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joevanty avatar image
joevanty asked

BMV 712 question...

I installed the 712 and it appears to be working fine. The only thing is, when I am hooked to shore power, or my engine is running, my ah and watts still show negative numbers. I flipped the shunt and the numbers displayed were only positive regardless of weather or not I was on shore power, and the battery never dropped below 100%.

I have since switched the shunt back as per the install instructions. Cant figure out why the numbers are negative while charging.

My settings are:

Battery Capacity :148 Ah

Charged Voltage: 13.2

Tail Current: 2.00%

Charged detection time: 3m

Peukert exponent: 1.25

Charge efficiency factor: 95%

Current Threshold: 0.10A

Time-to-go av period: 3m

installation
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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Can you give us some pictures and/or a simple wiring diagram of you installation?

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joevanty avatar image
joevanty answered ·

Here is my wiring diagram, its a sailboat, lead acid batteries. Shunt is installed between the charger (E) and the house batteries (H). When I installed th shunt, I added about 10 inches of cable.


img-2418.jpg (538.6 KiB)
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

O is the starter-battery? B+ and B- is for DC loads?

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joevanty avatar image joevanty Matthias Lange - DE ♦ commented ·

Yes, I believe so.

Additionally, the battery seems to be in a constant state of discharge even when connected to shore power (Charging). I have checked and re-checked that the shunt is connected properly, battery side to the battery and load side to the charger.


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Matthias Lange - DE avatar image Matthias Lange - DE ♦ joevanty commented ·

It's a strange wiring...
Without a look at the real wiring I would say the shunt have to be wired like so:
Only in this way you can measure all the current flowing out of/into the (H) batteries

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joevanty avatar image joevanty Matthias Lange - DE ♦ commented ·

Thanks, that makes sense.

I disconnected the negative wire between the house bank and the engine battery. The monitor is still displaying a drain of -2 amps and -30W while charging. Also...the SOC is falling. That doesn't seem right.

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