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Topic: Alternator Wiring (Read 548 times) previous topic - next topic

Alternator Wiring

Today I was trying to figure out the alternator voltage sensor wiring on our 97 270. I found the correct schematic and was pleased to see that this one is wired correctly. Anyhow, for future searches and my own documentation, here are a couple of photos. The first shows the exciter terminal (green arrow, wire E6) and the voltage sense terminal (red arrow).

The voltage sense wire is E59. It terminates at the 20 amp circuit breaker on the isolator board. Looks like the one with the red arrow pointing at it. Could be located anywhere on the isolator mounting board.
jor

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Re: Alternator Wiring

Reply #1 –
John, We wired the sense wire directly to the start battery positive terminal with an inline fuse.  More direct is more accurate.  Connecting to the breaker is probably a convenient place to find a fused connection.  Many have had problems from corrosions and poor connections.  I cable tied a PVC pipe to the frame members to carry the single wire from street-side to curb-side.

Re: Alternator Wiring

Reply #2 –
Quote
We wired the sense wire directly to the start battery positive terminal with an inline fuse.

I'm thinkin' that's a good idea. What size fuse did you use? Thanks.
jor
93 225
95 300
97 270
99 320

Re: Alternator Wiring

Reply #3 –
John we are not at the motorhome, so I don't know the fuse size.  I assume it to be low, like 1 amp installed near the battery.  It has never blown and is in place to protect the wire itself from a short.  I will check when we next go to motorhome.  Thinking about it, it may be better to have an auto-reset breaker.

Re: Alternator Wiring

Reply #4 –
Because it is a low-amp draw, there is no need to go all the way to the chassis battery.  The large gauge wire from battery isolator to chassis battery should have zero voltage drop across it.  Yes, this ASSUMES clean, tight connections.

So electrically, either location for the sense wire is the same.
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: Alternator Wiring

Reply #5 –
The sense wire on our coach is direct to the solenoid on starter
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Alternator Wiring

Reply #6 –
Wow, that isolator board looks factory new. Do you know who refurbished it? Nice job.

Mine looks all rusty and dirty.
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.
 

Re: Alternator Wiring

Reply #7 –
Quote
Mine looks all rusty and dirty.

Mine was the same. I just blasted and painted it. I moved it up under the bed so I'm hoping to keep it from returning to its previous state.
jor
93 225
95 300
97 270
99 320