# Analyzing data from Netgain WarP Drive controller



## corbin (Apr 6, 2010)

Hi all,
I'm looking at the log data from the WarP Drive controller and trying to make sense out of it. I have battery amps and pack voltage logged; something like this, logged for each second:

amp voltage
0	159
0	161
0	161
22	161
47	172
72	172
114	172
126	184
146	184
...

The battery amps are 0 when I don't have my foot on the throttle.

Maybe this is obvious to others...but how can I take this information and compute the kilowatts consumed? I can multiply the amps * voltage to give the watts being consumed at that moment. I can then sum that value up and divide it by the total seconds...but is that right?

I want to also compute the amp-hours consumed based on this information...but again, I'm rather ignorant on how to exactly do that. (I am reading an EE book at the moment to get up to speed)

corbin


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## corbin (Apr 6, 2010)

corbin said:


> Hi all,
> I'm looking at the log data from the WarP Drive controller and trying to make sense out of it. I have battery amps and pack voltage logged; something like this, logged for each second:
> 
> amp voltage
> ...


NOTE: I had contacted Netgain Controls about the voltage reporting -- apparently there is a bug in the hardware rev I have that reports the wrong voltage...so, ignore the fact that the voltage increases under load.

corbin


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## Guest (Feb 10, 2011)

Corbin,

Here is the graph of the Amperage rise. 

Pete 

Looks nice. How did the Bug feel? Strong? Quick?


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## corbin (Apr 6, 2010)

gottdi said:


> Corbin,
> 
> Here is the graph of the Amperage rise.
> 
> ...


Hey Pete -- thanks! I can graph the amps pretty easily...the trouble I'm having is correlating it to actual amp-hours and/or kw consumed.

The bug is nice! I tend to baby the throttle to try to get maximum range, and I'm still learning how to charge the batteries and the BMS settings. I don't think I have the BMS's SOC calculations quite right, so I'm going to play with those more. 

The bug feels quick to me -- if I do hit the throttle all the way (when in second) it picks up really quick; probably quite a bit faster than my wife's Prius (but, that isn't saying much!) but not nearly as fast as my old turbo-charged WRX STi. It goes up highway 17 (~6 miles long, and steep!) at 50-55mph in 3rd with out a problem. I can do it in 4th too, and prefer it past 55mph for fear of running too high an RPM (I don't have my tach working yet, and I'm just going off calculated numbers). 

I have the controller set to draw at most 600 amps (3C), and I think it is set for 35 amps / 10ms (I need to double check that value, as it is off the top of my head). I may up the acceleration and max amps to 1000 and see how that feels for a run or two.

corbin


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## GerhardRP (Nov 17, 2009)

I'll really be interested in seeing your data, once you/netgain get/s the voltage reporting sorted out. 
Meanwhile, since you log each second, simply adding up the reported amperes gives you Ampere*seconds. When you divide that by the number of seconds in an hour [3600], you get Ahrs.To get Watt*hours given up by the battery, multiply by the nominal resting voltage of the pack.

How many other parameters can the controller log?

Gerhard


corbin said:


> Hi all,
> I'm looking at the log data from the WarP Drive controller and trying to make sense out of it. I have battery amps and pack voltage logged; something like this, logged for each second:
> 
> amp voltage
> ...


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## corbin (Apr 6, 2010)

GerhardRP said:


> I'll really be interested in seeing your data, once you/netgain get/s the voltage reporting sorted out.
> Meanwhile, since you log each second, simply adding up the reported amperes gives you Ampere*seconds. When you divide that by the number of seconds in an hour [3600], you get Ahrs.To get Watt*hours given up by the battery, multiply by the nominal resting voltage of the pack.
> 
> How many other parameters can the controller log?
> ...


