1961 M16 - charging problem

[Cerberus]

It’s not been my week for a number of reasons…

To cap it all, on the way to a section lunch time meet, I noticed that the ammeter seemed to indicate that the battery was not charging. (It’s an alternator and coil ignition system). I switched off all lights, made my apologies to section members who had turned up and went straight home, working on total loss electrics. Battery was 6.1V when I got home. Put battery on charge on Optimate and left it for 24hrs, after which the battery measured 6.6V, so battery takes charge. With engine running, battery volts do not change! Ammeter shows increasing current with lights on. Took seat off, all connections seem good. Suspicion is that either the A-Reg-6 regulator has died, OR the Alternator has stopped working. Tried disconnecting the battery while engine running and it started misfiring and eventually stalled.

Suggestions to isolate the problem, other than testing by buying new parts

[Cerberus]

After a couple of suggestions that the battery may be U/S, I swapped the battery in my AJ for fully charged battery from my G9. Symptoms identical. Time to see if I can find a point in the feed between the alternator and A-Reg-6 to put a meter on to see if there is any AC feed to the regulator.

[desperate]

I found a couple of weeks ago on my G12 the cables from the alternator had slipped down into the chaincase due to a bit too much slack in the loom. The primary chain then proceeded to saw through the cable. For a couple of weeks the charging seemed dodgy and finally gave out all together. If you have a multimeter you could measure the resistance between the three output wires, it should be low ish, can't remember the exact figure now. but not zero or dead short obviously. Mine measured open circuit, nor should there be any connection to earth.
The archives have an article describing how to test the alternator output which I found very helpful.

Desp

PS

https://www.jampot.com/article_read.asp?id=102

[Cerberus]

Desperate - good point, have meter, will check.....

[Reynard24]

As you have a A-reg-6 rectifier/regulator fitted, Al Osborn has a comprehensive website with instructions for testing the alternator on his website aoservices.co.uk

[Cerberus]

Managed to get to the connector between the alternator and regulator. Started engine. On tick over, multimeter showed over 6V RMS, (difficult to get accurate reading, as had to use 30V scale and needle not static). On opening throttle slightly quickly went to over 12V RMS. This suggests to me that the alternator is fine and the problem is with the regulator . A pain, but much easier to replace than the alternator.

[jackstringer]

FYI,
https://uk.rs-online.com/web/p/bridge-r ... rs/9179010

That is the one I fitted to mine.

EDIT: It looks like they only want to sell them in packs of 10.
Maybe one of these, https://uk.rs-online.com/web/p/bridge-r ... rs/3954455 will do the job.

[Cerberus]

As I am using AGM sealed battery, I need something better than a full wave rectifier, to avoid over-cooking the battery, which as it is sealed would be a bit catastrophic. The A-Reg-6 is a combination of a full wave rectifier and I guess some form of zener diode regulation to limit charging all encapsulated in a chunky heat sink to disperse "wasted" power when the battery is fully charged. (have ordered replacement, waiting on delivery)

[g80csp11]

ive found that AGM batteries are only last 18 months on my bikes with Alternators , perhaps a wet battery is still best
They appear to work Ok until they stop taking charge .
I have asked the manufactures of batteries and electronic regulator/rectifiers and they all stay they are compatible
however the 6V one with a dynamo and original design regulator appears to work pretty well

[Cerberus]

New A-Reg-6 fitted, charging restored, both at tickover with no lights and lights on, small amount of revs equals out the load. Previous A-Reg-6 was fitted 10yrs ago. (All being well if this one lasts 10 years, at least my notes will help me diagnose.)