting the DDEC wires to the battery.
Possible Engine or Transmission damage?
Jon, thanks so much for doing this research! I think this may have been what caused my battery problem rather that the ignition being in the accessory position. I am going to install an auxiliary battery charger for sure. What will happen if the circuit breakers are tripped? I was considering the installation of a toggle switch in the line from the battery to the DDEC. Right now I have that wire disconnected from the terminal to avoid having my batteries discharge. Now I am concerned that I may have caused damage to the computer. When I had my electrical problem the batteries were disconnected for over a week and were dead prior to that. Did your research give you information about the consequences if items in the memory logging or the volatile memory are erased? I didn't have any problem running the engine but I didn't drive the coach after finally getting it started. Maybe I should connect my Silverleaf code reader prior to driving the coach.
Again Jon, thanks for all you do!:D