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how to figure max current available

Printed From: the12volt.com
Forum Name: Motorcycle Electronics
Forum Discription: Installing Stereos, Alarms, Remote Starters, Lights, Garage Door Openers and other electronics on motorcycles.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=124454
Printed Date: April 23, 2024 at 5:49 PM


Topic: how to figure max current available

Posted By: two12
Subject: how to figure max current available
Date Posted: November 14, 2010 at 9:07 PM

hello,

Im trying to figure out if my bikes stator is upto the task of running a heated jacket. its an old Honda, the manual says the output is 0.2kw@5,000rpm

how many amps is this? (@12vdc)

thanks



Replies:

Posted By: oldspark
Date Posted: November 14, 2010 at 9:32 PM
P=VI

Hence I = P/V

So I = .2kW/13.8V = 200/13.8 = 14.5A
(since normal 12V "ratings" are at 13.8V)
(else 13.8A@14.4V or 16.6A@12V).




Posted By: i am an idiot
Date Posted: November 14, 2010 at 9:44 PM

How much current does the vest draw?   You need to realize that the bike needs to run off of the available 14 amps.  Headlight, taillight ignition etc.  what kind of bike is it?  The stator on my Silver Wing failed at around 70K miles.  I installed an Alpine head unit which I figure draws between 3 and 5 amps of current.  I ride with my High beams on during daylight hours.  The bike has 2 separate lamps and they both burn when on High beam.  Since the failure I only flash the High beams when needed.  I would never attempt any kind of heating device on it.  A Gold Wing with an actual alternator, no problem, but I would not do it on any other Honda.

Unless of course the vest draws only a couple amps.  Does it have a wattage spec on the vest?





Posted By: two12
Date Posted: November 14, 2010 at 10:19 PM
hi Oldspark & IAAI

then it looks like I have ~210w total. the jackets that Im looking at draw 65w and upto 90w.

now I need to find out what the C.D.I (ignition) draws.

if I convert the lights (including headlight) to LEDs it might work.

I could learn to rewire the stator if I have to but Im trying to avoid doing that. I wouldnt hesitate if I had an identical back-up bike to play with though.

thanks




Posted By: oldspark
Date Posted: November 15, 2010 at 2:28 AM
The CDI is probably only 10W-20W.

If it is a stator type alternator, I wouldn't bother - probably not much to gain.
A rotor controlled alternator has possibilities. (Unlike stator type, it uses brushes for the rotor - it is not a spinning permanent magnet.)





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