[AL]

Where is the Bass meter connected to the battery or other 12V tap? There should be a circuit breaker or fuse near that connection point. Check the voltage before the circuit protection device.

Move the remote. It makes no sense for the remote to be were it is.

[AL]

The 12V + from the batteries goes thru a fuse (250 amp) and then direct to the buss bar on the back of the bass panel. I have not tried to verify the wire routing but I think it goes direct. There is no 12 V disconnect. No 12 V main breaker.

I think the voltmeter takes a signal off the buss bar. The individual circuit DC breakers are all feed off the same bus bar.

I cleaned all the positive and ground connections in the battery (spare tire compartment) bay while I was exchanging the batteries. I don’t think I have any voltage loss due to corrosion.

The batery readings I reported are before the fuse. The bass is after the fuse. I’ll check voltage directly after the fuse. But it is a fuse so if there is a voltage drop there it must be a bad connection.

[Archived]

If the buss bar in the panel is one volt lower than at the batteries, somewhere in between is either a loose connection or some resistance or even a small load such as a short to ground due to some worn insulation. That has all the earmarks of a potential fire.

It will be worth whatever time it takes to follow the DC from the batteries to the panel, verifying the integrity of the cables, connections, terminals, etc. It could be as simple as corrosion in a cable connection or something more serious, but whatever it is needs to be found and fixed.

[Bob]

Are you reading between the positive and neagtive buss bars? If so, you really need to find the problem. You are describing a 1 volt drop on the heavy gauge feeder cables between the batteries and the buss bars. That should not be the case. The fuse should be before buss bar, check its input. You may have a cut off switch or house disconnect before the bar, check its input. The ground connection should be direct, but check to make sure they didn’t use the chassis for ground conductor.

I’m pretty sure you indicated the voltage drop is when the DC loads are off. If not check with the loads off. If it was when the loads were high then it may simply be the gauge of wire used. Turn off the DC loads and check again. In the marine industry they have two wire gauge standards. One allows for 10% voltage drop at the engineered load and the othe allows for 3% for voltage critical systems. Your measurement could be as designed if you had significant loads when making the measurement.

[Paul]

First thanks for the suggestions. The short form is that this was a ground reference issue and not a safety issue thanks in large part to the design of the coach electrical system but thanks for the constant safety reminder Jon.

The longer version.

Yes Gill, I was comparing reading taken between the battery positive and negative terminals and those taken between the 12 volt positive and ground buss bars that are part of the bass electrical distribution panel. Yesterday those reading differed by 0.8 volts.

Today I made 50 ft jumper and attached one end to the main chassis ground where the batteries, both 2500 watt inverter grounds and their case grounds are attached to the chassis frame. Using this common reference point I got the same voltage readings at:

• the battery positive,
• the 12 volt main battery side of the fuse and load side of the fuse
• both side of the fuse protecting the 12 volt positive from the dedicated house alternator
• the 12 volt buss bar at the bass panel.

That indicated I had a ground issue. I did trace the 12 volt line between the batteries and the buss bar. I did not find any cracked insulation of other other issue. The bends were smooth radius and not rubbing at any transistition into and out of the raceways. It looked good.

The design of the coach using chassis ground, does not use the bass ground buss bar for the main loads, thus no safety issues. The only loads on this buss bar are the DC breaker indicator lights and the DC voltmeter. The designer didn’t expect much load here either as the ground buss bar is connected to the bass panel with about a 10 ga wire and the bass panel is then connected to chassis ground by about an 8 ga wire.

I tightened multiple ground lugs on the bass panel and ever other connection I could get a screw driver on. After tightening the grounds I get the same volatge readings between:

• the battery positive and negative terminals
• the 12 volt positive and ground buss bars
• the 12 volt positive and and any of the ground points in the bass panel

Tightening the grounds also helped resolve the installed voltmeter issue. It is still reading about 0.2Volts low than the handheld voltmeter but that is likely a calibration issue or other installed voltmeter issue.

All the above with no load on the DC except the panel indicator lights. I turned on a few more DC loads and nothing changed.

Since I had to remove the raceway cover between the steering compartment and the overhead panel I did re-route the two inverter charger remote cable and moved the remote upstairs. At least I won’t have to go outside and unloack the steering compartment to check on the inverter status any longer.

Issue resolved, except for the minor calibration issue. I’ll have to keep an eye on those grounds.

[Archived]

Good job. I once had a bad ground associated with the house batteries and inverters and it drove the inverter crazy, which in turn drove me crazy. As our coaches age we just have to try to keep up with loosening of connections, corrosion, etc.

[Jerry]

Joe, now knowing the buss bar wasn’t supporting the coache’s DC loads, you didn’t really need to fear too much. Glad to hear you easily resolved the problem and you moved the remotes up to where they can do you some good.

[Wayne]

Thanks for the replies guys. Yes it was an easy fix compared to many other potential issues but I now hate the spare tire compartment! There is not not enough room to roll over in that bay!

Looking forward to meeting some of you in Branson.