Battery charging system

The Battery on my Norton Commando 1973 has failed after 6 months daily use. While I can run the bike, if I use the Brake lights or head lights while stopped at traffic lights the engine stalls.
My Question what sort of current drain on the battery should there be with the ignition on with no lights. ( 1st key position) before the engine is started? I am reading about 3.4 amps is this about right for a standard 850 interstate?
I am trying to find out if there is something wrong with the system or if it is purely a battery failure.

I'd check the battery first. It could be a dead cell. With the cables disconnected, do you get at least 12 volts across the connections? If not, replace the battery. If the battery is fully charged, you should be able to run the bike and headlight for a little while even if the charging system is not functioning at all. Measuring voltage across the battery before you start the bike and then while it is running should show at least a slight increase in voltage as the alternator charges. Again this assumes you have a good battery.

A wiring short should blow the fuse. Check all the bullet connectors , especially on the alternator as it could be that they are corroded to the point that they don't allow sufficient current to pass.

Hope this helps.

battery charging

Thanks for the reply.
I think the battery has failed. Its still under warranty so i have it at the battery shop being checked out.
I will also check the alternator bulletconnectors & charge voltage.
I have to find a 1ohm 50w resistor to test the alternator output (according to the manual I have).

Thanks for your help

David

Just do a voltage check at the battery. Take a reading with the motor off, then start it and take a reading at about 3000 rpm. If the alternator, rectifier, and zener diode are working you should see at least a small rise in voltage. Does your warning light work? If the light extinguishes as the revs come off idle, then you have at least some charge coming from the alternator. If it doesn't go out, then it's probably a bad assimilator (and your alternator may be O.K. anyway!) and you need to check it.

If the voltage measurement does not show an increase or shows a slight decrease, then you need to start checking the individual components and you will need the 1 ohm resistor to check the alternator disconnected from the rectifier.

Well the battery failed the OK test at the shop. The plates were covered in sulphate making it high resistance and not able to be charged. This was said to be due to the battery standing not used for long times or the charging circuit not working.
Neither seem to be the case. I ride the bike regularly twice a day for 1/2 hour. The charge circuit givers over 13 volt at 3500rpm.

I think the problem is I commute to work at low revs and idle at traffic lights with the brake lights on. Prbably draining the battery more than charging it.

I will just have to gun it a bit more and keep the revs in the 3000 range in a lower gear.
Thankfully the Marshall battery shop still replaced the battery even though 1 month out of warranty and not according to them a warranty issue.
Thanks for your useful information.

dgwilson,
Since this is a daily rider, consider installing a three-phase alternator kit, either a Lucas three phase stator with an electronic regulator or Sparx kit which includes the regulator. These give much more juice at lower rpm and are ideal for your situation.

Helps a lot to have a volt meter to monitor the ratio of time discharging to charging and help select gear to keep mostly in the charging zone. A extra big battery goes a long ways to stay bright all day then charge back up at home. Helps a lot to have easy to reach terminal to hook charger too w/o opening up cover and fumbling clips on hard to reach/attach battery terminals .

Dg, Just returned from the battery shop where they did a total discharge then recharge , let it sit for the 3 months that I backpacked India to see if it held good charge . Watched them put it on a thousand dollar hand -held meter device to read 12.76 Volts and reading of 335 cranking amps. Odyssey PC 680 , a Gel type that is said to resist vibration and of course sealed. Norton stuff for sure. The technician said to periodically put the bike on trickle charge if dropping voltage issues persist ,that a headlight is a BIG drawer of power . Good luck,Peter. Oh Yes - check all connections and a voltmeter at battery then rev. the motor is a good check.

dgwilson said:

My Question what sort of current drain on the battery should there be with the ignition on with no lights. ( 1st key position) before the engine is started? I am reading about 3.4 amps is this about right for a standard 850 interstate?
I am trying to find out if there is something wrong with the system or if it is purely a battery failure.

Click to expand...

To answer your question
I have left my key on for days numerous times. I show no (0) drain from the battery with the key on. I have a 2 position switch, on and off. Pazon unit.

dgwilson said:

The Battery on my Norton Commando 1973 has failed after 6 months daily use. While I can run the bike, if I use the Brake lights or head lights while stopped at traffic lights the engine stalls.
My Question what sort of current drain on the battery should there be with the ignition on with no lights. ( 1st key position) before the engine is started? I am reading about 3.4 amps is this about right for a standard 850 interstate?
I am trying to find out if there is something wrong with the system or if it is purely a battery failure.

Click to expand...

what kind of ignition system?? if you have points and they are closed the coils will will draw current when the engine is not running but should not if they are open

dgwilson said:

My Question what sort of current drain on the battery should there be with the ignition on with no lights. ( 1st key position) before the engine is started? I am reading about 3.4 amps is this about right for a standard 850 interstate?
I am trying to find out if there is something wrong with the system or if it is purely a battery failure.

Click to expand...

If you're running points ignition, yes 3.4 amps is about right. It means one set of points is closed. If you slowly rotate the engine you'll see that drop to zero when both sets of points open. When running it's more like 1 amp due to the dwell time.

[To answer your question
I have left my key on for days numerous times. I show no (0) drain from the battery with the key on. I have a 2 position switch, on and off. Pazon unit.[/quote]

So with the Pazon you can leave the igntion on and it doesn;t flatten the battery? Cool.

Like you I have often left the ignition on accidentally. Unlike you I have returned to a flat battery and an unwanted ride on the train... :cry: Flat battery + Boyer + capacitor= :evil: :evil: :evil: