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Hoohaa · 14-08-2020, 18:37

I have recently redone my battery bank and wiring.
My BMV700 Is displaying the battery voltage. But only displaying 0.22 to 0.28 amps for the amp display.
Is it possible I have damaged the shunt?
I have checked wiring and reset the unit numerous times.
Perhaps someone could send me a link to a trouble shooting guide for this unit?
Jeff

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Hoohaa · 14-08-2020, 18:51

Update.
I just ran the engine and it shows the alternator charging amps.
So. It's working but just reporting on the crank battery. Not the battery bank.
It may have something to do with the new Blue seas battery switch and ACR I have installed.
Any Ideas?

Hoohaa · 14-08-2020, 18:57

Here's a pic of my wiring diagram.

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Uncle Bob · 14-08-2020, 19:09

Hi, if I recall correctly they display the amps going to the battery, if the batteries are new and fully charged they won't be accepting much energy at all.

Hoohaa · 14-08-2020, 19:37

Hi Bob.
They display amps in and out. So you can usually see the power consumption of fridge, lights ect.
Mine apears to be fixated on my start battery which is happily sitting there isolated from all the loads going on except the start and charge from the alternator.
I still can't figure out how I performed those wiring acrobatics.

Uncle Bob · 14-08-2020, 19:46

Quote:

Originally Posted by Hoohaa

Hi Bob.
They display amps in and out. So you can usually see the power consumption of fridge, lights ect.
Mine apears to be fixated on my start battery which is happily sitting there isolated from all the loads going on except the start and charge from the alternator.
I still can't figure out how I performed those wiring acrobatics.

Which side of the shunt is the start battery neg wired to and does the house neg go through the shunt??

smac999 · 14-08-2020, 20:36

Why is the shunt on the engine ground. It needs to go on the neg wire between house bank and bus

Acutuakly it looks like your bank is in 2 spots. You need to take the ground wires from both parts of the house bank to the shunt. Then shunt. To bus.

Hoohaa · 14-08-2020, 23:29

Quote:

Originally Posted by smac999

Why is the shunt on the engine ground. It needs to go on the neg wire between house bank and bus

Acutuakly it looks like your bank is in 2 spots. You need to take the ground wires from both parts of the house bank to the shunt. Then shunt. To bus.

You are correct.
I thought it needed to be at very end of the ground.
Also. My bank is split. So I have all battery negatives running to the neg bus. Then to the shunt and then finishing on the engine ground.
So. I should run both the battery bank earth's to the shunt first and then to the bus. With the bus going to ground on the engine. Effectively bypassing the start battery all together.
I can see the logic. I'll give it a go.
Side note. I would have thought that my current setup would have covered the entire system. Obviously it doesn't. But I can't get my head around why?
Anyway, I will rerun the wires as you suggested.
Thanks

Hoohaa · 15-08-2020, 00:52

Quote:

Originally Posted by smac999

Why is the shunt on the engine ground. It needs to go on the neg wire between house bank and bus

Acutuakly it looks like your bank is in 2 spots. You need to take the ground wires from both parts of the house bank to the shunt. Then shunt. To bus.

Thanks Smac. You have solved it.
Legend!

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mitiempo · 15-08-2020, 10:08

Quote:

Originally Posted by Hoohaa

Side note. I would have thought that my current setup would have covered the entire system. Obviously it doesn't. But I can't get my head around why?
Anyway, I will rerun the wires as you suggested.
Thanks

If it is a BMV-700 it is for the measurement of one bank - house. The start battery will not be counted. There should be one main negative from the house bank, even if it is in 2 locations. The shunt is the first connection after the house bank negative post. Then to the bus where all other negative wires including the start battery negative are connected.

Hoohaa · 17-08-2020, 06:43

Quote:

Originally Posted by mitiempo

If it is a BMV-700 it is for the measurement of one bank - house. The start battery will not be counted. There should be one main negative from the house bank, even if it is in 2 locations. The shunt is the first connection after the house bank negative post. Then to the bus where all other negative wires including the start battery negative are connected.

Thanks for the reply. All is working properly now.
I understand what you are saying, and now have it set up with the shunt on the banks negative lines and then to the neg bus and then to the engine ground.
But I still can't understand logically why it didn't work or rather just displayed the start battery. When the shunt was between the Neg bus and the engine ground? I would have thought that it would have sensed all of the goings on.
Unless the banks where using there own neg terminals as the ground, effectively cutting short the circuit and cutting out the engine ground?

smac999 · 17-08-2020, 23:53

If it’s between the ground bus and engine, it will only show current between the engine and ground bus. So it would have showed starting current as you cranked the motor going one way. And then charge current from the alt as it charged batteries (both, some of that current would be going to each battery) going the other way. (+ or -). Depending which way the shunt was facing.