This is a street light circuit. Previously, we used the controller’s dawn/dusk function to switch the light on and off. Recently, some customers requested a programmable timer as well, so I installed a GEYA THC – 30 A digital timer, which has now been running in the system for 30 days and is functioning as expected.
Since installing the timer, the peak battery voltage now typically reaches 27.5–27.9 V, whereas prior to the timer installation it consistently reached around 28.6 V. Over the 30-day period, the batteries reached 28.2 V on only one occasion.
Additional information:
The timer relay coil is powered directly from the battery via a circuit breaker. If powered from the Victron controller’s LOAD output, the relay does not latch correctly.
My main question is whether the batteries only reaching 27.5–27.9 V on a regular basis could have any long-term negative effects on the LiFePO₄ batteries.
Do You know at what voltage the batteries start to balance the cells? Could You check the cell voltages in batteries?
If voltage batteries often reach is above the balance start one and the cells balances nicely, You should be fine. Looks like You have enough energy stored for the load (lights).
The lower voltage could even give some extra cycle life.
I can’t really check the individual cell voltages without opening the batteries, which would risk damaging them. Prior to the timer being installed, the batteries were charging up to 28.6V every day without fail. Unfortunately, the trend data from that period has since been overwritten, so I can’t share before and after data, it would have been useful for comparison.
I agree that the slightly lower operating voltage could potentially improve cycle life, I hadn’t considered it from that perspective before.
Thanks for the insight, my only consideration is whether, during winter, the slightly lower peak voltage reached could have any negative impact on the batteries’ available runtime or would you say it is minor?
Like lxonline said - the graph smooths the data, loosing the extremes.
For me as control freak, it is hard for me to say is there something bad going on without knowing the cell data. I would keep an eye on recent voltages, looking if the situation changes. If You are in Northern hemisphere, it could improve, as days are getting longer.
And if it’s for some serious task, I would strongly suggest to use battery having possibility to see it’s “internal” life (as data by Bluetooth or like).
Oh right ok thank you, that is good to know, yes you are correct looking at the Vmin / Vmax has closer the excepted figures. i will attach for your reference.
