Temperature dependent wireless fault?

DeF said:

I've got a Trelock FC900 that I bought on a whim
from xxcycle when getting some other stuff.
For example, see http://www.bike24.net/p21559.html

Anyway, I put it on my MTB commuter and it has been
working fine until recently. When it gets cold, the
head unit doesn't get a signal from the sender. If I
take the head unit off the bars and move it close to
the sender, it works fine. I've replaced the battery
in the sender.

Any electronics experts who can explain this? I've
fixed it by moving the sender closer to the edge
of the rim but this means it's sticking out quite a bit
from the fork towards the wheel.

Cheers,
Duncan.

The distance these things work over is very short. I bought one with the
intention of using it on the back wheel. it didn't work, moving it about
150 cm closer and it worked. An earlier one I had wouldn't work when the
temperature got down to below 10 degrees C. Tried new batteries and
everything else, still didn't work. I've since given both of them away
and will never get another one again. I'm sticking with good old
fashioned wires.

Marty

DeF said:

I've got a Trelock FC900 that I bought on a whim
from xxcycle when getting some other stuff.
For example, see http://www.bike24.net/p21559.html

Anyway, I put it on my MTB commuter and it has been
working fine until recently. When it gets cold, the
head unit doesn't get a signal from the sender. If I
take the head unit off the bars and move it close to
the sender, it works fine. I've replaced the battery
in the sender.

Any electronics experts who can explain this? I've
fixed it by moving the sender closer to the edge
of the rim but this means it's sticking out quite a bit
from the fork towards the wheel.

Cheers,
Duncan.

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The voltage from batteries drop when the temp drops. This means the transmitter gets less power, and less reach. I think different types of batteries are less or more sensitive to this than others.
NiCd is less sensitive than alkaline for example. Not sure what LiIon works like. You could try to find a battery equivalent, that is non LiIon, and that could help.

Some wireless senders have a strength change facility - the Polar ones
in particular do - you can open them up and flick a dipswitch and they
transmit further - and use more battery of course! My speed sensor
lives on my back wheel with no problems with both a Polar S520 and
S720. Maybe yours has some way to boost its signal?

DeF said:

Anyway, I put it on my MTB commuter and it has been working fine until
recently. When it gets cold, the head unit doesn't get a signal from
the sender. If I take the head unit off the bars and move it close to
the sender, it works fine. I've replaced the battery in the sender.

My guess it's a cold battery under-performing.
Can you take the whole non-functioning unit off, put
it in a pocket to warm it up, then try again in 15
minutes. Doesn't solve your problem, but shows it's
something to do with cold... Hmmm, guess you knew that
already.

-kt

--
Kingsley Turner,
(mailto: [email hidden])
http://MadDogsBreakfast.com/ABFAQ - news:aus.bicycle Frequenly Asked Questions

kingsley said:

DeF said:

Anyway, I put it on my MTB commuter and it has been working fine until
recently. When it gets cold, the head unit doesn't get a signal from
the sender. If I take the head unit off the bars and move it close to
the sender, it works fine. I've replaced the battery in the sender.

My guess it's a cold battery under-performing.
Can you take the whole non-functioning unit off, put
it in a pocket to warm it up, then try again in 15
minutes. Doesn't solve your problem, but shows it's
something to do with cold... Hmmm, guess you knew that
already.

-kt

My first guess was the battery in the sender was flat. I pulled
it out and compared the voltage with a new one - it was 1.5V down
from the nominal 12V new battery.

There is a little more to this story. When I got the unit, it wasn't
working. Turned out that the connection from the battery to the circuit
board wasn't working. Long story, but, I pulled it apart and soldered
a new home made battery connection. All a bit jerry rigged but it was
working fine. I might have to take it apart again. Damn.

Cheers,
Duncan.

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To reply, you'll have to remove finger.

quote='DeF'kingsley said:

DeF said:

Anyway, I put it on my MTB commuter and it has been working fine until
recently. When it gets cold, the head unit doesn't get a signal from
the sender. If I take the head unit off the bars and move it close to
the sender, it works fine. I've replaced the battery in the sender.

My guess it's a cold battery under-performing.
Can you take the whole non-functioning unit off, put
it in a pocket to warm it up, then try again in 15
minutes. Doesn't solve your problem, but shows it's
something to do with cold... Hmmm, guess you knew that
already.

-kt

My first guess was the battery in the sender was flat. I pulled
it out and compared the voltage with a new one - it was 1.5V down
from the nominal 12V new battery.

There is a little more to this story. When I got the unit, it wasn't
working. Turned out that the connection from the battery to the circuit
board wasn't working. Long story, but, I pulled it apart and soldered
a new home made battery connection. All a bit jerry rigged but it was
working fine. I might have to take it apart again. Damn.

Cheers,
Duncan.

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e-mail: [email hidden]
To reply, you'll have to remove finger.[/QUOTE]

The Polar sender units have a jumper inside which allows you to select 3 different power output levels. Perhaps your unit has something similar? On second thoughts maybe the jumper is to keep the battery warm? 🙂