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Discussion Starter #1
i rode my 748 a few days ago and it started up ok. went for bout an hr cruise
stoped to top off and it wouldn't start(it tried to turn over but couldnt really do it) i was near my house so my buddy picked me up i put the batt on to charge over night, it started right up the next day. took it for a ride after work and got home. just to see tried to start it back up and same as before (nothing ) does it need a new batt or is there something wrong with the charging sys. i have no idea how old the batt. is but it doesnt look new.
 

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Easy to check your charging system. Put a voltmeter on your battery terminals. Start the bike and rev it up. Voltage should increase over 13 volts. If the voltage is not going that high then you have a problem with your charging circuit.

When batteries get old, they will not hold a charge. Very possible you just need a new battery.
Mike
 

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Discussion Starter #4 (Edited)
so i checked the voltage across batt. while runuing and its north of 13v turned it off and it drops to 11.5v so i thought it was a bad batt had batt. replaced and its now 3 wks later and the batt. is dead again a thought maybe it just wasn't gettin ridden long enough to charge batt. so took it out for 2hrs came back turned it off tried to start it back up and it was still dead. any ideas?
 

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Discussion Starter #5
so i just call the duc shop that sold me the batt. told them wats up and they think
it might be a defective batt. does that sound right?
 

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Could be. You might need to use a battery tender when not riding your Duc. Not having a reliable battery is a pain in the butt. My advice would be to spend some money on a decent battery, and have your worries be gone. At least for a little while. :)
 

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Discussion Starter #7
Could be. You might need to use a battery tender when not riding your Duc. Not having a reliable battery is a pain in the butt. My advice would be to spend some money on a decent battery, and have your worries be gone. At least for a little while. :)
it does get ridden every other day or so dependin on rain. the brand new batt was a $130 yuasa its supposedly good? i have tender just nowhere to plug it in on my internship
 

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Its a dead cell in the battery, it will not hold a charge over a lay period, it will also fail under a load test. get a new Battery , a good one with high cranking volts
 

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Odyssey PC310
 

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Nothing wrong with Yuasa..
Sometimes my bike sleeps for a week. Fires right up.
Trickle Charger is nice, but I don't think that'll help if you have an issue with your charging system.

Some snippet . .

Originally Posted by yellowducking
I don't have any experience with the Speedcell yet. But, that's a big weight saving.

I have one, and have had zero issue's with the battery so far. The battery has been steady as a rock. Great bike by the way, and amazing write-up!


To be a bit more specifics.


Let me take things apart and give you a bit more details. As pictured, from left to right: Flywheel, Magnetic Rotor, Stator, Rectifier/Regulator, and Battery.

The Flywheel is attached to the engine. So, when the bike is running, the Flywheel is spinning like a mofo. The Magnetic Rotor is attached to the Flywheel; so it also spins like a mad man.

The Stator is nothing more than just a bunch of coil wrapped round and round and round. The Magnetic Rotor spins around the Stator. Well, the magic of magnetic field allows a current to be produced by the Stator.

Unfortunately, the Stator produces AC current which cannot be used by our bike. So, its output is fed into the Rectifier/Regulator to convert AC into DC current.

The DC current is then used to power the bike and to charge up the battery.

 

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My S4 just did the same thing. It wouldn't start after a short ride, charge it up over night, it would start at first, but the next day, no starty. It was at 14.4v or so at 2000 rpm, so charging was good, Ducati dealers wanted $150 or so for a battery, Interstate wanted $105, Batteries Plus got me for $70, plus he gave me $10 off a battery tender ($25 for the tender). 1 year warranty, we'll see how it holds up.
 

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Discussion Starter #14
so looks like it was the rectifier. it was working intermittently but finally died
i need a new one if anyone is selling tried to post in the classifieds but it wouldnt let me
 

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Easy to check your charging system. Put a voltmeter on your battery terminals. Start the bike and rev it up. Voltage should increase over 13 volts. If the voltage is not going that high then you have a problem with your charging circuit.

When batteries get old, they will not hold a charge. Very possible you just need a new battery.
Mike
I think i mught have e same problem on my 916. B4 i start my bike, e volt reading on e meter was 11.5V and when I start it still remains 11.5V and occasionally it gets lesser as in 10V after some revving and back up to 11.5V.
Battery is 6 mths old. So is e batt or the charging system e culprit? If it's e charging system, would u recommend getting both e rectifier and alternator changed?

Bike can start normally now just that e Voltage reading would nt go up 2 13V.
 

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Discussion Starter #16
the way i checked mine was i pulled batt tray to get at the connection
from the stator its a three yellow wire plug. disconnect it then hook batt
back up to start bike check ac voltage on stator by putting the neg from multi to neg on batt and the pos from multi to any of the three wire then rev bike mine was 10v at idle 40v reving a little. so if that happens u know stator is working then check grds (green wires) off rectifier and the hots (reds). reving
a little one of the reds should read above 13v if rectifier is working. mine is not
 

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I chased a battery charging problem on my 916 for about half a year. Read 12.5V across the battery terminals at 2K.

FWIW, my problem turned out to be a failing main fuse. The fuse body over the years became slightly separated from vibration making the contact between the blades of the fuse and the link intermittent. When I pulled the main fuse to check it (as I had checked everything else a billion times), I noticed that the body was coming apart a bit. Testing for continuity with a voltmeter showed that when it was flexed a little, the fuse would open up. The fuse I replaced it with was constructed out of a single piece of metal so I won't be seeing the problem again.

Not because I think this is what is happening to your bikes, but because it is such a simple problem to eliminate as a potential source, I'd check your main fuse.
 

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I have the similar problem with my 916, but have a different result.

I've been chasing the charging for the last 6 month, the Yuasa YB16AL-A2 was new 10 month ago, holding 200CCA. New regulator (aftermarket) was installed about the same time. The charging circuit was tested OK at the time.

2 month later, the battery only has 50CCA left with 5V remain. So put it on charge, and the battery refuse to take charge. Measure static draw on the bike, only 0.1A was found with key off.

So now, when engine is running, the regulator will dump 16V into the battery, and eventually cook it dry.

The battery only has 50CCA with high resistance across its terminal (obvious short within battery), but still holds 12V if I put it on tender every weekend.


My question is, when 916 style 2 phase regulator failes, does it overcharge or undercharge?
 

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That all depends on HOW it fails. Typically, they won't charge enough, but in some cases, they overcharge and ruin the capacitance of the battery (excessive boil off, bulging, and/or leaking is a visual indicator). This results in, lets say, 13V available, but only 6-8V on pre-ignition draw. Essentially the cores are toast.

This drop-off of voltage is also a sign of an old and failing battery- without a charging circuit issue.
 
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