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Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: jimsizemore on February 22, 2018, 01:34:34 pm

Title: Battery isolator
Post by: jimsizemore on February 22, 2018, 01:34:34 pm
While son working on making the park brake set & hold, he noticed a wire not connected to the isolator. It looks to be the red wire from the alternator and it's coming thru a wire loom with a battery connector size wire that  is connected to  that  center post on the isolator. I've not seen a big cable like that connected to the center post before? Gonna go out with a meter in a few to see if that small wire IS the one(same color/diameter) connected to the alternator. I have not fooled with any  of this wiring since I've owned the coach(more than a year). It stays hooked to shore power when not being driven so I guess that's why I haven't noticed low batteries. The Trik L Start has only been installed a few weeks...

Could there be a reason why PO disconnected the alternator form the isolator? I also want to know where the big cable to that center post comes from...

Jim
Title: Re: Battery isolator
Post by: Roger & Susan in Home2 on February 22, 2018, 02:36:19 pm
The center post on most isolators is the incoming power from the alternator.  Be sure youndisconnect the negative cables from  the batteries (start and house) before connecting anything up again. 

If it is indeed the cable from the alternator you are lucky it didn't short to ground.  All sorts of reasons it might be disconnected.  Is the nut still on the center post?  It might have just come loose.  Maybe a bad alternator or isolator or some other issue downstream.
Title: Re: Battery isolator
Post by: jimsizemore on February 22, 2018, 03:13:15 pm
The nut that's there is holding that humongus cable. there is maybe an 1/8th" of threads that might hold the red wire from the alternator on but I checked the wire  and there is no voltage there with the alternator turning. Gonna look at other connections on alternator to see if it has all the inputs IT needs. I FINALLY made contact with the PO and he said he did not disconnect it and he had the alternator replaced about a year & half ago... Will post more as I learn. Son just drove the coach off to Cookeville. Gonna stop by Auto Zone to ask them to double check Alternator output. May be a first for them?

Jim
Title: Re: Battery isolator
Post by: wolfe10 on February 22, 2018, 03:28:42 pm
With a "replaced" alternator, first thing is to verify exactly what kind of alternator it is/what connections it has.

It will have a B+
It may have a separate ground-- separate from grounding through its metal to metal connection to the engine.
It may have a sense terminal-- if so, it will be a small-gauge wire from the chassis battery side of the battery isolator.
It may have an "ignition hot" terminal-- if so, it will need to be connected to a 12 VDC source that is hot when the ignition is on.

Let us know exactly what alternator wiring you have and we can help with how to wire it properly!
Title: Re: Battery isolator
Post by: AC7880 on February 22, 2018, 03:52:29 pm
Isolator connections should look something like this:

What year and model of coach do you have?
Title: Re: Battery isolator
Post by: Chuck & Jeannie on February 22, 2018, 06:16:45 pm
Jim,

If you want to understand the wiring of the alternator and the isolator, and how they relate to each other, you may find the thread linked below helpful.  Mis-wired alternators are common with our coaches because "mechanics" don't understand our electric system.  Once you understand the right way to hook things up, then you will be better equipped to trouble shoot your coach.

What is DUVAC? (http://www.foreforums.com/index.php?topic=33250)
Title: Re: Battery isolator
Post by: jimsizemore on February 22, 2018, 07:28:20 pm
All my sig info got lost when I had to re-register. I attempted to re-do it but it asked me for my old password and the scratch paper I had it written on is gone. I'll keep scratchin' and maybe it'll pop back into my head...
My coach is a 1992 ORED, with an 8.3 Cummings(all mechanical),36'.

Jim
Title: Re: Battery isolator
Post by: TulsaTrent on February 23, 2018, 11:01:27 am
Dan, et al.:
 
Your battery isolator picture shows a yellow substance on the wire connections. I have also seen some with red/pink colored protectant. What is the difference in the two? Is one more preferable?
 
Thank you,
 
Trent

Title: Re: Battery isolator
Post by: AC7880 on February 23, 2018, 04:26:34 pm
Dan, et al.:
 
Your battery isolator picture shows a yellow substance on the wire connections. I have also seen some with red/pink colored protectant. What is the difference in the two? Is one more preferable?
 
Thank you,
 
Trent





I can't help with what the yellow substance is. Our coach had it when purchased.
Title: Re: Battery isolator
Post by: Roger & Susan in Home2 on February 23, 2018, 07:02:03 pm
The colored protectant is what every the last person who serviced put on.  FT used something like that originally.  These shouldn't corode like battery terminals but you can get an electrically conductive grease that keeps them clean and dry from Bay Marine Supply or use CorrosionX on the studs, lugs, washers and nuts.  Doesn't take much of either.

NO-OX-ID "A Special" Conductive Terminal Grease (https://baymarinesupply.com/no-ox-id-a-special.html)

Amazon.com: Corrosion-X Corrosion Technologies 91002 Corrosionx 16 Oz.... (https://amazon.com/Corrosion-X-Corrosion-Technologies-91002-Corrosionx/dp/B0009GYRWW/ref=sr_1_2?ie=UTF8&qid=1519430442&sr=8-2&keywords=CorrosionX)

Comes in smaller sizes and spray cans as well.

I use both. 👍👍