Electrical issues

[cosmin.buta]

Hi guys, hope I'm posting in the right place.
I've been having some issues with my 2002 Monster and figured maybe I can get some advice from you experts or maybe someone had similar problems.
I own a 2002 Monster 750i.e., and, to make a long story short I've been having some charging problems that started out back in march.
I replaced the regulator/rectifier a few weeks ago, as it was failing (failed completely at one point) with a brand new Mosfet.
Though my electrical issues were gone, but a few days ago they came back.
Basically, the battery doesn't hold a charge or is not charging.
The bike won't start so I keep having to remove the battery, hook it up to a tender, charge it for a few minutes, then it fires up. At one point the engine completely shut off, while at a stop light, and wouldn't fire up again.
Today I took all the voltage readings, as described below:

I left the bike sit overnight. With the engine off, contact off, the battery read 12.7V

Turning the key made it drop to 12.5V

Turning on the lights dropped to 11.9V/11.8V (low/high beam) - this is still with the engine off, and the voltage seemed to be slowly dropping.

Trying to start the engine, it had no power to turn over, I was just getting 'clicks' and a voltage of 11.2V

This whole thing took about 5 minutes, I took the battery off the bike, voltage was at 12.6V

Set the battery up to the tender (while charging the voltage was 13.2V) It charged for exactly 12 minutes, then the green light flashed on the tender for full battery. I let it cool down for an hour, after that the reading was 12.8V

Got it back on the bike, this time it started just fine, the voltage dropped to ~9.0V while starting.

At idle (1000 rpm) the charging was 13.5V

At 2000 rpm (choke on) it showed 14.4V

Revving it up at any rpm (4000 - 5000) didn't get any higher than 14.6V



I checked all fuses, they are all intact.

Does this seem like normal charging?
Do you guys think it's the battery or maybe something else like stator/alternator?
I heard at one point that maybe the starter motor is drawing too much power, maybe it's failing. (this still does not explain the engine shutting off at the stop light though).

Any Ideas? Thanks.

[ducpainter]

From your numbers, the bike is charging.

Can you have the battery load tested where you are? It sounds, to me anyway, that the battery is failing. How old is it? You also might have excessive voltage drop while cranking. That could be a connection, or cable issue. Ducati cables are not very robust. Be very careful with the connection at the starter. It's easy to ruin the starter if you don't use 2 wrenches.

[cosmin.buta]

I removed the spark plugs and tested it again while cranking, I am getting like 7 - 8 - 9 V, can't really get a good reading as it keeps changing. Also I can only crank it for like 4-5 seconds before it dies out. I understand that it shouldn't drop below 9V?

[cosmin.buta]

From your numbers, the bike is charging.

Can you have the battery load tested where you are? It sounds, to me anyway, that the battery is failing. How old is it? You also might have excessive voltage drop while cranking. That could be a connection, or cable issue. Ducati cables are not very robust. Be very careful with the connection at the starter. It's easy to ruin the starter if you don't use 2 wrenches.

Not sure about getting the battery load tested until next week, no one is working this week.
How would I go about finding a bad connection if there is one?

[koko64]

If you can borrow a buddies healthy battery to try it would be a good comparison if you cant find a shop to do a load test. I agree that your battery is suspect as the failing regulator probably damaged it or finished it off if it was old. The charging seems ok from those numbers so the problem is most likely at the end of the line (battery). Its good to check all the cables for tightness and corrosion as mentioned. Follow the large  + cables running from the battery to the starter and solenoid. Look for corrosion at connection points.
Most likely your battery got taken out by the bad regulator rather than a bad starter. I hope so because I know which one is more expensive.

[Howie]

Step 1 is confirming the battery is good.  Borrow a known good one or jump from a good battery.  Car is fine as long as it is not running.  Testing a starting system with a bad battery is like pissing up a rope.