Quote:
Originally Posted by Islandsmith
I wrote a long reply over the weekend but for some reason it didn't post as I thought. I've re-written it here - I do appreciate the help and apologize for not being clear earlier.
First step was to remove the batteries from the coach, verify the water levels were correct and fully charge the batteries. I then tested the specific gravity of each cell and they all passed. I have NOT load tested the batteries as I don't have a load tester but that's on my shopping list this week.
Anecdotally all of the 12V systems seem to work fine (other than the inverter) and I am not getting any low voltage errors when running the levelers. Slide-outs and drop down bunk are working as expected when not plugged into shore power.
I ran the tests that Judge recommended and can verify the BIM is working. I'm getting charging voltage when plugged into shore power and when the engine is running.
Batteries are now re-installed. I disconnected the inverter and measured the voltage at the cable ends that power it. When not connected to the inverter the voltage there is 12.6V. The same measurement as at the battery terminals.
I then re-connected the cables to the inverter and measured the voltage at the input terminals of the inverter. Result is 7"ish volts. I walked around to the battery bay and measured the voltage at the battery terminals as well as on the downstream side of the fuse - these all measure 12.6V. Essentially it appears that 12.6V is arriving at the inverter but once it is connected something internal is malfunctioning.
With regard to the plugging and unplugging of shore power, I did this because when I plug shore power in there is an audible "click" from the inverter and when this all started it was because the battery charge had dropped and the inverter kept clicking over and over. I did notice that after plugging and unplugging shore power something was changing as the voltage at the input terminals would bounce from 7'ish to 11'ish volts.
(edited to mention) I did notice that power to my fridge and the outlet in the passenger computer desk routes directly through the inverter. With the unit uninstalled I had to tie the AC input to the romex that comes out of the inverter to those locations. Otherwise I have no power, even on shore power.
I'm really open to coaching here - what am I missing in my steps?
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Great write-up and I think I can say now that you definitely have a bad connection in the wiring between the battery bank and the inverter. At this point I don't think you need to load test the batteries as everything else seems to be operating normally. That also indicates the connection between the battery bank negative side and chassis ground is good.
So that leaves:
The positive cable from the battery bank, through the fusible link (or DC breaker) to the positive connection on the inverter, which you have had apart so it should be good when you put it back together.
or,
The negative side of the inverter (again, should be good) back to chassis ground.
You are dropping 5+ volts across a bad connection somewhere above. With the inverter connected and measuring 7 VDC the other 5+ VDC will be seen across the bad connection. If physically possible, with the inverter connected, measure DC volts from the positive side of the battery bank to the positive terminal on the inverter. Do that same for the negative side. Good connections will read 0 VDC on either of those tests. In your case, one should read over 5 VDC - that would be the side with the bad connection.
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