2020-11-14, 11:30 AM
I want to monitor battery current In/Out using an INA219 and my existing NASA BM1 100A/50mV external shunt.
Data to be fed into an ESP8266 running ESPEASY and then on to OpenPlotter via MQTT
Ive read Paddyb's thread in "How I did it" but I'm a little unclear on a couple of points...
1) Can you draw a heavy load through an external shunt in parallel with the onboard without blowing the onboard shunt?
If the load is drawing say 50A (e.g. battery charging) doesn't 50A get pulled through the (parallel) shunts thus destroying the (3.2A) on-board shunt?
I know the simple answer is to remove the on-board shunt but I note above that Paddy just "piggy-backed" the INA219 onto the external shunt - I'd like to understand why that didn't result in Blue smoke !
2) Unfortunately although INA219 is supported in ESPEASY it doesn't have a calibration option to support external shunts.
Has anyone used ESPEASY with an INA219 and an external shunt and if so how did you calibrate the external shunt?
Did you simply use a formula in ESPEASY ? and if so do you have the formula for a 100A/50mV or a 50A/75mV shunt (yes I know I'm lazy)![[Image: rolleyes.png]](https://forum.openmarine.net/images/smilies/rolleyes.png)
Thanks - Keep Safe
Data to be fed into an ESP8266 running ESPEASY and then on to OpenPlotter via MQTT
Ive read Paddyb's thread in "How I did it" but I'm a little unclear on a couple of points...
1) Can you draw a heavy load through an external shunt in parallel with the onboard without blowing the onboard shunt?
If the load is drawing say 50A (e.g. battery charging) doesn't 50A get pulled through the (parallel) shunts thus destroying the (3.2A) on-board shunt?
I know the simple answer is to remove the on-board shunt but I note above that Paddy just "piggy-backed" the INA219 onto the external shunt - I'd like to understand why that didn't result in Blue smoke !
2) Unfortunately although INA219 is supported in ESPEASY it doesn't have a calibration option to support external shunts.
Has anyone used ESPEASY with an INA219 and an external shunt and if so how did you calibrate the external shunt?
Did you simply use a formula in ESPEASY ? and if so do you have the formula for a 100A/50mV or a 50A/75mV shunt (yes I know I'm lazy)
Thanks - Keep Safe