Cycle Analyst V3 preview and first beta release

[teklektik]

...if you do select the Linear temp probe, then the options for setting the scaling factor and offset will also show up in the menu.

Config parm summary updated to reflect additional linear sensor parameters...

[Joe Perez]

Config parm summary updated to reflect additional linear sensor parameters...

Thanks for that- this had been causing me some consternation prior to actually receiving the unit and seeing how it worked.

Also, a note on the use of "other" temp sensors:

I'm awaiting the delivery of a MAC motor from Cell-Man. These motors are fitted with an LM35 temperature sensor, which is different from either the LM335 or the NTC thermistor that Justin suggests. Specifically, thermistors and LM335s act like resistors or zener diodes, which conduct current to ground depending on temperature. As such the CA-3 is fitted with a pullup resistor on the "NTC" pad. Although the part number seems quite similar (LM35 vs. LM335), these devices are quite different.

The LM35 is an active device, which outputs a positive voltage which varies with temperature. Cell_Man selected this device over the passive devices which Justin suggested to enable folks without CAs to use a simple voltmeter to measure temperature (the LM35 outputs 10mv / °C, so it reads nicely on even a simple $5 voltmeter.) However the internal architecture of the LM35 is such that it won't work properly with a pullup voltage applied to its output- it can only source current, not sink it.

So, to use one of these devices, you need to remove the pullup resistor (R17) from the CA board. It's a tiny little surface-mount part, but shouldn't be too difficult if you have a pair of irons to lift it up tweezer-style:




Having removed this resistor, you can pick up 5v at the adjacent pad to supply operating power to the LM35, and then calibrate the software for 0 degrees = 0 volts and 100 degrees = 1 volt.



EDIT:

The NTC input on the CA tends to float high when unconnected, or when connected to a device which cannot sink current to ground on its output such as the LM35. With the circuit configured as described above, I saw false-high readings of 100 degrees or more, just from the stray voltages floating around the circuit.

This has been solved by simply placing a pull-down resistor between the NTC pad and ground, to eliminate the stray voltage. I've tested the circuit with a 390 ohm resistor (simply because it's the first small-value I happened to pull out of the pile), and it is now giving me a believable indication of 22-23 degrees while resting at room temperature. I haven't load-tested the bike yet to see how it performs as the motor warms up (I'm tethered to my workbench at the moment owing to the lack of a functional battery, and I found out the hard way that using your rear brake as a dyno load doesn't work for very long.)

Too low of a resistor value will negatively impact the performance of the circuit, as the output of the LM35 is relatively weak- it can only source 10ma on its output. I may experiment with larger resistor values to see if I can still hold down the float voltages while pulling less current from the LM35, though even at 390 ohms I'm loading it pretty lightly- less than 4ma at 150 degrees (1.5v).

[lizardboy]

Hi everyone;

I have a few more details about my current sensing issue. I hooked up a constant current supply from my icharger through the controller. I set the icharger for 5 amps and recorded these readings.

Rshunt set to 1.000 CA reading. 1.2 A
Rshunt set to 5.002 CA reading. 1.0 A
Rshunt set to 9.903 CA reading. .5. A

As a test I plugged my old cycle analyst back in to the direct plugin. It measured the current properly so I could use some input on what to check from here. The voltage measures properly and the speed sensor and speed limiting work properly.I haven't checked the current shunt voltage at the CA pins but with such high voltage very nearby I didn't want to start probing around with the test leads.

Your gonna love that mac motor..

[lizardboy]

The problem with my current sensing has been solved,

Thanks to justin's late night and early morning tech support the culprit has been identified. Turns out at some point I must have set the rshunt value close to 9.999 which due to rounding rolled over in the internal register to a number larger than the display could hold. So my rshunt had in a sense an extra number that couldn't be seen or modified.

I must point out that this has totally been fixed and won't happen again. It was just a function of the software undergoing development and is fixed in the 3B13 firmware that will be out shortly.

