single phase alternator

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seattle##gs

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At what RPM does the lucas single phase alternator put out full power? I live in Seattle and a lot of riding is in town. I have been having battery problems ..or charging problems lately....and I hope the problem is the low RPMs . On the GS I have an Alton generator and still have the problem. I have been considering replacing the pilot bulb with an LED since the bike is running neg. ground.
 
By around 3000 RPM you should be charging ok but depending on age an condition of your wiring you may be wasting that charge. Also if you have the blue capacitor still connected it may be shorting (as many seem to do with age). On top of that your gearing may not be helping if you spend alot of time at lower speeds.

Changing as many lights as possible to LED type will help if it's just a matter of not having enough available charge for running lights at lower speeds. All the lights on my bike except the main headlight (soon to be changed over winter) are LED they are more reliable as a rule an easily available over Internet and ebay as direct replacement type bulbs at will go into your current holders. Plus if you have negative earth then you have less trouble get the correct type as it is now the standard method and most but not all replacement LED type bulbs are made to suit that system.
 
FWIW one thing I did that helped was to change my 55/60W H4 bulb to a 45/45W, found one at a scooter shop and it fit OK once I trimmed the locating tab slightly ...the 10W savings is significant on a 120W system and I rarely ride my Norton after dark so it works OK for me and is still an improvement over the OEM headlight. (I use a modern bike for night riding) Also replaced the charge indicator lamp in the headlight with a tricolor LED voltage indicator, works great and give early notice of under or overcharging...

[video]https://youtu.be/wB5yTpZoN8I[/video]
 
I wish led worked for pos ground. I had a suspicion that that was my problem...I need to pay a lot more attention to charging. I cleaned the terminals for the rectifier and zener, they were VERY corroded. The RM21 requires 5000RPM for full charge??? I'm in trouble

My Goldstar has neg ground and I was thinking of modifying the lens to accept an LED bulb where the pilot bulb is and use that for daytime riding.
 
LED does work for positive ground on the headlight for sure...I am running 1 in my Commando and 1 in my Atlas...
 
Just coming out of recovery from a failing Podtronics rectifier/regulator, I went back to the stock rectifier/regulator/RM21 setup. According to my Sparkbright voltage monitor, we're maintaining, at idle, somewhere between 12.25 and 12.45 volts. This is running stock ignition, 20W (on low/dip) LED headlamp, followed by incandescent pilot light, tail light, and instrument gauges. The light turns green (>13.2 V) at anything above 1500 rpm. My longest traffic light is better (worse?) than three minutes, and the voltage doesn't drop below 12.25 volts during that time. It may not necessarily be charging, but it doesn't seem like it's losing, either.

You mention an LED pilot light; can I assume that you do not run the main bulb all the time? My ride won't tolerate sitting at a traffic stop with the headlamp on and the brake held on, or the winkers running steady, but it does float the LED headlamp and (incandescent) pilot. If you aren't able to float the pilot light alone at an idle, I suspect you're having charging issues above and beyond merely needing more power. An issue that was pointed out by Thomas update-the-battery-charging-system-t23131.html?hilit=stator#p303781 is the possibility of weak magnets on the rotor. There's a procedure in the manual for checking alternator output at the source that would be a good starting point to ensure that part of the system is up to snuff.

You might consider converting everything else over to LED also (like I'll be doing this winter). Jean did a bang-up job with some home-brew lights here diy-led-lights-cheap-t21177.html Obviously, this won't fix a weak charging system, but it is a bit more tolerant of low power.

Nathan
 
seattle##gs said:
I wish led worked for pos ground.

You can get LED for positive earth if you look around. My bike is positive earth an as I said is all LED lite except the main headlight which is a 45/65 halogen and is on all the time. I do have one of those colour changing LED voltage monitor things instead of the charge warning light and an Alton Ekit which has a 150w altenator but by 3000 rpm the charge monitor is bright green 2500 rpm with headlight off. So the first thing to do to help your charging system assuming it all works as it should is fit LED lights wherever there are normal bulbs.
 
I lamented whether I should have rewired my bike to have a voltmeter in the headlight or just keep the ammeter that I wired into it more than 20 years ago....

As simple as this sounds, you can look at your ammeter and see at what RPM's your bike's alternator begins generating surplus amperage by watching the needle move past zero as you increase the RPMs. It always bothered me that the ammeter only showed charge or discharge on my system, and not total voltage.

If I had to do it again, I would put a voltmeter instead of an ammeter, but I am used to seeing the ammeter and can tell when I am charging and when I am discharging at an idle. I run a daylight bulb during the day and not my headlight which saves some amperage. There's no reason to run the headlight during daytime when the dim bulb makes the headlight cone glow enough to be easily seen.
 
there is a lot of issues that can cause charging issues. IMHO in no real order is 1 a week rotor magnetism IE old rotor as if it is the original it is 40+ years old, next is the stator as the same age but less likely, next is the OE rectifier and poor connections @ the bullet connectors . I like the 3 phase upgrade as it has a faster output curve and is better if you do a lot of city riding with lights on as most places require. 40+ year old parts in the charging system is NOT a reliable way to go.
 
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