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Adjusting Beta Value for Motor Thermistor.

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Ecyclist
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Adjusting Beta Value for Motor Thermistor.

I can't change default setting of Beta Value for Motor Thermistor. No mater what I do it gos back to 3380.0 K.

I think that I'm  doing everything correctly.

Developer -> Parameter Editor Mcconf -> m_ntc_motor_beta (Beta Value for Motor Thermistor) -> change from default 3380.00000000 to 3950.00000000 -> save (I get parameter updated in green in right bottom corner) I go back to General -> Advaced -> to check  Beta Value for Motor Thermistor and get the same default 3380.0 K

There is no change in temperature reading of my thermistor.

Help please.

Ecyclist
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So, no one has a clue why I can't change Beta Value?

Les

TechAUmNu
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What are you trying to do? Changing the developer settings only changes what the default is in VESC Tool before you read from the VESC. To change the default setting read from the VESC you need to recompile the firmware with the settings changed.

To just adjust it you don't need to go into developer settings. Just change the value and upload to vesc.

Ecyclist
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Thanks for the reply.

I changed value and uploaded to VESC but that doesn't adjust anything. 

I will try different thermistor. 

What is range of thermistors I can use?

How far can I go from 3380 default value? 

Les

Ecyclist
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So, I hooked up different thermistor, this time very close to 10 k ohms and tried to adjust beat value to have very accurate temp. reading. 

I used the method I described in my first post and the user method:

MOTOR SETTINGS -> GENERAL -> ADVANCED -> 

I changed beta value 3380.0K  between 3000.0K and 5000.0K -> READ CURRENT SETTINGS

The temp. reading stays the same. No change at all, but these numbers should change reading.

So, from what I can tell BETA VALUE CAN NOT be changed.

The only good news is that my new thermistor is giving me close enough reading. 

End of story.

2019 is almost here so Happy New Year!

Les

Danny Bokma
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Changing the beta value of the thermistor has only limited effect when the thermistor is at is nominal value (at 20 degree C). When at a higher temperature it should have more impact.

RSR
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Do not press "read _DEFAULT_ settings" if you really want to "read _current_ settings".

The "default" is what is used until you store another value.  

Ecyclist
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I do "read _current_ settings"  but get no change in reading.

This time I put the thermistor in an oven set to 212 deg, F (100 deg. C). VESC TOOL read 110 deg. C. I tried to change beta value between 2000 and 6000 and got no change in reading.

MOTOR SETTINGS -> GENERAL -> ADVANCED -> 

BETA VALUE changed from 3380.0K  to between 2000.0K and 6000.0K -> READ CURRENT SETTINGS. 

Can someone who actually was able to adjust the thermistor reading post step by step instructions?

Please don't post if you haven't done it yourself.

I'm tired of trying different ideas that don't work.

Les

RSR
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Changing the beta value should work just like any other setting in vesc_tool, but if it does not work for you, then you can change it in the source code (and compile + load your customized firmware).  Search for "NTC_TEMP_MOTOR" in hwconf/hw_60.h  or the .h-file for whatever vesc version you are using.

Ecyclist
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RSR, thank you for your posts unfortunately that is not what I was hopping for.

The good news is that I was able to find step by step instructions for different parameter that helped me to finally change BETA VALUE.

So far I only changed temp reading at ambient, but now I'm sure that I will be able to adjust temp reading at 100 deg. C.

Thank you all for participation in my ordeal. :-))) 

Les

Ecyclist
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THERMISTOR CALIBRATION.

The required thermistor for VESC is NTC 10KOHM. Check resistance with a multimeter. I had to order thermistors twice. The first bunch I ordered from China (10k ohms) was actually 2KOHM. The second from Digi-Key was OK. (MF52A2103J3470  317-1258-ND  THERMISTOR NTC 10KOHM  3470K BEAD). 

The thermistor needs to be connected to TEMP and GROUND of SENSOR plug.

In order to calibrate thermistor you will need to change the BETA VALUE.

You will also need 100 deg. C reference environment. 

First, I tried to use my kitchen oven but I couldn't get consistent temperature. 

My second idea was much better. I live in San Diego, CA so pretty much at the sea level. I filled a frying pan with water and covered it with ceramic tile. You can use a lid, but I used a tile because I wanted to have some mass and I wanted it to be flat. I boiled the water in that pan on the stove, placed connected thermistor on the top of the tile and covered it with the heat resistant mitten for insulation. I quickly  uncovered the tile and measured temperature with an infrared thermometer. (beforehand, I tested that IR thermometer with a couple of digital thermometers that I have all over the house). The temperature was 100 deg. C +1.0/-0.5. After that, I used the BETA VALUE to match the temperature reading between VESC TOOL, IR thermometer and the surface temperature of ceramic tile. 

You most likely don't need thermometer because the temperature of surface right next to the boiling water will be very close to 100 deg. C.

My final BETA VALUE was 3250.0K. Yours will be different, depending on your thermistor. 

To change BETA VALUE you need to go to MOTOR SETTINGS -> GENERAL -> ADVANCED ->and type in --Beat Value for Motor Thermistor-- your preferred number. (The default number in that window is 3380.0K). Your number most likely will be between 3000.0K and 4000.0K. After that, you need to push icon M with arrow pointing down. That icon is in a vertical bar in the right upper side of the screen. 

And now it is a no brainer.

Have fun.

 

 

Les

RSR
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so if I understand you correctly;  The correct answer to the original question should have been:

      Please remember to click the "M with down-arrow" to send/write the changed beta-value to the VESC,

Ecyclist
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Kind of. laugh

It is always good to know all steps from A to Z exactly.

Les