After much trying and yet more tech support from Justin I managed to use the programing cable from my lyen 9 fet infineon controller by soldering on the needed cable and jack. reflashing the firmware reset the stored value and off I went.

[Tench]

Glad you got it sorted

Justin, i have nticed an anomaly, sometimes when i switch the controller on (un-modded 72v40a from ebikes.ca) i get 74.9v on the CA main screen (18s) and then turn it off and on again and it might display 75.2v it has done this a few times now.
With the v2.25 it always displayed the same voltage. When i changed over to the V3 i only changed the board not the wiring other than reconnecting the green wire correctly after first doing it wrong. Earlier today i turned it on to see 74.9v, i turned the controller off waited a few seconds then turned it back on to see it dsplay 75.2v and had a little blip of life from the motor as the system turned on, i think the difference in voltage sensing changes one of the throttle values too causing the blip.

Simon.

[hjns]

Temperature:This input can be either a 10K NTC thermistor,

Anyone had a play with thermistors yet ?
I don't know much about them but there seems to be a fair variation in price ranging from THESE that are under $2 for 10 or others that are $5 each or more.
The LM235 seems to have a similarly suitable temperature range up to 125 oC. The LM135 goes up to 150 oC which would be nice for those pushing it to the limit but they're heap more expensive.
I'm happy for the CA to step in around 120 though!

I ordered these and will let you know. Datasheet here.

If possible, I will install 2 in the motor and two in the controller. I also have the Analogger, so will be able to compare data.

In the meantime, I hooked up a throttle and it is great to see the min and max voltage output on the CA. That alone is already a big improvement. I calibrated the CA/external shun combo without issues using fixed iCharger current through the shunt.

Justin, as I run 30S with an external shunt (0.35 mOhm), I run in high settings. Still I can not have LVC higher than 99.9V, which is way too low for my 30S lipo. Would prefer another digit here, so I can get at least 105V LVC.

Also, even with the temp log off on the Analogger, hooked onto the CA v3 beta, the Analogger shows me 3 to 5 additional collumns that I still need to identify. Having the CA send out a header when starting up, or sending out the summary stats with a header when shutting down would be a great help. Summary stats could include min, max, mean. Furthermore, having a time stamp in the CA would be very helpful, because without knowing this it is now less then accurate to link the CA data with GPS data. I know having a clock in the CA would be a bit too much, but if it could retrieve the date-time from the Analogger, and send it along in the CA dataset as timestamp, it would be great.

Tekletik, your guide is really great. However, I think it is worth it to add some info how to connect the CA to the controller regarding throttle output, as explained in your post here. I will assume that in the final version, the CA will come with a controller connection anyway, but for now it would be a good addition.

[justin_le]

I'll have a new Beta12 firmware version posted here in the next 3-4 days

Okay, attached to this email is the Beta13 firmware which has the following changes:

a) Fix the throttle surge issue (that was my goof-up from adding the throttle ramp-down rate control at the last minute and forgetting to initialize a related variable)
b) Adds the ability to control the Aux Input voltage range just like the throttle, so you can set a min and max input range instead of it only being 0-5V
c) Enables the Auxilliary control of the the power limit function
d) Completely changes the constant power feedback loop for a more appropriate gain range
e) Fixes the units display bug when miles are selected instead of km
f) Fixes thermistor lookup table. In the Beta12 code it was set for a 10K pullup, but we switched to 5K on the boards for better sensitivity at higher temps and forgot to adjust the table accordingly
g) Adds a throttle fault voltage that you can set a bit higher than Max Throttle to shut the system down if you have a break in the throttle ground wire
h) Enables the Quadrature encoder mode. So if you have a device where the Direction input is a quadrature pulse, you want to enable this for better response. But if you just have a magnet PAS sensor, then disable the quadrature mode and the DIR input is assumed to simply be FWD or REV direction signal
i) Increases the low voltage cutoff range with one more digit so you can set it >99.9 V

The instructions for reprogramming the firmware are explained back here:
http://endless-sphere.com/forums/viewto ... 4&p=564885

It seems that every sensible extension is blocked from uploading so I renamed the firmware as a .pdf, after downloading change this to a .hex extension to avoid attempts at opening it with a pdf viewer.

[teklektik]

It seems that every sensible extension is blocked from uploading so I renamed the firmware as a .pdf, after downloading change this to a .hex extension to avoid attempts at opening it with a pdf viewer.

ES allows posting zip files so if you just zip it up, the uploader will accept it and download access is somewhat easier than with the renaming ploy.

[teklektik]

Setup Summary for CA vB13

The setting summary for the newer v3B14 release is available here.
The setting summary for the previous v3B12 release is available here.
Unofficial basic setup notes are available here.
Values shown are defaults after loading firmware.

[...] = numeric entry field
{ ... | [...] } = menu chooser where [...] = default selection

1. Setup Calibrtion
   
   1. Cal -> Range
      { [Lo (W)] | Hi (kW) }
   2. Cal -> RShunt
      [1.000] mOhm
   3. Cal -> V Scale
      [31.05] V/V
   4. Cal -> Zero Amps
      (Press/Hold to normalize the currently detected Amp reading to 0.0)
2. Setup Spdometer
   
   1. Spd -> Units
      { mi | [km] }
   2. Spd -> Wheel
      [2075] mm
   3. Spd -> #Poles
      [23]
   4. Spd ->TotDist
      [00000] km
3. Setup Speed Lims
   
   1. SLim -> Max Speed
      [99.0] kph
   2. SLim -> Start Speed
      [00.0] kph
   3. SLim -> IntSGain
      [200] Gain
   4. SLim -> PSGain
      [0.59] V/kph
   5. SLim -> DSGain
      [002] Gain
4. Setup Power Lims
   
   1. Plim -> Max Current
      [99.0] Amps
   2. Plim -> AGain
      [150] Gain
   3. Plim -> Max Power
      [9999] Watts
   4. Plim -> W Gain
      [200] Gain
5. Setup Throt In
   
   1. ThrI -> Cntrl Mode
      { [Pass-thru] | Current | Speed | Disabled }
   2. ThrI -> Min Input
      [0.99] Volts
   3. ThrI -> Max Input
      [3.99] Volts
   4. ThrI -> Fault Volt
      [4.49] Volts
6. Setup Throt Out
   
   1. ThrO -> Output Mode
      { [Voltage] | R/C Pulse }
      (if ThrO->OutputMode = { Voltage }
      
      1. ThrO -> Min Output
         [0.90] Volts
      2. ThrO -> Max Output
         [3.74] Volts
         )
      (if ThrO->OutputMode = { R/C Pulse }
      
      1. ThrO -> Min Output
         [0.90] mSec
      2. ThrO -> Max Output
         [3.74] mSec
         )
   2. ThrO -> Up Ramp
      [500]
   3. ThrO -> Down Ramp
      [500]
   4. ThrO -> KV Comp.
      [0.95] V/kph
7. Setup RPM Sensor
   
   1. RPM -> PAS Poles
      [08]
   2. RPM -> Dir Plrty
      5v={ [Fwd] | Rev }
   3. RPM -> Quadrtr
      { Disabled | Enabled }
   4. RPM -> Strt Delay
      [50] x 18ms
   5. RPM -> Stop Delay
      [15] x 18ms
8. Setup Trq Sensor
   
   1. Trq -> Trq Scale
      [-200.0] Nm/V
   2. Trq -> Trq Offset
      {2.55V 4.71V}
      (Press/Hold to update eeprom offset voltage on left with current voltage on right - similar to Zero Amps)
9. Setup Cntrl Mode
   
   1. Ctrl -> PAS Mode
      { [PAS Off] | RPM Cntrl | Trq Cntrl }
   2. Ctrl -> Assist Level
      [0500] mA/Nm
   3. Ctrl -> Aux Funct
      { [Off] | Amps Lim | Speed Lim | Power Lim | Pas Level }
   4. Ctrl -> Min Aux In
      [0.99] Volts
   5. Ctrl -> Max Aux In
      [3.99] Volts
10. Setup Temp Sensr
    
