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Discussion Starter · #1 ·
For those of you that have played with alternator output and accessory draw: At what RPM does the engine need to turn to develope maximum output. I do a lot of commuting in the winter months with heated clothing and if I don't use lower gears at a given speed, eventually over the space of 2 or 3 days the battery seems to lose cranking ability as it doesn't turn the engine over as fast as I'm used to. My commute is only about 15 minutes at speeds of 35mph or less accompanyed by stoplight waiting at idle.
 

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Service manual suggest 5000rpm

The fjrforum suggested we need to keep the voltage at 13.1V as a minimum. To check this you need a voltmeter and Datel is the preferred model (waterproof etc). Do a search on Datel and you should find a lot of useful info

I have a 4 year old battery and I reckon that I can have headlights and heated clothing at the same time but not heated grips as well otherwise the voltage drops to about 11.8-12.1V. The grips draw a massive 50+amps. So for me if I want heated grips as well I need to turn headlights off and just make do with side lights.

Also, the consensus is to turn these addons off or at least down when in town as the revs drop so low.

Finally, get a battery monitor, tender or whatever - these keep the battery fully charged and can be left on all the time the bike is not being used.

Paul
01 fjr
uk
 

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yamaha1300rider said:
Service manual suggest 5000rpm
That engine speed was for the max rated measurement of alternator output (490-watts @ 5000rpm, nominal.)

For practical purposes while underway on the road, as long as your engine speed is no lower than the 2500-3000rpm range, your FJR's alternator is putting out close to the max it's going to, so you should be pretty much good to go....
 

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Discussion Starter · #4 ·
Thanks Paul and Dale.

I seldom find myself cruising at a continuous 5000 RPM, so I think a battery tender is probably a good idea in the winter months even though there is seldom a day that she isn't riden for at least the 1/2 hour to and from work. I've never had the bike fail to start even though the cranking speed is sometimes a little slow if it's sat outside in 35 degree weather while I'm at work.
 
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