The 12Ah battery is only just about capable of doing the heavy job that is being demanded of it, so a 10Ah jobbie would be significantly more stressed! David, what should the ideal regulated voltage be from a standard Ducati regulator?
After following this post a few comments, the battery voltage on starting, a normal volt drop could be anywhere down to 9v when cranking, i understand that nogs comment of 12.3 volts seems correct but thats lowest voltage that should be seen when running, i also think 13.8 is too low, should be around 14.5-14.7v. i think a 10ah batt would be up to the job of starting any ducati provided its in good order, it doesent leave much room for constant stop start though, and i dont think it would last as long.
Nelson, if your battery is a recent one (AGM or Gell) and showing less than 12.6v across the terminals at rest it needs a charge or is on its way out. 12.3v as Nog has suggested is really too low for a modern battery at rest and a good AGM one should be sitting around 12.7-12.8v at this time of year when fully charged, the 'acceptable' voltage will be slightly lower when the battery is colder in the winter. When cranking over the voltage can easily drop to single figures with a healthy battery especially as many folks start the bike with the headlight on. Check the voltage in the morning before you touch the bike and never check the voltage less than an hour after charging/running it otherwise the voltage reading will not indicate its resting voltage. If it is less than 12.5 - 12.6v then it needs a charge, the meter is out (may need a new battery) or your charger is not delivering. The charge voltage with a healthy battery and reg, lights off and engine running should be anything from 12.9-14.6 and if it is less than 12.8 or over 14.9 your reg may be on its way out. You may want to post up which battery it is, the bike, the charger and how often you charge it. Something like an optimate is a must but only really necessary on a newish battery every few weeks for a few hours depending on the use of the bike. Also is the battery the correct spec for the bike (size, Ah, AGM etc)?. Not all chargers work that well on smaller batteries (despite some claims), I have an Oxford one which is supposed to be suitable for cars and bikes and it does not work properly on the bike setting, its inbuilt voltmeter is a couple of volts out, its charge voltage and charge cycle are too low/wrong (against two known accurate meters) - I don't use it except on the car. If you can, you may find fitting a voltmeter to the dash will be useful to see what is happening in real time, the variation of volts at different engine speeds, resting battery charge state and engine temp is quite surprising but engine running should always be within the range I noted above - your engine running figure looks OK but the other readings are too low. However I don't think a cell is out as the voltages indicate otherwise. Finally when you bought the battery did it come filled and fully charged or did you fill it then fully charge it. Sometime folks fill a new battery and put it straight on the bike without giving a commissioning charge (overnight on an optimate) before using it - always give a new battery a first full charge before using it. Forgot to mention, the posts and battery connectors need to be clean and tight and smeared with a thin coating of petroleum jelly. If there is any sulphating salts (the white/green fir) on the connectors or battery posts it all needs to be fully cleaned off before you make the connections.
