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Limiter inverter with RS485 load setting
Hi, I was browsing Aliexpress and stumbled across this image of the same inverter, showing that there might be a new firmware update, or perhaps the image is displaying an older firmware? If you want the link I'll send it over but due to being aliexpress the URL is a mile long, you can probably find the product yourself easier.

Hi all,

I've updated some of MasterTH's code to control the inverter with either JSON or MQTT. It allows multiple units and a hard limit on maximum output, and a buffer amount which also includes the ability to export.

I am hoping to test it as soon as some max3232 UART/TTL/RS232 breakout boards arrive so I can make a reliable serial port on my Rpi. The USB to serial adaptors seem to constantly freeze due to driver problems.

If anyone would like to do code review or had any comments on it please let me know!

I've made a file to allow it become a system service too, it's all in the repo.
CarlosGS and completelycharged like this post
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...
Cell-King likes this post
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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