Lithium = About Turn?

[pat100]

Have I got this right? Having switched to Lithium I need to ensure that the battery isn’t being charged. It should rest between trips at roughly 50%. So:
1. I should turn off the 240v charger (The van is on permanent hookup on a “Well, why not?” basis)
2. I should fit a switch in the solar panel positive lead so that it is not trickle charging the battery.
3. I should fit a switch in the B2B booster's “D+” lead to the smart alternator so I can turn off charging when travelling.
4. I just switch on the mains charger the night before a trip.
It’s a 120Ah battery with a single (at present) 100W solar panel and a Renogy MPPT Bluetooth controller.
The only drain I can think of is the Battery Master to the starter battery. I don’t think that the fridge can draw from the leisure battery. Can it?
I should discharge the battery down to 50% after a trip if necessary. (I need to disconnect it and use a multimeter to establish that?)
I think that I can turn off solar charging by just selecting low voltages in the controller?
I’m a complete novice at MH-ing.

 

[pappajohn]

I believe lithium's like to stand at 80% charge.
Solar panel.....
Modern solar controllers need the battery connected BEFORE the panel is connected for it to acertain the battery voltage.

 

[Tombola]

1. I should turn off the 240v charger (The van is on permanent hookup on a “Well, why not?” basis)
yes, dont leave it keeping Full all the time, not ideal for Lifpo

2. I should fit a switch in the solar panel positive lead so that it is not trickle charging the battery.
You can do this, (I have) as it is handy for isolating the panel in future for any works etc, but your renogy app may possibly have a "off" function on it

3. I should fit a switch in the B2B booster's “D+” lead to the smart alternator so I can turn off charging when travelling.
I also have this is handy when b2b charge not needed but a decent b2b will tail off the charge anyway...dont forget to turn it back on like i do sometimes

4. I just switch on the mains charger the night before a trip.
Yes

It’s a 120Ah battery with a single (at present) 100W solar panel and a Renogy MPPT Bluetooth controller.
The only drain I can think of is the Battery Master to the starter battery. I don’t think that the fridge can draw from the leisure battery. Can it?
I should discharge the battery down to 50% after a trip if necessary. (I need to disconnect it and use a multimeter to establish that?)
anything less than 80% will suffice, and you will probably find natural "drain" will take it down soon enough especially if you have an inverter etc. I sometimes flick my inverter on to draw some power out if Im going to leave it a good while and switch off the 12v hab control.

I think that I can turn off solar charging by just selecting low voltages in the controller?
yes probably, though Im victron and not renogy, mine has an option to switch off charger function via the app

I’m a complete novice at MH-ing.
We all were at one time ! good luck

 

[pat100]

I believe lithium's like to stand at 80% charge.
Solar panel.....
Modern solar controllers need the battery connected BEFORE the panel is connected for it to acertain the battery voltage.

Thanks for reminding me! I’d forgotten about that sequence. Makes disconnecting and reconnecting the leisure battery more complicated!

 

[pat100]

good luck

Thanks for the helpful replies. It’s comforting to know that I’m not going out on a limb

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[Jimbohorlicks]

I think you will find that whilst you are using the battery its not so much of an issue.
When your motorhome is in storage or not being used for a while that's the time to reduce the charge. There is no need to turn off your b2b ,or solar charger whilst your using your van and if your on ehu most of the time. Why do you need a lithium battery?

 

[pat100]

if your on ehu most of the time. Why do you need a lithium battery?

Sorry, I meant when it’s at home it’s on EHU most of the time.

 

[Gromett]

If you have access to the BMS settings You could always create a profile and have it set at 80% full voltage max. The BMS would disconnect above this? I don't know what battery/BMS you are using so can't advise.
Wissel is the guy I turn to for all Battery/BMS stuff these days.

 

[Andy MacD]

I have a Fogstar Drift battery and can turn charging off from the app.

 

[Pausim]

I think people get overly concerned about storing LiFePO4 fully charged. My battery instructions say charge at 14.4V for normal storage. The 50% charge level is suggested for longer term storage of over 3 months.

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[Ingwe]

I think people get overly concerned about storing LiFePO4 fully charged. My battery instructions say charge at 14.4V for normal storage. The 50% charge level is suggested for longer term storage of over 3 months.

This is the advice I received from the fitter of our two lithium batteries. I was worried about leaving it on hookup whilst we are away for 4 weeks. The van is stored indoors so no solar and have a battery master fitted. I was concerned that the alarm, tracker etc would reduce the van battery to a level too low to start the van when we returned. So was advised to leave it on hook up for the 4 weeks and the batteries will be ok.

 

[Tomass]

BMS in battery, dont worry about it

 

[DavidCh]

We really over think this. An old lead battery gets abused and no one worries about it. A lithium is much more resistant to abuse and has a BMS installed to protect it. Worse case is that you can reduce the number of full cycles it will achieve and, given the fact that most are 3000 even if you full cycled them every day that takes nearly ten years. I doubt I will fully cycle mine more than four or five times a year so call that 600 years! I suspect that in 30 years time, if my MH is still going the only bit working well will be the lithium battery!