    1. Temp -> Sensor
       { [Disabled] | 10K Thrmstr | Linear Type }
       (If Temp->Sensor = { Linear Type }
       
       1. Temp -> 0 Deg
          [0.99] Volts
       2. Temp -> TScale
          100.0 Deg/V
          )
    2. Temp -> Thrsh Temp
       [090] oC
    3. Temp -> Max Temp
       [130] oC
11. Setup Battery
    
    1. Batt -> Chemistry
       { LiFe | SLA | NiMH | [LiMn] | LiPo }
    2. Batt -> String#
       [10] Cells
    3. Batt -> Capacity
       [10] Ah
    4. Batt -> RBatt
       [199] mOhm
    5. Batt -> Vlt Cutoff
       [19.0] Volts
    6. Batt -> V Gain
       [0800] Gain
    7. Batt -> TotCyc
       [0000] Cyc
    8. Batt -> TotAhrs
       [00000] Ah
12. Setup Display
    
    1. Disp -> Main Disp
       { [Watts] | Amps }
    2. Disp -> Averaging
       [5] Duration
    3. Disp -> RS232
       { [1] | 5 } Hz
    4. Disp -> Vshutdown
       [10.0] Volts

Printable version:

CA_vB13a_ConfigSettings.zip

(1.48 KiB) Downloaded 22 times

[teklektik]

Flashing will erase all configuration parameters so remember to jot down your settings before you do the deed. The Setup summary posts each have a printable text file at the end to make recording your current settings a bit easier.

A successful reprogramming session will generate a screen log like this:

FlashSessionLog.gif (12.3 KiB) Viewed 706 times

[Doctorbass]

I'll have a new Beta12 firmware version posted here in the next 3-4 days

Okay, attached to this email is the Beta13 firmware which has the following changes:

a) Fix the throttle surge issue (that was my goof-up from adding the throttle ramp-down rate control at the last minute and forgetting to initialize a related variable)
b) Adds the ability to control the Aux Input voltage range just like the throttle, so you can set a min and max input range instead of it only being 0-5V
c) Enables the Auxilliary control of the the power limit function
d) Completely changes the constant power feedback loop for a more appropriate gain range
e) Fixes the units display bug when miles are selected instead of km
f) Fixes thermistor lookup table. In the Beta12 code it was set for a 10K pullup, but we switched to 5K on the boards for better sensitivity at higher temps and forgot to adjust the table accordingly
g) Adds a throttle fault voltage that you can set a bit higher than Max Throttle to shut the system down if you have a break in the throttle ground wire
h) Enables the Quadrature encoder mode. So if you have a device where the Direction input is a quadrature pulse, you want to enable this for better response. But if you just have a magnet PAS sensor, then disable the quadrature mode and the DIR input is assumed to simply be FWD or REV direction signal
i) Increases the low voltage cutoff range with one more digit so you can set it >99.9 V

The instructions for reprogramming the firmware are explained back here:
http://endless-sphere.com/forums/viewto ... 4&p=564885

It seems that every sensible extension is blocked from uploading so I renamed the firmware as a .pdf, after downloading change this to a .hex extension to avoid attempts at opening it with a pdf viewer.

Justin, Is it possible to get 3 unit digit for the max speed limit? ( >99km/h...) ex: instead of having 99.9km/h, we could choose 999km/h

I.m asking because back in 2009 it was one of the issue in the pre-test for the max ebike speed record... the C-A was set to max 99.9km/h and i had to remove the throttle overide wire to allow max speed over 99.9kmh... or just to put it in MPH..

Many motorcycles project are using that great A-C ( including the TTXGP guys.. and i'm sure they wold appreciate too being able to set over 99.9km/h but to keep the LVC and other limiting function that use the throttle overide.

