Electrical plans for off-grid boat ....

[Baggywrinkle]

It shouldn’t make any difference. If the shunt is on the neg 48V wire as usual and solar is wired before it then it will count current the same. If the Integrel looks at volts instead, or maybe together with current it should still not change its data. An issue might occur with balancing batteries from different solar outputs. I expect the BMS can fix that. Alternatively maybe wire the 2 banks of solar to the 2 batteries at 24V in parallel.

A shunt measures the voltage drop across a known resistance to work out the current and then calculates the integral of the current value over time. If there are wires going off to MPPTs between the two batteries then the shunt at the ground end of the series batteries won't see the current flowing out (or in) through the connection between the two batteries.

The Integrel system uses a current clamp on the negative terminal of the battery bank to measure current flow, and this is used to ensure, regardless of other charge sources or loads, that the net charging current going into the battery bank is the max charge current set in the configuration .... again, injecting or removing current that then doesn't go through the clamp will be missed and the calculation will be off.

Or have I got this wrong? It's a long time since I finished my electrical and electronic engineering degree, and I've spent most of my life designing at a system level concentrating, on software design and functional partitioning - so I may be very rusty on the HW stuff.

 

[Zing]

A shunt measures the voltage drop across a known resistance to work out the current and then calculates the integral of the current value over time. If there are wires going off to MPPTs between the two batteries then the shunt at the ground end of the series batteries won't see the current flowing out (or in) through the connection between the two batteries.

The Integrel system uses a current clamp on the negative terminal of the battery bank to measure current flow, and this is used to ensure, regardless of other charge sources or loads, that the net charging current going into the battery bank is the max charge current set in the configuration .... again, injecting or removing current that then doesn't go through the clamp will be missed and the calculation will be off.

Or have I got this wrong? It's a long time since I finished my electrical and electronic engineering degree, and I've spent most of my life designing at a system level concentrating, on software design and functional partitioning - so I may be very rusty on the HW stuff.

Correct re the shunt. My thinking assumed you wouldn't bypass it and would wire the solar neg near it. Actually, considering it again, it still will be a problem as although the current might be measured the system surely will not be able to account for the lower voltage. A cleverer system would be needed with multiple shunts or better, power meters and I doubt it will have any of that.

As they use a current clamp, measurement could be solved by moving it to the shunt, but again as they probably can’t deal with the volt issue above it won’t work anyway