Trev Borg
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| posted on 5/1/05 at 08:12 PM |
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bike alternator on a car
My friend 'OWELLY' was thinking we might get the round the problem of having very little room in the engine bay, and not having an
alternator, buy using a bike alternator.
Will it work ?
We were thinking about mounting the rotor on one of the pulleys, and fabricating a bracket to hold the stator.
What do you all think.
Saves room
very small
Low output
need for rectifier / regulator
has anyone thought of this or used this, or is it a stupid idea ?
Before you judge a man, walk a mile in his shoes.
By that time, who cares.
You're a mile away, and you've got his shoes
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stevebubs
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| posted on 5/1/05 at 08:51 PM |
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will a small alternator (e.g. like one of the brise ones) not fit?
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niceperson709
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| posted on 5/1/05 at 10:44 PM |
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have a look at one from a yamaha they are a self contained discreate unit . the problem with doing as you sugest is the necesity of having very close
tollerence between the rotor and the stator if you were to use the yamaha unit you could have a coupling from the crank to the alternator and it would
tollerate being driven at engine speed .
best wishes
Iain 
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stephen_gusterson
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| posted on 6/1/05 at 12:06 AM |
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are not bike alternators fairly low output?
seems the common route is to use a small car / van unit from a daihatsu or similar.....
atb
steve
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James
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| posted on 6/1/05 at 11:05 AM |
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Trev,
As Steve says, Daihatsu or Bedford Rascal (and its other identical versions) have a lovely small alternator. It has a Pinto profile pulley which may
or may not be of use to you.
The 2CV one is tinier still as it has a separater regulator. Unfortunately new regulators are quite expensive.
HTH,
James
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DarrenW
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| posted on 6/1/05 at 11:52 AM |
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Does the bike alternator give its small output at lowish revs or does it need to rev quite high? it would be awkward if it doesnt start to give
reasonable outputs until (eg) 4 or 5K revs.
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Bob C
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| posted on 6/1/05 at 12:44 PM |
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Bike alternator is a permanent magnet device so it's otput voltage is proportional to revs. The regulator is likely a "buck
converter" that multiplies up the amps while dividing down the volts to 14V (ish).
So you'll get useful amps at whatever revs the output volts before the restifier/regulator goes over 14V - this is likely to be just under
idling speed.
So you'll get a bit of juice at idle & serious amps at higher revs.
I'll have better info when I've got mine going in a few months time......
Cheers
Bob
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Trev Borg
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| posted on 6/1/05 at 07:14 PM |
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Was just a thought.
I could most probably face it backwards in front of the engine, but was just trying to com up with alternatives. Space is tight
Before you judge a man, walk a mile in his shoes.
By that time, who cares.
You're a mile away, and you've got his shoes
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krlthms
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| posted on 7/1/05 at 05:45 AM |
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quote:
Originally posted by James
Trev,
As Steve says, Daihatsu or Bedford Rascal (and its other identical versions) have a lovely small alternator. It has a Pinto profile pulley which may
or may not be of use to you.
The 2CV one is tinier still as it has a separater regulator. Unfortunately new regulators are quite expensive.
HTH,
James
Isn't 2CV a 6V system?
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DaveFJ
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| posted on 7/1/05 at 09:02 AM |
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I (and a few others on here) have got a denso alternator of ebay, cost me £40 but is brandnew and only 100mm diameter. Might be worth a look ?
Dave
"In Support of Help the Heroes" - Always
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hector
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| posted on 9/1/05 at 10:45 AM |
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bike alternators are fairly low output-only 20-30amps depending on types and they also rev to 12000rpm ish to may not be very suitable for car eng and
yes you would need reg/rect
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VinceGledhill
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| posted on 14/1/05 at 08:36 AM |
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Low output 20 - 30 amps.
If that's the case then it would be plenty. We don't need a big alternator on a locost.
The alternator only needs to have an output that will ballance the loads. The loads on a locost are what???
Lights 55w each x 2 = 110w / Volts = amps used = aprox 10 Amps
Side Lamps 4 x 5w = approx 2 amps
Wipers Approx 8 amps
Heater blower approx 2 amps
Rad fan approx 10 amps
Total 32 amps with everything on (conservative figure)
You only need big alternators for large loads like electric windows, central locking, heated rear screens / windscreens etc etc.
Large output alternators are a waste of space and weight when not needed. Much better to get one that is about 10% more output than all your loads
added up.
If you were to look at the current profile of an alternator when it is working you would see that the large outputs are only given for a very small
amount of time (1 or 2 seconds) after starting. The current quickly drops off as the batter voltage comes up to 14v.
Contrary to popular belief, alternators do not fully charge a battery. They only bring it up to 14v. They never actually fully charge it.
Regards
Vince Gledhill
Time Served Auto Electrician
Lucas Leeds 1979-1983
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