Bluetooth shunt battery monitors

[HoleIn12]

Hey…

I have read (and believe) the state of charge on the display can be very inaccurate. I recently had all AGM battery ones replaced for warranty and still showing what seems to be excessively low SOC on the display.. on two different days I had the following results from the display and manually doing voltage check/SOC chart.

Wondering if anyone has used one of the Bluetooth shunt battery monitors and are they with the money? Do you get a different result than your display?


Day 1–
Start: 51.5v
7.4mi at 67% on display
Immediate voltage check @ 50.1v
40 mins rest @ 50.5… about 91% according to chart

Day 2–
Start: 52.1v
10.1mi at 64% on display
Immediate voltage check @ 50.0
40 mins rest @ 50.3… about 85% according to chart

SOC chart: https://octopusasia.com/battery-soc-to-voltage-chart/

Thanks

[AdamP]

I use this one I have Lithium but you probably can check for lead acid or agm works great https://www.amazon.com/Victron-BMV-7...2-8997e41410bb

[augiedoggy]

Yes the shunt style meters are the most accurate. I used to use them with lead acid batteries back when I used lead acid for solar power in my camper. many of them are completely programmable and some even "learn" after completing a full charge and use cycle on the batteries. The renogy model is very popular here for carts.

You will get different reading at idle after resting than under load with a voltage meter, thats normal. I believe you should always go by the voltage your getting before it rises during the rest and gives you a misleading reading. Even with all that a voltage based meter will only be accurate enough for a ballpark.
My father in law complains of this all the time.

[HoleIn12]

Thanks for the inputs… I opted out for now and just go by voltage as the voltage display seems to be accurate (minus decimals).

I built a programming cable and the computer currently gives me 96% SOC while the display gives 86%. Weird, you would think the display some read exactly what it is being told. I would think possibly dirty wires, corrosion etc etc but this cart is just shy of a year old, never rained on or washed with hose, garage kept in sunny Nevada. So I would think that yet but have seen stranger things…

Anyone know any of the battery settings to adjust to possibly make this more accurate?

Thanks