Solar charging in Storage

[SquirrellCook]

I may have missed the point somewhere, but why mains charge when you have solar? Also I'm never a bit fan of having two "smart" systems in competition against each other. Especially as they won't be smart enough to know the other exists.

 

[wildebus]

Not sure if the power of the AC charger will matter that much if it is a multi-stage unit? (mine is a 120A unit).
I found the key to having the (30A) MPPT working when it was light instead of the Mains Charger was to have the voltage set slightly higher than the AC Charger (so my AC Charger is set at 14.1V and my MPPT is 14.2V (my batteries prefer a lower CV voltage than the typical AGM battery))

I would expect if you set the MPPT CV voltage to below the float of the Mains (taking account of any temp/voltage compensation) the MPPT will either never go to bulk and/or absorption, or will go through those stages really fast? (I said mine skipped from bulk to float? It is possible it DID go to an absorption phase but for such a short time the monitoring system didn't pick it up (it samples every minute))


I would normally try some different settings with my kit to see if I could help investigate further, but about to head off in a couple of days for a week or so, so need to start my trip off with full batteries.

 

[PeteS]

I may have missed the point somewhere, but why mains charge when you have solar? Also I'm never a bit fan of having two "smart" systems in competition against each other. Especially as they won't be smart enough to know the other exists.

Because my demand from 12v exceeds what my battery can deliver particularly over winter when I may also watch TV/DVDs etc. I also dont have the weight allowance on long trips to add any additional batteries. Plus having this particular charger gives me a fast charge from say an electric point in an aire for a minimum time. It all seemed like a good idea at the time.

 

[PeteS]

Not sure if the power of the AC charger will matter that much if it is a multi-stage unit? (mine is a 120A unit).
I found the key to having the (30A) MPPT working when it was light instead of the Mains Charger was to have the voltage set slightly higher than the AC Charger (so my AC Charger is set at 14.1V and my MPPT is 14.2V (my batteries prefer a lower CV voltage than the typical AGM battery))

I would expect if you set the MPPT CV voltage to below the float of the Mains (taking account of any temp/voltage compensation) the MPPT will either never go to bulk and/or absorption, or will go through those stages really fast? (I said mine skipped from bulk to float? It is possible it DID go to an absorption phase but for such a short time the monitoring system didn't pick it up (it samples every minute))


I would normally try some different settings with my kit to see if I could help investigate further, but about to head off in a couple of days for a week or so, so need to start my trip off with full batteries.

Yeah we are off to head off to for a few weeks so while we were away in the New Forest I thought Id have a play Getting there I think. I'm really happy with the way it performs off grid, have no problem with that.
Thanks for your help, I may come back in a few weeks for more!!!

 

[wildebus]

I may have missed the point somewhere, but why mains charge when you have solar? Also I'm never a bit fan of having two "smart" systems in competition against each other. Especially as they won't be smart enough to know the other exists.

Solar is often not enough to provide the necessary charge and need another source to provide charge. You could just as easily ask why have a split-charge system when you have solar. It is the same question.
Ideally you would have all the charging systems aware of each other but that rarely is the case. One limited example is the Redarc 40A Dual-Input B2B/MPPT Combo. This is a "solar priority" system and will use the Solar Harvesting as the main input and use the current from the Starter/Alternator to bring up the total current to a maximum 40A (or whatever the battery demands, whichever is the lower).
It is usually the charging system that is set to the highest voltage that becomes the primary source of charge. Other units that are set lower won't provide any charging as the battery is higher than that charger can output. They don't compete as much as 'give up'.

 

[Markd]

I'm inclined towards SquirrelCooks view.
When in storage pesumably there's minimal load so why even bother with mains?
Whilst I may have an electric heater in the van over winter I just turn off the basic mains battery charger and leave the solar to keep both hab and van batteries topped up.
But then I don't have either a mega battery bank or a small power station on my roof!

 

[PeteS]

I'm inclined towards SquirrelCooks view.
When in storage pesumably there's minimal load so why even bother with mains?
Whilst I may have an electric heater in the van over winter I just turn off the basic mains battery charger and leave the solar to keep both hab and van batteries topped up.
But then I don't have either a mega battery bank or a small power station on my roof!

This all started when I noticed my Solar controller Victron Smart Solar was overcharging my battery when in Storage so I was looking for slightly different settings to reduce the impact and take it to a maintained state and not a fully charged state.
The battery had clearly been gassing in storage and the solar had to be the culprit.
Looks like from the graphs it had 4 hrs everyday of a full on charge even though it was in storage with nothing on.

It looks like the same thing could happen if your on mains with solar as they dont always talk to each other so while one is maintaining a charge the other (solar) seems to be trying to dump current into my battery 4hrs every day so I'm looking for a solution, nothing to do with mains and solar in storage.

So this is all about settings and changing away from the default setting which may or may not be damaging batteries when not in use

 

[Markd]

Thanks for the clarification, sorry I misunderstood.
Obviously overcharging on solar only needs sorting.
The rest is all a bit technical for me and I hope you get it sorted.