"The Ugly Truth" - 28 A down???

[Oldschool1]

Well - it happened this morning on the way to catch a plane! Stopped at a light, konk -hmm did I stall on take off, battery dead, push start - begin to drive - head lights off - motor dying so i switch off head lights - continue to drive to "somewhere off the road" ......konk konk konk. DOA.

So after the tow truck drops me off (oh did i forget to say I missed my plane!) I suspect the battery got an internal short (ok i'm an optimist) - so i needed a new bat anyway. Get a new Yuasa - put it in start up - but volts at bat are now at 12.5 and dropping like the value of US dollar. I'm looking for the next hypothesis the supports denial of the "ugly truth". Rats - can't think of any, hmmm - was it malicous attach from Martians?...........


Ok - dismissing every desire to suppress the "ugly truth": I don't see any burnt wires at the VRR connector, or the 3P connector (is that the one with the 30A fuse attached?) and the red connector with 3 yellow wires (to the left of the 30A connector just mentioned).

Bike has 43k miles, 1994, connections were never corroded and i've cleaned / greased them for 4 yrs (not because i'm a 28A paranoid, well actually.....!).

Any other connetions to find, fuses, or is it an electrical test of the 28A at this point?

Any thoughts about the "ugly truth" welcome!

THX U

Paul

 

[jim'll break it]

Set your multimeter to AC and check for voltage across the 3 yellow wires,
you should see 50 to 60 volts AC across each pair, if its not there the alternators blown, if it is there suspect the reg/rec and associated connections

 

[Oldschool1]

I'm baffled!!!!!


Just went out to do this voltage test - started it up and had 14.3 volts at the battery terminals at idle speed of about 800 rpm (still cold). Didn't get any voltage change with increased rpm.

Headlites off Idle (800 rpm): 14.3 VDC at bat terminals
Headlights on idle (800 rpm): 13.3 VDC at bat terminals

3 yellow wires measured at red connector - all connectors complete as normal.

Any yellow wire to frame ground: 8.X VAC at idle
Any yellow wire to each other 12.3 VAC
I must not have measures this right to get these voltages and get 14.3 VDC at the bat?


I'm baffled as to why I have 14.3 Volts at the battery now when I had 12.5 and dropping voltage last night with the lights off.

I think I will go ride if for a bit in the neghborhood and see if there is some heat related "open" or something going on - but it doesn't make any sense.

 

[maximark]

I'd try to borrow or buy off eBay a regulator first. I think that there's 50/50 chance that its either regulator or alternator failing, that's why it's sometimes working and sometimes not. I'd also monitor voltage going out of alternator if its constant. That way you'll have better idea what it is.
This is one of the reasons why I've installed voltmeter.
Mark

 

[Oldschool1]

I just drove 25 minutes with a voltmeter strapped to the bars. Voltage was 14.3 to 14.5 with lights off. When i turned the lights on (high beam) at idle, it would drop to 13.3 and then increase quickly to 14.5V

With lights off at 1500 rpm driving, voltage is at 14.5V, then switching high beams on it remains at 14.5V (if there is a drop is very short).

So i'll get a volt meter to insatall and watch it I guess.

Perhaps it was battery related as that won't charge over 12.0 Volts. But that does not explaing the no voltage output after installing the new battery last night.

Paul

 

[ST1100Y]

With lights off at 1500 rpm driving, voltage is at 14.5V, then switching high beams on it remains at 14.5V (if there is a drop is very short).

And while at it I would definitely correct the idle speed to the proper 1100rpm as rated... besides a low voltage your engine also suffers low oil pressure on its top parts while idling at a red light with only 800rpm...

 

[maximark]

And while at it I would definitely correct the idle speed to the proper 1100rpm as rated... besides a low voltage your engine also suffers low oil pressure on its top parts while idling at a red light with only 800rpm...

+1 on that!

 

[DeanR]

How are you measuring voltage with lights on and lights off. Does that not = bike running or not running?

 

[Oldschool1]

Two clarifications are needed - my mistake:

1. RPM is about 800 at startup - it takes a few minutes then it climbs to 1100. Though i suspect my idle mixture is not perfect and hence perhaps why it climbs slsowly during warmaup? I removed idles screws a few months back to make sure the circuit was clean - think i need to do the idle drop procedure but not sure i could ever get that screw driver to find the screws.


