There is one wire from battery ground post to dc negative distribution block. The issue is when I disconnect it the 12 volt system continues to function.
I have isolated the reasoning for this to the fact the DC system is also grounded to chassis. This is not inherently problematic as the chassis shouldn't be grounded to battery ground. But it is.
Apparently the chassis is grounded to the battery via the -12V ground from battery to genset starter relay. The generator somehow is also grounding this to the chassis, making the missing connection.
In other words an rv without genset would not have my problem.
Now I see no reason the 12volt system on the genset should be chassis grounded (on the other hand the 120v should be). That's neither here nor there.
The problem becomes is there's now an alternative path to ground and the ammeter reading won't see all the electron flow as at least some portion will transit via the generator ground link.
( one writer noted to use +12v. Actually this would be ok as I don't care about measuring power the starter draws and it woukd be the only path for all other 12v power). However the cheap $4.00 ammeter I have uses a common ground between the shunt feed and the lcd display making it not really an option.. there is no seperate ground wire to power the lcd screen on the ammeter itself.
tenbear wrote:
pc500 wrote:
I'm trying to hook up an ammeter and am discovering there is an additional connection from chassis to battery ground. It appears current is going from the Chassis to the onan generator starter relay back to the -12V on the battery.
Is there any reason that the genset is grounding the 12 volt to the chassis? Is this necessary?
I'm not certain but I'd imagine this would have some impact on my ammeters accuracy as their are multiple paths to ground. My ammeter was hooked up only on the main -12V going from the batter to the RV fuse block.
Is there one or 2 wires from the battery post to ground? There should be only one. Your ammeter should be hooked up in this one wire. Other things are connected to ground and do not affect the ammeter.
