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Discussion Starter #1
I've read through a bunch of posts and didn't find any similar scenarios. My knowledge of the starting system is limited, so I apologize in advance.

Just started happening today. Bike's in good shape, runs great, good battery, etc. etc. Normally takes two, occasionally three cranks to fire up. Now, when I hit the starter button it cranks only once and stops. Lights and dash stay lit, no clicking nor any other noises. I hit the starter again and it may crank normally, sometimes fires up on the first crank, and other times cranks once and just stops.

When it does crank, it cranks like it always used to and fires right up like normal, idles and runs great.

Any suggestions on where to look? TIA.
 

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There are a few possibilities, but I'd start with the solenoid. Disconnect the solenoid and measure resistance across the two large terminals when you apply 12v to the small cables and see if the solenoid clicks on properly and stays ON.
If that tests out OK, I'd start looking for corroded terminals/connectors.
 

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I’d try putting juice straight to the starter. I have a small jump pack that is great for this type stuff. If you can’t replicate the problem, then you know it’s an issue with the solenoid, the signal to the solenoid, the power to the solenoid, or the power from the solenoid to the starter. If you do replicate problems, you know it lies with the starter one way or another.

Upon further thought, I’d start with opening up the switch on the bars and clean the contacts. I had a buddy experience a lot of headaches trying to diagnose a starting issue with a 2008 Hyper.

Regardless, move through it systematically if the first couple stabs in the dark don’t work. Test a component. Based on those move to next in line. Test.
 

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Start with the grounds, make sure battery terminals are clean and snug, check ground to motor...easy stuff first
 

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Discussion Starter #6
Thanks for the replies thus far. I was out for a few days and haven't had a chance to dig in. Hoping two in the next few days...
 

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Well I just went through this exact scenario a month ago - thought the 3yo YUASA BS-12 battery was good, certainly fully charged day before; we just had a covid lay-off but was all fine prior. Then lucky if it even budged the engine more than an inch before dropping out. Diagnosing is not helped by the Ducati system of pushing that starter button being a request to start sent to the ecu. Doesn't matter if you keep pushing or not, you are out of the loop then. So it decides it will energise the solenoid if everything is 'go', which it does until a condition is met, typically rev count above threshold, but there will be a system voltage drop out test too.

So I changed the solenoid with a spare I had from a whoopsi buy-back a decade or so back as it sounded for all the world like the solenoid contactors were dirty and not conducting the current. Same deal. Swapped the battery out with this tiny thing the size and weight of a cream puff I put in the WR250 trail bike in 2007 and hadn't charged for 4 years and away she went. Hmmm, had a great day out but didn't catch up with the group, or much care in the end! Those solenoids are a can style - real labour of love to crack them open to do any cleaning up inside and I wasn't going to tackle it, turns out I don't need to as I know I have a good spare.

That old trail bike battery was an 8 cell Antigravity unit, so now I have a new 16 cell one (don't bother with the latest innovation of a spare start as that is just reduced capacity and you can't get at the battery anyway). This 16 cell will run the heated clothing longer before the bike is overcome from running two of them and I have to turn mine off (first sign is dropping a cylinder at revs) to let the alternator catch up. A YT12BS-16L if you are wondering, with the 'L' being the side for the negative terminal, use R if needed. Ducati batteries are narrower than most of the pleb bikes out there, so only get different models if you checked this first.

The funny thing is now it seems to start without barely hearing the starter kick in, guess that's what having double the cranking amps can do. I thought it started good before but this is ridiculous - I'm loving it!!!!
 

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In addition to above notes, smaller gauge (ie thicker) wire set helps starting immensely. I got some 6ga wire from a marine supply store and some eye lug ends (which they crimped on for me free). Three lengths total, for ground 18", solenoid 6", and starter 13". No starting problems since.
I also wired a headlight cut-out when the starter is engaged, though the usefulness of this mod is less obvious than heavier starter wire....
 

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Discussion Starter #9 (Edited)
Well... yeah. I was about to post that no way it's the battery. It's a Yuasa --installed new, end of August last year. It's been on the tender since then. But I figured I'd better go test before I started making ass-umptions.

Funny how every job starts with removing the mirrors.

After a couple minutes testing with the ignition on, it didn't have enough juice to start. Pretty shocked --my last Yuasa lasted at least 3 years.

