Blue Sea ML-ACR 7620 wiring question

[plarkin]

I have a 2012 Sprinter 2500 with a SMB conversion. The ML-ACR separator for the house and engine batteries has only 2 control circuit connections wired. The black lead is wired to wired to the ground vertical bus on the back of the Power Control (Progressive Dynamics, Inc.) and the red lead to a terminal under the drivers seat as show in the picture. The ML-ACR is proving 4.3V DC to this terminal. Anyone know why SMB wired it this way? When charging with Solar or the Shore Power via the MS2000 inverter the house and engine batteries are both being charged.

[Scalf77]

The red wire may only be hot when the engine is running, I would check to see if it goes to above 12 volts when engine is running. Most likely a switched circuit, so if floating it would go to about 4.3 volts and would be in auto mode. This means it will close and charge house from alternator when running, and also charge starter when house charger is on. By design the Blue Sea ML-ACR is bidirectional.

It being wired to a switched 12 volt source is wrong but is not the reason you are seeing the bidirectional charge.

Generally most people prefer it to work this way, especially since sprinters are notorious for parasitic loads.

I would check to make sure if the red wire is indeed wired to a switched source when running. If so I would remove from that circuit, as it means it is forced closed when the engine is running regardless of the alternator output voltage. You can leave the red wire disconnected(but protected). Or you could wire in the switch BS #2146. If you don't want the ACR to charge when the engine is not running let me know, if you find that the red wire input is indeed switched when running and can provide you with a relay circuit that will only allow it to charge when the engine is running.

-greg

[plarkin]

Greg - you are correct, when the ignition is turn on there are 12V present since I found on the Sprinter Forum it is Sprinter's X145/1 Terminal 3 (15), Ignition power, Color: black/yellow,12 V/15 A (180 W). So if I understand you correctly I am not charing the house battery when the engine is running. I will re-read some of your posts to determine the desired protocol for charging. Ideally I would like a battery to battery charger to ensure the float charge is presented to top the battery off, but that requires additional hardware and I already have space issues. First thing I am working on is a ME-BMK so I am not flying blind as far as the state of the AGM 4D battery that I replaced last July. The original battery lasted 6 years with just shore charging. I also added solar, 2 x 115W Zamp panels & controller. I was not aware of the BMK at the time and driving myself crazy trying to understand the SOC with the Zamp controller...not possible!! Learning a lot on this forum.

[Scalf77]

I apologize for the confusion, you are charging your house battery when the engine is running. The problem that is caused by being wired that way, is that it overrides the voltage monitoring functions of the ACR, and forces the ACR to combine the two systems. We really want the ACR to protect the van electrical system. If there was a heavy load on the house system , that causes the alternator not to be able to keep up, the voltage would drop and the ACR would disconnect to protect the van electrical system. The way sportsmobile wires it is wrong (IMO).

Just removing the red control wire from the sprinter circuit, would add that feature back to your ACR. As I said it would still be bidirectional. The following diagram shows as simple relay to essentially turn the unit into a unidirectional ACR.



Also you can use this relay with the remote switch, when the engine is off the ACR will default to the switch position (off - Auto - On)



You are correct you can't get SOC out of the zamp controller, solar controllers only know the current that they put out, nothing about the current being used.

-greg

[plarkin]

For now I have removed the fuse in the red lead by the front seat. So it is not energized now when the ignition is on, but it is protected. I want to concentrate on getting the ME-BMK installed before anything else.