Overall is it a good idea from a reliability point of view or - like increasing the power of an engine - can it lead to stress on other components unless they too are uprated?

I presume with a higher output either more heat is produced or more bhp is drawn from the engine?

Are high-output windings more bulky anyway, so will be limited by space?

My own bike*puts out 235w @ 8000 rpm so I presume at a more normal 3000 rpm cruise it's a lot less and won't be up to running a vest on a freezing night.

As we know, a standard factory-spec machine is usually best, but I don't know if that applies to high-output alternators too.

I know many of the latest adv bikes have massive output to run the OE gadgets. Old bikes not so good when it comes to heated clothing + extras.

thanks

Chris S

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Morocco Overland 4 (2025) • Trans Morocco Trail

You might have to fit a higher capacity reg/rect or give it a bigger heatsink and remount it in a place on the bike where it gets lots of airblast ,but I can't see much problem .You'll lose a couple of horse power from the engine but you won't notice that .

A 65 watt heated liner shouldn't overburden the charging system .
You can compensate by using aftermarket low draw lights .

Most modern big bikes bikes are using 400 watt alternators ,the big beemers use 700 watt because their riders feel the cold a lot more .

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Blessed are the cracked, for they let in the light. - Spike Milligan
"When you come to a fork in the road ,take it ! When you come to a spoon in the road ,take that also ."

My current overlanding bike has a 180w alternator and is quite happy running lights and my 75w electric jacket. I've run it for days at a time like this on long winter rides and the voltmeter tells me it's keeping the battery charged.

It depends on the design of your alternator whether it's putting out full power all the time or just producing enough to supply what's needed. If it's the latter type then an upgrade isn't going to make much difference to the stresses and strains on the rest of the system. If it's a permanent magnet type, they produce full power all the time and any excess is shunted off as heat. Maybe you could duct it into your gloves or something

Thanks for the tips. I've actually done the low draw light thing - at least on the indicators and back. Can one get low output headlight bulbs too?

permanent magnet type - is that an old Brit way of doing it - as opposed to less old Jap?

You say that as if it's the most ridiculous idea, riding around with hoses stuffed up your sleeves venting lukewarm air...

Ch

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Morocco Overland 4 (2025) • Trans Morocco Trail

1 hp equates to approximately 750w. So the engine wont care how much you turn to electricity. (even if you have 50% efficiency).

Reg/recs are not the most reliable bits of kit, they have a hell of a job to do, 150 watts is over 10 amps. (remember, bike electric voltage varies from 12.5-14 volts).

On my ta650 outfit, I had lots of electrical stuff, so I monitored the voltages closely, it was noticeable after a prolonged loading, the voltage would suddenly drop, this I believe was due to the reg getting to hot. It was mounted on a large slab of ally plate, to help with reliability. If you go for uprated windings, you need to look at uprating the reg/rec.

Most failures I have seen have been diodes going short circuit in the rectifier stage, or the rectifier failing high, this killed my ZZR in belgium, by frying the battery and then the CDI.

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Harley Davidsons,
The most effective way of turning petrol into noise without the side-effect of horsepower

Yes, you'll get permanent magnet alternators on old British stuff but also on a lot of Japanese trail bikes. The bigger stuff will use an electromagnet instead and they regulate the output by varying how magnetic the rotor is. You can rewind the stator poles on a lot of trail bikes to vary the alternator output and move it up and down the rev range but it's a bit of a tricky thing to do unless you have some electrical engineering background. There is quite a bit of info on the web about it, particularly for some of the easier bikes - Honda XR600R for example, and there are some commercial companies offering off the shelf upgrades. The XR is easy to do because as std Honda only used 4 of the 12 poles on the stator. Rewinding on all 12 ups the output considerably.

You can get low output headlight bulbs (although it kind of defeats the point of a headlight), this guy sells all sorts of bulbs, mainly for old Brit stuff but it's probably because they need it most. The alternatives are could be replacing the stock headlamp with a HID setup (but there may be MOT legality problems with it ) or using LED add on lights to supplement a low output bulb. LED driving lights consume very little current for the amount of light they put out so overall you could save a bit, (especially if you turn the headlight out )

I have tried venting hot air from the engine before, using hoses and stuff but not very successfully. With air cooled engines it only seems to work when the engine is hot - ie in the summer or when you're stationary (then there's no airflow) which is the opposite of when you need it. Don't think you'd get enough from the reg/rec to make it worth while.

Assuming that most of your travelling will be in daylight, and you are just using your headlight to be more visible, you can fit a 20w quartz halogen pilot bulb, and just use that for a daylight riding light.