I have a 24/3000/70 easysolar and have set the absorb voltage set to 28.20v for the 150/70 mppt via ve-direct Bluetooth dongle went to check the system as i’ve only had it running 2 days and the voltage got up to 28.35v yesterday!! My battery specs say not more than 28.2v for a 24v system. Can anyone help please??
What is the temperature in the morning before the MPPT wakes up?
The MPPT uses its own internal sensor to take a temperature reading at this time & then uses it to correct/compensate the charge voltage for temperature throughout the day.
25°C is the reference temperature and if it's colder the voltage will be automatically increased. If it's hotter the voltage will be decreased.
To confirm if this is the reason temporarily set the temperature coefficient to 0mV/°C or switch the toggle to disable temperature compensation and check the output voltage during absorption charge phase.
You should refer to the battery manufacturers specifications to confirm the correct coefficient to use with your particular batteries.
Also if you want the temperature to be monitored throughout the day & voltage adjusted according, consider adding a Smart Battery Sense device & Bluetooth pairing it with your MPPT.
Alternatively, if this higher voltage is not continuous & only seen as a max daily voltage in Victron connect, then it could have just been a brief spike following a large load being turned off while there was also high charge current output from the MPPT.
Please let us know how it goes.
Also, you may want to consider lowering the nominal charge voltage slightly if it's currently right on the maximum of the allowable range & you still have concerns.
The temp in the mornings the last few days has been i'd say between 10-15℃ but during the day has been as warm as 28℃ so if the mppt is reading say 10℃ when it starts up but then it climbs up to say 25℃ by lunchtime thats a big difference in temp as far as charging is concerned. maybe i need to get the "smart battery sense"? will keep an eye on it.
I turned the temp compensation off and the voltage didn't go above the set voltage so that proved it was what you were talking about so i'm halfway there i think.
Great to hear that the current behavior/logic is now proven & understood.
Yes I also agree that there can be a significant temperature variation over the day, so charge voltage based on morning temperarure only is far from ideal.
I notice that you actually have a fairly decent system... do you have a battery monitor yet?
If not maybe consider getting a BMV-712 battery monitor instead with the additional temperature sensor.
The BMV-712 can serve the same function (as Smart Battery Sense) & be Bluetooth paired to a Smart Solar MPPT via a VE Smart Network.
If you happen to already have a BMV-712 you may be in luck...
Hi Mark,
I already have a bmv-700 so may have to bite the bullet and get the smart battery sense.
i will also try lowering the absorb voltage slightly to see if that helps.
Hi J. This can happen from a spike caused by a load change or somesuch. The kit may only take milliseconds to react, but in that time a 'day high' gets recorded. Not for concern.
The main thing though may be temp compensation. The V will be adjusted to allow, unless you've turned it off.
If Pb batts, that's a modest Vabs anyway, and unless the batt maker has also supplied a temp correction factor, perhaps that limit is for the 'masses', a general safe level for all conditions.
I wouldn't be too concerned about it. What I would do though is check Vbat with a multimeter in (say) a stable Absorb condition, and check with the readings of the Victron.
If you haven't had a chance yet to hook your system to the VRM portal (I hope you can), then please do, a lot of this type of seemingly strange behavior is often explained on the graphs once you get the hang of it.
'Easy' does it, ha! Just monitor & measure for now. Adjust if necessary once you get a handle on it all. Nothing urgent to me, but I do sympathize with your concern for your system. Good luck with it too..
Edit/: Posted before I saw Mark's, I've a slow keyboard.. :)
Dont forget you have two chargers here in this system
ONE being the MPPT unit
the other the Multiplus 3000/70
so you must adjust BOTH UNITS to the correct settings. not just the MPPT solar reg