2.Lighs off, no this is when running - my low beams burned out the other day - no chance to chnage the bulb uet. So high beams were all that was working (so low beam is actually off, and high beam of course is High beam).

thx,

Paul

 

[touringfool]

All electronically regulated alternators are demand type generators. In other words, the charge voltage will drop when a battery is fully charged. 13.3 volts is fine if the battery is fully charged. 13.3 is at the lowest end of the range , though. An alternator will produce power according to RPM as well. Maximum wattage will be achieved at about 3000 RPM alternator shaft speed, (not engine speed, the alternator spins faster than the engine). At idle, you typically only get about 1/3 output. No 12 volt system alternator should charge over 14.8 volts. If it does, you'll be replacing bulbs far too often, and your battery will fail prematurely. So the bottom line is: is the output voltage ALWAYS between 13.3-14.8 at all times the engine is running? And, is the battery 'at rest' voltage 12.7 5 minutes after the bike is shut off? 12.7 volts 'at rest' (no electrical draw at all, measured across the positive to negative terminals) indicates a fully charged battery. 12.5 indicates a 50% discharge, and 12.25 indicates a 75% discharge. 12.7 volts when the engine is running indicates the alternator isn't charging. I don't know why you initially had only 12.7, but, if it is at or above 13.3, and 12.7 with the engine shut down, nothing is wrong at this time. Good Luck!

 

[Oldschool1]

Thanks Touringfool.

Since repeated monitoring falls into exactly the conditions above, over several trips. I'm going to close this chapter for now and pronounce a clean bill of health.

I can't explaing the single data point of 12.5V that night (oh a few hypothesis that will remian conjecture for eternity) but the current data oaver the last week and several trips, much more strongly points to a correctly functioning alternator and VRR

Thanks All ST'ers for your help. Now onto the next feat (I'm not quite happy with that idle issue but that'll be in the carb section - see you there shortly).

Paul

 

[Brant]

All electronically regulated alternators are demand type generators. In other words, the charge voltage will drop when a battery is fully charged. 13.3 volts is fine if the battery is fully charged. 13.3 is at the lowest end of the range , though. An alternator will produce power according to RPM as well. Maximum wattage will be achieved at about 3000 RPM alternator shaft speed, (not engine speed, the alternator spins faster than the engine). At idle, you typically only get about 1/3 output. No 12 volt system alternator should charge over 14.8 volts. If it does, you'll be replacing bulbs far too often, and your battery will fail prematurely. So the bottom line is: is the output voltage ALWAYS between 13.3-14.8 at all times the engine is running? And, is the battery 'at rest' voltage 12.7 5 minutes after the bike is shut off? 12.7 volts 'at rest' (no electrical draw at all, measured across the positive to negative terminals) indicates a fully charged battery. 12.5 indicates a 50% discharge, and 12.25 indicates a 75% discharge. 12.7 volts when the engine is running indicates the alternator isn't charging. I don't know why you initially had only 12.7, but, if it is at or above 13.3, and 12.7 with the engine shut down, nothing is wrong at this time. Good Luck!

13.8-14.2v IS ideal charging voltage for automotive systems.Bikes, alot of times run a bit higher on the tenths side, which IMO is the fault of the regulator and its factory setting. Anything above a 14.5-6v charge rate WILL shorten life and may overheat the battery

 

[Woonjas]

Mine had had irregular intervals where voltage would drop below 13V for a short time (<minute) until finally it would not go back up again - still trying to make the time to perform the upgrade (and replace the timing belt).

Luckily my wife's been kind enough to let me borrow her MT-03

 

[Oldschool1]

Ugly Truth 2.0 - Chapter RE-OPENED.




Well after several weeks of riding with new bat - just where I left off with voltage under control, I'm riding to work 10 miles, just about get to the parking lot - give a spirited twist of the throttle on a home stretch (stumble stumble stumble) -as the bat was running out of sparkies. Get the parking lot and push last .2 miles (ouch).

Rather than go the tow truck route i developed (plagurized from a good sole on this forum) the attached method and rode home (was a long day) but provides a new skill set should you ever be trapped in the great divide!

So back to the problem - it is intermittent - i suspect VRR with heat related open.

So i'm in the market for a known good VRR to troubleshoot this one - and my suspicion is strongly alligned the VRR being a solid state device - can very well fail this way.

Or other suggestions welcome.

Thx,

Paul