Battery Drain #2

Not sure if anyone will see an addition to the previous post I made, so I'll start an extension here.
So, it's been a while since we talked about this but I finally got a multimeter. Topped off fluid in the battery last and got it charging. Put it in the bike this afternoon and started her up (been sitting since last time we talked). Voltage across terminals was at 12 volts prior to putting in bike. Don't know if you guys are gonna believe this but voltage at idle was 23V, up to about 50V at 4500rpm!! This is definitely a very bad thing. Turn signal blew the minute I tried them. Situation has certainly deteriorated since last check-up. Any ideas??

I suspect the regulator/rectifier has failed. have you been to www.electrosport.com and used their troubleshooting page?

kzmitch wrote:

Don't know if you guys are gonna believe this but voltage at idle was 23V, up to about 50V at 4500rpm!! This is definitely a very bad thing.

I think the battery has to be bad. If it is a good battery, the alternator output would never be able to force the voltage that high. Your alternator's regulator may also be bad which would have destroyed the battery by over charging it.

NOTE: this assumes the voltage readings are accurate. If it is a digital meter, it may be getting goofed up by electrical noise.

Yea, those readings are impossible with a battery loading the circuit. Either a bad meter or battery is open circuit internally or the cables are not hooked to the battery.

Yea, those readings are impossible with a battery loading the circuit. Either a bad meter or battery is open circuit internally or the cables are not hooked to the battery.

I have actually seen this happen before, and most times there is some incorrect wiring or damaged component.

Unplug the 3 yellow wires that run from the alternator to the rectifier/regulator pack. Don't let them touch anything/eachother!

Then start the bike and check the voltage. The bike will run fine for a while on just the battery, allowing you to check all the lights, etc.
You can use a known good car battery as well.
Don't try to run the bike with anyhting over 16Volts or so, it could burn out the coils, or cause a wire-fire.

Keep extinguisher handy as per normal safety with bikes

On the other hand if the battery is bad, and the regulator is good and working properly, the regulator will sense that much voltage going through system and shut down charging voltage. If the rectifier is good but the regulator is shorted internally (pass through) you very well could see that high a voltage at the battery. Take the battery to a Napa or Autozone and have them test it under load. If it checks out okay then replace the regulator.

Wouldn't the main fuse blow from the Voltage spike and amp surge? Have you checked the fuses or am I out to lunch on this one?

YUKABODOS wrote:

Wouldn't the main fuse blow from the Voltage spike and amp surge? Have you checked the fuses or am I out to lunch on this one?

The amperage was probly not high, long enough. I would deffinately replace all the fuses with new, if not already done. The old glass fuses are notoriously unreliable, and can leave you stranded without notice. If you can switch to a blade fuse box, all the better.

Cheers.

polkat wrote:

If the rectifier is good but the regulator is shorted internally (pass through) you very well could see that high a voltage at the battery.

I don't think a stock alternator can output enough current to drive a decent battery voltage that high. I believe the battery's internal resistance would have to be significantly higher than normal to allow it.

It certainly is possible to see transients in the 50V range but those are not true battery voltages, they are transients that appear across internal inductance in the bike's electrical circuits. Such noise transients can make a DMM read goofy high voltages that are not really there.

TeK9iNe wrote:

YUKABODOS wrote:

Wouldn't the main fuse blow from the Voltage spike and amp surge? Have you checked the fuses or am I out to lunch on this one?

The amperage was probly not high, long enough. I would deffinately replace all the fuses with new, if not already done. The old glass fuses are notoriously unreliable, and can leave you stranded without notice. If you can switch to a blade fuse box, all the better.

Cheers.

If I recall, the main current outputs from the alternator/regulator don't go through any of the fuses. At least, they don't in my 750.

Alright, so we've come to the conclusion that my battery is fried, most likely due to the high voltages going across it. But a bad battery wouldn't be the cause of those high voltages? That should be a lack of operation of the regulator? I was using a dial MM, not digital set on the 50V range. Steps from here are to get the battery checked at NAPA. Do I really want to hook up my good car battery to the bike? IF it is the regulator, wouldn't it then just fry my car battery?

Your battery may indeed be fried, but the regulators in these bikes use the shunt method with thyristors (SRC) and are triggered by sensing the voltage in the electrical system (through the-usually-brown wire of the regulator). If the system sees more then 14.5 volts, the src's bypass the output back to the alternator (please-I'm simplifying here). This should work regardless of battery condition. If the system has enough voltage in it to fry the turn signals (as you mentioned) then the regulator is not doing it's job. Again, your battery may already be fried, but I think your regulator is gone too.