Verifying Battery Charging from Truck with BMV-712 Shunt

[pengle]

I've got a 2020 F350 truck, 2 Lithium batteries in my '21 310GK, factory solar, 3000W inverter/charger and a Victron BMV712 shunt. Should I be able to detect in the Victron app that the batteries are being charged from the truck? I can see in the app when the solar is charging and when the converter is charging - the Power reading in the app shows wattage increasing to the batteries. After connecting the 7 pin from the trailer to the truck and turning on the truck I do not see any difference in the Power reading in the app. Is there a wire from the hitch that should be connected to the shunt?

 

[triplethreat]

I would think that if the Victron BMV 712 is connected correctly, any amount of power going into or out of the battery will be seen on the Victron app. Just to be sure, is there ONLY ONE black wire/cable coming off of the NEG battery post?

 

[pengle]

I would think that if the Victron BMV 712 is connected correctly, any amount of power going into or out of the battery will be seen on the Victron app. Just to be sure, is there ONLY ONE black wire/cable coming off of the NEG battery post?

Since I have TWO batteries I also have a black wire connecting the two batteries. But otherwise the large black wire from the shunt goes to the battery on the left.

(Please pretend that the large black wire on the right from the fuse to the positive terminal on the right battery is RED - like the ends)

 

[Toy4Rick]

I can confirm my Victron shunt shows when it's charging when plugged into the truck

Good luck

 

[triplethreat]

Since I have TWO batteries I also have a black wire connecting the two batteries. But otherwise the large black wire from the shunt goes to the battery on the left.

(Please pretend that the large black wire on the right from the fuse to the positive terminal on the right battery is RED - like the ends)

That would lead me to believe that the power from the truck is NOT getting fed to the battery then. Can you check at the truck, where you plug your trailer 7 pin into the truck's connector (7 pin) that there is actually voltage on pin #4 when the truck is running, with a volt meter? If there is no voltage there, it could be a fuse in the truck's fuse panel that protects the aux. charging lead for Pin #4. If there is voltage there, something is open between that point and where the wire ties into your trailer for charging the battery.

 

[pengle]

In the past (I've been dealing with this for a few years) since I have TWO 7 pin connectors (one on the bumper and one in the bed) I have checked for 12VDC and it was there. As an aside, the Ford Super Duty has to have the 7 pin actually connected for it to pass the 12V. So having two of them makes it easy to check for voltage. Since Toy4Rick has said that THEIR Victron shows the truck charging, I am willing to start over and check for voltage again on pin #4. Then I'll check for a proper connection inside the hitch, then verify which wire goes into the battery area and see if I can locate it. A few months ago there was a thread on this (that I found AFTER posting my questions).

 

[triplethreat]

Not sure if this pic will help you or not, I've got a Momentum 394M and in the front compartment where the hydraulics and generator are, there is a terminal strip and the Blue wire to the very left of the picture is the charging wire that comes from my 7 pin cord, thru a Junction box and into the front compartment. I have mine disconnected and tape over the end of the Blue wire terminal.......lower left side of pic...

 

[pengle]

It'll be a lot easier searching for a BLUE wire than trying to chase a black or red one. Thanks. We're moving on Friday, so maybe I can get to this in the afternoon.

 

[triplethreat]

It'll be a lot easier searching for a BLUE wire than trying to chase a black or red one. Thanks. We're moving on Friday, so maybe I can get to this in the afternoon.

Well, just keep in mind.....it's a Blue wire in my trailer, and may or may not be a blue wire in yours......Momentum vs Solitude vs Grand Design's somewhat lack of adhering to color codes. Good Luck and I hope you get this solved.

 

[Steven@147]

Yes, I would think it should.
I'm using our LifePro battery's WiFi app to monitor the charging current amps going into the battery going down the road where you are using a shunt app, same difference.

Our 7 way pin 4 charge wire is connected to a bus bar in the front storage compartment and then the bus bar is directly connected to the battery. So in a roundabout way our pin4 charge wire is connected to the battery.

But I have noticed with our single LifePro battery the power from our RAM 7 way plug , charge wire pin 4, going down the highway at 60-65 mph will not supply enough current (amps) to show a positive number on our battery WiFI app.

