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[Doctorbass]

Well, It had to happen... one day...

I knew that the battery is 70Ah ( rated) and i had my Cycle analyst installed and calibrated and i was thinking that the BMS would protect the battery once it is at a voltage equivalent to something like 65Ah leaving 5Ah for safety and not drain the pack entirely... but it wasn't

Fortunately i was with my friend who have his gas motorcycle (250cc) and was at 4km from home.. so i used the  cahrger extension cord attached to both motorcycle and he towed me to destination... it was a little embarassing... but i assumed what happened..

I tried to crank the throttle couples of time but it reset( to protect the cells from overdischarging every times) and it does that well.

Once i got my zero in the garage i connected my celllog multi cell voltage monitor  to my battery to see at wich low voltage was the 14 string of cells. All was at 3.410V +/-10mV except the cell string no 1 that was at 3.002. I suspect that it's this string that had make the BMS to cut the power of the battery due to the low voltage portection detection.

So i  know now that i have a cell string that is 400mV lower when the pack is discharged... probably a lower capacity once or that it have a higher internal resistance. and i also know that the pack was fully balanced before the ride as usual.  the BMS actually balance the cell in +/- 5mV between all 14 string si it's really good. All cells are at 4,150V +/-5mV once the green led  of the charger is blinking that indicate a fully balanced pack.

Now if the string would have been equal to the rest of string at 3.400mV, I would be really surprised if  that wold have gaved me the missing 11Ah.. but i think not since the voltage slope between  the 3.400V and the 3.000V limit is really high , leaving probably few Ah but not 11Ah...

Now let's find at wich rate these cells were used:

I made 53.3km and used 59Ah at a rate of 57Wh per km for 3037Wh total capacity draw at 51.2km/h average

According to my calculations, the average power was  53.3km / 51.2km/h = 1.04h of run time s

the average power was3037Wh/1.04h= 2920Watts of power


The average voltage is 3037Wh/59Ah= 51.5V
the average current is 2920Watts/ 51.5V = 56.7 Amperes.

Now if the pack is rated 70Ah and that the average current i used is 56.7A, the C Rate that the cells were used is  56.7A /70Ah = 0.8C

Now according to the original specs and graph of the Molicells IMR26700 , these cells when drained at 1C at ambient 21 celsius , have around 80mAh capacity from 3.400V and 3.00V

The Zero DS 2011 is made of 14 string of 24 cells in parallel. so 24 cells x 80mAh is 1.92Ah.

This mean that the way i used this battery,  when it cut, it had still 1.92Ah left. And i used 59Ah so the total pack capacity is more like 60.92Ah,  when drianed down to 3.00V wich is the low voltage protection.

This is 13% less capacity than the rated capacity.

According to the specsheet of the cells, this is the equivalent resting capacity of a battery that would have been used 200 cycles !... but it only was used for ... 8 cycles from now

The advertised 4.4kWh is far too optimistic since i got 3.037kWh

Doc

[manlytom]

might be your battery pack. as 2011 is still under 2 yr warranty you might ask Zero to check ?

on my 2011 I seem to get 70km range in mixed riding.

unfortunately I do not have all the measuring equipment installed etc.... so cannot say details.

[protomech]

Zero says 4.4 kWh = max cell voltage * 14 * 80 Ah 75 Ah [Ed: typo] = 58.8V * 75Ah = 4.41 kWh maximum capacity

Actual "real" capacity is probably more like 51V * 70Ah = 3.6 kWh

[Doctorbass]

Zero says 4.4 kWh = max cell voltage * 14 * 80 Ah = 58.8V * 75Ah = 4.41 kWh maximum capacity

Actual "real" capacity is probably more like 51V * 70Ah = 3.6 kWh

Yes i agree, Plus, we should never use the max value of voltage of the cells to qualify the Wh since this is not the average voltage. so the 3.6 kWh make more sence.

Also, i observed that these celsl are charged at 4.15V and not 4.20V.. this might remove few mAh capacity per cells and probably 1 or 2 Ah over the entire pack. The 4.15V is probably to extande the life of the cells.


But i wonder why you say 80Ah ? the IMR26700 cells are rated 2.9Ah wich is 69.6Ah for the 24p string..

rating this battery to 80Ah mean that each cells would need to produce 3.32Ah each and to do that they would need to be cahrged to something like 4.4V wich is unsafe and not in the rated spec...

Oh.. wait a minute... It might be to allow the zero owners to get the gouvernment rebate if some of these require a vehicule to have like 4kWh like we have here... but guess what.. this is only for electric CAR !! they dont want to include the electric motorcycles!

anyway...


Doc

[protomech]

Woops, typo. Should be 75 Ah nominal capacity.

[polartek]

I drove my 2010 around my neighborhood until the bike started multi-beeping at me to get the feel for my real-life range.  The original 2010 range was tested by the manufacture doing 25mph on a flat surface without stops/starts.  They got around 44 miles/70.4 km in that range test.  I got 34 miles range on my test with stops and starts and max 25 mph.  The faster you go the more power it takes to overcome wind resistance and the less range you can get.  Zero's rating on the new 9Kw batteries on the 2012 at 114 miles/182km.  At higher speeds (70mph) their stats say the 9 Kw will go about 63 miles/101km - a 45% reduction in range.  Temperature can also have an impact on energy losses, but no one rates that impact.  I have run it dead once and was only a mile away from home.  I had to run it up to a light pole and plug in for 20 minutes to get home.  I try not to stretch past 24 miles so I don't have to worry about making it to my destination.   I also recommend downhill trips to for better range! 

Enjoy,
Polartek

[protomech]

Hi polar,

The 63 mile range for the ZF9 is a 50/50 mix of city and 70 mph highway miles. Steady 70 mph riding is good for 43 miles.

[Doctorbass]

The faster you go the more power it takes to overcome wind resistance and the less range you can get.  Zero's rating on the new 9Kw batteries on the 2012 at 114 miles/182km.  At higher speeds (70mph) their stats say the 9 Kw will go about 63 miles/101km - a 45% reduction in range.  Temperature can also have an impact on energy losses, but no one rates that impact.  I

Enjoy,
Polartek

No worries Polar, I alerady know that. I have my degree in physics and Electronic  .. i'm building overpowered  electric bicycle since 6 years now and i have to know that

If only all people could have the Cycle Analyst installed on their zero like i did, we could compare in Wh per km or Wh per mile our different experience.. this is THE number to look at for efficiency.


Doc

[polartek]

The 63 mile range for the ZF9 is a 50/50 mix of city and 70 mph highway miles. Steady 70 mph riding is good for 43 miles.

Ugh.  That is a 72% reduction.
Has anyone taken the Zero and built a shell on one yet and see how efficient they can make it?
This design reports 110mpg with Kawi KLR 650 diesel engine.

These micro-bikes reported over 300mpg in 1983:


-Polartek

[polartek]

... I have my degree in physics and Electronic ....

My bad.  I studied engineering in college and wanted to be an aeronautical engineer.  Got board pushing numbers in math and then ran off to get language and international affairs degrees instead.  

If only all people could have the Cycle Analyst installed on their zero like i did, we could compare in Wh per km or Wh per mile our different experience.. this is THE number to look at for efficiency.  

I am interested in seeing what the difference in Wh per unit of range and the max range would be with an aerodynamic shell on the bike compared to the stock profiles of the zero bikes.  Still hoping they will put some sexy light body work on them in future models - something like these -





Enjoy the Ride,
Polartek