CycleAnalyst temp sensor confusion, need help

[spinningmagnets]

Temp sensors are cheap, typically $1 each. I have been recommending that anyone who pulls their motor apart for any reason should add one, even if they do not have a read-out screen at the moment, or plan to have a read-out for a while.

The LM35 is calibrated to accurately run from freezing up to approximately 150C/300F max. A commonly stated heat limit for motors is 93C/200F, this should also be a good limit for controllers due to the heat sensitivity of some of the components and the melt-temp of cheap solder.

The LM35 is reported to be the temp sensor that cell_man is using on the MAC, when customers request a temp sensor be added to the inside of the motor before shipping, so the customer will not have to pull the motor apart. The LM35 can use a simple and affordable digital voltmeter as a Celsius read-out: 0.70V = 70C.

However...I am a big fan of the CycleAnalyst, and I promote it whenever I can. The newest CA has a very useful power "roll back" feature that can only work if you are using a compatible temp sensor. If you are approaching a dangerous heat level in the motor/controller/battery (where-ever the temp sensor is mounted), the controller will automatically limit the max amps it allows through. It will continue to pull down the amp limit until the affected component returns to a safe temperature.

I have tried to read posts about the CA and temp sensors, but I am finding conflicting info and I would appreciate the latest info from a trusted source.

I am weak on electronics knowledge, but I can follow instructions well, and I'm willing to put money and time into experimenting to verify something that I think is important. I would greatly appreciate a part number and link to a supplier for a "CA compatible" temp sensor, and a description of how it should be wired up. Thanks in advance.

 

[teklektik]

I have tried to read posts about the CA and temp sensors, but I am finding conflicting info and I would appreciate the latest info from a trusted source.
...
I would greatly appreciate a part number and link to a supplier for a "CA compatible" temp sensor, and a description of how it should be wired up.

I guess the matter of 'trustworthiness' is up to the reader , but here's an excerpt from the V3 Unofficial User Guide:

Supported Devices: This input can be supplied by either a 10K NTC thermistor or a linear temperature sensing IC such as an LMx35 (datasheet) that operates like a zener diode. Note thatthe LM35 (datasheet) is not part of this device family and is not formally supported. Unfortunately, the LM35 may come pre-installed in some motors as the only option. In such cases, CA/LM35 electrical incompatibly can be remedied by minor modification of the Cycle Analyst PCB. See ' 7.7 Using LM35 Temperature Sensors'.

Thermistor Selection: The present firmware has a hard coded calibration for 10K NTC thermistors with a beta constant of 3900. This gives workable accuracy for beta values of 3800 - 4000.

From eBay: search "NTC 10K Thermistor"
And example from eBay (B=4050... okay accuracy)....
Another example from eBay (B=3950...nice accuracy)...
Datasheet (linked from Guide) for LM335

In the case of either the thermistor or LM335 - just hook up device across black/yellow leads... (LM335 is polarity sensitive so check check datasheet for pinout)

 

[alsmith]

I added a temperature sensor into my motor last time I stripped it down. It doesn't go anywhere or do anything yet, but it's there for the next chunk of free time- or the winter. My CA is a 2.3 so I have a separate meter to display the temperatur, and it will let me know the time as well.

 

[spinningmagnets]

Thanks Tekletik. This info will be added to the "temp sensor too cool not to share" thread: http://endless-sphere.com/forums/viewtopic.php?f=1&t=25502

Here's a PM from Justin-LE:

LM335 is super easy to use since it behaves like a zener diode and can make use of the onboard pull-up resistor in the CA. You need to get the polarity right (- of the sensor goes to the gnd pin on the CA plug, + of sensor goes to the signal input of CA plug). Use the linear sensor option, set your 0 degrees voltage at 2.73 (273kelvin), and the scaling to 100 degrees / Volt (same as 10mV/deg), and it should be good to go.

