more electronics really, but maybe someone knows

[ollski]

Guys just a quick one I have a 12v system on my motocross bike with dual tail bulb and if I have the lights turned off the brakelight blows. I am guessing it throws excessive current for some reason. Basically I am wondering if I can fit anything in-line to restrict this surge. Sorry if its the wrong place but I need to squeeze this through an mot on monday

 

[plugwash]

my suspicion is that the battery isn't doing its proper smoothing job (either because of a bad connection somewhere or because its shot)

what voltage is the bikes electrical system? and what rating is the light? you could possiblly use a low dropout regulator as a temporary soloution depending on exactly how much power is needed. but really you need to get the whole electrical system checked over to find the root cause.

 

[mikeddavies]

Seem to remember from the distant past!! that some systems have a zener diode across them to dump/absorb over-voltage when there is no load on the system. If this blows then you get the symptom you describe - overvoltage blows the brake light.
Hope this helps

MikeD

 

[olly_k]

from what everyone has said here you need to 1. look at the bulb voltage and 2. take a voltage measurement at bulb point with break pressed and rev engine to see how voltage varies. I assume the bike has an alternator and the alternator should have a built in regulator? - which might include said zener mentioned by Mike.
If it is a 12V battery and a 12V bulb and NO alternator then I would call mulder & scully
Hope you sort it!

 

[ollski]

Sorry guys there is no battery, I presume it's alternator, regulator.