ebikessf's 2k thermal sensor?

[Joe Perez]

no cat background?

Heh. Sorry, I'm typing this from my tiny laptop while sitting on the couch waiting for some DP420 to dry, and I don't have PaintShop installed on this machine.

(I should probably rectify that oversight so that I can include more kittens in my data in the future.)

[auraslip]

Awesome post.

I'm currently using an lm35 powered temp sensor.

Is there any advantage to it? Perhaps easier to create a digital read out with it? Something tells me it should be fairly easy to do. I have the HK-VT. It works well and runs off 12v power, but it constantly flashes between voltage and temperature. Slightly annoying.

Ideally, I'd want a single display that will switch between controller temperature and motor temperature. I'm honestly surprised someone here hasn't made a circuit for that and is instead relying on BBQ meters.

[Joe Perez]

I'm currently using an lm35 powered temp sensor.

Is there any advantage to it? Perhaps easier to create a digital read out with it? Something tells me it should be fairly easy to do.

Yes, that's the primary advantage of the LM35 over the LM135/235/335. Its output is exactly 10mv per degree C, with 0v = 0º C. So the LM35's output voltage is always .01 * temperature, and can thus be directly displayed on any cheap voltmeter capable of accurately displaying small voltages from 0-2v, such as:
http://www.ebay.com/itm/3-DC-2V-Blue-LC ... 330wt_1169
http://www.ebay.com/itm/Class-2-5-Analo ... 1527wt_952

With any such meter, a temperature of 80º, for instance, will show up as ".80"

The LM135/235/335 is similar, but with one major difference. That device is calibrated for 0v = 0º Kelvin, which is -273º C. Handy for scientific purposes, but requires conversion to produce a meaningful display in ºC.

[GCinDC]

2000 ohms @ 25 °C
2417 ohms @ 50 °C
3392 ohms @ 100 °C
4280 ohms @ 150 °C

hooked white wire up to multimeter with other lead on hall GND to test resistance on the bench. read 1.930k ohms @ 72F ambient.

motor laced into heavy 19" M/C wheel/tire.

@80V WOT with no load, resistance rises to 2.6 on first steady throttle increase but then drops to 2k ohms when i release. then later, from WOT, i release, regen engages and it tops 3k and quickly drops back to 2k.

pulsing the throttle on and off, going quickly to WOT, then releasing and engaging regen, it bounces quickly between 2k ohms and 4k ohms.

i'm afraid axle is bending with only one end in vice, so will take a vid when i get it on the bike.

is that behavior to be expected?

[GCinDC]

interesting to see they added a 4th slot. surprised to see it attached to red, but forgot to verify what line that's on...


and of course the bearing stayed on the axle, and my gear puller claws won't fit, so i might trim them back to the lines i drew.

this is worth it right? the bearings won't seat perfectly otherwise, right??

[GCinDC]

interesting to see they added a 4th slot.

i was wrong: it's not a 4th slot - it's just the gap between the laminations, and the bamboo was cut short to accommodate it. here i'm replacing thermistor with LM35.

also, though the non-white wire is RED, i've confirmed it's connected to the hall GND, not the positive.

btw, the LM35DZ is a bit fat, but will it work fine? should attach the hall + to the +Vs and NOT the Vout?

lm35DZ.jpg (10.79 KiB) Viewed 455 times

i'd rather not toast it! thanks.

ps. i'm curious about your avatar. what's the story about it?

[Joe Perez]

btw, the LM35DZ is a bit fat, but will it work fine? should attach the hall + to the +Vs and NOT the Vout?

Assuming that you are borrowing power from the hall board, then yes. The hall's +5 wire (typically red) will go to the LM35's +Vs, and the hall's ground (typically black) goes to the LM35's GND. VOUT from the LM35 is a variable voltage output, and this should go straight to the (+) terminal of a voltmeter (or similar) with no pullup. Ideally, the voltmeter's (-) terminal will go back to the hall ground wire, both for safety and to minimize the opportunity for ground offset skewing your readings.

ps. i'm curious about your avatar. what's the story about it?

Well, it's a giant chicken dressed as Boba Fett from the Star Wars movies. Seems pretty self-explanatory to me.