Any temperature sensor with a linear or approximately linear output can work in linear mode, and a 10K NTC thermistor with a 3900-4000 beta constant will work fine for the thermistor mode

Here's one supplier of several possible, with an LM335 and a 10k thermistor

http://www.basicmicro.com/Temperature-Sensor-LM335_p_209.html

Also: I have ordered ten LM335's from this link, we will have to wait and see how they turn out http://avnetexpress.avnet.com/store/em/EMController?action=products&catalogId=500201&storeId=500201&N=0&langId=-1&slnk=e&term=LM335Z%2FNOPB&mfr=TIS&hrf=http%3A%2F%2Fwww.google.com%2Faclk%3Fsa%3Dl%26ai%3DCiJmCEBErUvSILPP36AH19IDwCdzUutYFxN-v_GjCpo9_CAAQAigDUMTO6v_6_____wFgye77iISk1BCgAZzB1uADyAEBqgQlT9DH4GXOg6I4UxmzqMUG69IxvCTu5o-srGUR8gDBphea6KbriIAHzL6pHw%26sig%3DAOD64_3hjsKTwvPMcN6Wg4N0APfP-iZ4_Q%26rct%3Dj%26q%3DLM335%2B10k%2BNTC%2Bthermistor%26ved%3D0CDAQ0Qw%26adurl%3Dhttp%3A%2F%2Favnetexpress.avnet.com%2Fpart%2Fe%2FLM335Z%2525252FNOPB%2FTIS%253FCMP%253DKNC-TI_Google_PPC_Feed%2526mkwid%253Da7OSP8Has%2526pcrid%253D28150436988%2526kw%253Dlm335z%2526mt%253Db&CMP=KNC-TI_Google_PPC_Feed&mkwid=a7OSP8Has&pcrid=28150436988&kw=lm335z&mt=b

You have to register to order, and the ten tiny sensors arrived in a UPS insured shoe-box size of package, the problem is that it would not fit in my mail-box, so I had to go to the Post Office during the week/during the day to pick it up. The tiny envelope inside the big box was a made from a static-free foil, nice touch, but un-necessary for temp sensors. Very high quality.

I will order in bulk from a China ebay vendor in the future (100 sensors fit in a padded envelope), and then test each temp probe before re-selling.

 

[teklektik]

Here's one supplier of several possible, with an LM335 and a 10k thermistor

http://www.basicmicro.com/Temperature-Sensor-LM335_p_209.html

The thermistor you linked does not have a stated beta which makes it unusable. (Incorrect - see EDIT below)
It's unclear if that is an actual or stock picture, but looking up the color code from the image shows a beta of 3528 which will not behave properly with the V3.

• EDIT - Hmmm - I see you edited in "part number and link to a supplier" to you original post - sorry that my post above did not provide that. For simple commodity parts like this, I prefer to go to eBay unless I am going to be placing a large order - the shipping from commercial suppliers can be crippling. However, some may not like to shop there.
  
  Commercial suppliers of these and other parts can be found by going to Octopart and typing in the desired part number or description.

EDIT - Oops- my Bad! I misread the datasheet - there is only a single 10K part of this type there with a beta of 3977K so although the beta is unspecified on the vendor page the beta must be 3977K. The image must be a stock photo - it's for a 1K part instead, hence the bogus 3528 beta. So - this is a good part for the V3.

 

[speedmd]

The thermistor you linked does not have a stated beta which makes it unusable.

Would it not just be easier to say that you need to order the part number ......103bo from the data sheet? :wink:

I would think this would be more of a straightforward part number buy /install for us tinkerers here on ES on this relatively well established product. : :|

 

[teklektik]

The thermistor you linked does not have a stated beta which makes it unusable.

Would it not just be easier to say that you need to order the part number ......103bo from the data sheet? :wink:

I would think this would be more of a straightforward part number buy /install for us tinkerers here on ES on this relatively well established product. : :|

From eBay: search "NTC 10K Thermistor"
And example from eBay (B=4050... okay accuracy)....
Another example from eBay (B=3950...nice accuracy)...
Datasheet (linked from Guide) for LM335

I did suggest a couple of very specific eBay options as examples of what to buy or look for. I felt these were entirely suitable and reasonably priced with negligible shipping charges. You may disagree - no problem.

SpinningMagnet's link was for an unidentified part - there is no means there to order by manufacturer part number. I was simply trying to deter 'ES tinkerers' from taking it at face value and ordering an unusable part. I thought that was useful.

Why not specify a part number? Well - as you point out, these are well-established parts. They are produced by many manufacturers in many styles and available from many sources which is why Justin simply specified 'beta=3900'. This is equivalent to specifying a resistance and wattage for a resistor. Depending on where you live in the world, you way wish to buy from some particular nearby vendor who may carry one of those many many equivalent parts - I did not feel it was useful to track down a single vendor for that particular manufacturer's part when there are so many other available options.

