I’m currently having trouble setting up my smart shunt (or could be something else) to reflect my SOC accurately. I have 2 Eco-Worthy batteries that have bluetooth so I’m able to cross reference that SOC relative to my Smart Shunt SOC. I’ve tried multiple “charged voltage” values to the point I’ve lost track of what value has had the least amount of deviation.
In regards to my charging profile, it is the LiFePo4 preset except my absorption is 28.6v (14.3v) as that’s what gets my batteries to 100% over the Eco-Worthy app. Setting it to 28.4v (14.2v) hangs me up around ~85% over the Eco-Worthy app. When I finally have full charge from solar, both the Smart Shunt and Eco-Worthy app start at 100% synced.
As I start depleting the batteries, I find that my Eco-Worthy SOC would be 15% and my smart shunt would be 30%. What changes can I make to have my Smart Shunt reflect my Eco-Worthy SOC? I’d imagine my Eco-Worthy SOC is the accurate one.
Note: I have a constant ~200 watt load from my inverter 24/7.
Set up is
-Smart Shunt
-2x 12v 280ah Eco-Worthy in series (24v system)
-1x 100|30 MPPT w/ 4x 200 watt panels in series
-1x 24|800 Phoenix Inverter
Hi, there is an FAQ on shunt config pinned to this section, and many similar topics available via the search function. I would suggest you start there.
IIRC the 24 800 inverter has a standby draw of 7watts much less than 200w. If it’s unloaded then that’s all it’s drawing.
check that the current threshold is set low enough to catch this draw otherwise it will be ignored.
I would say that the SmartShunt settings are OK. If the SmartShunt and Ecoworthy batteries both start at 100% and then deviate, the only factor that you can change on the SmartShunt is the Peukert constant, reducing that to 1.02 or maybe 1.00 may help a bit. The charged voltage have no effect on this drift.
Personally I would trust the SmartShunt more than the batteries, I do not know why you think the batteries are better. A lot of the cheaper lithium batteries have a current measurement device that is less accurate than a shunt and there are many cases of them not being accurate, especially when new, some take several charge/discharge cycles to learn the batteries and some like full discharge to fix the bottom of the range. I have run Victron shunt based battery monitors for years and do not doubt them.
The only other thing that can be used to bring them together is if the SmartShunt was set to say 240Ah.
I completely disregard the built in SOC in my battery as its current threshold is about 1Amp so it misses any low solar charging and completely ignores the draw of 0.5Amp from my RPi/Venus system which over a couple of weeks in winter can deplete the battery to 50% and the battery internal SOC will be reading in the high 90% region.
I suppose the fact that the built in battery monitor can’t be adjusted and Victron’s ecosystem is so customizable has made me incorrectly assume it could’ve been a setting issue and not the other way around
I’ve played around with so many different settings so it’s hard to really key in on what should be the source of truth.
And would having a constant load of ~200 watts be a factor to what my settings should be? Both on the MPPT and Shunt? To reiterate, my system will ideally be running 24/7 at said load.
The 200W draw should have no effect on the accuracy or otherwise of the SmartShunt or MPPT or the settings. How it affects the battery SOC measurement I can not answer.
Your SmartShunt settings above look good and I would leave them as they are.
The Eco Worthy site states
BMS estimates the battery’s SOC based on voltage and current measurements.
The SmartShunt is about £80 and is a piece of high precision measuring equipment, there is no way a £420 battery has an £80 current measurement device inside it.
I decided to manually change my Smart Shunt’s SOC to match the battery’s (wrong) SOC and began a complete charge cycle. Sure enough - near 70% my charge was complete and had re-sync’d to 100%. Good call, @pwfarnell !
In summary: Trust the Smart Shunt over an Eco-Worthy built-in battery monitor.
