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Recently added a 100AH Battleborn LiPo4 battery to my camper. Purchased a battery/victron BMV-712Smart package. wired into P/N busbars with the shunt between N busbar and the battery negative. The 712 monitor seems to work fine when not connected to shore power, but gradually reports lower SOC until SOC is now 0%, while the battery voltage continues to be above 13.60.
see picture showing wiring. upper left is morningstar ts-mttp-60. uppr right fuses and shutoff for solar and battery. switch to far right disconnects camper from battery/solar.
red pos busbar lower right. black neg busbar lower center.
bvm712 shunt lower right, connected to neg black busbar and battery.
when camper is not connected to shore power, shunt and victron bvm712 works properly.
when camper is connected to shore power bvm712 SOC drops daily.
now that SOC is 0%, need to figure out how to reset bvm712.
suspicion is the small ground wire from solar charger that is grounded to frame. though the solar charger battery pos and neg wires are connected to busbars, which should isolator battery behind the shunt, that small ground is the only ground not going though neg black busbar...
regardless, I don't understand how battery could charge without using ground to the battery
looking for suggestions as to what needs to change to get correct monitoring.
at the moment it is a $200 multimeter, which defeats the purpose for using a battery monitor
Damn, that does look right... the problem is clearly that something in your inverter/charger (whatever is taking shore power and using it to charge your batteries) is bypassing the shunt... that little ground wire goes to chassis ground, you say, but where does chassis ground come from? If you're grounding something on the system to chassis ground and the chassis ground is provided by, say, your start battery, then there would be a likely culprit, since your grounds should be common. But, given that it works properly when it's disconnected from shore power and being charged by the solar controller, I'd say that the little ground wire from your solar controller isn't the problem, it's something to do with your shore power. What's your inverter/charger look like?
98% of the time, an incorrect SOC reading from a BMV is caused by incorrect wiring of the shunt; that is, one of your charging sources most likely goes directly to the battery bank rather than running through the shunt.
The only thing connected to the battery negative should be a cable that runs to the "battery" side of the shunt. ALL other negatives including charger negatives, chassis negatives, and all load negatives, must run off the "load" side of the shunt, or, more practically, must run off a negative bus connected to the load side of the shunt. I see that you're using POS and NEG buses, but my suspicion is that you have your charger hooked up directly to the battery.
Remember that the shunt, and therefore the BMV, can only measure current (in or out) that runs through it. So if you have a charger that goes straight to the batteries (sounds like your shore power to DC charger), the shunt can't measure it, so it will report 0% SOC after a while because it's not seeing any charge current flowing into the battery.
I appreciate the responses.
Please be aware that the monitor worked fine for the first 10 days that it was hooked up. I ran multiple experiments consuming power, followed by charging battery with victron charger, with the shunt functioning properly showing SOC decreasing during discharge and increasing during charging. In addition, camped for a week, consuming ~50amps of power per day, and charging for 2 hours per morning. The monitor & shunt functioned properly, as expected for that entire week.
Per the picture, there is a pos busbar (red) and a neg busbar (black).
There are 3 wires connected to the battery:
1) a large black wire connected to the neg battery post and the battery side of the shunt
2) a large red wire connected to the pos battery post and the pos busbar (red).
3) There is a small red wire connected to the pos battery post and the shunt electronics. See fuse behind battleborn emblem on top of battery. That red wire drops behind battery and rises up in lower right corner before connecting to shunt.
Also, per the picture, just to the left of the battery, can be seen the black/red victron charging wires, splitting, with the red charge wire connecting to the pos red busbar and the black wire connecting to the neg black busbar. The victron charger is sitting to the left of the battery,
I'm heading over to the camper, tonight, to confirm that the battery neg wire is connected to the shunt battery side and the shunt load side is connected to the black neg busbar.
Will report back, tomorrow.
please review these 2 pictures that show (POORLY) that the battery negative post ONLY has a single black wire connected to the battery only shunt post and the other shunt post (load&drains) only has a single wire going to the black bus bar. further the battery charger wires are connected to the red & black bus bars. further the solar wires only connect to the bus bars.
as such, it isnt clear why the victron 712 is reporting negative +100 amp hrs while the battery voltage is at 13.60, which means the battery is > 80 percent charged.
since the battery is usually disconnected from the camper, the only draws on the batery is the solar controller and the victron 712. 12 hours a day, the solar controller is draining the battery (usually < 2 amps/day), then charging those 2 amps, each day.
though i can't imagine how, it does suggest that the chassis ground from the solar controller to the frame is somehow involved.
Just drop 2 cents into the jar.
Your wiring looks just right to me. So are your parameters set correctly?
Have you set the correct battery capacity in the BMV?
When you are absolutely sure that the battery is 100% full, perform a synchronisation to force to inform the BMV that this battery is currently at 100%
Also, some people are not aware: The BMV does not calculate SOC on battery Voltage at all. It counts energy out and energy in an accounts for losses defined by the Peukert and charge efficiency factors.
Once these parameters are tweeked just right then it works great.
> Have you set the correct battery capacity in the BMV?
Yes, the BMV battery capacity is set to 100AH, to match the battleborn spec.
> The BMV does not calculate SOC on battery Voltage at all. It counts energy out and energy in an accounts for losses defined by the Peukert and charge efficiency factors
agreed. the BMV Peukert and charge efficiency has been configured, per the Victron Documentation
