Alton Charging

Peter R · Aug 7, 2022

I have a Alton starter fitted since less than a year, and I am plagued with charging problems ever since.
Checked everything, and found the AC voltage output of the alternator low, at 15volts at 3000rpm. with cold engine
With the engine warmed up even less voltage.
I use a Podtronics regulator, that worked fine with the old Lucas alternator,
It looks like the magnetisme of the rotor is too weak.
Anyone experieced this problem ?

baz · Aug 7, 2022

Have a read through this post https://www.accessnorton.com/NortonCommando/alton-starter-alternator-rectifier.33801/

baz · Aug 7, 2022

You will see the open ac voltage on my Alton was 20v at 2000 rpm and 36v at 4000 rpm

Nortoniggy · Aug 7, 2022

I had to replace my magnet due to poor charging. Sadly mine was just out of warranty and they are quite expensive. You need to disconnect the two stator wires and measure the AC output with engine running. I think you should get over 20 volts at 1500 revs but Alton will tell you.

Baz beat me to it

ntst8 · Aug 8, 2022

I've had an Alton for a number of years, great as a starter but i have never had it produce a good charge. A friend has the same issue on his. The only way i can do multi day rides without plugging in a battery charger each night is to run with lights off.
I replaced the rotor and the old one had definitely lost magnetism. Alton warned that if the rotor rubs on the stator then magnetism will be lost. Despite careful clearance set up my new one rubbed straight away - evidence in the primary oil - and is already as bad as it was before. The bike has been sitting in the corner waiting for me to find a solution - check crank run out etc to work out why it rubs.

MexicoMike · Aug 9, 2022

My Alton starter/alternator has been totally trouble free in every respect now for 10 years. Charges as well as the 180W Lucas that was on the bike previously, even though the Alton is rated at 150W. That being said, clearance is tight on my Alton rotor and, during installation it took me quite a while fooling with shims and adjustments, including enlarging the holes in the stator to get an even .008" clearance all the way around. IMO, that's not really an Alton issue though I suppose the stator could have enlarged holes to accommodate the variation in Commando fitting alignment.

Peter R · Aug 12, 2022

Measured voltage again, 16V at high idle,(1500rpm) and 30 V ac at 3000rpm (regulator disconnected.)
That 16Volt seems a bit on the low side ?
Checked diodes of the Podtronics seems ok.
Fitted a bridge type rectifier and the original zener diode, and I will hope to see what the charging looks like.

Peter R · Aug 13, 2022

I am getting confused: charging voltage 13.8 volts, and initial charge current 4-5 Amps.
So far all ok, but afer riding for approx half an hour, the battery starts to drain to the point where the startmotor no longer works.
After charging the battery with external charger this process repeats.
Replaced the Podtronics with a bridge type rectifier and zener, same result.
Yuasa battery is less then a year old.
I am clueless, what the culprit could be, Battery? stator ? I am running out of ideas.

Nortoniggy · Aug 13, 2022

Batteries can die prematurely. Find a garage with a battery tester and see what that says.

MexicoMike · Aug 13, 2022

Sounds like the battery...

ntst8 · Apr 22, 2023

Hi Peter, over the last few months i have been putting some effort into resolving my poor charging, i've only had the starter 9 years!
- Alton advised that if not set up with adequate clearance the rotor will demagnetise if it rubs.
- Alton had also suggested checking clearance between the rear of the stator and the small starter chain - they have seen contact taking the epoxy off and shorting out a coil. They suggest a dab of epoxy to repair the coil and then remounting the stator with a washer to space it off the bracket and increase the chain clearance. Mine doesn't seem to have had this issue.
- i've removed the stator and the magnet ring off the rotor - thought i would check where the natural position for the rotor to sit vs the stator, assuming that where-ever the magnetism wants to hold the things in the vertical plane would give best charging. Not surprisingly Alton have this about right.
- next i noticed that the timing scale on the outer primary had scrape marks on the back, initially thought this might be the rotor contacting while running but checking through the inspection hole with the cover in place there seems to be plenty of clearance. Probably just contact when wrestling the cover off with the exhaust in place, but i have flattened that to provide clearance whenever it is needed. Will deal with timing accuracy another time.
- finally i spent an age trying to get rotating clearance all round between rotor and stator using the Alton spacers. Not sure whether it is the rotor or the crank but i get a rotating tight spot so tried to keep that clear all round.