As an example - here are several available styles from a recent post I made. Which is the 'best' configuration for you? I don't know - but they all have a beta of 3900 and all work with the V3. Which part number would be 'best' to post? Here in the US? In Oz?


Again, as I mentioned in a post above, my preference is to use eBay for simple items like this so I can see what I am getting and am not confronted with minimum order amounts and shipping charges.

However, if you wish to order a particular Vishay part and have located a commercial vendor perhaps you could post the information here. Wouldn't that be easier than taking me to task for not doing so because you don't like eBay recommendations? :wink:

 

[speedmd]

My apologies for the snippy post. Not been sleeping well and my mornings headach made worse trying to follow you less than difinitive post on a suitable part. My issues, sorry. You listed a b103 part from one of the ebay listings with a higher "beta" than other b103 parts listed for your beta range limit. :?

 

[teklektik]

No problem. I try not to bark back on those, but I guess I'm not at my best today either

I guess the actual implications of a 'bad beta' were not clear. Perhaps this blurb from another post will help:

The CA V3 is calibrated for a 10K NTC thermistor with a beta of 3900. Any beta in the 3800-4000 range is fine - this just determines the accuracy at the high end. A few degrees one way or the other isn't going to hurt since we are just setting a rule-of-thumb temperature limit anyway. Beta is usually specified with two temperatures 25degC and something like 50degC or 85degC and can be viewed as the slope of the temperature/resistance correction curve where the thermistor is calibrated to give 10K resistance at 25degC. So - a beta of 4050 is 'outside spec' but still workable for this application although it will be off by a few degrees at high temps.

So, basically anything near 3900 will work - just the error increases at the high temp end by a few degrees - but that error is constant so no big deal.

As the Guide indicates, the CA V3 design spec is for 3900K so +/-100 or 3800-4000 is fine. This spec came from an earlier post by Justin. Justin reports that his PM to SM was unnecessarily restrictive (3900-4000) - he's trying to get on the road amid a pile of emails and PMs and just shot from the hip and slipped up a bit. No biggie - he's a busy guy...

 

[teklektik]

speedmd-
Okay - I see you live in the US so I did a quickie eBay search and turned up this part for you from a US seller:

Available here on eBay that is reported be or be similar to this Vishay part from Digikey

• 7 for $2.75 incl shipping.
• beta = 3977K (nice)

Hope this helps.

• Whoops - I realized in looking at the DigiKey item that the cause of this fuss was misreading the original Vishay datasheet. I have edited the post above to reflect this. The part listed by SM from BasicMicro appears to have a beta of 3977K which makes it fine for this application. Sorry for the confusion!

 

[spinningmagnets]

Thanks Teklektik, I bought seven from the ebay link, we'll see how it goes...

 

[teklektik]

Again - apologies for any difficulties in the datasheet error....

I do see the issue here, though - it's difficult to structure the V3 Guide to address such a spectrum of users. I will update the temp sensor section with additional details about the supported thermistor, LM335, and LM35 components and add a sample NTC device part number that can be cross-referenced. Hopefully this will fill in the present gaps in presentation. Thanks for the thread and highlighting the issue!

 

[cell_man]

As has been mentioned we use the LM35 in our motors. It means a small mod, but it is not difficult to do. Here's a procedure I prepared previously.

Integrating V3 CA with LM35 Temp Sensor for Upgrade Mac Motor:
http://sdrv.ms/13geXSv

I've been using this component for a while and i like the fact you can easily measure the temp with just a DMM and it requires only 1 additional wire through the axle. It works absolutely fine with the V3 CA by just doing the above mods (no more is required), stable and no noise problems. We re-purpose the CA speed signal (almost always supply CA-DPS, so speed line is spare) to carry the temp signal, so it makes for a neat installation.

Thanks
Paul

 

[spinningmagnets]

Thanks Paul! I was sure that info was already posted somewhere, but this site has gotten very big. Nice to have the important info right in the places where it's most needed.

 

[teklektik]

BTW - Justin reports that the 10K thermistors on his site are suitable for use with the CA V3. He indicates that due to variations between different suppliers they can't specify the exact beta on the web site, but they are all good for that application.

Shipping is not good from Canada, but these might make a good add-on if ordering a CA or other goodies...

