Oasis2001

iTrader: (6)

I was testing my Mission today with a CS Rocket Max and wet tyres/wet weather cover as used in monsoonal conditions in Europe. I did a couple of laps with track wet but no puddles. Car looked fine and no water inside the car thanks to the cover. i then did about 15 more and the car came to a halt. Bad news i thought but I knew water wasnt getting in. I checked the car and there was no water inside the car and I had steering but no throttle. The ESC display indicated everything was right just no power to the motor. Thought I had done something bad

Went home and tried againa nd all is working again. Anyone experienced this. The ESC was a little hotter than normal due to no airflow but im sure ESCs get hotter than this was!

What are the shutdown procedures?

ChrisO

Id say that is has a Temperature cutoff when it gets too hot, check the manual to see if this is correct or not.

traxxasdude

does your esc have the special circuitry that stops it from doing circles when the batt is almost depleted? That is what th esc will do to prevent that by shutting down the motor. My guess is that when you took hme your esc the batt cooled down llowing you to get a little extra electricity to the esc.

dtm

Sounds like overtemp protection. Shouldn't be anything to worry about. Most probably a combination of 2 factors...the ESC did not get any airflow to cool it down and also, because it was wet you were running partial throttle a lot....this generates a lot more heat in the ESC than full throttle....

antoniop

I've seen a couple of Rocket Max shuting down in the rain due to moisture inside.

When they finally dry they work just fine. Usualy their owners have an hair dryer at hand.

However it's not recomended to run one in the rain without some protection. Inside a ballon and if possible with a little bag of silica that comes with some electronic equipement will guarantee that you wont ditch $200 just because of moisture.

WC

iTrader: (28)

Huh?

Why should a switching FET cause more heat?

This would always be *less* than full duty, in which case Ohm's Law (heat = resistance of FET X voltage) applies.


If what you were saying is true... my ESC would be hottest when its doing nothing or running at 1% throttle, yes?


We're talking ESC here, not MSC.

dtm

Yes, I am talking about ESC.....with that attitude I'd rather not waste my time explaining!

Diva

iTrader: (20)

schumacher

you get more heat when the fets have to switch, at full and no throttle there is no switching going on so the speedo is pretty cool.

running at partial throttle requires a lot of switching which causes the speedo to get hot.

a crap analogy would be think, of the switching like arccing when you turn a light switch on. when the light switch is off or on, there is no arccing, but if you want to get the light switch to blink repeatedly then you generate heat from arccing.

sanj

WC

iTrader: (28)

An Arts graduate, I'd presume?
(apologies, hope you enjoyed it whilst I wasted time at Eng school)



Prior to reading your gormless reply... was kinda curious about it myself whilst on the workbench last night. So out of pure curiousity I pulled out:

-charged pack
-TA04 sitting raised, stationary on a car stand, no shell.
-P2k rebuildable stocker in great condition
-Cyclone ESC (with the exposed FET tabs, not like on new ESCs)
-no cooling fans, breeze etc.

Room temp was 18 degC.
Battery fresh off charger was about 22 degC, everything else at 18.

1) pegged the throttle with a cable tie, at about 1/2. Let it run for about 3 mins. Result:-
ESC 25
Batt 32
Motor 36

2) repeaked the pack. Let everything else cool down to room temp, then pegged it at WOT. Ran for 3 mins, result:-
ESC 25.5
Batt 35
Motor 41.5

(Why 3 mins? Only because I was continuously checking the temp and it took about 2 mins for everything to stablise ie temp didn't rise any further.)

For the record, rechecked surrounding temp at the end, it now read 18.5 degC (about 30 mins from when I started).

Heck I know its not the most scientific test (motor not very loaded, its a cold day, Cyclones run cool normally anyway etc etc)... but definitely didn't find any significant basis for the "ESC running hotter" claims.

As an aside... what about airflow?
ie car driving Slower will have Less airflow over the ESC.



Anyhow, rather than all this speculation... what do the ESC MANUFACTURERS say about this??

alfa

no load...exactly.

schumacher

i think if you had a load on it then you would get the speedo very hot.

freewheeling is not enough load, to simulate load you should get some wheels made of steel or something, that will simulate proper driving.

sanj

dtm

You make a lot of "assumptions" in your statements and it certainly appears that you totally ignore what other people say anyway.....if you wish to remain in your world of ignorance then that is simply your choice. There is really no need for you to get offensive in your original post.

I am glad that people like schumacher does know what he is talking about. However, my advise to Schumacher would be that you are wasting your time explaining to this person. He will simply reply with rude and offensive remarks.

For the record, I graduated with a Mechanical Engineering degree (over 10 years ago) and I have been in Engineering since. This does not make me a "Electronics" experts (I never claimed that and it was you that started throwing around Ohms law!! ). However, that is a far cry from ARTS!!

Pls don't bring this forum down to the level of the old HPI forums...we are much more mature here!

dw

It could just be a brush sticking on the motor, and nothing to do with the speedo.

WC

iTrader: (28)

You started it my friend... with your "I'd rather not waste my time explaining" remark. Rather arrogant answer to a innocent query, don't you think? This is a chatboard, and differing opinions make the community what it is.


As all good engineers do, I'm constantly learning & always open to new ideas & concepts.



Sanj:- your suggestion of "steel wheels" will not provide a consistant extra load to the motor... the only extra load would be its momentum/mass at spin-up. Thereafter when spinning at constant speed for the 3mins, it would not load any difference.

Anyone correct me if I'm wrong anywhere there...?



re: assumptions on the test
Hey yeah, it was a unplanned rough-as-guts "what if" do.
It was 10pm and there was nothing good on TV that night before bedtime.


Thinking now... if I were to repeat the testing...
1) maybe lose the motor and use a bank of lightbulbs as the load instead? (or does a 3-pole motor differ to a pure resistance load for the purposes of the test?)
2) lose the battery... and use a benchtop supply instead (for consistant voltage)
3) lose the TX/RX for a control-pulse generator?

btw Anyone know what's the expected Temperature Difference that we're all so excited about here?

Is it just a minor effect, say a few degrees extra, or can we expect a big jump - enough to heat a nomally cool-running ESC towards TempFET protection??