Wondering how many people are doing this, because the internet doesn't have as much information as I'd expect on the matter.
On one of my packs I have a smart BMS and a BMV712. The ah consumption varies wildly between the two because the BMV almost always shows an idle load of 3-4 watts (a 4G LTE router with internal battery, so not a guaranteed consistent draw...) but the BMS shows 0 watts most of the time, and 3-4 watts occasionally.
Calibrating the above BMS involved bumping up the discharge current so the BMS would consistently show power being consumed, and then I dialed it in to match the BMV. Unfortunately, this made no difference because the BMS I guess is simply not sensitive enough to regularly detect the idle 3-4w load.
On my latest build I'm using another identical smart BMS and noticed with my usual load test that it's reporting 10 watts less than the first BMS, and some other packs (again all using the same smart BMS) so that's an obvious item of concern.
So what is the proper way to calibrate these? The best I can do is calibrate them off of other devices (BMV) or BMS units (each other) and I don't really have any way of knowing if any of them are accurate. And I'm still SOL as far as I can tell, for the minor loads. The first system with the BMV & smart BMS is in a vehicle and designed for camping, so the load most of the time is the occasional 12v fridge cycle and the LTE router. Unless I'm charging to full every day, which isn't happening consistently in the winter, my SOC is somewhat a mystery.
On one of my packs I have a smart BMS and a BMV712. The ah consumption varies wildly between the two because the BMV almost always shows an idle load of 3-4 watts (a 4G LTE router with internal battery, so not a guaranteed consistent draw...) but the BMS shows 0 watts most of the time, and 3-4 watts occasionally.
Calibrating the above BMS involved bumping up the discharge current so the BMS would consistently show power being consumed, and then I dialed it in to match the BMV. Unfortunately, this made no difference because the BMS I guess is simply not sensitive enough to regularly detect the idle 3-4w load.
On my latest build I'm using another identical smart BMS and noticed with my usual load test that it's reporting 10 watts less than the first BMS, and some other packs (again all using the same smart BMS) so that's an obvious item of concern.
So what is the proper way to calibrate these? The best I can do is calibrate them off of other devices (BMV) or BMS units (each other) and I don't really have any way of knowing if any of them are accurate. And I'm still SOL as far as I can tell, for the minor loads. The first system with the BMV & smart BMS is in a vehicle and designed for camping, so the load most of the time is the occasional 12v fridge cycle and the LTE router. Unless I'm charging to full every day, which isn't happening consistently in the winter, my SOC is somewhat a mystery.
