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Monday, October 15, 2012

LiFePO4 ESS - Changes to the control board

Another rainy weekend here, so it was easier to find motivation to work on the re-building of my LiFePO4 ESS control board: 
The idea is to put all the parts on the main board and detach them from the battery pack, charger and grid tie inverters

First Idisconnected the programmable voltmeter wires

Ampmeter too was removed along with the automotive 24V relay and the Tyco Kilovac contactor

I tried several times to arrange parts on the board 

and finally came out with this layout

The next day, it was time to make a strong support for the main switch (3 postions: 0, Charger, Grid Tie Inverters)

A used a left over piece of aluminum angle, drilled a 12mm diameter hole in it  

and cut if just the width of the big 24V 15A switch

(almost) finished product 


I then drilled 4 holes at each corner of the flat part to mount it very securely to the board

Here it is installed
Note that I got rid of the 2,5mm solid core wires going to each grid tie inverter; I am now using a thick multithreaded cable to connect the battery pack to the contactor, and the contacter to the grid tie inverters stack

A better view from the top: The Kilovac contcator is mounted flat with 2 screws
I will now have to work on the charger relay, charger leads inlet, fuse and wires layout

My father was kind enough to repair one of my grid tie invrter which had a shorted MOSFET; since it is not the first time, he used a spare one from a previous repair and wrote its reference on the post-it: MOSFET SSF7508

Since I do not have a 30A automotive fuse I simply used a 25A one, which should be enough to prtect the DC side, and anyways the input current goes up to 10, 15A maybe, not more

I then added this 6th grid tie inverter to my stack and will try it out with the rest when everything is functional

Note that I also added the 24V 10A LiFePO4 charger on top o fthe stack and it fits perfectly there :-)

To be continued ....

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