In attempting to follow the O & M Manual instructions for removing the alternator, I ran into a problem at the first step:
Disconnect the ground cable from the battery terminal.
Since most of us have two or three batteries in parallel, removing the ground cable from one of them will not remove battery power from the circuit. In our case, does the instruction mean to remove the ground cable from all of the batteries in the bank?
That would be hard to do, especially with the rearmost 8D battery in a three-battery bank. Would an alternative method be to remove the combined cable upstream from the negative terminals?
What is the best way to accomplish this in our real world?
Thanks,
Trent
If I were to want the ground cable from the batteries for the alternator on the engibe, I would be thinking the battery setup at engine, not the house battery string.
Maybe I miss read your comment, if so, sorry.
Dave,
You did not misread it, although you read too much into it. That was my mistake for mentioning the 8D's. I was just citing an example of how hard it would be to remove the ground from a battery bank by removing each of the grounds. I did not mean to imply that I thought the house battery was what powered the engine.
What is the proper method of removing the ground cable from the chassis battery bank?
Thanks,
Trent
Trent, I think Dave is onto something. Certainly you would want to disconnect at the engine. Disconnecting the main ground lead from your house batteries too would ensure that nothing is going to bite you at the alternator.
You probably have two or three normal-sized batteries tied together to start the engine. You can remove the main ground lead from those batteries, too. This would be an excellent time to disconnect all of the battery cables and clean all of the connections, then tighten everything.
Trent,
Just pull the negative from your start batteries. Your setup is probably like mine here in the photo. You'll have the three start batts in parallel with a couple of positives coming off one and a negative off the same one. Like already said, good time to get those connections all nice and shiny!
jor
Since this is my first RV, I am trying to follow the instructions. The first page of instructions for removing the alternator is on page A-18 of the Cummins O & M Manual. The first picture on the page shows the battery cable connected to the negative terminal being removed. The first instruction says to: "Disconnect the ground cable from the battery terminal."
As an electrical engineer, I have learned enough to know that removing the ground cable from one of my two Optima AGM yellow top batteries will not accomplish this. If I were asked to remove the ground terminal from my three Liveline AGM 8D's, that would be even more difficult.
Your suggestion of removing and cleaning the terminals for all of my batteries is a good one. Except I know I will have to replace all three of the Lifelines and maybe the Optimas. They still have hope; the Lifelines charge with the generator and go to float, but once the generator is turned off, they dive pretty fast, going to less than 10 volts in a day. The Optimas are still above 12, but may have been damaged from boosting them to try to start the generator.
I will discover the gory details in the next few days. But first, I want to remove the alternator and take it to an auto electric person to have the alternator tested. More decisions await the results of that test, which requires me to remove the alternator.
Has anyone on this forum figured out how to remove the ground cable from his (or her) engine battery bank? Or is there an addendum to the Cummins O & M manual that explains the steps in a little more detail?
I would appreciate any information, help, or assistance I can receive from some of the more experienced Foretravel owners on this forum.
Thank you,
Trent
Jor,
Do you mean removing the one "black" cable that goes from the negative "buss" of the three parallel batteries to the rest of the RV?
Thanks,
Trent
Jor,
Reviewing your photo again, I think I see at least two thin black wires (with yellow ends) that also connect to the negative buss. If I do not also remove them, won't they also form a path to ground?
Still confused, but getting smarter,
Trent
Yea, that's the one. Pull the positive too. Hit all the connections with a wire brush. There are a number of coatings you can use on them when you reassemble. Corrosion X is a popular one.
jor
Trent, yours will likely be a different. The extra wires on mine are for a couple of accessories and a fuel filter priming system. The important thing for you is to disconnect the big black ground cable from the negative post. This will disable all the automotive stuff. I usually wrap a rag around it or tie it up out of the way so it doesn't ground by mistake.
jor
With all respect, since disconnecting a battery ground is so difficult, I sure recommend having a mechanic touch the alternator, it has more complicated connections and less clearly marked.
Excellent advice! Many times paying someone else to do the work is the least-expensive way to get it done.
Easy guys - we have someone wanting to learn how to do something the correct and safe way. Everyone here on the forum started out with less knowledge they have now and the main way we learn is to ask questions. This forum has earned a reputation for being helpful; let's keep it that way :)
Don't think I have met many that I wasn't a little envious of a talent they had. That goes for our forum members. Many are new to not only RVs but vehicle mechanics in general as their vocation was in a totally different field. Newcomers may make some mistakes and have nothing but a red face and a good story to tell around the campfire but our Foretravels have other, more serious consequences for mistakes made.
Sometimes it's hard to find just the right words to tell someone, "hey, maybe you should look over someone's shoulder for a while" without sounding condescending and possibly bruising egos. Even the most mechanically knowledgeable of members started their apprenticeship with baby steps. Teaching others with only subcompact automatic transmission experience to drive emergency vehicles was not just a lesson in double clutch instruction but a learning experience for me in developing a positive teacher student relationship with so many different personalities. Takes a lot of work to do in person and much much more when you are only typing onto a screen. Especially when there are so many topics now and only a minute or two to type out a post
Hey, great forum. Don't see any problems.
Pierce
Pierce I usually just stay on the sidelines here, but I feel your comments are right on. Sometimes I KNOW I would be better off having someone else fix my problems, but the best way to learn is to ask questions and give it a try yourself. Sometimes I have saved alot of money doing it, others I know I really screwed up and cost myself. But I learned alot-what is that worth? My dad said why hire some idiot to do something you can do yourself? Still not sure what he really meant. Mark
Thank you, Michelle. I did find it a little over the top, especially since I had already stated I was an Electrical Engineer.
