Bidirectional Battery Monitor Wiring

[loverofpeace]

Looking to wire up my battery monitor but a little stumped as far as wiring goes. The negative part of the circuit I think I understand, to connect it in between the battery - and the load - however in this diagram, is the "charger" supposed to be my MPPT or is that supposed to be an Inverter or should I just disregard it?

For the external power supply I'm assuming that's the solar coming in?

Also how do would you secure the shunt safely to a wooden board? It seems to have absolutely no screws, lugs, holes designed for attachment.

 

[loverofpeace]

Photo of my setup for reference.

 

[Pierre]

The ‘charger’ can be any charger output e.g. SCC , mains charger or dc/dc converter. Your load would be any load e.g. inverter or other direct 12v loads. The external supply input is to power the monitor. Connect to battery + and -. The current required for the monitor is so low that it would not affect the shunt reading. Judicious use of fuses / protection devices highly recommended.
The charger output will try and supply the load first and the balance will flow to charge the battery. If the charger cannot fully supply the load the battery will supply the balance and the shunt meter will read accordingly (If bi-directional).

 

[Pierre]

I do not know why they make these shunts without attachment points. You may have to make little clamps to secure it the wood board but use spacers to allow for cooling and prevent wood catching fire.

 

[loverofpeace]

Thanks @pierre ! If I understood it correctly, for my application:

Vext + and - go directly to battery

Vin (+) I attach to the positive terminal of my fuse box

And I would wire the shunt itself between my battery negative and the DC fuse box negative terminal

Does that seem correct?

 

[loverofpeace]

 

[Pierre]

Maybe Vin can also power the monitor , so try it without the Vext supply. The issue is that if the battery voltage drops below a certain voltage the monitor will not work. I do not have the specs unfortunately. Have a look at the specs to see if you require the Vext. I think that Vin can be used to monitor a voltage anywhere in the circuit (or lack thereof) but then you would require an external supply at Vext. Shunt will go as you stated.
For interest , do you see the little drill mark on the shunt ? The shunt resistance is so low that they calibrate it by taking a bit of material away !

 

[loverofpeace]

Maybe Vin can also power the monitor , so try it without the Vext supply. The issue is that if the battery voltage drops below a certain voltage the monitor will not work. I do not have the specs unfortunately. Have a look at the specs to see if you require the Vext. I think that Vin can be used to monitor a voltage anywhere in the circuit (or lack thereof) but then you would require an external supply at Vext. Shunt will go as you stated.
For interest , do you see the little drill mark on the shunt ? The shunt resistance is so low that they calibrate it by taking a bit of material away !

Sorry for the delay Pierre, just saw your question now. Nope no drill mark on the shunt. I'm thinking of getting a small plastic box and mounting it that way but I'll try it out tomorrow and see if it works properly first before I do that. I can still return it so if it doesn't work properly I'll just return it and order the aili one will and others recommend.