regulator/rectifier and wierd electrial issue

[badj]

Start of the wierd problem was a flickering of the lights over some bumps, bike cut out and wouldnt restart - no electrics whatsoever. Bike is a 2000 Aprilia RS125

A check of the fuses showed the following....


Battery + ====(+12.4v)===[ 20 A ]=====(-12.4v)=====
=============(-12.4v)==[ 15 A ]=====(-12.4v)=====
=============(-12.4v)==[ 7.5 A ]=====(-12.4v)=====


I found a shorted connection on the horn which might have been to blame as it was touching the frame. Fixed it, still the problem there.

I thought the regulator/rectifier could be to blame as theres resistance between the ground/earth and the green/red circuit feed (which i beleive is earthing the circuits out as above), so changed for another ebay part (2nd hand) which does the same? I'm stupidly confused cos the whole loom has been out and the connections checked and still theres no life in the bike at all. Should a reg/rec do that? My honda one doesnt but tha bike is 10 years older? :/

[Kickstart]

Hi

If the battery has life then the regulator / rectifier probably won't affect whether the lights work or not. It is there to supply power and charge the battery, but the battery itself will also supply power as long as it isn't flat.

Not sure what you have done to check the battery by checking the voltage at the fuses.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[badj]

[Kickstart]

Hi

It isn't in series. If you check the red / orange wire it splits so it goes to the regulator / rectifier, part 22 (presume voltmeter on the clocks) and importantly number 18 which is the ignition switch. With the ignition on this will supply power to the green and orange wire that goes to the regulator / rectifier and which also supplies power to the 7.5 amp and 15 amp fuses.

Basically the red / orange wire from the regulator rectifier feeds the battery and the bikes electrics, while the one from the battery via the 20a fuse feeds the electrics. If the battery is flat the excess from the regulator / rectifier after powering the bike will charge the battery, while if the regulator / rectifier is dead (or the engine just not running) then the battery will supply power to the bike.

With the ignition off the 7.5a and 15a fuses should have no power at all (no voltage between them and earth). With the ignition on but the engine not running you should get battery voltage between them and earth. With the engine running you should get voltage which will vary with revs but will be maintained by the battery.

Not sure the current readings at the fuses matter for this. They will merely let you know how much power is being drawn on that circuit (or pop the multimeter if you are unluck ).

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[badj]

regardless, 20amp fuse present or not, the regulator/rectifier is earthing the electrics. ignition on, its earthing the electrics. Its obvious that the cross polarity will be causing this because the cross polarity goes away when the reg.rec is disconnected? I've been over the whole loom and can't figure out why its not working at all?

[Kickstart]

Hi

It shouldn't be earthing things out like that. If it did normally it would just flatten your battery when parked (as the battery positive would feed straight through it to earth).

My main guess would be a dead regulator / rectifier, but it seems unlikely you would have 2 dead in the same way. I am not sure how the units are wired up internally, but if there is a connection (ie, direct connection rather than an induced current) to the AC side then a short on the generator side could provide a path to earth.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[badj]

perhaps :/


sorry if I sound stressy, its just an absolute nightmare and it makes no sense at all why its doing it :/ appreciate the advice though - i'll check a few bits and let you know how it does

[badj]

Update:


Reg/Rec disconnected...
Generator disconnected...
CDI disconnected..
absolutely no shorts in the loom or bare wires..

Measured between the + terminal and the output of 20A fuse (which should be +12v, so technically in the pic, nothing)

https://imageshack.us/m/190/5641/imag0807e.jpg

[Kickstart]

Hi

Those should be directly connected (ie, wire goes directly from the battery to the fuse).


Not sure what you are measuring there but if it is voltage between those points it should be zero (voltage is the potential difference, there is no difference between those points).

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[badj]

If you read what I said I was measuring between the output of the fuse and the battery. I'm aware that it should be zero, but it isnt - its earthed - which is the issue.

[Kickstart]

Hi

I can't see what you are measuring, and reading your previous reply you say it should be +12v, when it clearly shouldn't be. I take it you mean that both sides of the fuse should be +12v (assuming the fuse is in place) so no difference and so no voltage between them.

If the output from the fuse is earthed then you would get 12V (but probably also an instantly blown fuse or smoking wiring if the fuse was all that went between the battery +ve and -ve terminals) between it and the positive terminal .

If the fuse -ve terminal is earthed then there is something that has broken and shorted to earth. I would suggest the first thing to try is to disconnect the ignition switch to determine which side of the ignition switch the short is.

The wire should be pretty much direct from the battery +ve to the 20a fuse. I would also check for continuity between the battery +ve leads and the fuse holder (disconnect the battery to ensure that you do not get any odd readings).

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[badj]

[badj]

[badj]

[badj]

[Kickstart]

Hi

Well, if the leak to earth is through something with high resistance (and assuming you are checking with the fuse out) then it could give that.

Disconnect the ignition switch and check then. That will let you know which side of the ignition the leak to short is.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[badj]

both sides of the ignition have negative current, but they dont share resistance

[Kickstart]

Hi

The difference in resistance either side of the ignition switch when turned on should be nominal.

I take it you mean voltage rather than current.

Resistance change if you remove either the 7.5a or 15a fuse, or both, and if so by how much in each case.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing