BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: A10 JWO on 01 Jun, 2018, 17:27

Title: Is it charging A65
Post by: A10 JWO on 01 Jun, 2018, 17:27
Had my first ride today on the rebuild, engine fine. Clutch dragging. I have fitted a new Motobatt 11.OAH Battery. How can I tell if the Zener Diode, the solid state rectifier and alternator are all functioning as they should. My new brakes are rubbish  ;D
Title: Re: Is it charging A65
Post by: DerekAnderson8 on 01 Jun, 2018, 19:13
i would have thought a meter across battery when running would tell you, put lights etc on and give it a rev and check voltage.
Title: Re: Is it charging A65
Post by: AWJDThumper on 01 Jun, 2018, 19:41
It's much better to put an ammeter between the battery and it's output lead so you can measure the charge current (+ve or -ve), with and without the lights on. With the lights off, you should get about 14.5V across the battery as you rev the engine depending on what Zener diode is fitted.
Title: Re: Is it charging A65
Post by: DerekAnderson8 on 01 Jun, 2018, 20:14
would the ammeter fitted in headlight not tell you that anyway?

the voltage across battery will tell you if regulator and zener diode are functioning to an extent.

;)
Title: Re: Is it charging A65
Post by: AWJDThumper on 01 Jun, 2018, 20:52
It's easier if an ammeter is already fitted! It will tell you whether the battery is charging with both the lights off and the lights are on. When you rev the engine in both cases you should get a healthy charge if everything is working ok. If you also check that the battery voltage doesn't go above about 14.5V that will tell you the Zener diodes is also working ok.
Title: Re: Is it charging A65
Post by: STAR TWIN on 01 Jun, 2018, 22:25
It's quite simple really. You point the bike at the shed wall and switch the headlight on. Rev the engine and the headlight brightens. Drop the revs to tickover and it dulls a bit. No ammeter needed.
Title: Re: Is it charging A65
Post by: Bess on 01 Jun, 2018, 23:41
Hi,
    I use one of these for fault finding and reassurance:

https://www.demon-tweeks.co.uk/tools-workshop/electrical-system-testing-diagnostic-tools/sealey-clip-on-ammeter-30-0-30amp-bt98-10

I  believe you can find them cheaper eslewhere.

Best wishes...
Title: Re: Is it charging A65
Post by: AWJDThumper on 02 Jun, 2018, 06:20
Quote from: STAR TWIN on 01 Jun, 2018, 22:25
It's quite simple really. You point the bike at the shed wall and switch the headlight on. Rev the engine and the headlight brightens. Drop the revs to tickover and it dulls a bit. No ammeter needed.
It might be a little easier using the ammeter mounted on the headlight shell - that's what its there for :)
Title: Re: Is it charging A65
Post by: JulianS on 02 Jun, 2018, 09:48
No ammeter on OIF A65 headlight shell.
Title: Re: Is it charging A65
Post by: ChrisG on 02 Jun, 2018, 12:24
If you have a multimeter switch it to voltage and clip to the battery. Should show 12.5 v as the Battery is new and charged up. Start the engine and rev to 3000-3500 revs and the voltage should go up to  around 14.5v . Switch the lights on and it should still peak at 14.5v. If i goes higher then the zenor is suspect. If it doesnt get there then check the alternator connections.
Aternatively there are cheap Draper battery checking gizmos that have a string of led's which light up as the voltage increases.
Title: Re: Is it charging A65
Post by: A10 JWO on 02 Jun, 2018, 18:14
Thanks lads.  ;D