Thanks Gerhard! I'll look into that tonight with the data from my last drive home. Unfortunately my DC-DC converter was having trouble this morning, so I didn't drive the car to work today (My "fix" may have not worked right: http://www.corbinstreehouse.com/blog/2011/02/plug-bug-iota-dc-dc-converter-fix/ )

The controller logs lots of data, at intervals of 1/10 s, 1s or 10s. off the top of my head: Motor amps, Motor voltage, battery amps, battery pack voltage, duty, throttle input voltage, throttle percent, 15v status, 5v status, errors, internal temperatures. No RPM logging, as it doesn't have a direct input for the RPM gauge (which I was sad about!).

corbin


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## GerhardRP (Nov 17, 2009)

Do you have a logging GPS system. With that and a data dump of battery and motor volts and amps I could do a complete analysis of the bug.
Gerhard



corbin said:


> Thanks Gerhard! <snip>
> The controller logs lots of data, at intervals of 1/10 s, 1s or 10s. off the top of my head: Motor amps, Motor voltage, battery amps, battery pack voltage, duty, throttle input voltage, throttle percent, 15v status, 5v status, errors, internal temperatures. No RPM logging, as it doesn't have a direct input for the RPM gauge (which I was sad about!).
> 
> corbin


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## corbin (Apr 6, 2010)

GerhardRP said:


> Do you have a logging GPS system. With that and a data dump of battery and motor volts and amps I could do a complete analysis of the bug.
> Gerhard


Yes, I do have a GPS, and I will have to do a run home with it on to sync up the data. That is a great idea!

Attached is the data for the ~27 mile drive I did along this path. For the first 3-5 miles I was in traffic. The last part is a steep road (highway 17):

http://maps.google.com/maps?f=d&sou...21.956482&sspn=0.299224,0.485115&ie=UTF8&z=12

(I cut off the last 2 miles to my house).

It is a .csv file zipped. Feel free to play with the data; I'll get a GPS run on it soon.

View attachment 09182901.csv.zip


corbin


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## Guest (Feb 11, 2011)

Corbin,

Nice numbers you got there. Freeway and road. So what do you think about the whole setup? Nice to see some information coming in from the Netgain controller. I should have some logging soon on my Synkromotive controller. Looking for a drive later today in the MG. 

Pete


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## corbin (Apr 6, 2010)

gottdi said:


> Corbin,
> 
> Nice numbers you got there. Freeway and road. So what do you think about the whole setup? Nice to see some information coming in from the Netgain controller. I should have some logging soon on my Synkromotive controller. Looking for a drive later today in the MG.
> 
> Pete


Hey Pete -- Well, it's easy to complain about the things I don't like, so I'll do that!

* RPM gauge -- I wish the controller had an input for the RPM sensor and would emit it on the Interface module. I think Netgain eventually plans to do this.
* The RPM sensor I have I have had trouble getting to work with a tach I bought; mainly my fault...I cut too much off the tail end of my motor shaft.
* I'm having trouble with my IOTA DC-DC Converter (see my post on the EVDL list)
* I'm having trouble getting the cells balanced; it is just taking time with the BMS shunting current at the top, and I have one cell that is *really low* compared to the others
* I need to update the software for the Elithion BMS; my version is old, and I'm loosing the SOC every so often.
* I'm not sure if the SOC from the BMS is correct or not, and sometimes it drops from 50% to 20% all of a sudden. I need to isolate why this happens (it is probably due to me not having a setting right).

Other than those things..the car is great! I only drove it twice this week..as I ran into the Dc-DC converter trouble.

--corbin


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## Guest (Feb 11, 2011)

Corbin,

I am using a Kelly DC DC and it is fine and puts out a steady 13.5 volts. It is isolated too. What charger are you using again? 
Sorry to hear you cut off some of that shaft. I would not have cut any. I'd have cut a hole in the apron before cutting the shaft. Anyway thats me.
BMS, please be careful with that. I'd hate to see trouble from that. You top balancing them? What is the cut off voltage your using and is that controlled by the BMS or charger? Does the BMS control the charger? 

I will not be using a BMS. I will monitor the pack by splitting the voltage so I can see what one side is doing vs the other. My charger will be in control of the cut off voltage. My controller will be in charge of the low voltage cutback and cutoff point. 

Throttle connected and ready to calibrate. Love that feature. 

Hows the power to the car? Is it strong? Hey, don't complain. Just as for upgradable features and post the positive features. State you'd like to see these as upgrades not as negative. 

How many cars are advertised by the faults or features the other guys have but wished they had. Frankly I'd love to see all the positive features of this controller. You are the one feeding us with that info. I know of no one else that is doing so. 

So you are the man for answers. Numbers are great but what about the seat of the pants type of driving experience? Never mind the rpm issue or those tiny little things. Those will get worked out.


