Bizarre Charging Problem

[comradeiggy]

Here's the dealio. I'm having some problems with my battery/electrical system on the bike. First thing, I'm almost certain my battery is on it's last leg, so that's getting taken care of today. When I start the bike, battery voltage dips down to about 8V (hence I know it's bad, it did this even after 10hours on the charger). Here's the strange thing. Once I get the bike started, I'm reading damn near 20V on the battery at ~4k RPM, and about 16 or so at idle. The PO added some glowing LED's to the bike so the wiring harness is a bit of a PITA to deal with, so I haven't checked it yet cause I'm still looking for the connectors, but I'm guessing my regulator is FUBAR. Thoughts?

[sledge]

The reg/rect could be compensating for the fact your battery wont hold a charge and has an increased internal resistance.
See how it behaves with a new battery before condemning it.


Ruling the battery out first is always best practice when dealing with charging issues.

[The Buddha]

Oh, of all the Idiotic mods that people do to bikes that have a negative value IMHO those neons and led's are the worst.
They're beaten only by Idiotic estended arms IMHO.

20v = the regulator is dead. You may want to donate it to science(me) and the scientist(also me) will soak it in acetone and open it and see what is in it and if we can externally repair it. Or even internally repair it.
Cool.
Buddha.

[comradeiggy]

Sledge - Definitely getting a new battery before I do anything else, since the bike runs fine once I get it started, but it shouldn't have too much effect on the voltage the R/R is putting out, it would bump up the current.

Buddha - I agree, especially about the swingarms, I saw a guy walking his 'busa across 3 lanes of traffic the other day, then get on and ride once he got it facing traffic. If it turns out the regulator is bad, I'll post plenty of pictures once I get it cracked open, I've been looking for something like this for a school project of mine. Though I have a feeling it's probably a really simple system, just a 3 prong ac-dc linear regulator that simply dissipates excess power as heat and some diodes to keep current flowing the right way.

[Kiwingenuity]

I would suggest from experience with a GN that your regulator has gone bybye and cooked your battery. It is likely if you check the battery terminals with the bike running with an AC voltmeter you will see some AC voltage there which will slay batteries.

While it is true that regulators will increase the voltage to compensate for a dying battery, they normally should never get up to that voltage.

If you do elect to trying swapping out the battery first (cheaper I realise) - make sure you check the charge voltage first thing for AC, and check it is happy at 13.3 -> 13.8V max.

At least its not a Cagiva.. ask me how I know..

[comradeiggy]

Took the battery back to where I got it and they're ordering me a new one, this morning I checked the voltage on it after 24 hours on a charger and the battery was showing 19V. Wtf? I know that, chemically, that is not possible, so I checked my multimeter. Took a reading of the battery in my car, and got roughly 20V. So it appears all I need is some new batteries: 1 for the bike, 2 for the multimeter. Though I am a bit disappointed, I was looking forward to seeing what was in that regulator.

[Kiwingenuity]

Ah - valuable lesson here - Proove - Test - Proove.. Hope you didn't buy the regulator.. those things are pricey.

In terms of what's inside them, not a great deal to see. most of it is silicon, epoxy and heat sink these days.