gt750 electrical issue: rectifier,battery,turn signal relay

[chance johns]

a week or two ago i took the gt out for a short test run, everything seemed fine except my turn signals werent flashing. all lights worked just didnt flash, so today i was going through the wiring, the relay thats in there worked when i installed it and is a replacement from a chain auto store, but after looking around for 10-15 minutes i noticed my battery was dead. previously to poking around the battery was good at 12.6 or so, its a newish gel battery. when i read it when it was dead it was at 4v or so. i was totally stumped and poked around some more and started fluttering the rectifier points. i noticed the voltage changing when i did so. so it must be related. i sanded the rectifiers contact points down, then my battery read 11.5 ish. so i started going through the wiring again, and it was dead soon enough. with the key off i saw the voltage continuously rise, a tenth a volt per second. im totally confused. i assume my relay isnt flashing because its not getting the full voltage it should because for some reason the battery is draining rapidly. i swapped it with a known good relay without desired results. but this is all strange to me because i rode the bike a week or two ago and it seemed fine. i have adjusted the rectifier and it was charging at 13.5 ish , previously. also i should add the cover for the rectifier is not present and it may have sat out with light rain for a little while. i need some insight.
my original relay worked then didnt, my replacement worked, then didnt, am i shorting these out some how?

is the 550 rectifier the same as the 750? does anybody know where to find a main wiring harness in new or refurbished condition?

[jabcb]

I assume that by rectifier contact points you referring to the voltage regulator contact points.

You might have a problem with the rectifier or alternator.

Remove the rectifier & check it.
Remove the rectifier & voltage regulator, then check the alternator + alternator wiring.

[chance johns]

i have tested the voltage regulator in the past and it was fine. also the bike was running fine before it sat for a week

[chance johns]

why is my voltage draining so quickly? why does the voltage return?

the battery will be at 12v it will drain to 4v then miraculously return to 11v.

or its a false reading? is the 550 regulator compatible?

[jabcb]

With a good charged-up battery, it takes quite a bit of current to drop the battery voltage to 4v.
Voltage drop when using the electric starter is much smaller than that.

Am a bit confused by your explanation.
The stock rectifier has diodes & no moving parts.
The stock voltage regulator is mechanical & has a relay with contact points.

[yeadon_m]

Batteries do 'bounce back', ie drop down then spontaneously recover without charging (to an extent).

Take a known good, charged battery, put volt meter across terminals, note voltage, then ignition switch on and hit the starter, watch voltage drop from say 13 to 11 during 5secs of cranking, turn ignition off, watch it bounce right back to 13.

If you ever really got a reading of 4v, battery is toast. Its not possible to have 6 cells operating and get 4v. Fully discharged will still read 9-10v I think, but voltage would then fall on its face if you put a load across the terminals.

Mike

[chance johns]

sooooo. i was referring to the regulator.

my battery wasnt actually toast. it just seemed like it? lights stopped working had 4v while hooked up. i took the battery out and placed it on the charger and it was fully charged within no time.

also my battery read 4v then i sanded the contact points on the regulator and it read back to 11 or so volts.


all of this is while the bike was not running. i know the lights put a draw on the battery and the draw deminishes when the key is off. this wasnt that type of situation. 12.6v-4v.

[chance johns]

battery reads 12.6v installed.

with the key on and no lights it drains .o1v every 3 seconds with the headlight or turnsignal on it drains .o1v a second or quicker.

it will go down to 8v or lower. when i turn the key off the battery reads around 11.5v.

the bike runs, ive been trying to adjust the regulator arm and it either reads up to 13v or up to 16.5v there is no middle ground.

i did have this adjusted properly at one point. i know that around 3-4k rpms it should read 13.5-14.5v , but i am not currently getting those results.

[chance johns]

also by main harness i am referring to harness #1. ive bought harness2 from knk but i would like to find harness1. any leads?

[tz375]

There are others on here far more electrically competent, but I won't let that get in teh way.

In my experience a dead battery will appear to charge up fast to 13v but has no "capacity" and when it's hooked up, the voltage tanks fast. My guess is that the regulator failed with the points closed allowing the battery to drain slowly but pretty completely. We had two batteries on our FZR die that way. They charge up and look fine on the voltmeter but lack enough electrons to fir up the bike.

Bounce back is just removal of load from the battery. With ignition ON and lights off, power is drawn through the ignition circuits unless all the points are opened with a sliver of card and if voltage is still dropping it's the condensers "leaking".

I would buy a new solid state R/R and a new battery and that should fix it.

[jabcb]

+1 on tz375's suggestion.

You get get a modern R/R.
Alternatively, Oregon Motorcycle Parts sells modern rectifier & voltage regulators that are direct replacements for the stock parts.
http://www.oregonmotorcycleparts.com

[chance johns]

nice. i wanted to keep the original regulator because i love that its mechanical! but i need to do what works for my bike, i found that website a little confusing, what is the suggested upgrade people here use? i dont want the cheapest(shittiest) option. but im also not looking for the craziest(expensive) option either.

[jabcb]

rectifier R255-SGT http://www.oregonmotorcycleparts.com/rectifiers3p.html
read text about ground wire

voltage regulator VR3-SGT http://www.oregonmotorcycleparts.com/vregulators.html
read text about the wiring harness connecter

[chance johns]

i just installed leds on my van an checked the draw on the battery. it is behaving in a similar fashion as the bike. with the key on the leds are drawing .01v every 3 seconds or so and then return voltage when the key was off. i know that leaving the lights on will decrease the battery voltage i just didnt think it would be sp much so quick. so maybe this isnt as much of an issue as i thought but the problem is its drawing at a quicker rate such as .01v per second or more. is it likely i have a short somewhere in the orange wire circuit, the wire that draws when the key is on? how should i test this theory? resistance through each componet wired through that circuit?

[chance johns]

basically we ended up coming to the conclusion the battery is bad. its a new gel battery i picked up from you. it reads full voltage when charged, and functions and charges when the bike is running. its when the engine is off and key is on,is where the issue is. so we swapped it with a much smaller battery and the voltage drop stopped. headlight is drawing 3 or so amps, coils are drawing 4-5 amps and the regulator(electromagnet) is drawing 1.5-2amps. does this sound ok? its about 9-10amps total draw with key and headlight on.


is the voltage drop a characteristic of a bad battery?