The only thing left to do is add the Raspberry PI and it's I/O boards and finish writing the software. I'll start on that next week, I've ordered a case for the R-Pi, ribbon cable and a few plugs and sockets to connect all the boards - annoyingly only two of the I/O boards have a hole to add a mounting post, the largest I/O board (PiFace) doesn't, and the smallest (2 in, 2 out analogue channels) is too small to have one, so I'll have to mount them in their own case and figure out some way of keeping them stable.
So in the meantime I wanted to test the assembled hardware. 9 SSR relays plus associated heatsinks, temp sensors and cooling fans, the three inverters, DC fuseboard, AC fuseboard, AC distribution block, and all the wiring and crimped connections.
I dug out nine nice old chunky switches to control the relays, fitted them to a bit of wood lying around, connected all the wiring up, used my DC PSU to provide the 12V for the relays and fans and, after a final check for short circuits, connected the battery and charger and turned the input mains power on.
I'm happy to say that everything works fine. At least to start with!
All three inverters running consumed about 45A, which is about half of what they should be drawing.
A quick check revealed that the main battery disconnect SSR was dropping about 1V, the 1KW inverter DC SSR was dropping about 0.7V, and the 500W SSRs dropping about 0.5V.
So the 1KW inverter voltage was 1.7V down, and both 500W inverters were 1.5V down. Not ideal, as the inverters are producing about 1KW between them. Without any voltage drop they produce approx 1.5KW. It'll do for now, my typical evening usage is 900W so it will cover that nicely.
The main battery disconnect relay did get nice and toasty, which tested the temp sensor and cooling fan which worked perfectly. Cut in at about 70 degrees C and turned back off at about 60 degrees C.
After running the system for 20 minutes the two smaller inverters turned their cooling fans on at an internal temp of about 45 deg C, and I know that the 1kw inverter cooling fan works when I tested it in isolation.
So, happy that everything was working properly I turned off both inverters, checked the battery charger and it's relays (both good), and was just turning everything off to finish for the evening.
The battery charger was on and charging at it's minimum of 6.6A. I turned the main battery SSR off, and the charger current sat at 6.6A. Uh? What's it charging? The battery is disconnected. Oh no it's not! The SSR has fried itself and short circuited. I was monitoring it's temperature and it only got upto about 80 degrees C, and I have checked the specs of reputable brand SSRs and they are good for 125 degrees C. Just goes to show that if you buy cheap SSRs, you need to derate their maximum current and their maximum temperature by a lot!
Not a big problem, as it was dropping 1V across it I think I will change it for a good old fashioned 300A physical relay. I didn't want any moving parts anywhere (yes, I know, the fans are moving parts!), but to get the system working at maximum output power it's looking like I'll need to change all the DC SSRs for normal relays.
If any readers know of any eBay sellers selling decent 300A relays (and 100A relays too) please do let me know.
Well, it is a prototype system so finding out parts aren't suitable is part of the game! :)
Piccy of the controller board (excuse the mess at the bottom of the board - this is all the controller wiring connected to the switches, this will all be tidied up when the R-Pi and I/O boards are installed)
Components from left to right, top to bottom:-
Top row
* DC current shunt (partially hiding behind the black box)
* DC fuse box (the black box just under the DC current shunt), 250A main fuse, 75A for 1KW inverter, 60A for each of the 500W inverters, 100A for the charger)
* Main battery SSR (fried)
* Charger DC relay
* DC ground distribution block (hey, it's huge I know, it's what I found on EBay and I couldn't be bothered to chop it down :) )
2nd row down
* DC relays for 1KW inverter
* DC relay for 500w inverter #1
* DC relay for 500w inverter #2
3rd row down
* 1kw inverter
* 500w inverter #1
* 500w inverter #2
4th row down (just below the 500w inverters)
* AC relay for 500w inverter #1
* AC relay for 500w inverter #2
* 4 x main fuses for the AC connection for the three inverters and the charger
* Main AC distribution block
5th row down
* Main 240V AC grid connection (almost off picture to bottom left)
* Charger 240V AC connection (almost off picture to bottom left)
* AC relay for 1kw inverter
* AC relay for 2.5kw charger
* Temporary manual switches used to test the other components
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