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Inverter/charger .. where to ground?
So...I have confused myself.

So..I have an inverter/charger.   It is "smart".  That will run directly from shore power if it is available, sending any extra to the battery.    otherwise it runs as an inverter from battery. seems to me that the ground has to go the the shunt and there to the battery monitor.

Here is the confusion.     The matter monitor would "See" more power going through the ground than was drawn from the battery when the inverter is running in charge mode...driving the 120v outlets then only giving the extra to the battery.   Wouldn't the battery monitor think there was a lot more load on the battery than is real in that case.

I think the 120v breaker panel must be hounded thru the shunt as well?

Ok.  I am worried that there is more load than charge since the monitor would not see the charge going directly from shore power to the 120v panel than can be accounted for in the ground.    

Ok..I am confused.  Someone straighten me out 

One guy says I should ground the inverter to the shore power outlier??.  What...that makes no sense...that ground goes nowhere when the system isn't plugged into short power.
"I never saw a sight that didn't look better looking back"

Kat, Smidge the cat, and Honey

1988 Honeywell.  E350 chassis   21'
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there should be 3 grounds. the 12v ground to the battery should go through the shunt. the chassis ground should go to the chassis. the 120v ground floats. the 120v ground is provided by what ever 120v source you are connect to. do not bond the 120v ground and neutral together like you would do on a house. highdesertranger
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The following 1 user says Thank You to highdesertranger for this post:
frater secessus (09-17-2017)
What make / model kombi unit?

12V is not a true ground, let's call that negative return. Should be same length and gauge of wire as positive, both direct back to charge source (battery bank, return outside of the BM shunt).

The unit's case, check its manual, if grounded, go to nearest negative buss, or chassis if you're sure it has clean path to engine block, I prefer to avoid that latter approach with modern build methods. This can often be left isolated NP but check the docs.

Now the built-in AC shore power transfer switch is a completely different and dangerous matter. Follow the unit's wiring diagrams and instruction very carefully.

Better to get a pro in on this last if you aren't sure.
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I am sorry to be dense. Let me try again....this is the whole thing..

Case one...running just the inverter to power 120v outlets from battery

All power from the battery. Ground then the common ground to the shunt...(of course shunt to battery, battery ground to chassis).
Battery monitor "sees" when battery low and contactor shuts off load to prevent low discharge.
BUT... then....

..... running inverter charger from show power. Outlet in use but is only taking 50% of available power..remainder goes to charge battery

Battery monitor "sees" more drain via the ground than is really happening and directs contactor to shut off load because it believes it is seeing too high a it prevents damage from load drain that isn't actually happening. The charging to the battery isn't balanced by the output from battery. So how do I disregard the power flow to the 120v when it is from shore power...versus watch the power flow to the 120v when it is from battery? One positive line and one negative line connect inverter to the circuit panel. two

Ground is directly from inverter to chassis.

Everything the battery monitor sees is inaccurate...if running from shore power...the charge does not agree with ground. If running directly from battery through inverter...still inaccurate reading by battery

So..I feel that I have to ground that inverter to the common ground that goes through the shunt that is used by the battery monitor...but..then what happens in the case of running from shore power?

See my confusion?

HDR.... where do I connect a floating ground? I don't understand that...sorry to be dense.
"I never saw a sight that didn't look better looking back"

Kat, Smidge the cat, and Honey

1988 Honeywell.  E350 chassis   21'
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can you post a link to the inverter/charger you are using. highdesertranger
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"I never saw a sight that didn't look better looking back"

Kat, Smidge the cat, and Honey

1988 Honeywell.  E350 chassis   21'
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ok you have 120v outlets on the inverter/charger. so disregard any 120v grounds and floating grounds. now look at page 10 of your instruction manual it shows the 12v hook ups. the positive(upper right of your pic) goes to 12v battery positive, the negative (upper left) goes to the load side of the shunt. the grounding terminal(lower right) goes to chassis ground. read the last paragraph on page 12 that refers to the grounding terminal chassis ground. does this clear it up? highdesertranger
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oh I forgot, on the 12v charger side the positive goes to battery positive and the negative goes to the load side of the shunt. highdesertranger
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Ohhhh Ayuh ^^
Stay Tuned

Weirdo Overlord  YARC CRVL edition
12 "Stinkin'Badges"  a "Full Monty Badge" 2 "Just Ignore Me" clusters  4 "Pine Cone" clusters  one "Stinkin' Badger" and 4 of the coveted "Flying Manure Spreader"awards! (What a "Stinkin' " honor !) + ROOIRIA

1981 Travelcraft Class C - 23'
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I'm confused. My battery monitor reads amps in and amps out for the battery. It doesn't care the amount of amps, it doesn't shut anything down. My inverter will shut down if the battery voltage drops too low. My charger shuts down if shore power is too low. My shore power line has the green safety attached to the van chassis. My chargers and inverter have a safety ground from their chassis to the vans chassis. My generator has a lug for a safety ground which gets connected to the van chassis or not. Mostly not. One side of my shunt has only the battery negative. The only way the battery grounds is through the shunt. The other side of the shunt has all other negative connections. Chargers, inverter, all the stuff that runs on 12 volts and the chassis return to the battery. Some of my 12 volt stuff returns ground by way of chassis connections. If there is a dedicated return ground wire, it has to be the same gauge as the positive, but does not need to be the same length. It helps with voltage drop if the wires are as short as possible. I have a terminal bar to keep all the wires neatly organized with one wire to the shunt and all other to the bar.
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