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OEM Battery isolator

Does anyone have a schematic showing the internal connections on an OEM four post isolator?
Why does FT use a 4 post instead of a 3 post?
I would like to perform a diode check because the PO didnt have it wired according to the schematic in my owners manual.

I also need to pull the alternator and have it checked, with 11.5 V to the sense terminal.... no output from the alt.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: OEM Battery isolator

Reply #1 –
My 2000 model has a 3-stud isolator.
 
I would also like to see a schematic of the innards.
 
Anyone got one?
 
Thanks,
 
Trent
Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: OEM Battery isolator

Reply #2 –
Quote from: FourTravelers –
Why does FT use a 4 post instead of a 3 post?

My 1991 also originally had the 4 post isolator with 2 posts connected together with a jumper for the house batteries. This is a 3 diode isolator designed for 3 battery banks. Foretravel paralleled 2 diodes together for extra current capacity for the house batteries.

The other possibility is it is an isolator with an ignition excite post. Are the posts all the same size? An excite post would be smaller compared to the others. Are you sure it is the original isolator?
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: OEM Battery isolator

Reply #3 –
Peter
Thanks for the reply,  it appears to be original but I have no way of knowing for sure. The post are all the same size, if you were to number them 1,2,3,4 left to right, the #2 post is slightly below the horizontal line of the other three and the alternator output is connected to it. the #1 post is connected to the House side of the boost solenoid with the large cable to the house positive. Post #3 & #4 were jumped and connected to the Chassis battery cables and the chassis side of the boost solenoid.
According to the wiring diagram in the manual, the #1 and #3 post should be jumped ....... not #3 and #4.
Maybe the PO just wanted the higher capacity for the chassis instead of the house batteries.

I have moved the jumper to term #1 and #3 with the House battery connected to term #1.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: OEM Battery isolator

Reply #4 –
Here is our isolator, which I believe is original.  Ours is wired properly, according to my wiring schematic.  Facing the isolator, the post on the far right is "start battery", and the post on the far left is "house battery".  The "house battery" post is jumpered to the extra aux battery post, and the alternator connects to the remaining post (slightly below horizontal line).

Check the back of your alternator for number of wires.  Should be 2 big wires, and either 1 or 2 small wires.  If there are 4 wires total (2 big and 2 small), your alternator might require both "sense" wire and "excite" wire to operate.  If that is the case, the "sense" wire should be always hot, and the "excite" wire should be hot only with ignition switch ON.

If you are reading 11.5 volts on the "sense" wire, that is very low (almost dead) - a fully charged battery should be around 12.6 volts at rest.  Try putting a good battery charger on the start battery, and see if it will actually take a charge.
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: OEM Battery isolator

Reply #5 –
Quote from: FourTravelers –
Does anyone have a schematic showing the internal connections on an OEM four post isolator?
Why does FT use a 4 post instead of a 3 post?
I would like to perform a diode check because the PO didnt have it wired according to the schematic in my owners manual.
I also need to pull the alternator and have it checked, with 11.5 V to the sense terminal.... no output from the alt.

Here is a PDF explaining the difference and installation instructions for 3 and 4 terminal isolators:
http://www.allbatterysalesandservice.com/graphics/INSTRUCTION_SUREPOWER_Isolators.pdf

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: OEM Battery isolator

Reply #6 –
Here is information that I found and used from a search of this foreforums site. the factory used an Isolator that had four (4) posts, by jumping the house battery side they increased the load capability of the house battery draw.

 OEM Battery isolator

Hope this helps,  I just replaced my isolator with a 240 amp three (3) pole, and it's working great.
The selected media item is not currently available.
Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: OEM Battery isolator

Reply #7 –
Chuck,
thanks for the pics, that is the way mine is wired now..... the PO had jumped the two posts on the right, only the House battery on the leftmost and the alt was on the correct post. I still want to do a diode check before replacing the alternator. Checked the voltage after leaving a 10 amp manual charger on all night and the start batteries now read 12.5 v.

