I have a SmartShunt 500a and a SmartSolar 100/20 charge controller. They are in the same VE network and sharing data. The shunt claims it is transmitting temp, current, and voltage. The charge controller claims it is receiving the same 3. Battery temp and voltage are the same. Current is not. Battery current is always higher on the controller than on the shunt. Why is this? Is there a way to fix? Which is the more accurate reading? Thanks!
Hi @MaxxManic
They're not supposed to be the same. But if you look in the mppt settings you'll see a 'Tail' function, and the shunt's Current can be used there by the mppt to terminate Absorb cycle from the actual battery current, rather than the mppt''s own, some of which may be going to loads. It's a great feature actually.
If you have no loads, the shunt is the accurate one.
Providing it's less than 10A, the upper limit on that Tail setting. Shouldn't worry you though. Check it out..
Thanks for the quick response!
I’m not sure I understand why they wouldn’t be the same, and I’d like to. They are sharing the data after all. Granted, I haven’t seen the difference above .5a but still. My 100/20 battery neg is connected to the most pos terminal of the shunt. There are no DC loads on the 100/20, it is set to Always Off. All DC loads are connected to the most pos terminal of the shunt. Only one cable is connected on the most neg terminal and it goes to the battery. No other connections are made on the neg battery terminal. Even my inverter connects to the shunt.
I did set the tail current to 500mv, per battery mfr, as you suggested.
Thanks for the assistance!
These are the battery parameters from the mfr. I have tried to duplicate them where possible. I do have Absorption time set to adaptive and not a flat 5hr as suggested.
Dear customer, this is our night, but I contacted the battery engineer by phone and got a positive answer. The parameters are as follows:
Absorption voltage: 14.6V
Absorption time: 10 hours (depending on the current size, if you use a 10A charger, it is 10 hours; 20A charger is 5 hours)
Maximum absorption time: There is a protection board inside the battery, which will not damage the battery and can provide overcharge protection. If you want to set it, you can set it to 12 hours
Floating voltage: 13.8V (depending on the current size)
Batch compensation voltage: 13.3V
Balance voltage: 14.2V
Balance current percentage: (only balance current: 200 mA)
Temperature compensation: -16 mV /°C (no need to set)
Low temperature cut-off: -20C (no need to set, there is a BMS protection board in the battery)
Low-voltage cut-off voltage: 10V (with built-in protection board for protection)
Tail current: 500 mA
Hope to help you, thank you!
