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EUC Math - Question #1


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42 minutes ago, Hunka Hunka Burning Love said:

I wonder what a speed going down of 35-40 kph would look like on the graph (not that I recommend doing it unless there is enough reserve speed available from the wheel!).

I think the results may be flawed, as a result of the rider crapping himself while (literally) screaming down the hill...

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Don't worry - I'm sure there will be a Russian volunteer rider to test things out shortly!  ;)  <searches for Msuper Maximum Speed Test Downhill Crash video Now with Datalogging!>

I've danced with the devil a little on a downhill, but thankfully my Ninebot tilts me back at 22 kph to tell me I'm gonna get a hurt real bad if I push it further.  If the Gotway can tilt back well before faceplant speed I wonder if a steady 30-35 kph might be doable for maximum recharge.

Remember those science exhibits where you crank the generator to light a bulb?  You have to get it going fast enough where it hits kind of like a threshold where things light up and that's where everything gets interesting?  I wonder if making the current high enough in a negative direction would do the trick for more regeneration, and how much does downhill speed have an influence on the charging amount.  I have a feeling that crawling down at 10 kph might not charge things up that much?

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2 hours ago, Hunka Hunka Burning Love said:

Correct me if I'm wrong, but doesn't the current have to be negative in order for charging to occur?  It looks like most of the downhill current is initially hovering around -5A then goes positive to around +8A.  Is there still charging potential when the current is positive?  I wonder if you were to go faster downhill whether that would drop the average downhill current towards a greater negative value resulting in greater regeneration.  

Regarding temperature I can see that going uphill draws some spikey current peaks around the 22:13 mark around +20A which would makes sense making the temperature rise as more current is drawn.  When descending it looks like the majority of the current spikes are from -5A to +8A which is moving a lot less electrons around so it cools down.  I wonder though if you were to go faster downhill whether things would heat up again say if you could create -20A to recharge.  Your speed going up looks pretty well mirrored with the speed going down.  I wonder what a speed going down of 35-40 kph would look like on the graph (not that I recommend doing it unless there is enough reserve speed available from the wheel!).

I place the current sensor between the battery and the board, so yes, negative current to charge.
Around 22:18:10, there is a small uphill, so the current is positive dominant. Apart from that, there are still positive current spikes because the road is not even.
The average uphill current is 16.4A, the average downhill current is -4.7A.

I tested another 8% hill another day trying different speeds, The length of the hull is 1.13km and the height is 91m. 
I tried to maintain 15kph on the 1st round, uphill 40.2Wh and downhill -11.0Wh, the efficiency is 27.3%, smaller than the previous test, probably because the hill is not very steep. 

Then I tried to ride at 25kph on the 2nd round, uphill is 42,7Wh and downhill is -9.4Wh making the efficiency of 22.1%. 

On the last run, I tried even faster but without looking at the speedometer, up=44.9Wh, down=-5.4Wh and the efficiency is only 12%. The current spikes is larger this time, but due to increasing wind drag, the charge is small.

Here is the GPS speed and elevation measured by the barometer on my phone:
V3-slope-test2-GPS.gif

Here is voltage, temperature, speed and current measured by GL220 and Wheellog:
V3-slope-test2.gif

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1 hour ago, Hunka Hunka Burning Love said:

I've danced with the devil a little on a downhill, but thankfully my Ninebot tilts me back at 22 kph to tell me I'm gonna get a hurt real bad if I push it further.  If the Gotway can tilt back well before faceplant speed I wonder if a steady 30-35 kph might be doable for maximum recharge.

Faster in speed create more air drag which will cancel the regenerative charge. Maximum charge only achievable down a very steep slope with reasonably speed. I've once rode my V2 down a hill of about 15 degree(27% slope) and the board got overheated(80 degree C) at the bottom. It is actually an artificial skiing slope.

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