Bit of an electrical quandary ....

[SquirrellCook]

That is an idea - use the temp of the alternator rather than the engine revs to control the remote input activation

You might find there will be a little more lag than you’d like.

 

[PeteS]

I've been looking at this for my own setup and just wondered if you'd considered temperature switches, the mechanical kind, I was considering 5C they come in NC or NO contacts, I believe the contacts are active above that temp so a NC one connected to 0V could control the B2B and another NC could connect the aux together on the Multiplus, removes the current overhead of the temperature controller.

I'm thinking of using one to control a relay on the output of the Victron Blue Smart to stop it charging below 5C

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Ive been testing these and to my disappointment Ive discovered that there is a 10 degree hysteresis, they are designed for rising temperatures so the 5C Normally Closed unit turns on at 5C but turns off at -5C so will not work as a protection for charging lithium, however a 10C would work as it would be on above 10C but would turn off at 0C so would work.

Just for info really

 

[wildebus]

thanks for update. That is a remarkably wide range. great shame.