Doc

[shorza]

The purchasing page is live right here:
http://www.ebikes.ca/store/store_CAV3.php

I'll have photos and a bit more details put up in the next day or two.

Just note that these units do not have any of the new accessory features pre-wired. So you will need to open them up and solder cables to the PCB to use the throttle input, aux input, temperature probe, PAS sensor, ebrake cutoff etc. as required for what you want to use. That is part of why the price is lower than earlier suggested. In about 3-4 weeks, we'll have a pilot batch made up that does include a cable assembly bringing all these things out of the enclosure like this:

Cable Harness.jpg

So for people less keen or comfortable doing board soldering, it would be wise to wait for the pilot batch. -Justin

So the beta versions do come with the accessory cables, but they are just not connected?
How hard was it to do the soldering yourself? I am fairly solder savy but don't want to get over my head.

[justin_le]

Justin, Is it possible to get 3 unit digit for the max speed limit? ( >99km/h...) ex: instead of having 99.9km/h, we could choose 999km/h

Yes, it would be annoying for most people to have an extra digit to go through when setting max speed, so what I'll probably do is have it so that in high range mode you can set max speed to 3 digits with no decimal, or 0-999, while in low range mode the max speed is 3 digits with one decimal digit, or 0.0-99.9

Pretty much guaranteed that anyone going over 100 kph is running in the high range with kW display and <1mOhm shunt, so this should accommodate all I would hope!

-Justin

[justin_le]

Glad you got it sorted

Justin, i have nticed an anomaly, sometimes when i switch the controller on (un-modded 72v40a from ebikes.ca) i get 74.9v on the CA main screen (18s) and then turn it off and on again and it might display 75.2v it has done this a few times now.
With the v2.25 it always displayed the same voltage. When i changed over to the V3 i only changed the board not the wiring other than reconnecting the green wire correctly after first doing it wrong. Earlier today i turned it on to see 74.9v, i turned the controller off waited a few seconds then turned it back on to see it dsplay 75.2v and had a little blip of life from the motor as the system turned on, i think the difference in voltage sensing changes one of the throttle values too causing the blip.

Hmm, nothing has fundamentally changed about the voltage sensing circuit compared to the V2 devices, except that the voltage divider in V3 is set up for 150V max while in V2 it is about 110V, and hence the internal resolution is a bit worse in V3. A difference of 0.3V on a 75V pack is about 0.4%, which is will within the 1% accuracy that we're aiming for but normally you'd see that kind of drift after some amount of time or changing temperatures etc. and not immediately after cycling the power. Has anyone seen something similar to this?

[justin_le]

Flashing will erase all configuration parameters so remember to jot down your settings before you do the deed.

That's a great point Teklektik. It is possible for me to compile a firmware hex that doesn't overwrite the eeprom so that future upgrades don't change any of the parameters, but that will only happen once the complete parameter list and associated eeprom locations are finalized. Those things are still in a bit of flux at this point as new parameters will keep getting added for a little while.

Also, the B13 code I just uploaded here is a bit different than the one I sent you by email yesterday which hadn't yet been finished, so when you get a chance update with this copy.

-Justin

[justin_le]

Also, even with the temp log off on the Analogger, hooked onto the CA v3 beta, the Analogger shows me 3 to 5 additional collumns that I still need to identify. Having the CA send out a header when starting up, or sending out the summary stats with a header when shutting down would be a great help.

Right, the serial output stream spec hasn't been finalized, but at the moment it sends the following:

Ah, Volts, Amps, Speed, Distance, Temperature, RPM, HumanWatts, Torque(Nm)

There should be a header on the start of the datastream that goes:

Code: Select all

Ah     V      A      S      D      T      R      W      N

I know having a clock in the CA would be a bit too much, but if it could retrieve the date-time from the Analogger, and send it along in the CA dataset as timestamp, it would be great.

