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Battery Isolator Question

I am trying to install a Trik-L-Start (Starting Battery Charger/Maintainer) on my 97 U295.  According to the install directions, it says that you can determine which post on the isolator is for House and which is for Start batteries by the voltage displayed on a multimeter.  The House battery should measure between 13.5 to 14.5 volts, while the Start battery should be around 12.3 to 12.7 volts.  I don't get a reading on either post, but when checking the battery directly, I get the readings as stated above. 

I tried this both with the engine off, and while running, with the same results.  Everything else seems to be fine, just not sure what's going on with the isolator. 

Bruce & Jen Evans
Montgomery, TX
1997 U295 36'

Re: Battery Isolator Question

Reply #1 –
The terminal looks really corroded so you should really scratch to make a good contact.
I missed diagnosing a problem a long time ago  because I didn't get a reading because
of the corrosion. 
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Battery Isolator Question

Reply #2 –
Yup, you have a bad connection on either the studs on the battery isolator OR where you placed the voltmeter ground.

You will read each battery's voltage on those studs.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Battery Isolator Question

Reply #3 –
Why even mess with the isolator when you can go straight to the chassis batteries?
1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Battery Isolator Question

Reply #4 –
Actually, I would go for a cleaner area than at the batteries themselves.

But, electrically, any place with a direct connection to the chassis battery positive and house bank positive.

The battery isolator is a reasonable location.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Battery Isolator Question

Reply #5 –
I installed a similar charger for our chassis batteries inside the rear basement storage compartment. I removed the white fiberglass cover on the street side of the rear wall and located the connections for the chassis batteries. I installed the charger on the back wall of that compartment. Everything in that area is protected from the outside elements and the installation was easy. The Trik-L-Charger can easily be installed in the same location since the connections for both sets (chassis and house) of batteries are in that location.
David and Carolyn Osborn
1995 U320C SE 40' Build 4726 Feb 1995
FMCA 147762
Motorcade 17186

Re: Battery Isolator Question

Reply #6 –
Quote from: wolfe10 –
Actually, I would go for a cleaner area than at the batteries themselves.
Agreed, but the coach came this way and it's survived for at least the 20k miles I've put on it and then some ¯\_(ツ)_/¯

1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Battery Isolator Question

Reply #7 –
Need to cleanup the posts and connections on the isolator.
Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: Battery Isolator Question

Reply #8 –
You might consider one of these.  ACR.

  Automatic Combiner Relay from Lithonics Battery. 

  It replaces the isolater,boost solenoid and removes the need for an engine battery charger. My alternator also now charges better than it ever has but this thing reduces the duty cycle so it doesn't overheat.    And the engine batts are never below 12.2 now. 

  I haven't integrated the auto gen start to it yet because it wanted to see how it performed.  So far it's working great.

  Off-The-Grid RVs in Quartzsite does the install and has a Foretravel so he's familiar.  And likes Lithionics, JR says there a top shelf co.

  The drawback for some might be the $400 price tag but it's a Foretravel and we go with top shelf stuff.
Robert and Susan
 1995 36' 280 WTBI 8.3 3060r
 1200 watts on the roof, 720 Ah of lithium's
 Build # 4637. Motorcade # 17599
        FMCA  # 451505
        18  Wrangler JLUR

Re: Battery Isolator Question

Reply #9 –
Bruce, the OP, is trying to install a Trik-L-Start.  The Trik-l-Start requires one wire connected to the Start battery bank, and one wire connected to the House battery bank (plus a ground wire).

The suggestions telling him how to connect a battery charger to his Start batteries are not much help because that is not what he is trying to do.

The suggestion for an alternative device like the ACR is not really helpful, because he already has the Trik-L-Start in hand.

All of the suggestions telling Bruce to clean up the isolator posts and cable ends are certainly worthwhile, since his multimeter is having a hard time reading the voltage on the posts.

Dan's post (Reply #7) is very helpful, because it shows an example of how to mount the Trik-L-Start next to the isolator (with CLEAN posts), but it still doesn't tell Bruce how to identify which isolator post is the Start battery post, and which is the House battery post.

Bruce - you are on the right path.  After you clean up the isolator posts, you should be able to get a voltage reading off the two outside posts.  Once you reach that point, if there is still a question which is which, try turning on your headlights (high beams) for a few minutes (with the engine OFF).  This will draw down the voltage on the start battery.  Then check the isolator posts again.  The outside post with the lowest voltage should be the Start battery post (assuming your House batteries are fully charged).

Another means of identifying the isolator posts is to look at your B-2126 Automotive wiring diagram.  You will find a depiction of your isolator with the cables attached to it.  Each cable has a white paper tag with a ID number.  By comparing the wiring diagram to your actual cables, you should be able to tell which post connects to which battery.

PS:  I'm gonna guess the right hand post (in your photo) is the Start battery post...

Good Luck!

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"
 

Re: Battery Isolator Question

Reply #10 –
Quote from: Chuck & Jeannie –
Bruce, the OP, is trying to install a Trik-L-Start.  The Trik-l-Start requires one wire connected to the Start battery bank, and one wire connected to the House battery bank (plus a ground wire).

The suggestions telling him how to connect a battery charger to his Start batteries are not much help because that is not what he is trying to do.

The suggestion for an alternative device like the ACR is not really helpful, because he already has the Trik-L-Start in hand.

All of the suggestions telling Bruce to clean up the isolator posts and cable ends are certainly worthwhile, since his multimeter is having a hard time reading the voltage on the posts.

Dan's post (Reply #7) is very helpful, because it shows an example of how to mount the Trik-L-Start next to the isolator (with CLEAN posts), but it still doesn't tell Bruce how to identify which isolator post is the Start battery post, and which is the House battery post.

Bruce - you are on the right path.  After you clean up the isolator posts, you should be able to get a voltage reading off the two outside posts.  Once you reach that point, if there is still a question which is which, try turning on your headlights (high beams) for a few minutes (with the engine OFF).  This will draw down the voltage on the start battery.  Then check the isolator posts again.  The outside post with the lowest voltage should be the Start battery post (assuming your House batteries are fully charged).

Another means of identifying the isolator posts is to look at your B-2126 Automotive wiring diagram.  You will find a depiction of your isolator with the cables attached to it.  Each cable has a white paper tag with a ID number.  By comparing the wiring diagram to your actual cables, you should be able to tell which post connects to which battery.

PS:  I'm gonna guess the right hand post (in your photo) is the Start battery post...

Good Luck!


I appreciate all the responses, and yes, the posts were corroded enough to keep me from getting a good reading.  With a little effort, I was able to get some readings.  I was going to clean up the isolator and in the process, snapped the middle post in half. I went ahead and ordered a new isolator from FT, and it should be in tomorrow. 

I will research the location suggested by David (D.J.) and see if I have the same access, otherwise, I will most probably put it (Trik-L-Start back in the engine bay, on the wall to the left of the hydraulic tank, which would be behind the safe in the nightstand next to the bed.  And thanks Chuck, for the detailed answer and the suggestion to look at the Wiring diagram. 
Bruce & Jen Evans
Montgomery, TX
1997 U295 36'