Initial run and i thought i had gone mad - perfect charge initially then made a stop and on restart it was same old poor charging, was i imagining the good charging? Home again and have another go at set up and success again, have since done an overnight 500km trip with lights on all the way and above 2500 rpm the regulator was earning its keep. 4 days later and still 12.8V in the battery so not an illusion.
I can't test it again at the moment as the oil tank top rear mount failed on the trip and is away for a birthday, but it seems that it is just all about careful set up.
The only other recent change i have made is fitting a TriSpark Mosfet Regulator, but that alone didn't change things.
Good luck.
Iain

gortnipper · Apr 22, 2023

ntst8 said:
Hi Peter, over the last few months i have been putting some effort into resolving my poor charging, i've only had the starter 9 years!
- Alton advised that if not set up with adequate clearance the rotor will demagnetise if it rubs.
- Alton had also suggested checking clearance between the rear of the stator and the small starter chain - they have seen contact taking the epoxy off and shorting out a coil. They suggest a dab of epoxy to repair the coil and then remounting the stator with a washer to space it off the bracket and increase the chain clearance. Mine doesn't seem to have had this issue.
- i've removed the stator and the magnet ring off the rotor - thought i would check where the natural position for the rotor to sit vs the stator, assuming that where-ever the magnetism wants to hold the things in the vertical plane would give best charging. Not surprisingly Alton have this about right.
- next i noticed that the timing scale on the outer primary had scrape marks on the back, initially thought this might be the rotor contacting while running but checking through the inspection hole with the cover in place there seems to be plenty of clearance. Probably just contact when wrestling the cover off with the exhaust in place, but i have flattened that to provide clearance whenever it is needed. Will deal with timing accuracy another time.
- finally i spent an age trying to get rotating clearance all round between rotor and stator using the Alton spacers. Not sure whether it is the rotor or the crank but i get a rotating tight spot so tried to keep that clear all round.

Initial run and i thought i had gone mad - perfect charge initially then made a stop and on restart it was same old poor charging, was i imagining the good charging? Home again and have another go at set up and success again, have since done an overnight 500km trip with lights on all the way and above 2500 rpm the regulator was earning its keep. 4 days later and still 12.8V in the battery so not an illusion.
I can't test it again at the moment as the oil tank top rear mount failed on the trip and is away for a birthday, but it seems that it is just all about careful set up.
The only other recent change i have made is fitting a TriSpark Mosfet Regulator, but that alone didn't change things.
Good luck.
Iain

Maybe you should have a bit skimmed off the rotor?

ntst8 · Apr 22, 2023

The rotors are interesting, not sure whether skimming would be wise?
There is an internal ring which looks to be steel, presumably the magnet, and what looks like a crimped on external ring which looks to be aluminium?
Not sure what the external ring does but there isnt much of it so was nervous about reducing it.

gortnipper · Apr 22, 2023

@Fast Eddie has done so on his rotor, IIRC, as have other.

Fast Eddie · Apr 23, 2023

gortnipper said:
@Fast Eddie has done so on his rotor, IIRC, as have other.

Yes but only on Lucas type rotors.

Nortoniggy · Apr 23, 2023

I'd be very reluctant to skim anything off it. Rubbing does seem to reduce the magnetism so turning some off may have the same effect so seems risky.

The story I heard about the alloy ring on the outside was that early magnet rings didn't have it and sometimes the magnets in the steel ring came loose due to centrifugal force. However, the steel ring does just look like a solid steel ring and if it does have small magnets attached they must be very small. I did ask Villiers Services if they could re-magnatise an Alton magnet ring as they can do Lucas ones, but they said no.

baz · Apr 23, 2023

I would not skim an Alton rotor
There is not enough meat there

MexicoMike · Apr 23, 2023

"The story I heard about the alloy ring on the outside was that early magnet rings didn't have it and sometimes the magnets in the steel ring came loose due to centrifugal force."

Per discussions with Paul at Alton in early '13, That is correct and is the reason that ring was added. Don't remove or weaken it. The earlier versions could come apart with the combination of centrifugal force and sufficient heat. Two of them did that on my Commando in late '12. The "new" style rotor has been on my Command since '13 and no issue since then.

jimbo · Apr 23, 2023

I have a rotor and a stator both have some issues, but the rotor spins true on my lathe and the stator tests good , $100 each USA

if anybody needs spares. IMHO flimsy stuff , and I wonder if CNWs are stouter (couldn't use that type as I have the OEM plastic air box)