question

Thanks for your input.

I understand that the SOC value will not stop the discharge, however it will triger alarms, relays...

it is just that the actual draw doesnt reflect the SOC. be it a new install, I will keep a close eye.

Hi @JohnC, as always I i patiently await your response and expertise. Thank you very much indeed for your time and input.

you commented on my setup last year 8x parallel. and you were right again, the MPPT can not get them to absorption, but again UK weather what to expect :).

I would like to think that my wiring is good, I followed a balanced wiring schematic where each battery have same number of knots . I know that unless there is lab conditions it would be hard to achieve equal draw, but so far the batteries seems fine (touching wood) no difference in temp and when I disconnected them recently to move them they all measured the same voltage...

Now if I go back to my question, I think I made mistake attaching the wrong battery spec sheet, I followed your advice and have been monitoring usage this afternoon, I can see some progress where the SOC dropped to 95%.

as you can see from the history I have just installed the smartshunt. I havent synchronised the shunt manually, as I am not sure when is 100%. and since the batteries havent seen float since the summer I have been just topping them up from driving around, I can see initially 70A coming from the alternator which drops to 30A and not below whilst the voltage go up to 13.9-14v. is this 100%? that is what the shunt think.(an Orion-tr is on my bucket list although no VE.Direct),

Can you kindly review the correct spec sheet attached below and advise if the Peukert , Charge Efficiency and Tail are same as previously advised?

Can I be sneaky since you are here and get you to take a look at my MPPT set up and see if everything is correct or close?

I have everything connected to a PI running venus OS, I have some reading to do about DVCC, is this a better route to get the best of everything?

Hi @Slopz01

That default 1.25 isn't necessarily wrong, but it may be more accurately applicable to high discharge rates of like C5 or C10, which most of us don't use. Usage like that may well deserve the SOC 'penalty' it applies. Typical usage might be closer to C50, drawing down batts overnight, so a high Peukert then will give a high 'credit' to the SOC, and can lead to an overly optimistic SOC. So I start with a Peukert from the Victron calculator (using C20 to C100 batt specs = 1.16), then reduced it to 1.10 to err on the safe side.

Critics might say that's rough. Even Mr Peukert, whose algorithm is empirical anyway, admitted that temperature isn't considered. So I agree it's rough. But you can get awfully close if you get to know your batts and experiment.

Like you, I don't like to see my Pb's go below 48.0V. But they can, even at SOC >80%. A little load and winter batt temps can easily drop them below 48. With confidence in your SOC you can shrug that off.

Your 4% Tail is too high for my liking, but if your Charged V is up around Absorb charge level, then you'd sync to 100% at maybe 98% true. Close enough if you're happy with that and understand it.

With the two factors Charge Efficiency and Peukert, the aim is to adjust them to return to 100% SOC on a daily basis, naturally, at the right time. Gotta be careful of what your sync is doing though, that's a step that can foul up your careful work.

Note too that VictronConnect can show in real time what an adjustment to Peukert will do to the SOC if the batts have discharged some. And it's reversible, a good tool to experiment with..