Since I live in an area with midnight sun and ambient light throughout the night, my victron mppt does not turn off charging during night even if there is 0 W, I suppose because the PV voltage is higher than my battery voltage. End of May until August.
Problem is, the MPPT will not start a new cycle the next morning, meaning my lifepo4 bank never enters absorbtion mode. I have to manually adjust “float” to 14.0 now and then to balance.
Is there something I can do to fix this? Firmware that have a time set charge cycle instead of relying on the PV voltage, for example? Ideally I would like to set a time when the charge cycle should reset every night at 00:00. Like a manual option, instead of the PV voltage.
This will get even worse when I soon will add another string of solar that will double the PV voltage…
You could use some expert mode settings like re-bulk offset. Equalisation: set it to every day to the absorption voltage, try 1hr. That’s a really interesting problem you have there.
This is wierd it should be bulk abs float. To replicate the ploblem you would have to set up a light source did you try the Equalisation set to daily that might take a while to do it that is the thing to watch.
Adjust rebulk offset, then set a really long absorption time.
Summary
An example: If the re-bulk offset is set at 0.1V and the float voltage at 13.8V, the charge cycle will restart once the battery voltage drops below 13.7V (13.8 minus 0.1) for one minute.
Summary
Maximum absorption time
This setting sets the absorption time limit. This setting is only available when programming a custom charge profile.
Enter the maximum time in hours and minutes (hh:mm) the solar charger is allowed to spend in the absorption stage. The maximum time that can be set is 12 hours and 59 minutes
Equalisation simply involves charging a battery at a higher voltage for a specific period, which is generally reserved for AGM batteries or other chemistries that require it. For lithium batteries, the equalisation process maintains a higher voltage in comparison to the bulk stage. If you set the equalisation voltage to be the same as the absorption voltage, it will sustain that voltage for 1 to 2 hours, depending on the duration you set. Nothing more it won’t hurt it. You are probably confusing equalisation with something else.
Equalisation is available only with a flooded lead acid profile.
When you choose a lithium preset it is disabled and low temp cut off is added to the profile and temperature compensation is removed.
It doesn’t help that some lithiums call their absorption voltage stage equalisation voltage (essentially the same thing though at the end of the day as the purpose was to get all the cells to the same level).
What is possible with a lithium profile is to shorten the re bulk and extend absorption time.
As a thought @Pex some guys with the 24 hour sun just switch offf their pv breaker and thennon again after a few minutes to restart the whole process.
Use custom put whatever you want in there all the settings will be disabled if you use the lithium profile. I know what equalisation is for. All the man needs is a high enough voltage for balancing for 1-2hrs a day or every 2-3rd whatever he wants. All the settings are there just start using them its a sanbox no right or wrong.
It’s a remote cabin. Can go months between visits and I want my batteries to reach balancing voltage (around 14,0) like once a week at least, if not daily.
It’s a shame there isn’t a option for scheduled absorption on the Smartsolar MPPT.
I don’t have 24hrs “sunlight”. Although I get voltage from my panels higher than my 12v battery voltage, allthrough night. Even at midnight I get 15v. Will be 30v once I add a panel.
I use a inverter a couple times per day when here. The battery voltage certainly drops below re-bulk, but the MPPT just does a bulk/float charge after a re-bulk event. Not absorption.
Only thing that will make it enter absorbtion is if I reboot the MPPT or shut off the panels for an hour or so. Then absorbtion will work for one day. After that, it goes into this bulk/float limbo again.
Usually to start in the day the PV voltage has to be 5v above the battery voltage, but usually once started it can track right down to 1v above.
But i wonder how that pans out if voltage never leaves the panel. Not a situation i have encountered.
Maybe you are having a combination of a few things that contribute to the charge not happening
Do you have a fixed absorption charge set or adaptive?
No, it never reaches Off state because PV voltage is around 15v over the night. It switches to off state when PV voltage falls below battery voltage (~13,2v). Which never happens for me during may-august. I think that’s the whole problem.
Tail current is disabled. Absorption is set to fixed (currently 2hrs). Have tried playing with the absorption set time, and the re-bulk voltage offset but it doesn’t make a difference.
My parameters are:
Absorption 14,2
Float 13,4
Re-bulk -0,2
Tail current disabled
I have verified with my fluke that I don’t have any voltage drop between batteries and the MPPT. It’s reading the correct battery and PV voltages.
Edit: A function where I could set my own limit to the PV voltage, when the mppt should turn off charging could also fix this problem. I could then tell the mppt that when my PV input is below 16v for example, it’s night time and it should start a new cycle including absorption when PV voltage rises to my set voltage plus a couple volts.