Charging

[Glynn]

Question about Victron MMPPT’s


On my motorhome I have 2X 195 W panels coupled to a Victron 100/30.


There is no isolator between panels & charge controller.


It would be to awkward a job to install an isolator due to lack of room & the need to remove too much trim etc.





So since its best not ( so I hear ) to leave the lithium battery on permanent charge, is it ok to switch off the charger in the Victron Connect app ?. if it is ok to do that, would you recommend setting the charge limit to say 70% ?. Is that even possible ?.





Is there any truth that keeping a Life Po 4 battery at 100% can cause problems, I read that it is harmful & also that it’s fine to do so.





I do use the motorhome , so its not like Id leave in on or off charge for ever, probably its left parked up for 5-6 weeks between using. Poss longer over winter.





Look forward to advice.

 

[Raul]

If is only days, I leave it alone, if is weeks standing, or more, I disconnect the panels.

 

[Tombola]

I switch off the charging function in the mppt if standing for a long time

 

[Jimbohorlicks]

There is no isolator between panels & charge controller.


It would be to awkward a job to install an isolator due to lack of room & the need to remove too much trim etc.





So since its best not ( so I hear ) to leave the lithium battery on permanent charge, is it ok to switch off the charger in the Victron Connect app ?. if it is ok to do that, would you recommend setting the charge limit to say 70% ?. Is that even possible ?.





Is there any truth that keeping a Life Po 4 battery at 100% can cause problems, I read that it is harmful & also that it’s fine to do so.





I do use the motorhome , so its not like Id leave in on or off charge for ever, probably its left parked up for 5-6 weeks between using. Poss longer over winter.





Look forward to advice.

Just put a fuse it before the controller you can then use it to isolate the panels from the charger . No need to go on the roof.
We are currently at Brid and with our solar we are back up to 100% before lunch every day despite using the kettle to drop the soc and filling up a flask with hot water. When fully charged.

 

[Raul]

You can get an inline solar fuse, and fuse each panel. Then you just disconnect the fuse.

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[stevewagner]

Had my lithium’s for a few years and just leave them. The BMS seems to manage them perfectly well

 

[JockandRita]

I switch off the charging function in the mppt if standing for a long time

I did consider doing this myself, however a screen message advises otherwise.

Raul. The only way I can isolate the 2 x solar controllers, as to pull the fuses...............which is a right PITA due to their locations.

Cheers,

Jock.

 

[headlight]

Question about Victron MMPPT’s


On my motorhome I have 2X 195 W panels coupled to a Victron 100/30.


There is no isolator between panels & charge controller.


It would be to awkward a job to install an isolator due to lack of room & the need to remove too much trim etc.





So since its best not ( so I hear ) to leave the lithium battery on permanent charge, is it ok to switch off the charger in the Victron Connect app ?. if it is ok to do that, would you recommend setting the charge limit to say 70% ?. Is that even possible ?.





Is there any truth that keeping a Life Po 4 battery at 100% can cause problems, I read that it is harmful & also that it’s fine to do so.





I do use the motorhome , so its not like Id leave in on or off charge for ever, probably its left parked up for 5-6 weeks between using. Poss longer over winter.





Look forward to advice.

I was very cautious about leaving my LifePo4 at 100% SOC at first so religiously made sure that it was at about 50-60% the weeks I didn't use it by discharging the battery and pulling the fuse in the MPPT.
This was a bit of a bind to do.
I then spoke to Fogstar and Vanbitz who both said that if I was using the van regularly, say every month, that the number of cycles I would loose would be inconsequential compared to the thousands of cycles the battery is rated for.
They said if I wasn't using it for 5 or 6 months, say over winter, then in that circumstance it would be worth draining the battery to 50-60% and disabling my solar, in my case by pulling the Victron MPPT fuse.
As I use the van every month I just leave the system ticking over.
My battery is 18 months old and has 22 cycles on it.
It will out live me.

 

[Glynn]

I think I’m do what you do then, ours gets used probably every 6-10 weeks.

 

[headlight]

I think I’m do what you do then, ours gets used probably every 6-10 weeks.

I'm not saying what I do is right just repeating the advice I was given by both Fogstar and Vanbitz whose advice I respect.

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[Raul]

I did consider doing this myself, however a screen message advises otherwise.

View attachment 1070289

Raul. The only way I can isolate the 2 x solar controllers, as to pull the fuses...............which is a right PITA due to their locations.

Cheers,

Jock.

Hi Jock, just to clarify, I do not pull the fuse on the controller, I have fuses on the panels coming too controller. I disconnect those, not the controller. Leaving the controller on, without the solar, helps a bit to drain the batteries when they are idle and not used.
I'm talking weeks at a time. Few days, I don't bother.

 

[Raul]

I then spoke to Fogstar and Vanbitz who both said that if I was using the van regularly, say every month, that the number of cycles I would loose would be inconsequential

You don't loose cycles, it just degrades quicker sat at full for long time. Eventually will loose capacity NOT cycles.
Cycles are relative, but, all batteries that uses organic electrolyte, it will have a calendar life. That means it will degrade with time anyways.
Calendar life depends on degradation, and it may come sooner than the cycles quoted.

To recap, a battery degrades whether it is used or not, and sat at full charge for prolonged time, that degradation is faster.