Hill Gradient Suddenly went "WONKY"

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mlennox
Posts: 45
Joined: Sun Apr 20, 2008 8:23 pm

Hill Gradient Suddenly went "WONKY"

Post by mlennox »

So I was out for my first "real" ride with the boys this morning hoping to impress everyone with my iAero, but unfortunately something went wrong with the device part way through the ride and from that point forward the device was showing that I was climbing anywhere from a 5% - 12% grade when I was actually on flat ground, which of course gave me ridiculous power numbers (upwards of 1000W sustained, which would make me super-human if true).

It was a cold morning to start the ride, around 38F. I let the iAero sit outside for a good 20 minutes prior to the start, verified the tilt calibration (it was within 0.1%) and did a good wind offset calibration. At about 50 minutes into the ride, the power numbers started spiking to ridiculously high values, whereas to that point they were good. I had "auto-hill" turned on so I immediately saw the problem since it started flashing to me that I was climbing when in fact I was not.

I checked the battery voltage and it was showing 250 - 255. I guess the cold air caused the voltage to drop. I turned the iAero off and back on, and for a brief moment it showed correct gradient but quickly reverted to showing me climbing, so I just left it and ignored the numbers from that point forward. :-(

After getting home and getting the device up to room temperature, the battery was still showing 255 but the gradient was showing correctly again.

Do I have a "lemon" iAero? Would low battery voltage cause a tilt error like this? I thought I read that low battery may cause wonky wind numbers but I don't remember any mention of tilt errors.
mlennox
Posts: 45
Joined: Sun Apr 20, 2008 8:23 pm

Re: Hill Gradient Suddenly went "WONKY"

Post by mlennox »

John or Rich, any ideas on this? Defective unit or battery issue?
Velocomp
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Re: Hill Gradient Suddenly went "WONKY"

Post by Velocomp »

Most likely it was low battery voltage. We say in the owner's manual that tilt readings can go crazy with low battery voltage.

Battery voltage should be above 275 before riding, and in cold weather batteries go only a few hours so I'd recommend a stronger battery if possible. Note that batteries will come back to life when they are warmer...
John Hamann
mlennox
Posts: 45
Joined: Sun Apr 20, 2008 8:23 pm

Re: Hill Gradient Suddenly went "WONKY"

Post by mlennox »

Velocomp wrote:Most likely it was low battery voltage. We say in the owner's manual that tilt readings can go crazy with low battery voltage.

Battery voltage should be above 275 before riding, and in cold weather batteries go only a few hours so I'd recommend a stronger battery if possible. Note that batteries will come back to life when they are warmer...
OK, thanks John, since the battery voltage was reading 250 once it got cold enough I'll assume that is the problem.
Velocomp
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Re: Hill Gradient Suddenly went "WONKY"

Post by Velocomp »

250 is definitely below the threshold! Your screen probably was fading too.
John Hamann
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racerfern
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Re: Hill Gradient Suddenly went "WONKY"

Post by racerfern »

Check the battery in the wireless head also. I've had to change that more often than the iBike battery, especially when transmitting to the 705.
Fernando
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