UK Monster Owners Club Forum » .: Technical :. » Electrics » Battery Voltage

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Old 03-10-2019, 10:32 PM   #16
Flip
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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.
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Old 03-10-2019, 10:55 PM   #17
CarloL
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Great info thanks

My battery got very low after sitting up 3 days and one night was very cold

Just about started , drove into work (13 miles), was difficult to get it started after work due to lack of power in the battery

Does not seem to get enough of a charge within the 13 miles
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Old 04-10-2019, 12:47 AM   #18
350TSS
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Not sure if you have changed this cable yet but the one to the starter motor, if the connection on the post is seized be very careful. If the post turns in the body of the starter motor it pulls the connections from the brushes and it gets very messy (expensive) when you eventually get inside the starter motor. Do not ask me how I know.
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Old 04-10-2019, 09:57 AM   #19
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Quote:
Originally Posted by 350TSS View Post
Not sure if you have changed this cable yet but the one to the starter motor, if the connection on the post is seized be very careful. If the post turns in the body of the starter motor it pulls the connections from the brushes and it gets very messy (expensive) when you eventually get inside the starter motor. Do not ask me how I know.
I use a nut splitter or Dremel on that one!
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Old 04-10-2019, 10:27 AM   #20
mickj
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Quote:
Originally Posted by Flip View Post
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.
Interesting, tells me that you should never fit a lithium battery to a 97 M900.
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Old 07-10-2019, 08:53 AM   #21
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The difference of .75 of a volt or so is just the tolerances in the voltage regulator.
You could buy four identical regulators and they would all vary slightly.
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Old 19-10-2019, 06:43 PM   #22
CarloL
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Last Saturday, charged battery fully on a trickle charger , went for a good spin, parked up , came back after an hour , bike would not start (Starter button did nothing) , I started to scratch my head , I could not leave it in town, would get lifted over night, fiddled with the cables, all of a sudden the starter button fired it into life

Went home I took the battery out to see if something was loose on the starter solenoid ; turned out the 2 pin plug on the starter solenoid came loose

I said , lets get this fixed once and for all , cannot relax thinking , will it start again if I take this out for a spin

Sanded the OE loom Cable (looked fine, just slightly tarnished, light coffee colour)
Cable to the starter Solenoid is new (this was replaced 2 weeks ago)
Ground Cable is a new OE cable from during the summer
Starter Solenoid is new from the Summer
LED Battery Health indicator is new from the Summer(trickle charger quick connect on it & led looks like an Alarm)
I still have to replace the Starter Solenoid to Starter Motor cable

Greased up all the cables/battery posts with electrical conductive paste, ensured the OE Loom + cable was the first on the post , followed by the new cable to the starter solenoid , then the Tracker eyelid on top, then the eyelid for the LED battery health indicator

took it for a spin , no issues , no hesitation (misfiring); she looks a fully charged battery

Left it for the week with the expectation the battery will be flat , I headed out with the intention of having to remove the battery to charge it

Bike started fine today , was sitting up a full 7 days

I presume the arrangement of the cables on the battery post made a difference to the charge across the battery

Last edited by CarloL; 19-10-2019 at 06:46 PM..
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Old 20-10-2019, 03:59 PM   #23
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Installed the uprated Ground cable today , put it all back together ; hit the starter button nothing

Strip it all again , to get at the suspect 2 pin plug on the starter solenoid

It was not loose this time , looks like it is corroded (green has formed on the contacts)

Filled it with conductive gel , works again

What do you guys do with corroded pins like that ?

Its near impossible to get at the metal butt connectors due to the plastic enclosure
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