Low voltage suggestions

[Steam]

What can cause low voltages? Measured anywhere, the voltages on my GN250 are 9.5 volts at idle, and 11.9 volts when revving hard.

I have to crash start it each day.
I charge up the brand new battery and it starts fine for a few days, but then runs down and lacks enough juice to start the wee beastie.

Things that could cause the low voltage;

rooted regulator, alternator, or.....?

I want to have a go at fixing it myself before paying a shop $75 an hour.

Thanks everyone!

[T.W.R]

possibly the regulator/rectifier is poked, stator coil open or shorted, or there's a ground somewhere in the electrical system thats earthing out (ignition, charging, or lighting)

[Motu]

How much in the battery? If you've got less than 12 volts it's stuffed.

[davereid]

There are only a few reasons that your bike wont charge.

1. Check the obvious

- If the battery is stuffed it won't charge. But if you can charge it overnight on the bench, and it starts the bike on the electric foot it may be allright.

- Check all fuses are OK and all earths are good. LOSE EARTHS are the single most common cause of bike electric faults.

2. Check the less obvious

- Use a ohm meter to check the alternator. It is likely a 3 phase device with an earth connection. So Take the cover off, and look for 3 or 4 wires. Commonly 3 will be white and one will be black, or not there at all. Unplug the alternator, and measure the resistance from each white wire to both others. 0.45 to 0.65 ohm is OK. If substantially different stator is shagged.

If stator is OK problem is rectifier/voltage regulator - as long as all items in (1) are checked checked checked !

[notme]

Dave mate we're meeting in all the electrickery threads tonight aren't we? :doobey:

Try this:
http://www.offwidth.co.uk/bike/general/electrical_fault_finding.pdf
( I have a local copy if it dissapears on ya)
Sounds like
the battery is OK since you say it's new.....one questin though - why did you get a new battery? Symptom or cause? :blip:

People are continually surprised at automotive electrical faults - very often (as Dave suggests) it's nothing more than dirty/loose/corroded connections.

[Steam]

Thanks all, great suggestions so far.

Allun, that chart is amazing, thanks! The kinds of people who make that stuff, I can only stare in awe.

I replaced the battery because I thought it was poked, but it's doing the same thing with the new battery too.

It's nice to have a go myself before handing it over to an expert, my GN is the first vehicle I have been brave enough to attack with a socket set. It's great fun unbolting and replacing bits!

[notme]

Well, have a go with that chart - do you have a multimeter? If not, well shit mate you can get them pretty cheap nowadays!

Multimeter - $11.94 inc GST
http://www.dse.co.nz/cgi-bin/dse.storefront/44d5a8730a2e0c62273fc0a87f99071c/Product/View/Q1469

The best way to learn is to do it yourself - isn't that how we all learn about sex? :blip: