Voltage query.

Hi all! I own a v reg (2000) sv650s. The day I bought it I rode it back to my house from berkshire (1HR 30 MIN) when I tried to start it the next day the battery was flat. So I got a new battey. I put a multimeter on the terminals when the engine was running (with new battery) with a few revs and these were the results.
LIGHTS OFF: 15.5v
LIGHTS ON : 13.2v
I have been told to get this checked out. Could it be that it was just the battery not holding the charge or could it be something else? Can anyone help?

Generally speaking batteries are rated around half way through their discharge. For instance a fully charged 12V battery starts around 15V say and then as it gets drained the voltage will drop. 12V is simply the average, it may vary from that quite significantly depending on how much the battery is drained. It's nothing to worry about.
Rob

[Geodude]

Have a read of my thread as it might be of some use http://forums.sv650.org/showthread.php?t=164281

Repeat that test, measure the voltage (at the battery) at Idle and again holding the revs at 5K rpm and post the results.

Thanks for the reply, was just worrying about it only charging at 13.2v with lights on. Is that enough? And dont want it to boil the battery at 15.5v.Some people have said it could have something to do with v/reg. or corroded plugs. Could this be a possibility?

When I measured mine I got these results

Idle 13.6v,
5K rpm 14.4v

Mine is a Pointy though so the dip beam headlights are on all the time, bike batterys are made to deal with 15V so don't worry about that (IIRC 15.2 is the boarderline for Overcharging)

Ideal maximum charge voltage is 14.4 volts, the regulator should prevent the voltage going above this. If you have the lights on, ignition etc then the alternator will have trouble achieving this ideal voltage, if you are getting above 13 volts then that's fine. Once the battery is fully charged then you will find the charging voltage will rise towards the ideal of 14.4volts with higher revs. The regulator circuit is robust and simple so may give peaks a little higher than desirable but this wont matter. As Joules mentioned, poor connections to the regulator can make it give a higher output. (check the earth connection)
A good Battery measured with no load and no engine running will tend to give 2.2volts per cell so x 6 = 13.2volts. As soon as a load is placed upon it this will drop towards 12 volts. On high current start up then this will drop a volt or so but restore to 12volts once the high load is off.

[mikerj]

Originally Posted by warmshed

The regulator circuit is robust and simple so may give peaks a little higher than desirable but this wont matter.

I was agreeing with everything until I saw this bit

[yorkie_chris]

15.5 is too high, suspect regulator has failed.

Peaks around 15Volts is quite normal on solid state regulators, this is instantaneous peaks not sustained voltage.