Hi Sarah and John (thanks for getting back to me),
John:
I'll see if I can increase the levels - thanks for the feedback.
Sarah:
If possible could you send me links to products you have already bought so I can take a look at them? Which specific leisure battery, solar charger, buck vconverter did you buy?
I used buck converters on a previous project and had an issue with them - if the battery depleted their output changed (decreased) - maybe this was specific to the buck converters I had? I'd be interested in your experience with them?
In a similar vein, I tried using resistors configured as a voltage divider to drop 12v to 5v and this has a similar effect - if the battery depletes the output drops. Ideally i'd like something that always outputs 5volts and maybe tracks the battery level in some way to achieve this.
Maybe the setup needs further capacitors to smooth out any voltage spikes from the panel via the MPPT pcb? Have you added anything like that to your design?
To answer your question - the Arduino does work at 12v but becomes very hot - (I removed the Atmel chip so it didn't get fried), i'm wondering if this could be the issue and causing the Pi to flake out every so often - maybe the 7805 voltage regulator on the Arduino is being overwhelmed, it might need a more substantial heat sink?
Bw,
Ben