Pierce...... thanks for the link

Gerry,
what brand / model did you purchase..... just in case I have to replace mine?

Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: OEM Battery isolator

Reply #8 –
This is the one I purchased, as recommended from this site.

Sure Power 24023aIB Battery Isolator
The selected media item is not currently available.
Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: OEM Battery isolator

Reply #10 –
What is your coach and alternator? This isolator is fine for OEM replacement and also has the added ignition excite post for use with a Delco alternator.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: OEM Battery isolator

Reply #11 –
@ibrocun,

Another replacement isolator you may want to consider is the Victron ArgoFET Model 200-2.  Available from Bay Marine Supply in San Diego - a popular vendor often recommended on this Forum.  Last time I checked they offered a discount to Forum members.  Use the code FFMEMBER at checkout and see if it still works.

Victron ArgoFET Battery Isolator


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: OEM Battery isolator

Reply #12 –
For those of you with lithium house batteries, What are you doing with the isolator?    I have mine disconnected at this point due to mysterious electron loss. 
I have one additional alternator as well as the 2000 watts of solar feeding the house LIpo batts/.
  The system voltage being different  with the  LA chassis battery, lead me to think that My isolater  was compromised.    I should not need the engine alternator charging my house batts.
  Thanks for any insight.

Re: OEM Battery isolator

Reply #13 –
Quote from: Protech Racing –
I should not need the engine alternator charging my house batts.
Sounds like you could just eliminate the isolator.  Run two separate battery systems.  Let the main engine alternator charge the chassis battery.  Solar and the 2nd alternator (plus your inverter/charger) can take care of charging the house batts.  If necessary, you can always tie the two battery systems together with the boost switch.

I ditched my isolator a while back and get along fine without it.

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: OEM Battery isolator

Reply #14 –
Quote from: Ibrocun –
Hey Gerry, thanks again for the advice on the oil pressure switch. Generator has run great ever since!

You posted this 7 years ago. Still recommend this one? The OEM option is $400.

Yes, I have had this one installed on my coach for over 7 years without any problems. In fact has solved most all of my battery charging problems. I also use a "Trickle Charger" for charging my engine batteries from the house battery side...  ^.^d 
The selected media item is not currently available.
Gerry & Brenda
CHARLOTTE HARBOR, FL
1994 Grand Villa - # 4466
U300 Unihome - 6V92 Detroit
4 speed Allison - Jake Brake

Re: OEM Battery isolator

Reply #15 –
Update ; Removing the isolater  has removed my dormant voltage loss .
 Back story. I'm sure that i created the issue by adding an additional alternator in place of the long tossed chassis AC compressor .
  This was the result of my OE alternator failing enroute to a race in Canada  , in the middle of the night , a long way from anywhere, etc.  The culprit turned out to be a broken exciter wire  , about 8 in long, that runs from the fuel injector solenoid to the alternator.
  But with all of that time to drive home I decided to reduce my chances  of being dead in road as much as I could . Adding a simple GM 100 amp one wire alternator seemed like a good idea.

 "Current" status;  GM alt  and 6 solar panels  charge the coach LIpo batts. The lipo batts have 2 inverters, one is 3000watt for the minisplit , and inside  outlet for my blender.
  One 1500 watt for the fridge and work station.
  The 6 12volt  electric engine cooling fans  are directly powered by the GM alt and solar  .  BTW the fans have been a solid 1plus MPG( almost 2)  over the last 3000 miles.  So the ROI may come to pass in my lifetime. 
 The OE alternator charges the chassis battery  and system. 

Re: OEM Battery isolator

Reply #16 –
Quote from: Gerry Vicha –
Yes, I have had this one installed on my coach for over 7 years without any problems. In fact has solved most all of my battery charging problems. I also use a "Trickle Charger" for charging my engine batteries from the house battery side...  ^.^d 

Good to know!

I ended up getting a Cole Hersee 48160, which is a 3 post. I also got two new solenoids. We have a three day storm rolling into town tomorrow, so as soon as it dries up, I'll get to work.