Lithium Winterisation

[the1andonly]

I am in the process of changing to Lithium for LB. I have had to change the position of charge controllers due to length of temperature sensors hence some things are up for grabs. (Battery has bluetooth BMS)
I expect to be laid up for long periods, and used in others. Lets call them summer and winter.
Summer all things are on
Solar A and Solar B and B2B. Votronics 1212-30, Solar A 330W panel Votronics mppt350 output to LB Solar B 120W+100 panel Votronics mppt250 duo output to LB 2nd connected to SB
Winter (L battery 50-70% SOC) Storage no charge. still need to charge SB
Solar A panel issolated. Solar B panel connected output to LB issolated 2nd connected to SB.
The winter scenario any comments? will the controller still work with no 12v on the output? Will i be better off each time rewiring Solar B or some other option. Would i need to issolate LB terminal to prevent B2B interfering

 

[cmcardle75]

I am in the process of changing to Lithium for LB. I have had to change the position of charge controllers due to length of temperature sensors hence some things are up for grabs. (Battery has bluetooth BMS)
I expect to be laid up for long periods, and used in others. Lets call them summer and winter.
Summer all things are on
Solar A and Solar B and B2B. Votronics 1212-30, Solar A 330W panel Votronics mppt350 output to LB Solar B 120W+100 panel Votronics mppt250 duo output to LB 2nd connected to SB
Winter (L battery 50-70% SOC) Storage no charge. still need to charge SB
Solar A panel issolated. Solar B panel connected output to LB issolated 2nd connected to SB.
The winter scenario any comments? will the controller still work with no 12v on the output? Will i be better off each time rewiring Solar B or some other option. Would i need to issolate LB terminal to prevent B2B interfering

For winter storage, direct your solar to the starter battery and literally disconnect the LiFePO4. Check that its BMS won't cause any parasitic drain. Unlike a lead acid, it will easily last a winter without discharging if there are no parasitic loads. It will do so with considerably less wear than it would get kept on a maintenance charge.

 

[the1andonly]

For winter storage, direct your solar to the starter battery and literally disconnect the LiFePO4. Check that its BMS won't cause any parasitic drain. Unlike a lead acid, it will easily last a winter without discharging if there are no parasitic loads. It will do so with considerably less wear than it would get kept on a maintenance charge.

Thanks for heads up on BMS drain.
I Will have to swap SB/LB charge leads slightly remotely due to access. which is why i ask now.

 

[cmcardle75]

Thanks for heads up on BMS drain.
I Will have to swap SB/LB charge leads slightly remotely due to access. which is why i ask now.

In reality, the BMS drain shouldn't be a problem. Most will have less drain than the tiny internal drain of the battery, but it is worth checking.

 

[the1andonly]

Not having all consumables to hand ive had another thought. Rather than physically change charge leads Put in a 2 way switch to the 2 batteries or even a switch over relay., SB on nc side normally connected. Ie volts required from LB to charge LB. Defaults to charge SB. (NB SB always connected to bat 2 trickle charge) . Is this sane or is there a better option?

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[the1andonly]

Reply from roadpro

The Switches are for determining the Leisure battery charge settings, the Starter output is a fixed rate voltage and maximum amp rate so doesn't require setting separately from the leisure battery.
If you disconnect the leisure battery and leave the starter battery connected to the same input it will still charge as it would do if the leisure battery was still connected.

The previous idea of A simple switch or relay to move output from LB to SB not on as i forgot about the difference of settings required. The above reply give the way forward: a switch to isolate output or even remove a fuse, switch pointing to to summer or winter a better idea.
The fuse removal not preferred as i did something similar on my bongo and almost buggered a battery Not doing exactly the correct thing. KISS. So time to make some huge summer and winter stickers