LiFePo4 batteries in winter

[bigtwin]

I realise this a 4-month old post I am replying to, but I am fairly sure that the instructions for the Votronic solar MPPT units state that the Habitation battery must always be connected as the regulator cannot regulate the voltage charging correctly without the hab battery being connected ?

If there is no load connected, there is no requirement for regulation. Hoovie?

Some regulators require the battery to be the first to be connected to the regulator as this tells the regulator that it needs to regulate at 12V (and not 24V) and the solar panels to be connected to the regulator after the batteries have been connected.

Ian

 

[Hoovie]

If there is no load connected, there is no requirement for regulation. Hoovie?

Well, with no load connected, if there is no hab battery connnected either, the controller is doing nothing

as far as the comment "the instructions for the Votronic solar MPPT units state that the Habitation battery must always be connected as the regulator cannot regulate the voltage charging correctly without the hab battery being connected ?" goes .... it sort of makes sense as without the hab battery connected, there is no charging going on.
However ... I had a strange occurance a while back on my own setup. I use the LOAD output on my Victron 100/20 MPPT to drive the Hab Electrics. The MPPT controller developed a fault - a dry joint on the Battery +ve terminal - and I used to lose the battery connection. However the Hab electrics still worked during the day as the solar still provided power and the voltages didn't look particuarly unusual (took a while to work out why the Hab electrics seeming randomly cut out as the daylight thing didn't twig at first). So the controller didn't need the battery at all to work!
So .... I guess different controllers may have different ways of working though.

Some regulators require the battery to be the first to be connected to the regulator as this tells the regulator that it needs to regulate at 12V (and not 24V) and the solar panels to be connected to the regulator after the batteries have been connected.

This is definately a recommended order for any controller that could work at multiple output voltages. Going back to the Victron MPPTs, the first time you connect one, the battery should be connected first. After the first time, the controller remembers what voltage system it is set for (12V, 24V or 48V) and will work to that voltage no matter what order the connections are made later on. But chances are plenty of other controllers won't remember in the same way.

Ian

 

[bigtwin]

Well, with no load connected, if there is no hab battery connnected either, the controller is doing nothing

Yes, my use of the term ’load’ included the battery.

Ian

 

[Adriaadventure]

If there is no load connected, there is no requirement for regulation. Hoovie?

Some regulators require the battery to be the first to be connected to the regulator as this tells the regulator that it needs to regulate at 12V (and not 24V) and the solar panels to be connected to the regulator after the batteries have been connected.

Ian

I wonder if my Votronic BtoB unit would be affected as it's output sits across the hab battery +ve and -ve line ( ready to charge any connected hab battery ) but additionally it monitors the hab battery voltage and activates a 'charging bridge' if it see's the voltage go over 13.5 volts eg from the solar controller and will attempt to charge the engine battery at up to 1A. So there is actually a load connected even if the Hab battery is disconnected.
I suspect there could also be other electronic's eg in the 12v control system of the power supply, electroblock or nordelectronica etc.
I think it could be risky to disconnect the hab battery without other potential sources of charging being disabled first ?

 

[the1andonly]

the Votronics duo is happy to have no LB connected if the SB is connected. When LB connected again its happy knowing its 12V. What would happen if you had a 24V LB and 12V SB i dont know.(or visa versa, not likely to try either.)

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[Hoovie]

the Votronics duo is happy to have no LB connected if the SB is connected. When LB connected again its happy knowing its 12V.

What would happen if you had a 24V LB and 12V SB i dont know.(or visa versa, not likely to try either.)

probably not be a good idea!