Electrical "power"(28amp) questions from an electrical dummy?

bushpilot

bushpilot

Joined
Dec 2, 2008
Messages
13
Location
Thailand
Bike
95 ST1100
STOC #
7759
My new to me ST1100 already has a new 28amp alternator.

So there's a whole lot of talk about "the upgrade" but not much discussion that I could find regarding how many actual watts are available from the 28 amp critter.
Being an electrical dummy I had to look up what amps, volts, watts really meant in terms of how much power I have.

I'm concerned about "power".
Is the equation of (volts x amps = watts) going to work?
Which I figure 12 x 28 = 336
Is 336 the number of watts available?

Has anyone put up a list of the power draws of the ST electrical system?
How much of the 336 watts is really available?
Is it safe to load the system close to maximum?
Thanks
 
ina nut shell, yes you got it! 336watts is propably at intersate speeds- and at slower stop n go traffic, lower...AND from that 336 you have to subtract the the power that the bike needs for running.... lights, stop lights, battery charging, and ignition.
 
As long as you *never ever* sit in traffic with all those electrics on at the same time you'd probably be fine (for a while!).
The problem is when you hit stop and go traffic... you'll see your head light dimming every time you drop to idle.
 
I wont be running many electrical gizmos.
Just maybe the upgrade of the stock headlight bulbs, a pair of 35 watt fog lights from wallyworld, a GPS, and a possibility of an electric vest if it gets too nippy on the way to Alaska in July.
One of my first additions will be the Datel voltmeter, so I can monitor this issue.
 
75 to 100 watts is high for a vest. I think Warm And Safe says 50 watts and it's a warm one. Check their site.

If yur really concerned about load, you can unplug one headlight while running the vest. I did that a lot on STick until I did her upgrade at ~150,000 miles. Her 28 amper was working fine despite some severe abuse over the years. Since you have a new 28 amper in place, just check closer for high resistance at any/all connectors, clean and grease'em up, and...

GO RIDE!!!​

A quick search for alternator and/or upgrade will turn up a lot of info. Sounds like you've got that figured out.

Keep us poSTed.
 
I have a 91 ST with a 28 amp alternator. At idle I have over 14 volts and @ 2000 rpm around 15.5. Most alternator figures are computed with 14 volts which would compute to 392 watts. Stock 45 watt bulbs and no other electrical farkles. Voltages are checked at the batter terminals.

I have a home made vest with 3 ohms of resistance, at idle the voltage drops to just over 13 and 15 at 2000 and above.
@ 14 volts the vest is 65.333 watts or 4.6 amps. @ 15 volts it is 75 watts or 5 amps. I believe the 91 ST has a 5 amp axillary circuit.

Ralph Sims
 
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