Torch / bike light goes off after a bump

[RedBike]

I've got one of the dealtime extreme torches.
http://www.dealextreme.com/details.dx/sku.32590

I've used it on my helmet while MTBing without any problem but when it's mounted on the bars of my road bike it changes its mode whenever I hit a bump.

Has anybody got a solution?

 

[heliphil]

its the battery moving inside causing it to momentarily lose contact ( ie smae as pressing the on switch) making it change mode or turn off. Mine (similar torch) did that so wrapped some tape around the outside of the battery so its a snug fit and that seems to have cured it 99% of the time.

 

[tyred]

Probably is the battery moving but could also be a poor connection/dry joint or an over-sensitive switch.

 

[RedBike]

Could be.

I've tried shaking the torch and tapping the torch on the table to try and replicate the problem.
The only way to get the torch to switch modes is by tapping the torch (quite hard) vertically on the table.

ie if you point the light either at the ceiling or straight down on the table then tap the torch on the table it will switch modes. However, if you just shake the torch or if you tap the side nothing happens.

 

[RedBike]

I've wrapped a piece of paper around the battery so it's a snug fit and the torch still changes mode when knocked.

Is it the switch?
Any ideas how to stop it?

 

[tyred]

I would check any soldered connections you can get to easily, make sure the battery contacts aren't corroded, possibly give them a small bend to grip the battery tighter.

In theory, this should be easy to sort but I had a similar issue with a seatpin mounted LED tail lamp which kept switiching itself off. In various stages, I taped the batteries in place, tightened the battery contacts, re-soldered every joint on the PCB, removed the switch completely and switched it on by shorting out the contacts with a screwdriver, none of which made any difference so I threw it in the bin.

 

[RedBike]

I think its going to be a case of mounting the torch better on the bars. (i'm using a lockblock at the moment)

If the light, while mounted on my helmet, isn't effected by vibration/bumps while MTBing, then it must be possible to mount it on the bars of a road bike so that most* bumps wont effect it.

 

[Davidc]

Your neck is a good shock absorber, has to be or your brain would get bruised, so the light's probably getting much sharper jolts on the bars.