Sense voltage on mppts

DIY
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1

Hello,

We have a marine system made up of several mppts, shunt, bms etc. We have (2) 100/50’s, (1) 100/20 and (2) 75/20’s that are all connected to an array of panels both fixed bifacial and flexible. Our issue is that the shunt and mppts are mounted at opposite ends of our boat and are seperated by 2 walls and a cabinet. Most of the problem lies with the mppts thinking that the battery voltage is higher than it actually is resulting in a premature change from bulk to absorbtion then to float. I.e. true battery voltage is 13.19v but mppt says its 14.20v. On these furthest mppts in this example we have #8awg tinned wire between our distributor buss and the mppt so i dont think its a voltage drop related issue. These are all interconnected across our v.e. smart network but we have set the shunt as the sense for all mppts and due to the distance/walls it seems to come and go. We attempted to put the mppts into expert mode set some new settings and they seemed to work better charging but after speaking with a tech it was recommended to not leave in this configuration and go back to the default lithium settings.

So we are hopefull there is a software option for us so we dont need to pull another cable (v.e. direct) between the cerbo and the mppt. We also saw they make a v.e. conn bluetooth dongle which could be placed on the other side of the wall and plugged into.the mppt to extend the range but i was advised by our local supplier that they did not work that way.

Any advice on this would be great. Just as advisement currently the mppt settings are set to standard lithium default in v.e. connect.

2

Where is this reading taken?

In the Smart Battery Sense manual it says this:

Smart Battery Sense is not needed for installations which already have a BMV-712 (battery monitor) with a temperature sensor accessory.

Voltage drop could certainly be an issue. When I used dual 100/50 solar charge controllers I used 6 awg wire and the distance was maybe 2’.

If this was my install, I would have run 10 awg PV wire to the battery compartment and placed the solar charge controllers in that compartment.

Do you have the solar charge controllers connected by VE.Direct now? I doesn’t sound like it but if you do, then take the solar charge controllers out of the Smart Network.

3

That’s the way to do it !