On ours, just setting there ready to take off ( truck off) 7 way connected, the battery app shows like a minus 3 or 4 current number. Then (truck on ) going down the highway running 60-65 mph, the battery app current number gets closer to 0 or slightly negative. So more power coming out of the battery than going in from our truck.
So in our case our truck is supplying charging current to the battery, just not enough current through the 7 way plug pin 4 to turn the battery app current number to a + number. I missed what was happening, I thought the truck wasn't working right on pin 4 until I realized the battery current number was going from -3 to -1 or 0 truck running. It was working, just not enough.

So maybe you're seeing the same thing? Your truck is supplying current through pin 4 but its not a positive enough number for you to recognize it? Not like you would see from your solar charger.

Yeah I know, that means we need a DC to DC charger installed in the truck.

 

[triplethreat]

Yes, I would think it should.
I'm using our LifePro battery's WiFi app to monitor the charging current amps going into the battery going down the road where you are using a shunt app, same difference.

Our 7 way pin 4 charge wire is connected to a bus bar in the front storage compartment and then the bus bar is directly connected to the battery. So in a roundabout way our pin4 charge wire is connected to the battery.

But I have noticed with our single LifePro battery the power from our RAM 7 way plug , charge wire pin 4, going down the highway at 60-65 mph will not supply enough current (amps) to show a positive number on our battery WiFI app.

On ours, just setting there ready to take off ( truck off) 7 way connected, the battery app shows like a minus 3 or 4 current number. Then (truck on ) going down the highway running 60-65 mph, the battery app current number gets closer to 0 or slightly negative. So more power coming out of the battery than going in from our truck.
So in our case our truck is supplying charging current to the battery, just not enough current through the 7 way plug pin 4 to turn the battery app current number to a + number. I missed what was happening, I thought the truck wasn't working right on pin 4 until I realized the battery current number was going from -3 to -1 or 0 truck running. It was working, just not enough.

So maybe you're seeing the same thing? Your truck is supplying current through pin 4 but its not a positive enough number for you to recognize it? Not like you would see from your solar charger.

Yeah I know, that means we need a DC to DC charger installed in the truck.

Great explanation Steve.....and a keen observation on your part

 

[traveldawg]

I've got a 2020 F350 truck, 2 Lithium batteries in my '21 310GK, factory solar, 3000W inverter/charger and a Victron BMV712 shunt. Should I be able to detect in the Victron app that the batteries are being charged from the truck? I can see in the app when the solar is charging and when the converter is charging - the Power reading in the app shows wattage increasing to the batteries. After connecting the 7 pin from the trailer to the truck and turning on the truck I do not see any difference in the Power reading in the app. Is there a wire from the hitch that should be connected to the shunt?

What year/model truck? If Ford, you pretty much have to be in drive before 12v is passed to the trailer. I don't think you can just measure the voltage with it simply plugged in and running. Probably the same for other new model trucks.

I doubt the Victron can tell (or cares) whether the converter, solar, or truck is providing the charge. All it knows is that there is current going into or out of the battery.

Maybe disconnect the solar charge and the converter and then check what the app reports?

Maybe disconnect the charge line from the truck and put a meter on it and measure there with truck in park and in drive to see if there is voltage?

 

[pengle]

Maybe disconnect the solar charge and the converter and then check what the app reports?

Maybe disconnect the charge line from the truck and put a meter on it and measure there with truck in park and in drive to see if there is voltage?

Excellent diagnostic suggestions. Turning off the controller and converter are easy. I don't think it would have occurred to me to put the truck in drive in order to get 12V at the 7 pin. I'll report back as soon as I'm free from planning visits to far off countries with the DW.

 

[pengle]

Maybe disconnect the charge line from the truck and put a meter on it and measure there with truck in park and in drive to see if there is voltage?

Thanks Larry, triplethreat, and Steve for your input. With my Ford truck I have to have the truck in DRIVE in order for the charging line to send voltage to the trailer battery. MY charging line was black.

I checked for continuity between the 7 pin connector "+" slot and the wires in the box in the hitch to determine black was the "+" line. Disconnected the black wire at the battery "+" bus bar and checked for continuity.

Now to start testing. Plugged in the 7 pin connector to the truck.
Left the black wire disconnected at the bus bar and checked for 13.6VDC with the truck RUNNING - No.
With the brake on and the truck in DRIVE - Yes, I've got truck voltage of 13.6VDC.
Connected the wire back on the bus and tested again. Reading the Victron app it appears that the truck charges the battery at about 9 amps/hr - when the engine is running and it's in DRIVE.

