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General Category => General Discussion => Topic started by: rider7 on February 24, 2017, 10:57:20 AM

Title: Less power at lower SOC ???
Post by: rider7 on February 24, 2017, 10:57:20 AM

I did do a search before posting this but at least the way I worded it no previous thread showed up.

I am expecting everybody to jump all over me and tell me to shut up since everybody but me knows the details of this  : ???

I have had my new 2017 zero now for a month or so, put about 600 or so miles on it and think I feel that the bike has less power when at lower SOC.
Yes, I felt that for pretty much since the first week.

I thought the controller algorithm was going to modulate voltage and amperage in a way that you always have the same power all the way until the SOC gets to levels where they want to extend the last little drops of electrons a bit to help you to stretch a bit.

But, I clearly reveal right now that I don't even know how the power output is controlled on this brushless motor.
Clearly some of the possible values of frequency, voltage and amperage are controlled just like on an industrial servo motor.
And if I am down on voltage and that is what is one of the main values used, it would explain why I experience less power.

I thought that the controller, being an inverter would modulate the little electron guys in a way that the power output stays linear until the above mentioned last "oh shit miles".

Not afraid to admit that I am lazy and simply want to tap into y'all's knowledge.
I can search the heck out of this and learn this, but I know that you guys have been at this a lot longer and have quick answers.

Thanks.

Rider7

Title: Re: Less power at lower SOC ???
Post by: anton on February 24, 2017, 12:11:04 PM

Yes. You can see that if you pull your logs and look for lines like these:

Code: [Select]

00331     01/07/2017 20:08:26   Riding                     PackTemp: h 26C, l 26C, PackSOC: 54%, Vpack:102.447V, MotAmps: -15, BattAmps:  -1, Mods: 10, MotTemp:  49C, CtrlTemp:  27C, AmbTemp:  18C, MotRPM: 622, Odo: 7426km
 00332     01/07/2017 20:08:26   Batt Dischg Cur Limited    625 A (90%), MinCell: 3656mV, MaxPackTemp: 26C
 00333     01/07/2017 20:09:26   Riding                     PackTemp: h 26C, l 26C, PackSOC: 54%, Vpack:102.339V, MotAmps:   0, BattAmps:   2, Mods: 10, MotTemp:  54C, CtrlTemp:  28C, AmbTemp:  18C, MotRPM: 658, Odo: 7426km
 00334     01/07/2017 20:09:26   Batt Dischg Cur Limited    619 A (89%), MinCell: 3638mV, MaxPackTemp: 26C
 00335     01/07/2017 20:10:26   Riding                     PackTemp: h 26C, l 26C, PackSOC: 53%, Vpack:102.438V, MotAmps: -56, BattAmps: -19, Mods: 10, MotTemp:  54C, CtrlTemp:  28C, AmbTemp:  18C, MotRPM:1437, Odo: 7427km
 00336     01/07/2017 20:10:26   Batt Dischg Cur Limited    611 A (88%), MinCell: 3646mV, MaxPackTemp: 26C
 00337     01/07/2017 20:11:26   Riding                     PackTemp: h 26C, l 26C, PackSOC: 53%, Vpack:102.180V, MotAmps:  47, BattAmps:  15, Mods: 10, MotTemp:  50C, CtrlTemp:  27C, AmbTemp:  18C, MotRPM:1307, Odo: 7427km

Title: Re: Less power at lower SOC ???
Post by: Erasmo on February 24, 2017, 02:59:23 PM

The power is modulated to have the same feel, but if your SoC drops so does the Voltage, and if the voltage drops low enough the amperage goes up too high for the controller/cells to cope with and it is limited.

Title: Re: Less power at lower SOC ???
Post by: clay.leihy on February 24, 2017, 08:24:33 PM

Depends on ambient temp as well. At 30F and 50% my FX won't do over 60 mph. Same conditions but warmer, say 70F, it'll do 80+.

2015 FX ZF6.5 👹 DoD #2160,6

Title: Re: Less power at lower SOC ???
Post by: rider7 on February 28, 2017, 10:53:46 AM

Ah.... ok.

I somehow assumed that it was like a derated air craft engine that only allows to produce a set (lower than possible) amount of power at sea level (gauged by your maximum allowed manifold pressure, which is controlled by your throttle valve opening)
When you go up in altinute it allows you again to pull up to your maximum MAP for the density altitude (pressure corrected for non standard temperature) you're at which in turn allows you to still pull the same amount of power than you had at sea level.
In short, you are now allowed to open the throttle more to keep the engine at the same power output as at sea level, but your're still only pulling up to your derated power.

The power loss at altitude would be the equivalent of your decreasing SOC.
I thought that the motor could theoretically produce more power at high rate of charge, but the algorithm doesn't allow it, that way, you would be able to keep the available power constant over the entire SOC, but....... we would have an overall weaker bike to begin with.

So I guess I can live with the decreasing power for the benefit of having even more umpff... at high SOC.

Thanks for enlightening me.

Rider7