Author Topic: Monitoring all working now  (Read 1301 times)

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frackers

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Monitoring all working now
« on: March 03, 2009, 10:02:50 PM »
The Linksys router with the 1-wire mods is now earning its keep by monitoring the battery bank with a Dallas DS2438 battery monitor chip. This uses an external shunt that it shares with the panel meter and I finished the software last night that tries to make sense of the voltage/current I can now read. The wifi link seems pretty solid over 70m from the router perched on the top of the inverter under a plastic bucket in the middle of the paddock to the router on the server machine under my desk.


The first cut at displaying that data is on my web site where I'm looking at power, voltage, current and accumulated charge along side the wind speed from my weather station.


The graphing package reads the values every 5 minutes so an explanation of what the values means is called for!!


 * The voltage is the instantaneous value at the time of the poll

 * The current is also the instantaneous value

 * The power is smoothed over the previous 5 minutes from samples taken every second

 * The accumulated charge is read direct from the chip which sums the current internally 30 times a second. Its an indication of remaining charge but not an absolute value since the batteries didn't start from zero charge!!


The controller is the simple 555 based voltage comparator which dumps to a 1kw load on the other side of a 240v 3kw inverter.


I'm hoping to learn how the voltage changes with charge current, where the accumulated charge level sits etc in order to have the router become the controller rather than a dumb voltage only control. I've got all the bits for a 1-wire GPIO circuit to drive a relay - so a bit of work to do here.


The monitor chip also has a few other values that I'm going to try and do something with - for example it tracks total charge and discharge current over the lifetime of the system (it even has non-volatile backups of these values) and temperature (which is the temperature of the chip, not of anything useful!!). We'll see how it goes :-)

« Last Edit: March 03, 2009, 10:02:50 PM by (unknown) »
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