 

[Steven@147]

Now to start testing. Plugged in the 7 pin connector to the truck.
Left the black wire disconnected at the bus bar and checked for 13.6VDC with the truck RUNNING - No.
With the brake on and the truck in DRIVE - Yes, I've got truck voltage of 13.6VDC.
Connected the wire back on the bus and tested again. Reading the Victron app it appears that the truck charges the battery at about 9 amps/hr - when the engine is running and it's in DRIVE.

Glad you got it figured out.

You gotta ask yourself, I wonder why they do that? Boy you got to give credit to the truck manufacturers for their inconsistency through the recent years of how they enable and handle external power going to the 7 way plug. Now on our RAM, which is a 2018, pin 4 of the 7 way has power all the time whether the truck is running or not. This works out for us because sometimes when we are not towing, we put our portable refrigerator/cooler in the bed of the truck and plug it into the 7 way. Keeps our drinks and picnic food nice and cold while we are out exploring. Most of the time the refrigerator/cooler sets inside the truck plugged into the console cigarette lighter plugin.

On the other hand, if we stop for the night and plug the RV into campground AC power, I make sure I disconnect the 7 way RV plug from the truck. Since our trucks 7 way pin 4 is hot all the time, I don't want DC power from the RVs converter/charger back feeding into the trucks electrical system. Now RAM might do something to mitigate this happening, but who knows..........

anyway, glad you got a handle on it!

 

[traveldawg]

Thanks Larry, triplethreat, and Steve for your input. With my Ford truck I have to have the truck in DRIVE in order for the charging line to send voltage to the trailer battery. MY charging line was black.

I checked for continuity between the 7 pin connector "+" slot and the wires in the box in the hitch to determine black was the "+" line. Disconnected the black wire at the battery "+" bus bar and checked for continuity.

Now to start testing. Plugged in the 7 pin connector to the truck.
Left the black wire disconnected at the bus bar and checked for 13.6VDC with the truck RUNNING - No.
With the brake on and the truck in DRIVE - Yes, I've got truck voltage of 13.6VDC.
Connected the wire back on the bus and tested again. Reading the Victron app it appears that the truck charges the battery at about 9 amps/hr - when the engine is running and it's in DRIVE.

So glad to hear it worked out for you. Safe travels.

 

[Ken Fike]

I would think that if the Victron BMV 712 is connected correctly, any amount of power going into or out of the battery will be seen on the Victron app. Just to be sure, is there ONLY ONE black wire/cable coming off of the NEG battery post?

 

[Rideblue51]

I haven't seen any mention of a DC/DC charger for Lithium mentioned here but I may have missed it. I have one it it shows on my app. I may have a different shunt though.

 

[Roll With The Changes]

What year/model truck? If Ford, you pretty much have to be in drive before 12v is passed to the trailer. I don't think you can just measure the voltage with it simply plugged in and running. Probably the same for other new model trucks.

My 2020 F350 does not need to be in drive for trailer charge to be active.... it's worse!

Engine running (not just on). Driver door closed. Press brake pedal to activate trailer charge. Then when you open the door to put a meter on the 7 pin, it shuts off again!

There is zero mention of this in Ford documentation. The only way I was able to find out about this was to ask Google.... and they sent me back to this forum. ?

 

[BobWestdorp]

I haven't seen any mention of a DC/DC charger for Lithium mentioned here but I may have missed it. I have one it it shows on my app. I may have a different shunt though. View attachment 110820View attachment 110821

Hi- According to Adventure RV in Shipshewana IN ( they changed our Norcold frig to a 12 v only) if you want to run a 12 v frig while traveling (who doesn't?) a 7 pin is not enough. They added a DC to DC charger (pictured above with 30 amp fuse to enable LFP batteries to be charged during travel. Your other equipment may well be fine just not able to pick up current draw. I'd suggest you check with Adventure RV ([email protected]) 260-336-0540 to discuss your specific needs. And your truck batteries will be dead if you leave the 7 pin connected w/o shore or solar power. Adventure RV is also a solar installer so they understand that as well. Also, our Lippert One Control shows the LFP batteries level of charge.