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## corbin (Apr 6, 2010)

Hey Pete
The IOTA 55amp DC-DC converter is what has been troubling me lately and preventing me from moving. I'm using the Manzanita Micro PFC30 for my charger. The BMS does control the charger, and I trust it. It works fine to turn it on off, but I also have the charger set to go into constant current mode once it hits the pack voltage. So, it is doubly safe from overcharging. Also, the way I wired it to the BMS, it keeps a circuit open when it *can't* charge and the BMS closes it when it *can* charge. This means if my 12v source for the BMS dies it won't let the charger charge and overcharge the cells. Yes, I am top balancing the cells, and using the shunting feature of the BMS. It is working..it is just taking a while to get my low cell up there.

How's the car? It is pretty strong and quite peppy, especially if you hit the throttle all the way. It surprised people when they hop in the car. I don't have any clutch slippage or anything yet. I nearly always start in 2nd. 

The controller is great! I don't know why more people aren't using it. Sure, it has a few little bugs, but it sounds like Netgain Controls has them solved. The issues I have are:

* Sometimes it has some bucking or hiccuping when you accelerate hard
* The reported pack voltage increases under load, and isn't correct

Ryan at Netgain Controls has been very helpful and very fast at responding to the few questions I have had.

I'm going to eventually send my controller in at some point and have these things fixed; I just haven't wanted to give up driving the car!

I especially like the logging feature, and I hope to write my own UI for the iPhone/iPad to display real time info sucked out of the Can BUS. I just have to figure out how…

One thing I don't like is the 12v fans that come with the Netgain water cooling kit; they are quite load. If I run without the fans, the controller will start to overheat when running up a steep hill for a long time, and reduce output power. I may try mounting the radiator under the car in the airflow instead of in my rear engine compartment to solve that problem. And/or, get different fans.

corbin


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## Guest (Feb 11, 2011)

Excellent news. I just got power to my motor and will be going for a quick drive here real soon. I will be doing some data logging too. It was nice hearing that contactor connecting and hearing that motor spin up. 

I'd think that you could just update the firmware at home to fix those issues. Maybe not.


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## GerhardRP (Nov 17, 2009)

corbin said:


> <snip>
> * The reported pack voltage increases under load, and isn't correct
> 
> Ryan at Netgain Controls has been very helpful and very fast at responding to the few questions I have had.
> ...


Hi Corbin,
Oddly, when I looked at your first data dump, I found that the (Motor Voltage)/(Battery Voltage) and (Battery current)/(Motor current) are very close to the PWM%, as they should be. This means that all the analog measurements track with the same error. That error is obvious in the battery voltage numbers, but not the others. I suspect there is a noise problem on the ADC reference signal.
Gerhard


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## corbin (Apr 6, 2010)

GerhardRP said:


> Hi Corbin,
> Oddly, when I looked at your first data dump, I found that the (Motor Voltage)/(Battery Voltage) and (Battery current)/(Motor current) are very close to the PWM%, as they should be. This means that all the analog measurements track with the same error. That error is obvious in the battery voltage numbers, but not the others. I suspect there is a noise problem on the ADC reference signal.
> Gerhard


Hmm..interesting! After I get at least 1000 miles under my hood, I'll mail the controller back. I should have done it this week...as I've been out of driving for a few days already, and might not be back on the road till next week
corbin


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## corbin (Apr 6, 2010)

Well, I mailed the controller back and got it upgraded. It now reports the correct voltage levels when under load.

Here's some info from the controller for a 20 mile drive home, including a huge hill:

amp hours: 41.955
watt-hours: 6444.288
watts/mile: 322

Based on my 200ah pack, that would be ~21% discharged or 79% DOD. 

I'd say 322-350 is a good value for watts/mile for the driving I do. This also considers the large hill that I drive on the way home, that consumes a lot of power. I was also driving quite conservatively, but keeping 55-60mph up Highway 17. I was hoping for a better watts/mile value...but it is what it is.

The overall actual ah consumed is slightly higher, since the Dc-dc converter also consumes power. I BMS said I was at 77% DOD, so it pretty well correlates with what the data I'm getting from the controller.

At 322 watts/mile, and a 200ah*153.6v pack that would be a 95 mile range to 100% DOD. Times a max 80% discharge that gives: 76 miles as my useable safe range. 


corbin


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