BenB
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| posted on 24/11/06 at 03:20 PM |
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Current drain
Does anyone know what current the
average BEC draws?
I'm just wondering if my battery isn't dead- that just maybe I'm just doing a vampire on it when driving at night....
My ST1100 has a rather gentle 28A alternator(!).... The upgrade to the 1996 onwards 40A alternator is well documented if not totally straightforward..
For one it requires taking apart £100 of 40A alternator and combining with the 28A one (different splines on the driveshaft)...
Assuming the worst case scenario (ie everything is switched on), what does anyone think re:
- Fan= 6 amps
- Headlights= 9.5Amps (ie 2*55)
- Rear lights= 1 amp
- Fuel pump= 1 amp (supposed to be 0.5A!)
- ECU / coils= ??
Total 17.5Amps
Occasional braking..... not much more...
Can't see the ECU / coils taking 10 amps... Not sure I'll have enough juice for my 12v electric blanket for SWMBO though!!!
Fingers crossed it's just a goosed battery...
Ben
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DIY Si
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| posted on 24/11/06 at 03:32 PM |
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I not sure what the answer is, but my bec used to need topping up once a week if driven with the fan or lights on. My fan pulls enough current to dim
the lights at low revs, and can be a pita. I try to drive during the day now. 
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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02GF74
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| posted on 24/11/06 at 03:34 PM |
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rear lamps are LED? ! A is a bit low.
ecu/coil - my quick calc says about 6+ amps so 10 A is a possiblilit although on the high side - unless you are running wasterd spark?
and what about the tunpity tump 20 inch bass box in the back 
oh, your sums assume 12 V but the alternator will be chucking out closer to 14 V so current will go up a tad.
[Edited on 24/11/06 by 02GF74]
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BenB
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| posted on 24/11/06 at 03:51 PM |
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I think that that is a problem with quite a few alternators- that at idle they are producing less than the bike / car is using....
I'm going to fabricate a simple amp detector comparing the voltages at either end of the main battery cable with an op-amp. At least then I can
quickly see if the battery is be charged or decharged.... I might also keep my spare car battery in the passenger footwell with some jump leads for a
while!!!
Ben
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BenB
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| posted on 24/11/06 at 03:53 PM |
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Yup ST1100 runs wasted spark at the moment... Won't do when I go down the forced induction route... So I suppose I could be pulling > 28A
Then again, it will be less of a problem cause as well as the supercharger the belt off the crank will also be running a nice 90A alternator I whipped
off a Nova....
Ben
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nitram38
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| posted on 24/11/06 at 04:12 PM |
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What sort of current should an 05 R1 produce?
You are getting me worried!!
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DIY Si
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| posted on 24/11/06 at 04:30 PM |
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If I end up keeping my car for a good while, I'll be plumbing in a car alternator to run off the prop adapter, this should cure most of the
problems I'm having with my electrics, ie low voltage/current. It got that bad once, my rev counter stopped working!
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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nitram38
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| posted on 24/11/06 at 04:34 PM |
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Won't that interfere with the bike alternator?
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chockymonster
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| posted on 24/11/06 at 04:34 PM |
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quote:
Originally posted by nitram38
What sort of current should an 05 R1 produce?
You are getting me worried!!
The 03 has a 32A alternator with a 35A Rectifier.
PLEASE NOTE - Responses on Forum Threads may contain Sarcasm and may not be suitable for the hard of Thinking.
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nitram38
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| posted on 24/11/06 at 04:35 PM |
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quote:
Originally posted by chockymonster
quote:
Originally posted by nitram38
What sort of current should an 05 R1 produce?
You are getting me worried!!
The 03 has a 32A alternator with a 35A Rectifier.
PHEW!
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BenB
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| posted on 24/11/06 at 04:45 PM |
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The ST1100 alternator is made of two halves- one bit stays in place and is engaged on the flywheel, then the back half is removable. When I put the
Nova alt in place I'll just remove the back half and put an ali plate across to seal it (protect the bearings)....
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DIY Si
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| posted on 24/11/06 at 04:53 PM |
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Pretty much what I intend to do, unless I just remove it and Ebay it! Could also remove the bike rectifier too, and use an alt with one in already.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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Bob C
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| posted on 24/11/06 at 10:12 PM |
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It's down to the type of driving - a lot of time idling in winter traffic means you get nothing out of the bike alternator (only really gets
going at 4krevs) but the lights and the rad fan are on! Summer days/quiet roads = no worries!
Bob
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BenB
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| posted on 25/11/06 at 10:41 AM |
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Aha! Might be attaching the pulley wheel onto the front of the crankshaft sooner than planned then... To be honest, I think it's faily simple
(though I've said that many times before and regreted it!)- the ST1100 has a key'd crank pulley at the front of the engine (drives the cam
wheels)- and it has a nice plastic cover over it (for checking timing) which is just big enough to put a little piece extension and a pulley to drive
a belt to the alternator and voila. 90A of healthy goodness  Ditch the unreliable 28A alternator (they have a habit apparantly of slowly going Pete
Tong). At least it's a way of gently testing the extra load on the crank bearings before I strap the blower on....
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Schrodinger
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| posted on 26/11/06 at 11:52 AM |
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One thing you will need to remember if you are going to use a car alternator is that they are normally designed to deal with a max engine speed of 6k
- 7k rpm what revs do your bike ingine pull? One solution is to use the pullies to slow down the speed of the alternator (larger drive pully smaller
alternator pulley) but then it will not be producing much at low revs!
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tks
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| posted on 30/11/06 at 10:05 AM |
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also
if you don´t drive it won´t be spinning..
sow you wont charge if you connect it to the drive shaft.
the VFR has a 0,47KW rectifier.. thats 470Watts almost 40amps.. (@ 12 volts)
but only when spinning at 5000Rpm...
today cars know when the alternator needs more horses to charge.. (you can hear the engine being regulated)
anyway rear bulbs are 21watts thats almost 2 amps each.
brake is also 21watts..
indicators also 21watts..
worse scenario is
all lights on.. 42Watts +
alarm on.. 42Watts + fronts + sides
and braking.. 42Watts + 3rd light
and fan..100Watts
and headlights... 110Watts +
210 + (3*42) = 336Watts...
P=U x I
I = P / U
= 336 / 12
= 28Amps
not taken into account is fuel pumps,MCU´s, Coils etc. etc..
Cheers
Tks
The above comments are always meant to be from the above persons perspective.
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