Oh well, whatever makes him happy.
Trent
I think all of us have attempted a task that turned out to be beyond our abilities, so now we ask lots of questions before tackling something that is unfamiliar. We learn by asking questions, and sometimes the best answer to the question is to hire an expert. Just recently I asked about MCD shades, and was told that I can easily install them myself and that it is best to let the experts do it. I'll try one myself, and if I can't do it I can take it with us until we get to an expert who can. If I can install it myself then I'll be able to install the others as their turns come up.
To the original question: those batteries were put in there by somebody, so there ought to be a way to get to the terminals, either before or after removing the batteries. Those 8D batteries are heavy, so I understand being reluctant to move them if that isn't absolutely necessary. Trent, can you post a picture or two of how those batteries are buried? Perhaps someone else has a similar arrangement and can tell you how to get to the terminals.
I didn't disconnect anything at the batteries when I removed the alternator. Just marked each alternator wire with a different colored electrical tape and took a few pictures with my phone, in case there were any issues later, before disconnecting the four wires on the back of the alternator. After each connector was removed it got a good covering with more electrical tape and it was done. Took 15 minutes.
Thank you very much for the colored tape idea. It will help because I have heard they are less clearly marked.
I just happen to have several colors I used to use with my tinker toys.
Trent
David,
Actually, the pictures that Jor posted of his chassis bank is a lot like mine, except I only have two batteries in parallel and they are yellow tops instead of red. (His suggestion was actually what i suggested as an alternative method in my original message.)
I was not trying to find out how to remove a wire from a battery terminal, but how to remove the ground from a bank of batteries. Jor has explained it (with vis-aids). Rsihnhold added the idea of using different color tape for each of the connections.
I think I am good now and looking forward for the sun to come up tomorrow.
Thanks,
Trent
The sun may well rise tomorrow but you will be hard pressed to find a ground conductor on your Foretravel as a ground goes to earth.
Best way to proceed would be to work it hot as suggested using colored tinker tape if necessary or, alternatively remove all positive or negative bonding conductors from respective battery terminals.
If you choose to disconnect only one bank, start or house, recommend that boost switch be disengaged.
my suggestion is to let someone who actually does not have to think what he is doing do it and watch, then in future you will know what to do. Having this explained in half a dozen different ways surely does not make one feel competent.
I actually know someone that thought they were connecting up battery cables correctly and in the process added a few hundred dollars to the job to fix the result of making a very quick mistake. NO, it was not me. Batteries have a very dangerous side effect and I feel that the 3 members that suggested having another person do it were totally correct. If you do not have help alongside to direct you it may be a mistake. Like Chuck said I too would do it hot if I were not quite sure, but watch out for the wrench touching something too. Working on something that powerful (batteries) is not for the faint of heart.
JohnH
Chuck,
According to the Cummins O&M Manual for ISC engines, the first preparatory instruction for removing the alternator is: "Disconnect the ground cable from the battery terminal."
You seem to have some expertise in this area. What does that instruction mean to you?
Thank you for any information you can provide.
Trent
It wouldn't hurt to remove booth grounds as both sets of batteries are charged by the alternator. If it is too hard to get at the ground cable, pulling the
positive cable or a cable between batteries will have the same affect. In pulling the positive lead or the in between leads you must be careful not to ground
out you wrench
Thank you for that information. All this time, I had been assuming the instruction referred to the engine battery bank. Looks like I have to go out and buy a second rag. :)
After that I will be ready for step two: "Remove and tag all wires." Guess I better buy some more tags; I know I don't have that many on hand. ;)
Thanks,
Trent
All this discussion over how to disconnect a battery bank. I assumed as an EE you were questioning loose use of grounding terminology per NEC or this was one of those "how many angels can dance on the head of a pin" discussions.
What Cummins instructions are saying to me is to detach one end of every conductor between negative terminals on batteries and frame of coach. What they are not saying is important also....before disconnection measure potential at each wire running to alternator with key on and off, and label wires. Safety first, disconnect both battery banks.
Also an EE and fully aware that there are lots of things electrical that I'm not qualified to do. That field has moved in so many different directions and that doesn't even count the simple fact that being an "electrician" is something else entirely.
So when my alternator on my '93 U225 was clearly not working the first thing I did was disconnect the lead from the start bank's negative terminal that went into the RV through the bulkhead... then I removed the cable from the positive terminal that went into the RV through the bulkhead. (There was only one of each.)
Then I did the same to the house battery bank.
Then I checked to see if there was power to anything (especially the alternator) and there wasn't.
Then I took the alternator off and took it to a repair/rebuild shop (one I will never use again, btw).
If you send the alternator away to be rebuilt you will almost certainly get it back with jumpers installed for trucks (jumping the "sense" terminal to the 12vdc terminal). Watch for this and search for lots of information regarding just how those should be wired.
While the cables are disconnected you can go to HF and get their battery tester for under $40. (Walmart seems to be selling the same product for about the same price now.) This puts a resistive load onto the battery. It pegged one of the red-tops in my start-bank as bad and sure enough, replacing it made that bank work a whole lot better.
Craig
Craig,
Thank you for the complete and detailed procedures. Will follow your guidance.
BTW, the HF battery testers are currently about 1/2 price!
Trent
Another EE ... here's my opinion.
The "battery" is a collection of cells wired in series forming a "battery" of cells. Two or three of these batteries wired in series is still a battery of cells. Removing the ground cable (any and all wires from the negative terminals to chassis ground) makes all the wires connected to the positive terminals safe.