Skip to main content ↑ ↓
Topic: Identifying Isolator board components on 99' U270 (Read 602 times) previous topic - next topic

Identifying Isolator board components on 99' U270

Isolator Board Project plan...
I am planning a fairly significant engine compartment upgrade. The project overview includes new engine compartment insulation (Soundown), Sterling 210 Amp Alternator to Battery Charger (adds multi-stage charging to alternator output), Sterling ProSplit R 250 Amp Zero Voltage Drop Battery Isolator (3 outputs, only using two for now), Sterling 3 Amp Auxiliary Battery maintainer (take charge current from house batteries and apply it to chassis battery), and a Blue Sea 500A Remote Battery Switch model #7713 to replace the boost function of the boost solenoid or put another way, to combine house and chassis batteries. I plan on placing some of the components in the area under the bed where the transfer switch and breaker panels are located, maybe even all of the above mentioned components depending on cable lengths etc., but for sure the Alternator to battery charger.
I have removed the deteriorated insulation and am now in the process of identifying all of the components on the Isolator Board, some of which will be replaced now in this process. I believe I understand what all of the components are, but I am trying to get a handle on the boost solenoid. Looking at the wiring diagrams (pages B-2126 and B-2198), it looks to me like the boost solenoid actually functions as the starter solenoid. Can anybody set me straight on this? I have taken pictures of the component board that are located near the battery isolator and labeled them according to my interpretation of the schematics. If I have gotten any of it wrong, I expect the wisdom of the forum will shine a light on it. If I have gotten it right, these pictures might speed up the learning curve for the next guy... at least with this vintage of coach.
Don
The selected media item is not currently available.
Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Identifying Isolator board components on 99' U270

Reply #1 –
Quote from: Don & Tys (AKA acousticart) –
it looks to me like the boost solenoid actually functions as the starter solenoid.

If I'm understanding your question correctly, I think the answer is: No, the boost solenoid has nothing to do with the starter, at least not directly.  The boost solenoid should have a hot wire on both sides at all times, 1 from the house battery bank & 1 from the engine batteries.  That solenoid simply connects the 2 banks in boost mode, which does send more amps to the starter solenoid.  But the starter circuit is independent of the boost circuit.  i.e. - when you turn the ignition key, the boost solenoid should not activate and the starter should spin regardless of booster switch position.  That's true for my '97, anyway.

Re: Identifying Isolator board components on 99' U270

Reply #2 –
Don, you are probably about to run out of projects on your coach. Happy to trade with you for a couple of years in case you need to have some things to do to keep you busy.
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Identifying Isolator board components on 99' U270

Reply #3 –
Don I agree with Tim, your pictures look great compared to the scrambled mess that I have on my 95
1995 U320 40', 2013 chevy sonic toad, my real love are corvettes have owned 30

Re: Identifying Isolator board components on 99' U270

Reply #4 –
Don on my 99 the Boost sol is just to combine the 2 battery banks nothing at all to do with the starter. I'm thinking about adding a 4Th AGM in place of the 2 red top starting batteries, and doing away with the whole isolator boost switch mess.  With solar, and an on board charger I don't see how you could kill the batteries.
Bruce, Linda, and Macy
Zoey RIP 1/20/19
1999 U295 40' build #5400
2017 silver Jeep Wrangler, 1260 watts of solar on top
Moving around the country

Re: Identifying Isolator board components on 99' U270

Reply #5 –
Don,
 
I am really glad you have started this project. I have been thinking of cleaning up that wire mess on mine. Our mounting plates are similar. I have one plate that is about 6" x 23", one that is smaller, and then a smaller one yet.

The existing steel plate is rusty and dirty, and full of caca looking stuff. I have a piece of 12" x 36" x 1/8" stainless steel. I thought with careful planning, I should be able to move all of those things onto it. I have never worked with SS plate before. Is it going to be difficult to drill all those mounting holes through it?
 
Keep blazing this trail and take lots of pictures. Your annotations on these pictures have already upgraded my knowledge about what some of those doodads are.
 
Thanks,
 
Trent
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Identifying Isolator board components on 99' U270

Reply #6 –
Thanks for the responses; bdale and Bruce, That was my understanding going into this project. Boost Solenoid= 2 hots, one from each battery bank, joined when boost switch engaged. What throws me is that the diagrams I looked at show only one side of the Aux start solenoid and one side of the boost solenoid connected to the the starter. I haven't looked closely at the starter yet, but I didn't see any heavy duty solenoid on the starter when looking down on it from the bedroom. There must be a heavy duty solenoid to engage the bendix drive on the starter... the ignition relays on the panel in front of the passenger chair surely don't do it! From looking at that relay panel, those two bosch relays divide up the bus bars powering the circuits which are energized when the ignition is turned on. Adding up the amps on those circuits pretty much uses up the capacity of those two Bosch relays... Well, if what bdale and Bruce says is correct, it simplifies things. I can just insert the Blue Sea magnetic latching relay remote battery switch in place of the boos solenoid and have a reliable battery combiner that doesn't use any power except while changing state and has a remote switch with an LED indicator so I can easily tell when it is on, which will be seldom! I am also redoing the start battery cables (upping it to 4-0, adding some heavy duty bus bars to clean up connections, a heavy duty Blue Sea battery disconnect switch for the start bank etc.), adding a Victron battery monitor to the start battery, and cleaning up the cable management.
Tim, no danger of running out of projects... just running out of time!
Don
The selected media item is not currently available.
Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Identifying Isolator board components on 99' U270

Reply #7 –
Don, are you missing some wires?  The boost solenoid should have a wire from the isolator house post connected to one side and the isolator start battery post to the other side.  #4 Red.  From the start side post on the boost solenoid a 3/0 wire goes to the common post for the start batteries and the starter.  The boost switch wire (white, probably 12 ga) goes to the small actuator post. If there is another small post it goes to ground.