Now I have to determine if the battery is junk, if it's not charging while riding, or if it's draining while sitting (didn't put it back on the tender after my ride last weekend).
 

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Discussion Starter #10
Now I'm puzzled..

I left it on the tender overnight and it was up to 13.26v this morning. I disconnected the tender and it let the battery rest for a few hours. It maintained the same reading over that time.

At key-on it drops to 12.65v, and at start it drops to 11.9v. So load test appears good. It idles around 12.7v and goes a bit higher the longer it idles. In the 3-4k rpm range, it reads around 13.5v.

I believe these values are in the 'normal' range for an AGM battery. Can anyone confirm?

I don't run any accessories. Typically ride with the high beam on for visibility, which hasn't been an issue in the past.

Any thoughts on what might be causing this apparent discharge during riding?
 

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Earlier content focused on starting given original inquiry (though you did raise charging in the subject line). If your battery is maintained on a charger but then not charged from the stator while riding I would imagine that enough cycles of this will weaken its cranking ability over time. I went though a ton of batteries on my ST2 along with a ton (4) of regulator/rectifiers before finally going to a mosfet type r/r. Same battery since, and reliable charging since. Took very little effort to mod the stator wiring and direct wire the r/r to the battery. Wish I'd made the change long ago.
 

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Discussion Starter #12
Earlier content focused on starting given original inquiry (though you did raise charging in the subject line). If your battery is maintained on a charger but then not charged from the stator while riding I would imagine that enough cycles of this will weaken its cranking ability over time. I went though a ton of batteries on my ST2 along with a ton (4) of regulator/rectifiers before finally going to a mosfet type r/r. Same battery since, and reliable charging since. Took very little effort to mod the stator wiring and direct wire the r/r to the battery. Wish I'd made the change long ago.
Right. Initially I thought there was no way it could be the battery, since it was less than a year old and had been on the tender the entire time. But it clearly had discharged.

So... I ran to get some gas in it and tested again after it had been running for a bit. It's starting fine with a full charge, as expected. It idles right at 13v. With the high beam on, it drops below 13v. Holding rpm's steady at 2.5k, 3k and 4k it never gets above 13.58v.

Other posts I've come across indicate it should hit 14v and/or slightly above. I don't know if that's accurate for this bike, though.

Does anyone know what 'normal' or expected voltages are for this bike?
 

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Yes, it should consistently be above 14V when running at about 4K RPM (maybe dipping to very high 13's occasionally). Mine is a '98 ST2, fwiw. With the mosfet r/r I get a solid 14.5V. The stock and replacement r/r's prior would barely hit the low 14's, though one only could manage13.6V from new (this is when I finally went mosfet). Yours may not be gone yet but it is on the way (in my own experience a r/r tends to degrade slowly, except one time it went rapidly during the course of a short ride). The stator is rarely the problem, but it is worth testing while you're in there installing a new r/r.....
 

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I agree with stomp - you should be reading around 13v at idle and up to around 14.5 to 14.8v at above 3k rpm.
Assuming your battery connections are tight, it may be worth looking at the large connector on the cable with the 3 yellow wires coming out of the alternator. This seems to be a common fail point - they get hot, make poor contact and so the supply to the regulator/rectifier is disrupted. Pull the connector apart and see if you can any signs of melting. I, along with many others, have had to cut this connector out and solder the wires.
 

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Discussion Starter #15
Thanks to @Punch for this helpful post. Electrickery is not my strong suit.

I cut the connector off and tested at the bare wires. All three combo's were consistent:
1.1k rpm ~ 17VAC (idle)
5k rpm ~ 70VAC

Does this seem seem at least adequate?

The 3-prong connector was fairly toasted. I'm guessing that rewiring/replacing it will get a bit more juice to the RR and the battery in turn, but not sure if it will be sufficient.
 

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Thanks to @Punch for this helpful post. Electrickery is not my strong suit.

I cut the connector off and tested at the bare wires. All three combo's were consistent:
1.1k rpm ~ 17VAC (idle)
5k rpm ~ 70VAC

Does this seem seem at least adequate?

The 3-prong connector was fairly toasted. I'm guessing that rewiring/replacing it will get a bit more juice to the RR and the battery in turn, but not sure if it will be sufficient.
I would say those voltages indicate the stator is probably OK. The proof will be once you ditch that burnt connector and join up those yellow wires to the RR and see if you get more like 14.5V at the battery ( at say 2-3k rpm ).
 
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