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

Re: Battery Ground Cables

Reply #25 –
Quote from: TulsaTrent –
"Disconnect the ground cable from the battery terminal."
 
You seem to have some expertise in this area. What does that instruction mean to you?


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.
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Battery Ground Cables

Reply #26 –
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
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Battery Ground Cables

Reply #27 –
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
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Battery Ground Cables

Reply #28 –
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.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer