Battery Ground Cables

Topic: Battery Ground Cables (Read 1094 times) previous topic - next topic

Battery Ground Cables

September 05, 2014, 04:24:11 pm

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

Re: Battery Ground Cables

Reply #1 – September 05, 2014, 04:48:35 pm

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.

Re: Battery Ground Cables

Reply #2 – September 05, 2014, 05:08:15 pm

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

Re: Battery Ground Cables

Reply #3 – September 05, 2014, 05:10:59 pm

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.

Re: Battery Ground Cables

Reply #4 – September 05, 2014, 05:38:10 pm

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

Re: Battery Ground Cables

Reply #5 – September 05, 2014, 05:49:26 pm

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

Re: Battery Ground Cables

Reply #6 – September 05, 2014, 05:57:21 pm

Quote from: jor – September 05, 2014, 05:38:10 pm

Just pull the negative from your start batteries.

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

Re: Battery Ground Cables

Reply #7 – September 05, 2014, 06:01:41 pm

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

Re: Battery Ground Cables

Reply #8 – September 05, 2014, 06:02:04 pm

Quote

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?

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

Re: Battery Ground Cables

Reply #9 – September 05, 2014, 06:08:21 pm

Quote

Reviewing your photo again, I think I see at least two thin black wires (with yellow ends)

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

Re: Battery Ground Cables

Reply #10 – September 05, 2014, 06:35:44 pm

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.

Re: Battery Ground Cables

Reply #11 – September 05, 2014, 07:24:14 pm

Quote from: Dave M – September 05, 2014, 06:35:44 pm

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.

Re: Battery Ground Cables

Reply #12 – September 05, 2014, 08:19:53 pm

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

Re: Battery Ground Cables

Reply #13 – September 05, 2014, 08:55:57 pm

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

Re: Battery Ground Cables

Reply #14 – September 05, 2014, 09:20:33 pm

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

Re: Battery Ground Cables

Reply #15 – September 05, 2014, 09:31:07 pm

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

Re: Battery Ground Cables

Reply #16 – September 05, 2014, 09:32:54 pm

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.

Re: Battery Ground Cables

Reply #17 – September 05, 2014, 10:01:42 pm

Quote from: TulsaTrent – September 05, 2014, 04:24:11 pm

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

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.

Re: Battery Ground Cables

Reply #18 – September 05, 2014, 10:21:45 pm

Quote from: rsihnhold – September 05, 2014, 10:01:42 pm

Just marked each alternator wire with a different colored electrical tape and took a few pictures with my phone

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

Re: Battery Ground Cables

Reply #19 – September 05, 2014, 10:35:51 pm

Quote from: kb0zke – September 05, 2014, 09:32:54 pm

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.

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

Re: Battery Ground Cables

Reply #20 – September 05, 2014, 11:06:42 pm

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.

Re: Battery Ground Cables

Reply #21 – September 05, 2014, 11:22:57 pm

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

Re: Battery Ground Cables

Reply #22 – September 05, 2014, 11:47:39 pm

Quote from: Chuck Pearson – September 05, 2014, 11:06:42 pm

you will be hard pressed to find a ground conductor on your Foretravel as a ground goes to earth.

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

Re: Battery Ground Cables

Reply #23 – September 06, 2014, 12:32:55 am

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

Re: Battery Ground Cables

Reply #24 – September 06, 2014, 02:21:40 am

Quote from: oldguy – September 06, 2014, 12:32:55 am

It wouldn't hurt to remove both grounds as both sets of batteries are charged by the alternator.

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

Affiliate Notice