If you have the GPS analogger, then it should automatically time stamp all the current files in their filename, as explained in AppendixA here http://www.ebikes.ca/drainbrain/Analogger_Manual_Web.pdf

[hjns]

Thanks for providing the new firmware with 3-digit LVC. I fully support the request for speed limiting higher than 99.9km/h as well, if only in high current settings. Not that I am running really high currents, though, as with 126V 4A can get my HT to fluctuate between 99 and 103 km/h.

Right, the serial output stream spec hasn't been finalized, but at the moment it sends the following:
Ah, Volts, Amps, Speed, Distance, Temperature, RPM, HumanWatts, Torque(Nm)
There should be a header on the start of the datastream that goes:

Code: Select all

Ah     V      A      S      D      T      R      W      N

Thanks for the prompt response. Well, it should provide a header, but it doesn't. These are the first few lines that are being produced.

-0.0000 125.64 0.00 0.00 0.0591 -273.0 0.0 0 -10793 2999
-0.0000 125.64 0.00 0.00 0.0591 -273.0 0.0 0 -10793 3000
-0.0000 125.63 0.01 0.00 0.0591 -273.0 0.0 0 -10793 3000
-0.0000 125.64 0.01 0.00 0.0591 -273.0 etc

I will try again tonight. It does correspond nicely with Ah, V (30S), A, S, D, T (Celsius), RPM, humanW, and N...., and also shows I have no torque sensor nor thermistor attached as yet, so thanks for your answer. It saves me a lot of time. Maybe there is a setting in the CA that tells whether or not to send the header?

If you have the GPS analogger, then it should automatically time stamp all the current files in their filename, as explained in AppendixA here http://www.ebikes.ca/drainbrain/Analogger_Manual_Web.pdf

Yes, I have, and that it does. However, that does not allow for linking individual rows of data to specific time points (or specific parts of the road), only the time of generation of the file is being recorded.

My idea was to record the CA data on a specific hilly road at a predefined speed driving for about 30 minutes, recording the changes in altitude using the GPS, so that I can correlate the increases in current and/or temp with the steepest incline that I encounter. Now, in order to do that, at this moment I need to assume that the CA log starts at the same timepoint as the first GPS date-time stamp, then calculate the difference in seconds between the time of start of recording until the time that I start with the hill, next multiply the number of seconds with the frequency of datatransmission, in order to calculate where the CA data is co-inciding with the hill. It works, but it is a bit fault prone due to the multiple derivations.

Anyway, the temp threshold - current limiting features should result in recordable differences in speed and/or motor/controller temp. Only the CA v3 beta can do that! So hurray!! This thing has got a very nice future!

[teklektik]

Also, the B13 code I just uploaded here is a bit different than the one I sent you by email yesterday which hadn't yet been finished, so when you get a chance update with this copy.

Thanks for the heads-up. Sort of stuck in a spate of rainy days anyhow...

[Doctorbass]

Justin, Is it possible to get 3 unit digit for the max speed limit? ( >99km/h...) ex: instead of having 99.9km/h, we could choose 999km/h

Yes, it would be annoying for most people to have an extra digit to go through when setting max speed, so what I'll probably do is have it so that in high range mode you can set max speed to 3 digits with no decimal, or 0-999, while in low range mode the max speed is 3 digits with one decimal digit, or 0.0-99.9

Pretty much guaranteed that anyone going over 100 kph is running in the high range with kW display and <1mOhm shunt, so this should accommodate all I would hope!

-Justin

Thanks Justin!

[lizardboy]

About the voltmeter readings someone reported on...

Hitting reset brings up a different voltage for me not much.. but every 2nd time or so the motor blips a bit and the diplayed voltage changes a few tenths of a volt. Sometimes there is no motor blip but the voltage changes a couple of tenths from before the reset.

It's like sometimes it pays attention to the v/v calibration and sometimes it doesn't. I have changed my v/v value from the factory setting and it seemes to ignore my changes on power up but if I reset it a few times the voltage drops and matches the calibration.

I'm not sure if theres a difference between the version you emailed me and the posted version but suddenly my throttle is cutting out the voltage input stays the same but the output just drops to the minimum output setting and stays there reactivating the throttle doesn't help if you hold the throttle in place after about 5 seconds it seems to start the ramp up.

