Modern Vespa

Has anybody had experience with GTS 250ie having a faulty voltage regulator? It is a 2007, and I have a feeling this is a somewhat frequent proble. It has been dying at stoplights (at low idle) and then a bit hard to start and then this weekend, completely dead wouldn't start. Battery would hold a charge, but I had to add distilled water. I may have already ruined the battery, but after adding water, the bike stared. Supposedly, that may meana bad voltage regulator fried my battery. How much am I looking at to have this replaced, and should I get a new battery? I am probably not handy enough to replace the voltage regulator myself. What does it actually do?

The voltage regulator keeps the power output of the stator within the required range. If the voltage reading at the battery reads over 15v while revving the engine, the voltage regulator is malfunctioning.

As Drew said, test the battery at the terminals with a volt meter and see what the voltage reads at idle and again at over 3k rpm. If it doesn't go over 15 volts while being revved, the voltage regulator is not the problem. Also, the check engine light usually comes on when you rev the engine if the voltage regulator has gone bad. If your voltage reading is in spec then you may just need a new battery. If you replace the battery, buy a sealed model, preferably an AGM type. (absorbed glass mat)

I had a bad voltage regulator. I decided I didn't want to tackle this for my first job but I don't think it would have been too difficult. Search "remove Vespa glovebox" on youtube. There's a good video. Also, the workshop manual has some good exploded diagrams showing where the VR is located. There are some good threads on diagnosing a bad VR here on MV. Try a search for "voltage regulator" and "charging system" here on MV. You should get a good idea if this is something you want to do yourself. I opted to have it done. The replacemen VR ran $160 and the labor was about $110.

Let me know if you can't find the info. I haven't taken the time to post links in the message but if you come up blank I'll see if I can track down the info I found.