Strange electrical Q?
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Pro
Joined: May 2003
Posts: 684
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From: SF Bay Area
Strange electrical Q?
Hi everyone,
I've just finished up the "one-touch top down" mod on my Cab. Part of this mod involves timing the up and down operation for programming into the device that will replicate the up/down button pushing (basically a big latch). I'm no stranger to degrees in EE, CE and CS but something in this struck me as odd. Let me explain.
I did the timing using a stopwatch feature on my cellphone. The first time I did the timing, I went out to the garage, started the car up cold and measured up and down several times. There was not much deviation in the measured times so I took the worst case and sent that in to be programmed.
I received the programmed unit, installed it and tested it (cold start). Worked fine. Then I took the car out for a run. Upon return, the top-up operation stopped just short of closing the windows. That's funny, it worked when I cold started the car??? I repeated down and up. Same result. Hmmmm... I turned the car off. Next day, I started the car cold and what do you know, up and down worked perfectly! What??? I then took the car out for a run and again upon return, the up operation fell just short of closing the windows! I retimed the up/down operation after the car had been driven and it was roughly about 0.7 seconds longer than cold start.
Radio On/Off made no difference. The headlights were never on. Why would the timing be longer after the car had been driven, only to be shorter again after the car sat and got cold? I had thought driving the car would recharge the battery (isn't that what the alternator is doing?)??
In any event, I had my device reprogrammed with (very exact) longer timings and it works perfectly now, so all has ended well. I just don't like nagging unexplained events...
Thanks.
I've just finished up the "one-touch top down" mod on my Cab. Part of this mod involves timing the up and down operation for programming into the device that will replicate the up/down button pushing (basically a big latch). I'm no stranger to degrees in EE, CE and CS but something in this struck me as odd. Let me explain.
I did the timing using a stopwatch feature on my cellphone. The first time I did the timing, I went out to the garage, started the car up cold and measured up and down several times. There was not much deviation in the measured times so I took the worst case and sent that in to be programmed.
I received the programmed unit, installed it and tested it (cold start). Worked fine. Then I took the car out for a run. Upon return, the top-up operation stopped just short of closing the windows. That's funny, it worked when I cold started the car??? I repeated down and up. Same result. Hmmmm... I turned the car off. Next day, I started the car cold and what do you know, up and down worked perfectly! What??? I then took the car out for a run and again upon return, the up operation fell just short of closing the windows! I retimed the up/down operation after the car had been driven and it was roughly about 0.7 seconds longer than cold start.
Radio On/Off made no difference. The headlights were never on. Why would the timing be longer after the car had been driven, only to be shorter again after the car sat and got cold? I had thought driving the car would recharge the battery (isn't that what the alternator is doing?)??
In any event, I had my device reprogrammed with (very exact) longer timings and it works perfectly now, so all has ended well. I just don't like nagging unexplained events...
Thanks.
Drifting
Joined: Sep 2001
Posts: 2,467
Likes: 16
From: redmond wa
Thermisors at work....
Many of the electric motors in today's vehicles have protective resistors, thermistors, to protect the motor and circuit if someone ( 6 year old grandchild??) inadvertantly holds the control button down long after the device has reached the end stop, end of travel.
My 01 AWD RX300 shows one in series with each of the window motors.
These thermistors change, increase, resistance with temperature, mostly due to high stalled motor current flow, but also due to ambient temeprature levels.
Got it?
Many of the electric motors in today's vehicles have protective resistors, thermistors, to protect the motor and circuit if someone ( 6 year old grandchild??) inadvertantly holds the control button down long after the device has reached the end stop, end of travel.
My 01 AWD RX300 shows one in series with each of the window motors.
These thermistors change, increase, resistance with temperature, mostly due to high stalled motor current flow, but also due to ambient temeprature levels.
Got it?