I've been pretty heavily involved in the Mazda Miata (MX-5) aftermarket for a number of years, principally with regards to forced induction, ECUs and engine tuning. Back in 2007, a specific manufacturer of supercharger kits started making some false and unsupportable statements about a specific ignition-control device which he was offering, which a user on one of the Miata forums posted a link to. (It should be noted that a state of inter-forum cold war has also existed for many years between the forum in which said posting occurred and the rival MiataTurbo.net form, on which I'm a moderator. I routinely frequent both forums, however.)

An epic thread ensued, with forum members allying themselves both with and against the vendor in question, mostly reflective of the long-standing and nearly religious debate which has long waged between fans of supercharging vs. fans of turbocharging. The vendor in question started digging himself into a hole and throwing out a lot of obfuscation and pseudo-science in an effort to confuse the populace and thus draw attention away from the matter at hand. At some point during the debate, I used the "walks like a duck, quacks like a duck" analogy. Mr. pseudo-science then said (and I'm quoting directly) that "a duck, chicken and goos are all the same. Although the feces is completely different."

If you're particularly bored, you can read the whole thread here: http://forum.miata.net/vb/showthread.php?t=255415

At that point, the whole chicken / duck / goose concept virtually became a meme within the forum community. And at the suggestion of a user at MiataTurbo.net, I decided to adopt a poultry theme for my avatars, as both an inside joke and a persistent jab. Since then, I've used chickens and ducks exclusively as my avatar theme, both on the Miata forums and elsewhere, as it's quite memorable.

The fact that Ernie the Giant Chicken is wearing a Boba Fett costume in the current avatar is of no particular significance. I saw it in an episode of the TV show Family Guy, thought it was funny, and took a screen capture of it.

[amberwolf]

and of course the bearing stayed on the axle, and my gear puller claws won't fit, so i might trim them back to the lines i drew.

If you pull on that outer race the bearing will likely be damaged. You want to only pull on the inner race, because that's where it's connected to the motor. Pulling on the outer race is going to force that race against the bearings, which then force against the inner race.

[GCinDC]

If you pull on that outer race the bearing will likely be damaged. You want to only pull on the inner race, because that's where it's connected to the motor...

eek, grim thought. i've seen other wheel develop wobbles and i wonder if unseated bearings are the cause. i'd rather ruin the bearing and have to replace it. i carved up the ends of the gear puller and the bearing came off just fine:

i did notice a bit of rust developing underneath, so it'll be an area to keep an eye on..

[auraslip]

to be fair, a decent set of bearings is a good and cheap upgrade for an ebike. the ones that come with them usually suck, and USA made replacements can be had at a local bearing shop for $20.

[amberwolf]

Easy way to tell if the bearing was damaged is to spin it with your finger thru it. If turning the outer race it feels grindy it's probably done. If you flick it, it really ought to spin freely by itself at least several rotations if it's a *good* bearing, but many cheap ones stop after you remove the drive source, even when they are new. :/

[999zip999]

Open up my new - used H hub and it has a defect in side cover as a casting hole. Shitty metal. Plus one bearing is shot and both axle seals. Bearing ez but seals ?
Sorry for jumping thread.

[GCinDC]

Easy way to tell if the bearing was damaged is to spin it with your finger thru it. If turning the outer race it feels grindy it's probably done. If you flick it, it really ought to spin freely by itself at least several rotations if it's a *good* bearing, but many cheap ones stop after you remove the drive source, even when they are new. :/

yeah, we're getting OT here, but outer race definitely not grindy. looks like a quality bearing to me. i didn't do the flick test, but i doubt it spins like that. feels very smooth, which i figure means well lubed. how can it spin if it's thoroughly lubed? w/o a bigger wheel around it, that is... stamped JAPAN, not china, for what that's worth..

i'm very happy with the quality of the motor so far. definitely some improvements over last years batch, from what i can tell. the wiring hole is better. and there's a green urethane covering of some sort protecting windings from stator/lamination edge. i don't recall that w/ last one.

the whole chicken / duck / goose concept virtually became a meme within the forum community. And at the suggestion of a user at MiataTurbo.net, I decided to adopt a poultry theme for my avatars, as both an inside joke and a persistent jab.

hilarious. i love it. thanks for the story! your giant chicken looks like he means business. not to be toyed with!

anyway, i decided to replace my thermistor with an LM35, jumping the hall + inside the motor. more details to come on my build thread.

and this is how i will probably wire it on the outside, fwiw:

[GCinDC]

fyi

[auraslip]

I have a question about the HK sensor. After reinstalling the motor the temp sensor shows 164c. It's like it's shorted, but it shows no shorts with a DMM. Could the LM35 be shorted when it powers up?
The white sensor wire (not the ground or V+) was broken at the connector so it's possible it could of shorted out on something.

[Joe Perez]

I'm not entirely clear on what you're using for a temp display, however I encountered a similar problem when first connecting an LM35 to the beta version of the new CycleAnalyst 3.

In the CA, there is some voltage bleeding from the throttle input line into the temp sense line due to the way they designed the A/D multiplexer. It was originally designed for use with a NTC thermocouple (which is inherently a current sink) so they never noticed this, but the LM35 can't sink current to ground, so it became a problem. I was seeing indicated temps of around 100 degrees any time I applied throttle.

The solution was relatively simple. I placed a 390 ohm resistor between the LM35's output and ground, which was sufficient to sink the relatively small amount of leakage current and yet not so low as to exceed the LM35's current-source capability. The value does not have to be exactly 390 ohms, but it needs to be close. The LM35 can only source 10ma, so you can't go much lower than 300 ohms without distorting the reading, and yet significantly higher values (eg 1k) weren't enough to drain the leakage current. 390 simply happens to be a common value that I had lying around in my big pile-o-resistors (anything in the 330-470 ohm neighborhood would probably suffice- try to stick to the lower end of that range.)

Give this a shot and see if it fixes the problem.

[auraslip]

I'm sure that explanation will be extremely helpful to someone using the new CA.

I'm using the hkvt though - http://www.hobbyking.com/hobbyking/stor ... oduct=9744

I've tried another unit, so it's not the unit that's bad. It's like the lm35 itself is bad. PITA because they're only a buck, but I have to wait and pay for shipping.

When turned on the white wire is showing 13.07v and the red wire is showing 10.30v - so it's not a dead short. Very weird.

[GCinDC]

Flip the connector.

[auraslip]

Flipped the red and the white connectors and it did the same thing. Bugging the heck out of me.

Does anyone know which lm35 I should order since mouser has 43 of them?
http://www.mouser.com/Sensors/Temperatu ... 35&FS=True

[Joe Perez]

I'm using the hkvt though - http://www.hobbyking.com/hobbyking/stor ... oduct=9744

I understand, I'm just not familiar with that device or its wiring, and I can't find a manual or any other kind of documentation on it anywhere. So I'm wondering whether, internally, it's applying a pullup to the line and expecting ground conduction.

Is there someplace I can see the instruction manual for that device?

Does anyone know which lm35 I should order since mouser has 43 of them?
http://www.mouser.com/Sensors/Temperatu ... 35&FS=True

Electrically, they all mostly do the same thing. They have slightly different tolerance specs, mostly. And we're still in the transition era in which leaded and lead-free devices are both available, so that accounts for some of the duplication.

This one has +/- 1.5° accuracy, in the most compact footprint, without any unnecessary bells and whistles:http://www.mouser.com/ProductDetail/National-Semiconductor-TI/LM35DZ/?qs=QbsRYf82W3EsDJ6nROSwPSCIPq9l3%252b1KfAEJj0kZY5g%3d

[amberwolf]

And many of those listings are for large multiple quantities, if you look in the Quantity column. Like whole tape-reels of them in some cases.

[GCinDC]

guess mine is just an lm35dz:

[Joe Perez]

And many of those listings are for large multiple quantities, if you look in the Quantity column. Like whole tape-reels of them in some cases.

And in different packaging for the different quantities, to fit different automated production machines. So you might have one part which can be purchased:

Loose in a bag
Stacked end-to-end in a plastic tube
Stacked side-by-side in a plastic tube
Taped onto a reel
Taped onto a reel upside-down
(etc)

But long story short, typically the first half the part number describe the part itself, the next few characters are things like tolerance, mil-spec, lead-free status, etc., and then a couple of characters to describe the packaging that the part comes in. For most DIY purposes, only the first half really matters.

[mvly]

So anyone able to get this to work with off the shelf LCD display?

[Stryker16]

So anyone able to get this to work with off the shelf LCD display?

I have a hard time relating Celsius degrees to Fahrenheit. So I compromised and went with an analog meter and then printed out a new scale onto a label and presto...

photo (7) by jakevogt16, on Flickr