I have the protection set at 1.5 volts higher so it isn't this. It does it in current, speed, passthru and disabled modes. all the wiring seems good. I'm thinking a voltage spike is activating the throttle protection but the real time screen doesn't show any spikes. It does show that the output drops back but I can't see why. The throttle slider on the main screen moves up but the throttle output voltage on the real time screen stays at the minimum.

To early to call this software but it only did it after I reloaded the firmware again but it could be unrelated seems intermitant I have times it works fine. but it makes me nervous to get far from home. It would be great if there was an on screen indication that the protection has been tripped.

UPDATE: reflashed with the emailed version and all is fine could be the reflashing reset something and it has nothing to do with reloading the software with the version posted here on ES

[Doctorbass]

What is the input impedense of the current sensing input?

I plan on using my C-A v3 with an external current sensur that is not a shunt but it agalvanic insulated sensor with a 0-5V output.

Ijust wonder if i could use a voltage divider to drop the output range to the +/-200mV range of the C-A.. unless it have changed and have a wider voltage range input?

The current sensor is the one on the zero motorcycle system and it also have a 2.5V ext voltage ref.. i dont know if i could use it to offset the output?


This is the exact model i have: http://media.digikey.com/pdf/Data%20Sheets/LEM%20USA%20PDFs/HASS%2050-600-S.pdf

it's the 200 model.. ( ± 600A)

The output is proportional to :
VOUT Analog Output voltage @ IP VOE ± (0.625. IP/ IPN) V

any idea Justin?

[justin_le]

What is the input impedense of the current sensing input?

It's pretty high impedance

I plan on using my C-A v3 with an external current sensur that is not a shunt but it agalvanic insulated sensor with a 0-5V output.
Ijust wonder if i could use a voltage divider to drop the output range to the +/-200mV range of the C-A.. unless it have changed and have a wider voltage range input?

You can totally do that, just make sure that the common mode voltage stays between about -0.4 to +2 volts relative to ground. The input range of the CA is still +-200mV. The main issue with galvanically isolated hall current sensors is that they have problems with offset hysteresis and have nowhere near the dynamic range as a shunt resistor for accurately measuring Ah. So they can work OK for looking at and accumulating amps when you are riding under normal load, but if for instance you want to measure the current draw of a small load like your headlight etc. they'll be fairly inaccurate.

If you have one, try measuring the output with no current, then briefly apply full scale current through the sensor, and then measure the output with no current again. Repeat this after putting full scale negative current though the sensor.

With a shunt resistor, no current will always equal 0mV. But the datasheet on the LEM transducer you are using says up to 0.4% offset error after exposure to the full current (Ipm) of 600A, which means the amperage shown with zero current can vary by +-2.4 amps or so.

-Justin

[Doctorbass]

Thanks Justin i now 100% understand your point.

well adding a shunt seem now like the easyest option

Doc

[justin_le]

I'm not sure if theres a difference between the version you emailed me and the posted version but suddenly my throttle is cutting out the voltage input stays the same but the output just drops to the minimum output setting and stays there reactivating the throttle doesn't help if you hold the throttle in place after about 5 seconds it seems to start the ramp up.

Hey Lizardboy, I think I know what might have been going on there. If you do reflash the posted code on ES try changing the Watts Gain from 200 (which would have been the default setting) down to about 50 or so and see if you still have that issue with the throttle ramp. -Justin

[lizardboy]

okay I gave that a try I reinstalled the ES version and it's exactly the same I reduced the Wgain to 50 and to 10 but no difference at all. I reinstalled the version you emailed me with gain set to 500 as it defaulted and it works perfectly.

The throttle slider on the main display stays at full when the signal fails and goes up and down in response to the throttle. There is just the minimum output voltage when I look in the real time screen. My understanding was that the throttle slider reflected the throttle output voltage. What conditions could cause the output slider and the output voltage in the real time screen to be different?