Wattage Output/Heated Gear Help!

All:

I ride a 2002 Honda Shadow VT750DC. Anytime I've mentioned heated gear of
any kind, people generally warn me that my system might not handle it. I
figured I'd sit down and add the numbers and see if a pair of gloves would
work out. From Haynes:

Charging output = 333 W at 5000rpm. I'm assuming this drops
proportionally as the rpm does?

If I add up all the standard stuff (headlight, brakelight, turn signals,
license plate bulb, speedo bulb, indicator bulb) I get about 130W. Does
this seem reasonable?

This seems to leave me about 200W extra. This can easily handle a pair of
Gerbing gloves at 27W. Heck, a Kanetsu liner runs at 75W so I could put
one of those on too. I feel like I must be missing something because what
I'm finding contradicts what people have told me.

Any thoughts welcome.
Justin
'02 Shadow VT750DC

 

High or low beam on the headlight?
Ask yourself what rpm you typically run at. If you only rarely hit 5k,
that 333W doesn't really help much, as you need to know how much power
you're generating at the rpms that you run.

Also remember that you want a bit of reserve power after you've added
everything; eating up all your theoretically "free" power will cause you
trouble if there's a bit of power loss in wires and connectors (there
is, and it's in your interest to minimize it by keeping connections
clean and corrosion free).

OTOH, I do know of people who have their alternator loaded to the point
that they get to choose between accessories (e.g. warm hands or
headlights?) or can only run the accessories from time to time so as to
allow the battery to maintain a charge. I don't recommend this approach,
but it _can_ work.

You will find that there's lots of people out there with opinions. Some
of them know what they're talking about. I try (and sometimes succeed)
to keep my written comments limited to topics on which I know something.
That's one reason why I've only given general advice here: I don't know
much about your bike.

You might look online for owner's/enthusiast groups for your bike and
ask someone with the same model about adding accessories. There's
nothing like having instructions from someone who's already done what
you want.

--
Later,
John



'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

 

: High or low beam on the headlight?

Haynes lists 60/55 W, which I assumed is high/low beam, though I'd have
thought the difference would've been greater.

: You might look online for owner's/enthusiast groups for your bike and
: ask someone with the same model about adding accessories. There's
: nothing like having instructions from someone who's already done what
: you want.

Will do, thanks. I'll also as another poster suggested test the voltage
as I run the thing.

Many thanks,
Justin
'02 Shadow VT750DC

 

You can add 100w no problem. Any late model bike over 500cc has plenty of
spare capacity.

John

 

Alternator output is not linear. You will get 80-90% of max output at
2000rpm and it gradually increases to full output.

John

 

So if you're spending lots of time at red lights in rush hour
traffic idling at 1100 RPM you may get a nasty surprise when
you stop the engine to fill your tank.

You can rig a simple LED voltage indicator for under $10
that can tell you pretty accurately whether the charging
system's keeping up with the load.

 

Have a schematic in mind?

Ian Singer

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All responses are right on. I've used heated clothing on my V-Twin for
about 8 years and have a volt/amp meter on the bike. The alternator is
rated at 26 amps (312 watts) at 3000 rpm (about 70 mph :>) V-Twins are
low rpms. bike I need to be at 1500-1600 rpm to break even on amps
(i.e. not pulling current from the battery) when the bike is warmed up
and BEFORE turning on the electrics.

I use an electric vest and gloves through one 10 amp fuse and I've have
never had a fuse blow out. I will unhook/turn off the electrics if I'm
in stop and go situations for a while where I'm below 1200 rpms in
order to not run down the battery. I can see the bike voltage run
below 12.5 VDC and the bike pulling amps from the battery at idle
WITHOUT electrics. IHTHAB.

Ride safe,

Manjo

 

I bought a $5.95 "Alternator and battery tester" from
Radio Shack, waterproofed it and fabricated a simple
mount for it. Worked fine through a winter's rainy riding.

Not sure if they still sell this item but definitely worth
looking for. I think it's probably twice the size it needs
to be just so it looks impressive, but I've been too
lazy to try to reduce the size.

 

Good idea. It could also be hacked so that just the LED was brought up
to the handle bars, or I suppose if wearing heated gloves put inline
directly with the glove.

Ian Singer
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It's a 6 LED display, with each LED triggered at a different
voltage (11.5 - 14 V) if I remember correctly.

I'd figure just a set of 6 voltage comparators and LEDs.

Mine hooks into a switched +12 lead in the headlight shell.

 

On ebay they are advertising some 30watt units that are not heated grips
but rather a heted element that rolls up and fits in the bar. Comes with
a Hi-Off-Lo switch. Inside seems like a good idea and also offers
better protection to it with easier wiring.

Ian Singer


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These are ones I was thinking of on ebay.com #330043405915
There was also another listing that was cheaper but it sold already.

Ian Snger


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There are at least one or two versions of in-bar heaters for about $30.
I've got a pair that were already on the bike when I bought it.
I think they're sold mostly for snowmobiles. Only drawback is
some heat gets absorbed by the bars, making them a little
slow to warm up. Mine were installed with some kind of insulation
behind them.

 

Self-galvanizing-rubber plumbing-repair tape. You can find it in most
hardware stores. You only have to do the left side because the throttle
on the right grip is typically plastic.

Putting the left grip back on can sometime be a little tight. If so, buy
an extra right grip and use that instead.

Oh, and back to the original question of wattage: the switch and resistor
that come with the Kimpex (snowmobile) kits draw full power whenever it's
on. If you only want to draw as much power as you need, use a
Warm'n'Safe hand-grip Heat-troller.

http://www.warmnsafe.com/motorcycle_handgrips.php

 

The ones I've got are inside the bars, not between the bars and
grip.

I used a big honking ceramic resistor, ~2 ohm, 25 watt for "low".
Total cost was ~ $2.00.

It very definitely does not draw full power all the time, as it's a
series of resistors, though a PWM setup like the Heat-Troller
would be more efficient.