Friday, October 12, 2012

LiFePO4 ESS News - 24V charger security relay and 12V power supply to Arduino board

Last week end activities on my LiFePO4 ESS (Battery Energy Storage & Power Supply System):

- Swap the 12V charger security automotive relay for the 24V (30/40A) one (received quite a while ago):

The contact is better now because this relay is just more adapted to this voltage and it is heating up a lot less than the 12V one 
Also the 12V relay used to get stuck from time to time, and being a security charger side cut off, in case the charger does not stop, it would not be of any help !

- Power the Arduino board through its power supply inlet:

I am now running the programmable dual relay voltmeter and Tyco Kilovac contactor from the 24V battery pack directly, and then used the DC-DC converter to power the Arduino board, switching it on when the ESS is in Power Supply Mode ... and it worked perfectly ...

... only in the beginning, because something strange happened: the automated power on and off of the relays activating the grid tie inverters did not seem to work well anymore after that, and it took me little time to find out why. I thought : "What's wrong, this program loaded in the Arduino board micro-controller has not changed for weeks, Wattson color voltages thresholds can not change, they did not for weeks... The only thing I changed today is this power supply: from micro-USB 5V to power inlet 12V"
I also realized that this power inlet area on the board was heating up abnormaly ... (?)
So I removed it, switched back to micro-USB 5V and everything worked like a charm , as it did for the last weeks :-)   I still do not understand what is wrong with this power supply inlet, the DC-DC converter provides exactly 12V, nothing more

Nice green (small) negative usage, the (almost) perfect situation when running in Power Supply Mode

Also received in the mail, the 4 4700uF 35V 105°C capacitors to replace the vented one in the last damaged Grid Tie Inverter

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