Test Ride and voltage question

[A10 JWO]

Took my 500 out this weekend, no real issues apart from the carb ( sorted ). Decided to check the voltage running. My Fluke Meter is reading right on 12 volts how ever much  I rev the engine. It is a new Gel Battery. Fitted with one of those square rectifier type things and a Zenner Diode. The lights do not get any better if I rev the engine. I am running a Pazon Mark 8 ignition and the bike is plugged into an Oxford Oximiser 600 most of the week when I get a 13 Volt reading. Have I got a problem with my charging system ? Thanks.

[Richard Mills]

I think that it would be interesting to see if the voltage reading rose as you gently increased revs with the Zener disconnected.

[chaz]

zenner is there to burn off excess voltage in the form of heat. could it be too efficient? normally when they fail voltage is higher and boils battery. possibly rectifier

[ChrisG]

Assuming your meter is working OK and reading accurately, after freshly charging the battery, before connecting it to the bike check and it should read 12v+. Anything less and the battery is suspect. IF OK connect up the battery, start and rev the engine and the voltage should rise to 14.5V and stick around that area. If it goes higher, say above 15v then the Zener is suspect. If it doesn't reach 14.5v then the charging is suspect. If this is the case, before replacing expensive items, check the terminals on the wiring, for instance if one of the alternator wires is frayed and not connecting you will have lost a third of the output at a stroke.
Good luck!
Chris

[A10 JWO]

Thanks for replies so far, where would be the best place to take a reading to see if the generator/alternator is doing it's job. ? I don't want to take the bike out and break down once the battery is flat.  Thanks again.

[chaz]

thing to remember is that the electricity causes heat and can breakdown the wire.
you dont say how old the wire is, another place to look is generator wires in primary chest, hot oil does not help but makes brittle. the connections could be removed and as long as wire is good then clean ends and solder to make a good connection, dont just rely on crimps.
the meter across the battery with the engine running as Ed says should give reading.

[Caulky]

A fully charged 12V battery should read 12.6V+ on load, engine not running.
After charging on the bench it should show 14V+. This is the 'surface' charge, it will drop to 12.6v+ on load, ignition on.
If it reads 12V, it is discharged.
With the engine running, the battery voltage = the zener breakdown voltage ~ 14.5V.
A simple test is turn on the headlight without the engine running.
If it dims quickly after a few minutes, the battery is suspect.
New batteries can be faulty, get it checked first before parting with your cash.

[A10 JWO]

I put a good charger on the battery and it is showing fully charged at 13 Volts. I checked the two alternator leads and have a buzzer when I put the meter on. I also have a buzzer across all terminals on the solid state rectifier and the leads to the Zenner and Battery. I have all the same readings on my A65 stable mate. Is it possible that my bike is charging and I am not picking up the reading. I did disconnect the battery whilst it was running and it cut out straight away. How far can I ride the bike on a new fully charged battery if it is not charging. Thank you.

[Caulky]

What is the battery voltage with the engine running at about 2000 rpm?
You could temporarily wire in an ammeter inline with the fuse or a meter on the amps 10A range.
It will show a discharge without the engine running and a charge at 2000 rpm.
Check the fuse holder continuity/resistance with it disconnected from the battery.

[A10 JWO]

I have 12 volts with the engine running. I have removed the two alternator wires from the rectifier and it is showing 17 volts AC at about 2000 rpm I don't have a rev counter. Does this now show that the alternator is kicking out enough power ? thanks.

[Caulky]

12V is too low with motor running. What was the battery voltage without the motor running?
17V AC is low for 2000 rpm, does it rise with increased revs? I would expect that voltage at idle, and ~30V AC at 2000 rpm.
Check the alternator stator wires (on Ohms range) between wire/s and chassis (earth).
If the reading is anything other than infinity/open circuit, you have shorted windings, get another.
If your battery is bad, it will hog the current, leading to low voltage.

[DerekAnderson8]

I have 12 volts with the engine running. I have removed the two alternator wires from the rectifier and it is showing 17 volts AC at about 2000 rpm I don't have a rev counter. Does this now show that the alternator is kicking out enough power ? thanks.

i think 17vac calculates out at 12vdc approx if i remembered calculation correctly, maybe the windings arent great on the generator.

[A10 JWO]

Bought a new stator today 10 amp two wire. The old one was fried. Thanks for replies lads.

[Caulky]

Good news, hopefully that's the end of your woes!

[A10 JWO]

All fitted and now have good AC Voltage and showing 13 volts at the battery with the engine running, job done I think. Thanks lads.