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Limiter inverter with RS485 load setting
#53
Add in handling of the packet from the units, which returns the voltage at the terminals and the input amps. Volt meter accuracy is not that great though... also sense check the voltage as incoming packets do collide and get voltage readings all over the palace. Frequency of data packet is about the frequency of coulds in the sky...

myBytes22 = 14 byte buffer / packet

batVolts = ((myBytes22(5) * 256) + myBytes22(6)) / 10
batAmps = ((myBytes22(7) * 256) + myBytes22(8)) / 10

Then.... with the volts (either from this reading or a more accurate reading from your BMS) you can then create a proxy formula to estimate the battery Wh remaining..

lblWhRemaining.Text = (-(1) * (-21.6661623 * (batVolts ^ 3) + 3569.24955115 * (batVolts ^ 2) - 197572.81504691 * batVolts + 3637661.56366712)).ToString("#,##0Wh")

This gives me a rough indication of Wh remaining with accuracy of +/- 15% of pack capacity. Yeah, not "ideal" but more than good enough to use consistently without worrying about coulomb counting resets and drift.

Tip : You don't need to be a math guru to get the formula.... just use Excel. Get a few readings from your battery Wh and volts... add them into a scatter plot....... add a polynomial trend line...... edit the trend line to show the formula...... change the formatting to add enough digits to get the values accurately....... you have your formula withut any working out...
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If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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RE: Limiter inverter with RS485 load setting - by completelycharged - 06-29-2020, 10:43 PM

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