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[rustygman]

OK, as per advised I have checked the alternator. This is putting out around 32 volts (once I remembered to switch to AC on the voltmeter). I then removed the seat and cover and I see a separate regulator and rectifier. Both looking pretty fuzzed up and old but all connections seem to be good. Am I jumping the gun if I just replace the pair or should I do some sort of check on them first. Thanks in advance. Can't believe I am learning this stuff at 55 years old but then my previous bikes never needed this sort of attention (even my MZ's, CZ and Guzzi).

[rustygman]

Just noticed the reg/rec come in at around £85 so I didn't want to necessarily take pot luck and just replace them.

[Aethelric]

Disconnect the regulator. If you now get a charge with the engine running the regulator i goosed.

[stinkwheel]

Well, having checked the battery and found it not charging then checked the alternator and found it to be working there are now only two possabilities. 1) A regulator/rectifier fault. 2) A wiring fault between the alternator and reg/rec or the battery connection.



I'm actually thinking the latter is reasonably likely because a reg/rec fault would NOT affect the lights on an AC/DC bike

So, Aethelrics trick sounds worth a try. Also worth checking the wiring. It could well be very cruddy by now. There will be a series of bullet connectors which connect the alternator to the reg/rec sub-loom. Follow the wires up as they come out of the primary chaincase and you'll come to those. Pull them apart one at a time, give them a good clean and reattach. The ones on my '07 350 were so green and fuzzy I landed up cutting them off and relacing them.



You can test the continuity of any of the wires by setting your meter to measure resistance and applying a probe to either end of the wire. Resistance should read almost zero if the wire is intact. If it reads high (or whatever the meter reading is when the leads aren't touching anything, often a 1), you have an open circuit so there's a chance the wire is broken inside the insulation.



Ok. Now my best guess for your fault: Bad main earth connection. Follow the fat wire from the battery negative, the other end normally attaches to a ring terminal which is connected to the frame by being trapped under the bolt that holds the battery shelf on. Take it off and have a look. It needs bare metal to metal contact with the frame. Rust does not conduct electricity in any meaningful way. Deploy old screwdriver/emery paper etc to make that a good contact then cover it with a smear of dielectric grease/vaseline after reassembling it to prevent it corroding again.

[Aethelric]

My best guess is an unwanted ground connection in the alternator. Easily checked and eliminated.

With your meter on continuity, check that there is no connection from any of the alternator wires to chassis. Do this with the alternator disconnected.

My bike, a sixty5, has one side of the AC connected to chassis in the harness (apparently some don’t!). If there is another connection to ground in the alternator then one or more of the coils will be short circuited. I had a short in the alternator caused by a wrong sized lock washer touching a winding. Maybe shorting enough AC coils would stop the ones meant for battery charging from giving enough charge??

[rustygman]

I will state the obvious (to some) to make sure I am not being stupid. I disconnected the regulator, ran the engine and tested the voltage at the battery but there was no change. 12.4 volts at the battery, revving engine made no difference. I deduce from this that the regulator is OK. I checked the earth on the back of the battery. A bit rusty but not bad. Did a clean up to make sure we have metal to metal here. I also disconnected and the pin sockets in this area. The only really nasty green fuzz was found in the connection to the back light and indicators on the black wire (5 pins here) but cleaned up as well as I could. Does this now mean i have one of those elusive earthing problems. No work for me next week so I either spend a day going through the bike or i phone up my local enfield mechanic (the first time he would have worked on it since I bought it new from him in 2007). One question to stinkwheel regarding using the voltmeter to test between wires - what do i set the voltmeter to when doing this?

[Aethelric]

Hi rustygman it sounds like it's not the regulator which is causing the problem. And the alternator sounds like it's OK.


Using the multimeter on the ohms, or resistance, scale

make sure it's working by touching both wires to the primary chain case. You should read between 0 and 2 ohms depending on your leads.

now measure between the primary chain case and each of the alternator wires in turn. You should get a very high reading - between 1megohm and infinity

If you get a lower reading you have a connection to chassis in the alternator.

[Aethelric]

PS. a connection to chassis in the alternator is not wanted and would need fixing. Mine was a simple fix.

[another Allan]

If a meter across the battery only registers 12.4 V with the engine running, I don't think that this proves that the reg and/or rec are ok. I assume that you don't mean running at tickover.

At higher revs, the meter across the battery terminals should be showing over 13 V, probably 13.5.



Mine isn't at the moment, which is likely to be the subject of a post from me shortly!

[rustygman]

Anotherallan - yes, 12.4 at tickover and no increase when revving engine. Aetheleric, sorry I missed your 3.52 post as I was composing mine i presume. However I will look into this tomorrow. When you say about checking the wires for a ground and running between the alternator wires and the primary is this at tickover. I am way out of my comfort zone now. It's my local bike show tomorrow so looks like the Enfield will be sulking at home. Many thanks again.