Looks like the alt wire to your center isolator post is gone as well.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Identifying Isolator board components on 99' U270

Reply #8 –
1/8" isn't that tough to drill with the right technique and a good drill bit. Using a big box store "Cobalt" bit will make it pretty painless as long as you don't burn the bit. Vary the drill speed to prevent work hardening and don't rush it. Do use a moderate amount of downward force and some lubrication. One issue is that stainless fasteners into stainless plate have a strong tendency to gall the threads, plus 1/8" is on the thin side to tap the holes. I would use Aluminum rivet nuts to solve those issues, however that means drilling a much bigger hole, and that gets more difficult fast. I will use some 1/4" aluminum plate to mount the components that stay on the engine side of that partition with tapped holes (or may use rivet nuts even there) and stainless machine screws. I will make a lift out board to mount some of the stuff in the void where the A/C breaker panel is (possibly also out of aluminum) that is similar to the lift out board in the dog house area of the dash. I will be documenting... not only for the benefit of others, but also for my future self which will likely forget the details if I don't :facepalm:
Don
Quote from: TulsaTrent –
Don,
 
I am really glad you have started this project. I have been thinking of cleaning up that wire mess on mine. Our mounting plates are similar. I have one plate that is about 6" x 23", one that is smaller, and then a smaller one yet.

The existing steel plate is rusty and dirty, and full of caca looking stuff. I have a piece of 12" x 36" x 1/8" stainless steel. I thought with careful planning, I should be able to move all of those things onto it. I have never worked with SS plate before. Is it going to be difficult to drill all those mounting holes through it?
 
Keep blazing this trail and take lots of pictures. Your annotations on these pictures have already upgraded my knowledge about what some of those doodads are.
 
Thanks,
 
Trent

The selected media item is not currently available.
Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Identifying Isolator board components on 99' U270

Reply #9 –
Thanks Roger,
That center post is bare because my isolator failed (incidentally, frying a bunch of $ components in the process), I moved the wire as a by the side of the road fix to the right side post. Now, the alternator only charges the house bank when the boost switch is engaged. When it failed, the alternator started putting out 17 volts according to the Seelevel 914 gage before it fried. The only thing that makes sense to me is that the alternator sense wire wasn't reading the voltage of the start bank and started putting out max voltage. When I moved that center post cable to the right side of the isolator, it was putting out the normal 14.2v. This was a couple of years ago, so details are fuzzy, but I have been living with it that way pending my"big" redo... Not to much of a problem because of the solar, but the boost switch isn't always responsive and sometimes I have had to switch it on and off several times to see the effect. This project will put those problems in the rear view camera...
Don
Quote from: Roger & Susan in Home2 –
Don, are you missing some wires?  The boost solenoid should have a wire from the isolator house post connected to one side and the isolator start battery post to the other side.  #4 Red.  From the start side post on the boost solenoid a 3/0 wire goes to the common post for the start batteries and the starter.  The boost switch wire (white, probably 12 ga) goes to the small actuator post. If there is another small post it goes to ground.

Looks like the alt wire to your center isolator post is gone as well.
The selected media item is not currently available.
Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Identifying Isolator board components on 99' U270

Reply #10 –
The starter solenoid is not serving any purpose in the sense of the boost solenoid but what they have done is run the wire from the isolator to the large positive post on the solenoid instead of direct to the battery. Many big trucks are wired the same way that the direct cables from the battery go to thatvpost then wires from it run power to everything else. It works well but then when you change the starter there is lots of wires to keep straight and reconnect.
Toby a 94 u280
Cummins 8.3
6 speed Allison
Exhaust brake


Adopted by Derek and Annabelle

Re: Identifying Isolator board components on 99' U270

Reply #11 –
Trent,  stainless is tough to work with.  I did my wet bay in 12 ga stainless (a bit less than 1/8").  Cutting it with a sabre saw or drilling big holes with a hole saw is very hard.  I drilled and tapped all of the holes in the SS that I expected a screw to hold.  Self treading screws (normal machine theads) may work but stainless work hardens very fast. 

If I were redoing my wet bay it would be done in heavier polished aluminum. Easier to work with, cheaper, less spent on drill bits and hole saws.  And it would still look great!

Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: Identifying Isolator board components on 99' U270

Reply #12 –
Boelube stick works well for drilling, cutting, anti-galling.  Use it early and often.  Many other uses as well.  I would include a link if I were not IT challenged...ya'll will have to Internet search.  (G-word)
Mike and Mari
'98  36 270 WTFE
Build #5272
Club #17504

Re: Identifying Isolator board components on 99' U270

Reply #13 –
Don, does this Starter Wiring writeup help?
 

Re: Identifying Isolator board components on 99' U270

Reply #14 –
Thanks Barry, there is some info in there I can use ^.^d
Don
Quote from: Barry & Cindy –
Don, does this Starter Wiring writeup help?
The selected media item is not currently available.
Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson