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djbrooksy

Newbie

Joined: 01/02/2010
Location: Australia
Posts: 2

Posted: 12:06pm 01 Feb 2010

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HI to everyone
Sorry for posting such a noob question i hope i at least
posted in the right spot.
A bit of background info i have been playing with a custom fuel injection set up on a single cylinder motorbike and have ran into a bit of a problem. All was going great till i went to power it all from the stator. when the bike's
rpm is low the stators output is to low to power the system and charge the battery

but when i started playing around with the magneto i found that there is only 3 magnets with plenty of room to add 3 more in between the three already there

now before i go destroy a magneto, in my noob way of thinking with 3 more magnets in there and the bike at idle. In around about way i have doubled the surface speed of the magnets and doubled the output

could someone please confirm or shoot me down in fames

cheers mick

Joblow
Regular Member

Joined: 05/01/2010
Location: Australia
Posts: 54

Posted: 12:52pm 01 Feb 2010

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How are you defining low revs? could be anything from idle to 2000 I would think for single cyl bike, if you haven't enough power from the alternator for the bike to run at idle there could be a fault in the battery or charging components because a fully charged battery sould be ok for a bit of drawdown and would recharge when you sped up

The man who never made a mistake never made anything

Downwind

Guru

Joined: 09/09/2009
Location: Australia
Posts: 2333

Posted: 02:36pm 01 Feb 2010

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Hi djBrooksy

A good mate of mine rewinds stators for bikes and all electrical systems for bikes etc.
He has for many many years and is one of a few who still do them.
His name is steve and trades under Betta Bikes and i would send him a email asking your question if i was you as good advice might save you a lot of dollars.

It is not uncommon that at low rpm (idle)the standard stator will not supply enough power for higher than average loads.
This is the sort of thing Steve deals with and if need be will rewind the stator to handle the higher current required etc etc.

I will PM you with his details as dont wish to have him a target of SPAMMERS.

Pete.

Sometimes it just works

djbrooksy

Newbie

Joined: 01/02/2010
Location: Australia
Posts: 2

Posted: 07:43am 02 Feb 2010

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thanks for the replies
and thanks for the contact info Downwind

i should have given a bit more info
the bikes charging components are fine as there only 3 months old

the bike itself is a mini bike or pit bike
or what ever you want to call them and
the stator is only good for 55 watts @ 7500RPM
as they where only ever used for the elec start

so the break even rpm is way to high for my likings

cheers
mick

Greenbelt

Guru

Joined: 11/01/2009
Location: United States
Posts: 566

Posted: 07:46pm 02 Feb 2010

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djbrooksy;

Most of the PM charging systems use a load dump to protect the battery from overcharge and destruction. In effect it is a controlled short circuit to ground like is used in the windmill circuits, installing more mag's will likely overload this protection system and burn up the alternator. the regulator - diode system may not be rated for extra current Here is a link with Info. if your in a hurry,
Read the 6th paragraph.

Charging system]Edited by Greenbelt 2010-02-04

Time has proven that I am blind to the Obvious, some of the above may be True?

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