"manual" thermal readings

some time ago, I thought i read an article that converted how long you could keep your hand on a motor to approximate motor temperature.

anyone remember or have insight to this?

After a particular tough long hill climb, I could only keep my hand holding the cyclone motor about 4 seconds... app. temp anyone?

thanks


And OBTW i fixed my 20ah24v Lith iron ph Headway pac... one slightly loose screw on top of one cell, and the Harbor freight cutout switch went intermitent... Again. now back to no more low voltage warnings.

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I think it depends on the temp of your hand and pain tolerance so pretty hard to get an accurate number.

A typical pain threshold is somewhere around 50C. So you can guess that it was somewhere between 45C and 55C as a swag.

REdiculous said:

I think it depends on the temp of your hand and pain tolerance so pretty hard to get an accurate number.

Click to expand...

Very true, if you have a totally messed up super sensitive nervous system like mine. My darn finger tips have about the same thermal sensitivity as my tongue.

The components on the inside are usually hotter than the outside, so

If it's cool to the touch, to luke warm, you have a happy system.. ( My A2B metro )

if it's noticably hot but not too much that i can keep my hand on it .. running at optimum.. ( clyte 409 in 20" at 100v 40 amps )

if it's too hot to hold my hand on it for more than a 2 count, the system is running at it's max... ( BMX with 9C in 20" on 72v playing off-road )

if you loose your fingerprints it's about to fail... ( my RC bike if i push it, 48v 100 amps. i can make water sizzle on the motor after an ev-grin inducing run.. but so far so good.. still runs !)

Funny how this post represents a ? just asked. the ? was will black paint help get rid of heat. I figure if the can is warm or hot, the armature is way hotter, but how much hotter!!
example a quick hard ride, the can feels warm to touch, the bike is parked for 5 minutes and the can is way hot! That tells me the armature is hot as hell upon return. I am sure you get the drift here.

Well yesterday I tripped the overtemp sensor on the 360w cyclone.

Rode all day in the 90f heat making my rather senior body a bit worn out , heavy load, climbing a steep long hill when pretty tired and let the motor do most of the work; after the top it stopped helping and I was back to pedal only mode after a short rest. Flat and down hill most of the remaining one mile home. I had stopped to remove the power from the cyclone, when I got home reconnected it and all was well.

when it tripped, the motor was too hot to hold more than one second.

I bought some sheet metal heat sinks and will be strapping them around the motor casing with a 4" hose clamp next week, maybe will get another 10F of temperature rise.

I was thinking that most hub motors have more surface area to dump the motor heat effectively. any thoughts you science guys?

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My 1200w cyclone motor tripped its temp sensor pretty much every single commute. Apparantly the aluminium heat sink things make a big difference. Another Cyclone user told me back then (when I used the cyclone), that after attaching the heatsinks his never once tripped.

But using how long you can hold your hand on something as a calibration/test method is hilarious to me. For example my wife can do the dishes in dishwater heat that has me screaming for mercy and poking things out with spoons. But at the same time, I will walk around in a Tshirt whilst she is rugged up in an overcoat. The variables in human subjective temperature sensation surely make the mind boggle.

Your point about heat dissapation re hub motors is true, and operates within that class of motor. For example, I moved from a X5303 to a 9C 8x8. The 9C has about 1/4 to 1/3 less weight than the x5, and for months I slammed 3kw of trailer towing horror into my x5 without a peep. But on the first decent ride under same condition for my 9C 8x8 and smoke flowed. I thought moving to the 9C was genius for the loss of weight, but by losing the weight, I lost the heat dissapation I needed. Unlike the Cyclone's with their heat trip, a hubby will just smoke if you push it too far.

I agree that manual temperature perception is subjective, however having been a lifeguard at a pool with a hot tub, things start to hurt at about 105F-110F. My main hot water heater is set to 120F, which I can barely hold my hand under for more than a couple seconds. My 6 gal under kitchen sink water heater is set for 135F to clean the dishes. I can't touch that without yelling.

My uncle who's been a postal mechanic for 30 years can hold a flame to his fingers for a while, but his fingers are almost black with grease stains and are abrasive enough to probably sand metal...He's a REAL man! Unlike most of us :lol:

And if we're talking about a geared motor, very warm on the outside = crazy hot on the inside due to the hot parts not directly contacting the motor case.