Location of Domestic battery ground?

[ido70]

Does anyone know where the main ground connection is for the domestic batteries in a 2004 Windsor Monaco? I have traced down a problem starting my generator to a poor supply battery ground.

I noticed that I could start the gen when I engaged the battery boost even though the domestic volt level was higher than the truck battery. I tried temporary jumping the domestic battery negative to the truck battery negative and got a normal start every time, so I figure the truck battery ground is better than the domestic one. 
 

I crawled under but cannot locate the grounds and all the cables are wrapped in the flex hose. 

[Tom Cherry]

23 minutes ago, ido70 said:

Does anyone know where the main ground connection is for the domestic batteries in a 2004 Windsor Monaco? I have traced down a problem starting my generator to a poor supply battery ground.

I noticed that I could start the gen when I engaged the battery boost even though the domestic volt level was higher than the truck battery. I tried temporary jumping the domestic battery negative to the truck battery negative and got a normal start every time, so I figure the truck battery ground is better than the domestic one. 
 

I crawled under but cannot locate the grounds and all the cables are wrapped in the flex hose. 

OK….GENERIC.  Somewhere behind or near and under the battery box, there are TWO ground studs with at least one 4/0 cable connected….maybe a few more.  One is the HOUSE and one is CHASSIS.  Loosen or remove both….clean and reassemble….obviously turn OFF both the house and chassis positive disconnects.

that happened to me.  You have diagnosed it correctly…. BUT.  Go up front ALSO.  Chase the cables from the rear studs and clean the ground one and check the positive one.  Everything worked fine and had ample battery for inverting….but the corroded House ground stud in the back was it.  Spray the studs with Battery Corrosion protectant…

[ido70]

Tom, I found two ground studs and was able to overhaul both however once all done, tried Gen again and same-o, will only start if booster switch held in. I’ve put hat problem away for now; the solution is an easy fix. Thanks for your input.

[Tom Cherry]

11 hours ago, ido70 said:

Tom, I found two ground studs and was able to overhaul both however once all done, tried Gen again and same-o, will only start if booster switch held in. I’ve put hat problem away for now; the solution is an easy fix. Thanks for your input.

I don’t remember which bank starts your Genny…. I THINK….  The House.  If your work around is enough…great…

BUT…the proverbial “teaching” moment…..is at hand.. You can, eventually, trouble shoot thusly…..and this is real world.

First…you will need a helper and a VOM and probably a 50 ft or so length of #16 or #14 hookup wire with alligator clips on both ends.  

Helps to have both probe leads and alligator clip leads on the meter.

Shinny under and hook up or hold the meter leads on the rear terminals of the Genny.  Measure the voltage and record.  Then, have your helper try to start the Genny.  OK….repeat….except have then hold on the boost. Measure the voltage….then crank and note the voltage while cranking.   ODDS ARE….you are gonna see WHY it will not start.  That means….a bad cable or a bad switch (House Bank) or a bad connection.  
 

NOW….go back to the batteries.  Again….measure the House….then have the helper try to crank the Genny.  Record the voltages .  Now repeat and have them hold on the boost.  IF the House drops close to what you measured up front with the HOUSE only….time for new batteries.  BUT if the House was 12.7 or so and hardly any difference with the boost ….then a down stream issue.  Where…..hard to find…but you LEARN A LOT.

If your disconnect switch kills the House battery…..then….go there.  Measure each stud to a GOOD ground (you can run the hookup wire to the negative on the house bank).  Should be less than 0.1 - 0.2 VDC if that much in the readings,  NOW….put the leads across the terminals.  NOW crank the genny.  IF you get more than 0.1-0.2 VDC….bad switch.  What is happening is there is a contact issue or high resistance in the switch.  Since the house load is way less….you don’t NOTICE it.  BUT it must be replaced. If you have electric motor or hydraulic motor slides, the bad switch is damaging the motors.  The voltage there will drop or be low, under load, just like the genny.  This causes the amperage to increase, exponentially…..and the motor will even fail.  TRUST ME….this happened.  My FIRST issue was a bad ground.  But I eventually found out, after replacing the entire hydraulic pump package….the bad switch.  Mine would work great….drive 1000 miles….great.  Drive a mile….voltage drop. When I replaced the pump, I out in a selector switch and then put the hydraulic on the chassis,  Just a few years ago, I discovered the bad switch…caught it when it was in the failure mode.

Past that….what you then need to do….you measure the voltage across a set or terminals….or a cable…. Then start the genny.  When you find a big voltage drop….then you fix or replace the connections or the cable.  We have had folks that has an internally corroded cable.  LOOKED GREAT…but it had a voltage drop…from end to end….under load.  New cable….fixed.  Cut old apart….found the wires “gone” or corroded….

It happens.  Tedious process….but it works….and is the ONLY way to chase and troubleshoot….

Good Luck…