 

[spinningmagnets]

I have a question, concerning the two-wire thermistor...is there any combination of one of those with a graphene nano-resistor, a left-handed metric diode, or a di-lithium crystal...that will allow a 10K thermistor (3900-Beta) to read out centigrade degrees on a simple voltmeter? (like the LM35)

 

[teklektik]

Nope. You used to be able do that by adding a cheapie transmyopic field inverter ordered from Alderaan eBay, but - no longer available....

 

[bee]

http://www.ebay.ca/itm/Lot-of-5-Glass-Encapsulated-Thermistor-10K-Ohms-J-Curve-Beta-K-3890-DO-35-/120974193211

these are the most accurate ones I could find with a beta of 3890.

 

[icecube57]

I like the thermal roll back feature. My sensor is right under the winding. But some reason I think 120c is conservative.

 

[spinningmagnets]

But some reason I think 120c is conservative

Yes, but we must allow for the weakest link. Cheap Chinese solder with lower-than average melting-temp, solder in one particular spot that is thinner than it is supposed to be because of assembly-line speed pressures, etc...

I would also suggest that if your motor/controller is regularly attaining 120C, you might be better served by switching to a diferent component or configuration. I am becoming a fan of the non-hub motor that has at least 3 gears available to it, so as to keep its RPMs in the upper 1/3rd of its range, which avoids most of the heat production in the first place.

Then, add one of several heat shedding upgrades (side-plate ventilation holes, 1/3rd oil-filled, External fan on an inrunner like the GNG...)

If a motor stays cols under load...it is probably larger, heavier, and more expensive than needed...but a hot motor could die at any given moment from a longer than average hill, a warm motor with 3+ gears is a great design for the given application IMHO.

 

[icecube57]

To keep this thread and post on topic I bought my NTC 10k Temp Probe from this vendor here. http://www.ebay.com/itm/2-ea-10K-High-Stability-NTC-Thermistor-1-25mm-w-lead-covered-tubings-USA-Seller-/321011608617?pt=LH_DefaultDomain_0&hash=item4abdc86c29

It easily slipped under the winding. I RTVd it in place and ran teflon leads through the axle. I used an ebikes CA temp probe extension cable and its reading dead on with my indoor outdoor thermometer.

On another note.

Tonight I did some playing around on my street and I changed my Thermal Rollback on the CA to 90C start and 140C finish and I like the response that I'm getting even with the Magic Pie. Mines is vented. Even being restricted it still pulls the hills and the temps aren't getting out of control. I didnt past 125C pulling my hill over and over again. Yes it was in thermal rollback but it still pulled the hill without much effort and a trip around the block cooled it down 10-15C I pulled the hill again and went around the block and it felt great I didnt get that dead in the water limp home feel like before when it was set at 90-120C. Unrestricted I'm averaging about 4500w with the thermal roll back in effect I was seeing about 2000w at 120-130C which definitely puts the motor in a range where the temps stabilize and not saturate the motor. Im sure the temps can be taken higher but at least the temp display has me self conscience of my beat down on the motor. Im faintly smelling the motor varnish at 125C no smoke or anything. I will keep my eyes peeled on when the motor actually starts to break down the varnish.

 

[spinningmagnets]

That's the kind of data that I think is really useful, thank you very much for posting it!

 

[icecube57]

Last night during the CM ride it was a true test on if the CA could do what it was designed to do. There was a strip where I got the bike up to 50mph for about 1/2 a mile and hit a succession of about 4 San Francisco style blocks of hills. The limiter kicked in at 90C and while it was pulling the hill I felt the power loss as the CA was dialing back the current but it was still pulling the hills like a boss with no effort from me. I peaked up to about 123C when I finished that section roughly about 5 minutes later of conservative riding i was back below 100C. This ride was a slow ride and roughly maintained temps between 60-80 do to me lugging the motor. The windings still look perfect. Only a small hit of varnish after pulling that section. No smoke. THe plastic thats protecting the copper from the laminations of the teeth of the stator is still intact and looks new. The string on the windings is still white and no discoloration. It seems i can easily hit the 120 area and stay there I havent been able to pop it up to 140 yet. My sensor is in the windings not on the stator.

 

[spinningmagnets]

Thanks again! this is wonderful data.

 

[icecube57]

This maybe more behavior modification than the CA doing its job possibly. But then again if it was I would stop at 90C when it kicks in... or maybe the performance diminishes so much you want to wait and let it cool so you can ride dirty again.... hard to tell. I think both ways.