Battery Voltage

Flip · 03-10-2019, 09:32 PM

Sorry this has been a while coming- work and stuff kind of took over for a while.

Anyway, here are my findings for my 1997 M900 with a Motobatt 16Ah battery, single phase 350w alternator and the original regulator/rectifier-

Static voltage after two weeks of sitting un-used: 12.80v
Tick-over lights off: 14.90v
Tick-over lights on: 13.50v
3000rpm lights off: 15.00v
3000rpm lights on: 15.00v
*Note: Revving higher than 3000rpm made no difference to the measured voltage.

By comparison my 1996 Yamaha YZF600R Thundercat with an unknown make 12Ah battery (it came on the bike when I bought it November 2018), 3phase alternator and it's original regulator/rectifier-

Static voltage after three weeks sitting un-used: 12.93v
Tick-over lights off: 14.47v
Tick-over lights on: 14.45v
5000rpm lights off: 14.25v
5000rpm lights on: 14.05v
*Note: Revving higher than 5000rpm made no difference to the measured voltage.

The Yamaha's results were quite interesting as the Haynes manual doesn't give an output for the alternator in Watts like they do for the Ducati but states it as 18.1amps and gives a battery charging voltage at 5000rpm as 14.70v which mine is a little under but has less than 0.5v difference under all conditions while my Monster has a 1.50v difference.

Going on from this, I have tonight bought home from work, a 'Current Clamp' meter which (assuming it will read at those frequencies) I shall be able to measure the current from the alternator on both bikes which should show up just how undersized the wires are on the single phase Ducati.

I will post up further results when I get them.

03-10-2019, 09:32 PM	#16
Flip Registered User Join Date: Mar 2010 Location: Beachtown Bike: M900 Posts: 2,188	Sorry this has been a while coming- work and stuff kind of took over for a while. Anyway, here are my findings for my 1997 M900 with a Motobatt 16Ah battery, single phase 350w alternator and the original regulator/rectifier- Static voltage after two weeks of sitting un-used: 12.80v Tick-over lights off: 14.90v Tick-over lights on: 13.50v 3000rpm lights off: 15.00v 3000rpm lights on: 15.00v Note: Revving higher than 3000rpm made no difference to the measured voltage. By comparison my 1996 Yamaha YZF600R Thundercat with an unknown make 12Ah battery (it came on the bike when I bought it November 2018), 3phase alternator and it's original regulator/rectifier- Static voltage after three weeks sitting un-used: 12.93v Tick-over lights off: 14.47v Tick-over lights on: 14.45v 5000rpm lights off: 14.25v 5000rpm lights on: 14.05v Note: Revving higher than 5000rpm made no difference to the measured voltage. The Yamaha's results were quite interesting as the Haynes manual doesn't give an output for the alternator in Watts like they do for the Ducati but states it as 18.1amps and gives a battery charging voltage at 5000rpm as 14.70v which mine is a little under but has less than 0.5v difference under all conditions while my Monster has a 1.50v difference. Going on from this, I have tonight bought home from work, a 'Current Clamp' meter which (assuming it will read at those frequencies) I shall be able to measure the current from the alternator on both bikes which should show up just how undersized the wires are on the single phase Ducati. I will post up further results when I get them. __________________ You're perfect, yes, it's true- But without me you're only you!