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Discussion Starter · #1 ·
Late last summer I was out riding for several hours, in 95° heat, and then stopped at a friend's for dinner. Bike sat for probably 2-3 hours and went to start it and had nothing, no click, no lights, completely dead. Turned ignition on and off several times and nothing.

Was in the process of removing the battery cover, to check connection, and my friend turned the key back on, and lights etc came on as normal.

Rode home, all good, and kinda forgot about it.

Out again a few weeks later, another HOT day, and electrics died while riding. Check engine light was on, but no speedo, no lights / signals, no odometer. Engine kept running, so got it home. Every time I'd slow down at a stop sign dash would flash on and off intermittently.

Noticed a couple of times if I held the turn signal switch one way or the other, dash would come back on (but speedo didn't work).

But then bike was completely dead. Battery at full voltage, but nothing getting to the bike.

Replaced reg/rec with the 05 Road Star unit late 2020. Never had any other electrical issues.

Bike seat over the winter and I finally started looking at it today.

Checked the ground to start with. All clean, good connection.

Battery at ~12.5v.

Turn the key on, and everything looks normal. Hit ignition and electric all dies instantly. Display, lights, everything dead.

Turn key off. Same thing a couple of times.

Then nothing when the key is turned on.

Hooked up multimeter, and still getting ~12.5v, but as soon as I turn the key on, it's reading <1.5v, a couple of times, reading even down in millivolts.

Battery was replaced with the reg/rec in late 2020. Taking it to get load tested in a couple of days, but to my (amateur) eye, seems odd that not even the display is coming on when the battery is still reading to charge with the key off.

Was previously suggested that reg/rec might be bad, but can't start the bike to test.

Loathe to fork out for a new one if that's not the issue...
 

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If you have a multi-meter you can do your own load test. I recently replaced the battery in my Stratoliner. One day it cranked the next it didn't. The battery was about 1.5 years old.

Connect your meter directly to the battery. Turn the key on, hit the starter and watch the meter. The battery voltage should not drop very much. If it drops below 12 volts, odds are the battery is shot. I saw mine drop down to 9v. I took the battery to O'Rielly's and they tested it and said it was good. I didn't want to chance getting stuck somewhere, so I decided to replace it.

I learned that just about all of the motorcycle batteries only come with a 6 month warranty. That tells me the manufacturer doesn't expect them to last a real long time.
 

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It sure does sound like a ground issue, There is a diode check for the regulator but that doesn't sound like it.I found the diode test on youtube. When the voltage goes down the speedo and odo is intermittent. I had that happen when my regulator went out on my 1100 because the battery voltage was low because of charging problem.
 

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Discussion Starter · #4 ·
Well, had the battery load tested today, and it's toast.

Wondering if the reg/rec crapped out from the heat last summer, and fried the battery.

Will report back when the battery has been replaced.
 

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It is possible. Just watch how hot it gets. I had read that the regulator that you got is an up grade from the stock 1100.
Were the sides of the battery bulging? That would be a sign. I would test with the cover off and see if it gets hot.
 

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Discussion Starter · #6 ·
So installed new yuasa battery today, and bike fired up straight away.

Voltage with key off: 12.75
With key on: 12.35
Dipped to 11.5 ish while cranking.
Voltage at idle: ~13.5
Voltage at higher revs: 14.

Which all points to reg/rec being just fine.

Could previous battery have crapped out and caused issues from something other than reg/rec?

It was no yuasa, but it was only 3 years old.

Maybe ground was bad, and coincidentally battery was shot?

At a loss as to what else I should consider, but don't want to trash another battery, or get caught 50 miles from home with a dead bike again...

Any thoughts?
 

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Entirely possible the 3 year old battery was end of life. Doubt if bad ground would have killed the battery and I've seen many car and motorcycle batteries fail at around 3 years old. The voltages you list look well within normal, so I believe your diagnosis of the rectifier/regulator being good is correct.

Retake your readings every couple of weeks for a little while and see if any anomalies show up. If not, I think you are good to go.
 
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