Yet another question, Charging related
- Thread starter mittens
- Start date
ChopperFred
Member
Of course, it could be that BOTH the battery AND the charging system have issues. AND you might have sticking compression releases (CR's) that contribute. The fact that you can start the bike after you externally charge the battery suggests that the charging system is not recharging the battery. Also you mentioned that the voltage at the battery with the bike running does not get above 12.7 volts regardless of engine RPM.
That does not rule out the battery. A weak battery may have too much internal resistance to charge properly. Yet you charged it off-line and it cranked the bike albeit with a large voltage drop.
Other possibilities include poor electrical connections. The large battery cable to the starter must be tight at both ends. And the large negative cable that goes to the starter ground (with star washer) should also be tight. You mentioned problems when the bike is hot. Heat can cause some things to expand (hence move) and some electrical connection might be lost or degraded.
You must also determine if the CR's are activated DURING the starting process. If you unplug the green wire to the starter so the noise of the starter doesn't mask the CR "click", you should be able to hear them. Or even better, put a finger on each one sequentially so that you know they BOTH activate when the start button is pressed.
I have the 2004 Big Dog Service Manual. There is a chapter called "BATTERY and CHARGING SYSTEM". It describes some troubleshooting procedures for testing these components. If you want to send me a Private Message (PM) with you email address, I'll scan that chapter and email it to you.
mittens
Well-Known Member
THanks guys, I got a PM and shoul dbe getting a copy of the manual if not I will pm you sir.
I hope its just battery, but the mutlti meter make me wonder.... next step is to fire it up, and do a few higher rpm holding it out to see if voltage rises.... also a ride for some tiem and then test voltage to see if its highter, lower, same..
will test CRs too. with them if you manually push them down, do they stay? or pop back up? unless they are getting juice.
I hope its just battery, but the mutlti meter make me wonder.... next step is to fire it up, and do a few higher rpm holding it out to see if voltage rises.... also a ride for some tiem and then test voltage to see if its highter, lower, same..
will test CRs too. with them if you manually push them down, do they stay? or pop back up? unless they are getting juice.
once the motor fires, the CR's should pop back closed.
as far as where to check the stator, follow the wires from the VR backwards to the point where it hits the front of the motor. that should be a 2 pronged plug. remember, on this you will be looking for Volts AC not DC.
as far as where to check the stator, follow the wires from the VR backwards to the point where it hits the front of the motor. that should be a 2 pronged plug. remember, on this you will be looking for Volts AC not DC.
ChopperFred
Member
If you have the electric CR's that came with the bike, they will not stay down (compression released). When you push them down they will just follow your finger back up. It's kind of like pushing a spring up and down. That is unless the CR is rusted or defective. In which case it might stay down until that cylinder fires.
If someone installed manual CR's (non-electric), I believe that those stay down until the cylinder fires. I've never used this type so I'm not sure.
BigDogBro1
Made in the USA
I think there is too much current draw through the starter because your battery voltage is dropping way too low. Normally it should stay around 9-10 volts when cranking. Possible battery but seeing how the voltage recovers quickly it indicates less of a battery problem if its a known good battery.
It could be that the starter motor windings are beginning to fail. And as they fail or short together internally the current draw will increase and the motor power decreases. This assuming your compression releases are functioning properly.
You can tell if your CR's are working but pressing down on the bubble just till you feel the CR stem and hold your finger in that steady position. Then when you press the START button you should feel the CR stem drop away just a bit from your finger. If it does then the CR is working.
It could be that the starter motor windings are beginning to fail. And as they fail or short together internally the current draw will increase and the motor power decreases. This assuming your compression releases are functioning properly.
You can tell if your CR's are working but pressing down on the bubble just till you feel the CR stem and hold your finger in that steady position. Then when you press the START button you should feel the CR stem drop away just a bit from your finger. If it does then the CR is working.
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BigDogBro1
Made in the USA
Well that's possible now knowing it's a 250cca. Minimum recommended for a Bigdog V-twin is 310cca.
Could be the starter requires more current than the battery can deliver and gives the illusion of a poor battery or a failing starter. Go get a good MAT style 310cca minimum new battery. All signs lead to getting the proper battery.
Also running an under capacity battery could cause starter motor damage due to overheating the windings. If there isn't enough voltage available from the battery when the starter motor spins then more current will be required to do the work.
When you are cranking the starter and only getting 7.9 volts, that's barely enough voltage to get a decent spark from the coil to start the engine or to properly run any electronics.
