08 K9 Battery or Voltage Reg?

olddog58

olddog58

Member
I've read through several posts related to bad batteries or bad Voltage Regulators, but I still could use some advice...
I have similar symptoms but not exactly, so let me tell you my symptoms and ask for advice.
1) My K9 started having trouble cranking over a few months ago, if I let it sit for more than 2 weeks. The Speedo would not work due to low voltage check.
2) The situation has gotten progressively worse over the last month and this past weekend it had a hard time turning over even though I put more than 20 miles on it between each start. Next morning almost nothing, took several tries to get it to turn over.
3) I bought a battery tender, plugged it in and in 30 seconds it read 80% charged, and in an hour it read fully charged. I put a battery tester on the battery and it zipped right up to the top of the "good" range. Like I said I don't have a volt meter, but everything indicates the battery is good and fully charged...
So the question of the hour- Does the Voltage Regulator control how many Amps/volts are passed from the battery to the starter motor? And the speedo (which hasn't worked all weekend). Or does the Voltage Regulator control how many Amps are routed to the battery to charge it?

- My guess is I'm looking at a bad VR, are my symptoms clear enough to make that conclusion or do I need to find a friend with all the right equipment and experience to measure pin A to battery B and all that 'stuff'?
 
Brew

Brew

Troop Supporter
Best thing to do is get you an ohm meter so you can see the volts your battery actually has. I would charge the battery then take a reading should be around 12.7 or better volts DC. Keep the charger off the battery for an hour or two and then check the volts again, if the volts drop significantly then you know your battery is toast. If the battery holds a good charge then start the bike and put the ohm meter on the pos and neg terminals of the battery while the bike is running and see what kind of volts your charging system is putting to your battery. If low then you know your charging system is fouled.
The thing that catches my eye is you mentioned in an hour you had a full charge, it shouldn't take that long to achieve a full charge...
 
07bigdog

07bigdog

07BIGDOG
I just sent back a brand new Braille battery that tested bad. The battery tested at 3.06 volts at the factory. I charged it up to 3.1 volts and after sitting for 8 hours it dropped to 12.2 volts. Charged it up again and it wouldn't even turn the Bigdog over. It was charged to 3.1 volts and when i hit the starter botton it read 11 volts. Dud right from new. Sent it back on warranty and waiting now for my replacement.
 
jaggerz

jaggerz

Active Member
The voltage regulator controls the amperage and voltage going to the battery. It has nothing to do with the amperage going to the starter. Low voltage when cranking will cause the speedo not to work. Have the battery load tested at a battery shop.
 
olddog58

olddog58

Member
Ok, updates from this morning... and new symptoms...
Last night I charged the battery (it didn't take an hour, I just didn't check on it for an hour) and put the ohm meter on it 2 hours after charging... 12.7volts. Checked the battery again this morning before starting it up, still 12.7 volts. Next tried to start... wouldn't crank... third try it finally cranked over and started. In this process the emergency flashers started flashing (why???)... After starting, I checked the voltage, and with it running, I read about 14 volts on the battery.
New symptoms...
My idle has been running low (under 1,000) and rough. And when I did get it started this morning, I noticed lights in the battery compartment- I assume on my computer, one solid yellow and one flashing green... anyone know what these are?
Ok, back to this morning. After getting gas and having it not crank, I turned the key off for about 5 seconds, and then went through the start up sequence again (it's an EFI), this time it cranks over like a son of a gun, fires up, my speedo works, my idle comes back up to a smooth and consistent 1,100-ish...
- What the hell is going on? I'm starting to think my computer/control unit may have gone bad. Anyway, it's acting so weird that I think I have to take it in to the shop (50 miles away)... it's only 14 months old, 6,500 miles, so I think it's still under warrantee.
 
olddog58

olddog58

Member
Ok, nevermind...
I took the battery in for test and it turned out to be perfect! And I'm getting a good solid charge. Next step was to trace the wiring and see if I could find a reason for a significant voltage drop between the battery and the starter...
I found the large battery cable between the starter and the selenoid had it's rubber sheathing split and the copper strands were loosly wound and exposed to the frame and other equipment next to it. I taped it tight with electrical tape and then went through the start sequence... and sure enough, she fired up strong as ever, everything working, and running smoothly!
I'll take it in to have the cable replaced on warrantee, but it sure felt great to trace it to something simple and not a new ECU or VR...
 
V

V

Guru
That cable problem you discribed is not un-common. The wrap appears to dry out and fail (maybe from heat when starting). Anyway lots of bikes have had this. also next time you're in a shop see if they have new old stock and take a look some of these have it as well. local dealer had 06 and 07 Ironhorses still on the floor and they were doin the same. Not just a big dog problem.

Also check all starter and ground connections
 
Last edited:
erldawg

erldawg

Guru
V said:
That cable problem you discribed is not un-common. The wrap appears to dry out and fail (maybe from heat when starting). Anyway lots of bikes have had this.
Click to expand...
I had the insulation issue as well. Took the cable off on one end and put new shrink wrap over the old took about ten minutes to fix...
 
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