Thanks for your efforts HR1. Sorry it proved so time consuming....

Thanks for your efforts HR1. Sorry it proved so time consuming.

I have a background in science (originally geology trained - 50 odd years ago  but never entered the professional field) to the extent that I think I am able to comprehend the electrochemical side of the battery. What I don't have is any practical experience in charging batteries from say a PV source or for that matter any "sustainable" source. I am pretty sure that I agree with your assessment of the graph and company potential.

Just for interest here's what I think this graph is telling me and maybe you can correct any mis-understandings I might have.

I think that the battery was able to provide power ( or maybe had the capability to provide power?) at 5 units on the vertical scale (Pity no units were shown). This probably corresponded to 25 kW because if it passed the test it had to have the capability to provide 100kWH of energy which it did successfully when the system was disconnected from the grid for 4 hrs.

During the first Day charging period the power output or potential output of the battery is being met by the grid and the PV energy collected during those approx 5 hrs (represented by the area between the green line and the axis) is available to charge up the battery. 

At approx 1.5 hrs before dark the system is swung to discharge mode for 4 hrs. During this time the 25kW of power is provided by the battery but the PV energy collected in the 1.5 hr late afternoon helps reduce drain on the battery ie charges it a little. . (I am not sure why the red line goes below the blue though unless the battery has been designed to overshoot the power output required??) 

Approx 2.5 hrs after dark the system is connected to the grid which meets the power requrements and charging is topped up ( maybe during off peak times as is indicated for the next night)

Approx 1.5 hrs before sunrise the discharge cycle clicks in and the drain on the battery power is met satisfactority by the collected PV during the 4 hrs (passing probably the hardest of the conditions requred!) During the remainder of the day,  although connected to the grid, the energy requirements appear to be met largely from PV sources (the area under the green line seems to approximate pretty well to the 5 x 6 hr rectangle under the blue line). My original question concerned why the red dog tooth appeared at all but I can only suggest that maybe when the very dark cloud came over very quickly the battery power was almost the sole source of power while some switching mechanism chimed in. I really don't know so hence my question. 

The rest of the test continues and can be interpreted in a similar vain.

Hope I haven't bored you and other HC's but I agree that this company seems to be on the right track. That said I have to admit that the reason I started keeping an eye on it was because of its involvement with wave energy which has always appealed to me as a logical energy source of Australia given its population spread so near to the water avoiding the costly loss in transmission. Sorry to see it largely gone but it's no good having good IP and no brass to do anything with it!

Regards

PS The other thing I find confusing is to be talking about charging during a discharge cycle but I'm now good with it if the context is taken in regard to "Is it connected to the grid?" ie Charging or not