If any SOURCE (battery or power supply) power (current/CCA) capacity is too small then you will get the voltage drop like you are seeing.
Could be the starter requires more current than the battery can deliver and gives the illusion of a poor battery or a failing starter. Go get a good MAT style 310cca minimum new battery. All signs lead to getting the proper battery.
Also running an under capacity battery could cause starter motor damage due to overheating the windings. If there isn't enough voltage available from the battery when the starter motor spins then more current will be required to do the work.
When you are cranking the starter and only getting 7.9 volts, that's barely enough voltage to get a decent spark from the coil to start the engine or to properly run any electronics.
If any SOURCE (battery or power supply) power (current/CCA) capacity is too small then you will get the voltage drop like you are seeing.
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mittens
Well-Known Member
I have stated the info on the battery in this thread a few times. I know it needs a different battery. (this battery is brand new, just a shitty 250 CCAs, advance auto lost model, the guy i bought it from tossed in there to make the sale)
Wil be verifing CRs, and see what happens when bike is ran down the road voltage wise.
Wil be verifing CRs, and see what happens when bike is ran down the road voltage wise.
BigDogBro1
Made in the USA
You just answered your own question (highlighted above)...The analysis is proven by your earlier voltage checks listed below.
From you:
"12.86v resting with Key off. 12.77v Key on but not running.
hit starter Voltage dropps to 7.91v while turning motor, bike spins over and fires up
12.64v at idel, and stays there with small quick reves
Once shut back off reading 12.77v"
You're sucking the guts out of that under capacity shitty battery.
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BigDogBro1
Made in the USA
Right...12.8volts to START should be good enough but you should still check the voltage regulator output to start with. Post#4. You should see a rise in voltage across the battery at around 2k RPM to get a clue.
Hot starts can sometimes be more troubling depending on the ignition timing and other causes.
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mittens
Well-Known Member
So after its sat since last run, day before yesterday
Battery was at 12.6v before any activity.
Then put a finger on compression release button, Hit key, did not feel them move away from finger.
started motor, battery goes down to 12.38v while running and even with multiple extended long hi rpm revs no change in battery voltage. Did several long extended revs still no rise in voltage
Once turned off it goes back to 12.68v
Both CRs, do move freely when pushed by hand up and follow finger back to the top. Also you can push them when its running and hear each cylinder change so the valves work, just not maybe not engaging electronically. (Most testing on that to come) A side note, the front rubber condom is fine, but the rear is cracked / hole where the button is. (dont think it matters just a note)
Going to test stator according to steps with muti meter, and remove wire from starter to lesson for CRs follow wires for more info on them.
Also will ride it around some and compare before and after ride voltage.
Battery was at 12.6v before any activity.
Then put a finger on compression release button, Hit key, did not feel them move away from finger.
started motor, battery goes down to 12.38v while running and even with multiple extended long hi rpm revs no change in battery voltage. Did several long extended revs still no rise in voltage
Once turned off it goes back to 12.68v
Both CRs, do move freely when pushed by hand up and follow finger back to the top. Also you can push them when its running and hear each cylinder change so the valves work, just not maybe not engaging electronically. (Most testing on that to come) A side note, the front rubber condom is fine, but the rear is cracked / hole where the button is. (dont think it matters just a note)
Going to test stator according to steps with muti meter, and remove wire from starter to lesson for CRs follow wires for more info on them.
Also will ride it around some and compare before and after ride voltage.
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BigDogBro1
Made in the USA
Sounds like multiple problems. Replace the carb nipple covers. Automotive stores should have a selection or McMaster Carr has some, we bought the silicone covers, just get the size right.
Charging system sounds suspect at some level. Not sure if there is an in-line charging circuit fuse in the 2004 but probably is...check it.
On my 2007 EFI the CR's kick in when you press START and manual claims they stay on for about one second. CR's are controlled by the EHC.
Good luck and keep us posted.
Charging system sounds suspect at some level. Not sure if there is an in-line charging circuit fuse in the 2004 but probably is...check it.
On my 2007 EFI the CR's kick in when you press START and manual claims they stay on for about one second. CR's are controlled by the EHC.
Good luck and keep us posted.
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BigDogBro1
Made in the USA
I would think the CR's are then energized when the START button is pressed.
Make sure that the voltage regulator has GOOD CLEAN ground contact to the frame mounts as well. There are external star washers between the frame post and the regulator to get extra bite into metal for better contact at least on our 2007's