Hello. I just rewired the system in the back of my pickup and now the BVM-712 monitor is showing positive current when there’s a current draw (i.e. when the fridge/cooler is running) negative current when the system is charging (i.e. when the engine is running and the alternator is charging the battery)
Here’s an image of the app when the fridge is running
Hopefully it’s not too busy for you to see the negative lead from the battery goes to the shunt. Then from the shunt to the bus bar which connects to the chassis.
I’ve had this system wired up before and it worked flawlessly. Only then I had a 50Ah battery and in a different compartment in the truck. But otherwise it’s was wired up pretty much the same.
From the manual, it seems i have it wired up the same way:
Thanks in advance
(edited 4 July to reverse the images to match what I was saying. ~+3A when the fridge is pulling power. ~-30A when the alternator is on).
Are the images the correct way round, you say that you see a negative figure when charging. It appears to show a discharge of 34.73A when the fridge is on and a charge of 2.67a when charging?
Julian,
Sorry I haven’t gotten back sooner. Yeah, I had my wording and images backwards. I edited the original post.
I actually started to doubt myself so I re-looked at the photo I took and the manual again before replying and it looks like it’s wired right like @pwfarnell commented (thank you, too).
I’m really at a loss. In my old configuration it worked just fine. I don’t have any photos of it, unfortunately, but I’m sure I wired it the same…oh…wait.
Hmmmm, I just had a thought. I did take their amazingly long data cable, cut it, and then re-terminate it so that I don’t have so much left over. 10m…really.
You can see in the photo that I have a small length of it in the box. That connects to a RJ-12 passthrough bulkhead connector. Then I have another length that goes from there
to the box where I mount the display. Within that box I have an off-the-shelf RJ-12 bulkhead connector with a 6" whip that connects to the back of the BVM-712.
I wonder if I reversed two of the wires at one of the connectors I crimped.
In the manual it looks like there’s a way to reverse the direction of the current measurement (section 7.6.13). But that doesn’t really “fix” the issue if I’ve wired something backwards.
I guess I’ll ring it out from end to end and make sure that they are the same/correct. I didn’t do that because, visually, they looked the same. And I’m pretty adept at making wiring harnesses and crimping RJ-45’s for networking. But I can’t same I’m always perfect.
This is just a guess, but you’ve got that battery on it’s side. Usually the LFP cells which are inside of that kind of battery NEED TO BE UPRIGHT, otherwise you can/will lose electrolyte and risk having a fire.
Please mount that battery upright with the terminals on the top. The cells inside have valves which need to be upright.
