Friday, July 22, 2011

LTC4151 voltage and current measuring board


I was looking for simple ways to monitor my charger boards for the V2 equalizing battery bank charger and came across this awesome chip by Linear. The LTC4151 is an I2C voltage and current monitor that can be powered from the same voltage source it's measuring (7v minimum, up to 80(!)V) and can measure current up to 4 Amps. It made it very easy to monitor the chargers.
On my board I just basically implemented the datasheet-recommended design including the kelvin sensing connection for the current sense resistor.
Since getting anything under 0.1ohms seemed to be an impossible feat over here I just bought 0.1s and stacked 2 on top of each other to get 0.05ohm sense resistors.

Combining this with the Nokia display project after some calibration (calculating the divisors for the ADC values after measuring with a trusted source) the outcome is promising:



Now we're getting somewhere. I still needed 5 volts for the micro-controller from the 20volts used by the chargers. Will deal with that in the next post.

Eagles:

Schematic
PCB

2 comments:

  1. Replies
    1. I published the code in the final post for the project. "Equalizing battery bank charger V2". You can find it in the Blog Archive widget to the right under September 2011. Search for "Bascom" within the post.

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