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Logging battery amps
#41
(2020-11-14, 12:50 PM)PaddyB Wrote:
(2020-11-14, 11:25 AM)affinite Wrote: 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 !

Yes, it's fine on an external  shunt like 50mA/100A.
The sense resistor in the ina219 is massive compared to the external shunt so next to no current goes through it. It would be more 'proper' to remove the internal sense resister on the ina219 but I didn't bother (yet) , just calibrated by hand to measured current when setting up.

Thanks that make sense
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