3G Magna Alternator/Rectifier Ratings

[Sledge Hammer]

Just wondered if anybody in the forum knows the maximum amps the alternator and rectifier are rated for on a 3G Magna. The official service manual gives information only as it pertains to battery charging, and the dealership service manager said he had no better information than that. That puzzles me because in the automotive world, I have never had any problem finding out how many amps an alternator was rated to supply to a load, but for some reason the same information is hard to rack down for a Magna.

[Curtis_Valk]

Just off the top of my head I think around 350 watts, but someone more knowledgable should verify (or dispute) that.  I know Bob mentioned that his electric clothing will overtop the charging capacity of his 3rd gen and begin to drain the battery.

Curtis

[Sledge Hammer]

Much obliged, Curtis. The reason I ask is that I bought a couple of 55 watt lights to install on my bike. Adding a controller to cut the lights off if battery voltage drops too far should be easy enough, but I also don't want to overheat the diodes in the rectifier and shorten their service life.

I could only find one link about Bob's electric suit and that was here http://www.magnaownersoftexas.com/forums/index.php/topic,1026.0.html

[TLRam1]

.374 KW which equal 374 watts as stated in the manual.

[Sledge Hammer]

Thanks much, Terry. So much for my reding comprehension skills. Doh!

[lragan]

Well, add me to the list of folks who missed it in the manual. 

Owner's?

Magna specific shop?

General shop?

[TLRam1]

It would be Owners.

I have looked it up a number of times, for my own benefit,  but forgot to come back and respond to his question. I could give you a page number but that would require me to get up out of my Lazy Boy. 


If you do want the page number let me know.

[Sledge Hammer]

It's in the owner's manula under Electrical Specifications toward the back, right after the general mechanical specifications. I can't give you a page number but I think the manual went through a couple of printings, so the page count might not be the same in all copies anyway.

By the way, to be specific, the specification is 374 watts at 5000 rpm.

[lragan]

Thanks, guys, for the guidance to the specs.  I keep my shop manuals in the house, and the owner's manual on the bike, in the place provided for it, where it is a pain to get to.  So, naturally, it is the last place I look.

As for stressing the rectifiers, the regulator should prevent damage from overcurrent.  High peak currents, such as turning on a couple of 55 watt bulbs, should not hurt the rectifiers either.  It is overtemperature that damages semiconductors, and even though the regulator may not be fast enough to control a surge from a switch coming on, the rectifiers can't heat that fast either.

The worst surge occurs when you connect another heavy steady load while the alternator is running -- like a dead battery.  This is why, if you are going to "jump" a dead battery from a good electrical system you need to start with the engines off, connect the leads, then start the good system, let it charge a while, and then engage the starter in the vehicle under charge.

Aside from operation at high temperatures, thermal cycling is the next culprit in reduced semiconductor life.  This translates to "a few long rides do less damage than a lot of short rides". 

It has been at least ten years since I smoked a rectifier pack in an alternator, so either I am getting more careful or the rectifiers are getting more rugged.

[Chad in Michigan]

so thats how i smoked the alternator in my 03 ford focus company car, hehe good to know - thanks