Electrical failure

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Lewes96
Posts: 171
Joined: 20 Nov 2016 20:22
Location: Lewes

Electrical failure

Post by Lewes96 »

Bike runs but no other electrical systems. All fuses are ok. Any ideas?
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: Electrical failure

Post by MickeyMoto »

Check the fuse that is 'loose' running from the battery. My 500 had this 'fail' - no electrics except ignition.

It was the fuse holder, not the fuse itself, the spring had lost tension.
Lewes96
Posts: 171
Joined: 20 Nov 2016 20:22
Location: Lewes

Re: Electrical failure

Post by Lewes96 »

Hi, I don't appear to have such a fuse, where is it located? The other issue is the battery is not holding a charge, although the charging circuit appears to be working. It sparks across the terminals when the bike is running but still won't run the lights or anything else?
penman
Posts: 325
Joined: 08 Mar 2016 09:20
Location: Milton Keynes, UK
Location: Milton Keynes

Re: Electrical failure

Post by penman »

If your bike is wired normally, the red wire from the battery +ve terminal should go straight to a tubular fuse holder located under the r/h side panel. As MickeyMoto says, these are prone to failure, especially 40 years down the line! For your exact symptoms, that is a likely source of trouble. Other possibilities include the ignition switch or of course any number of possible disconnected wires.

It's not a great idea to short-circuit the battery, especially with the engine running, that is very likely to blow the fuse or damage the voltage regulator. Use a known accurate voltmeter to check the battery. It should read greater than 12v under all conditions and with the engine running at medium revs, you should see around 14v if it's charging correctly.

Good luck with it, electrical faults can lead you on a merry dance all right!

Joe.
1984 Moto Guzzi V65
1969 Honda CB450
1975 Triumph T160 Trident
2019 BMW F750GS Sport
1978 Morini 500
Lewes96
Posts: 171
Joined: 20 Nov 2016 20:22
Location: Lewes

Re: Electrical failure

Post by Lewes96 »

Thanks, I will have a look for the fuse holder in question.
Lewes96
Posts: 171
Joined: 20 Nov 2016 20:22
Location: Lewes

Re: Electrical failure

Post by Lewes96 »

No sign of an in line fuse in that box. All the other fuses are in there on the fuse block, and there is the box below: the 'adjuster' I believe. This is a 77 Strada, so am assuming the always have an in-line fuse somewhere? And could a failed battery explain this? It was new 6 months ago but the bike gets spasmodic use.
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: Electrical failure

Post by MickeyMoto »

Hi,

As already mentioned...

1. Measure battery voltage with engine off. ~12v
2. Measure voltage with engine running. As you rev it it should increase to ~14v.
3. Check your earths. Take them off, emery cloth them until there is bare, clean metal then reassemble. Do you have an earth lead from the engine to the battery?
4. Check the fuses. You should have ~12v on one side of them all and the same on the other with the ignition on. I believe the rectifier / regulator needs a battery connection. The blue book has all the details.

Good luck,

Mike
Lewes96
Posts: 171
Joined: 20 Nov 2016 20:22
Location: Lewes

Re: Electrical failure

Post by Lewes96 »

Thanks - a job for the weekend
Lewes96
Posts: 171
Joined: 20 Nov 2016 20:22
Location: Lewes

Re: Electrical failure

Post by Lewes96 »

Turns out to have been a failed battery. It was new in November but sporadic use meant it never really got charged properly. A new one, and a good old clean of all the earths and other connections, seems to have sorted things. We shall see how long it lasts.
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: Electrical failure

Post by MickeyMoto »

Good news. Now buy an Optimate charger... :) - or not... some people like them some do not. I have always rated them to keep batteries charged and they do other 'maintenance things', too to keep the battery 'optimised'.

Other brands are available. I believe Lidl or Aldi used to do one for bikes.
3potjohn
Posts: 1243
Joined: 02 Jun 2007 13:58
Location: Devon

Re: Electrical failure

Post by 3potjohn »

Or fit a PC680,run the bike for 10 years,not much in winter,never charge it remotely and it works as good as new,cranking my starter motor with impunity.
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