BritBike Forum logo
BritBike Sponsor BritBike Sponsor BritBike Sponsor
BritBike Sponsor

BritBike Sponsor

BritBike Sponsor
BritBike Sponsor BritBike Sponsor BritBike Sponsor
JWood Auction JRC Engineering dealers JWood Auction
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons, "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Photo posting tutorial

Member Spotlight
Hector Catre
Hector Catre
Toronto/Ontario/Canada
Posts: 106
Joined: August 2008
Show All Member Profiles 
Shout Box
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Who's Online Now
206 registered members (68 royalstar tony), 1,714 guests, and 551 spiders.
Key: Admin, Global Mod, Mod
Newest Members
David Stothard, iansouthoz, Lightning Sim, Simon.Holyfield, Bushcreature
10036 Registered Users
Top Posters(30 Days)
Lannis 147
kommando 113
Stuart 62
Popular Topics(Views)
478,362 mail-order LSR
Forum Statistics
Forums33
Topics65,740
Posts635,506
Members10,036
Most Online3,995
Feb 13th, 2017
Like BritBike.com on Facebook

Previous Thread
Next Thread
Print Thread
Rate Thread
First Run Squawks - Voltage #438232
06/04/12 2:57 am
06/04/12 2:57 am
Joined: Aug 2010
Posts: 205
Texas USA
D
DaveOfTexas Offline OP
BritBike Forum member
DaveOfTexas  Offline OP
BritBike Forum member
D
Joined: Aug 2010
Posts: 205
Texas USA
Zener diode, new 12V 9aH flooded cell battery fully charged, no lights etc on. Only draw is the electronic ignition.
The voltage across the battery terminals reads 15v when it is running at a fast idle (see video in By Gawd thread).

That will surely boil the battery.
How to tone it down?? Needs to be 13.8-14.2V ime.


1969 BSA B44VS PC8113
Engine PC8113B44VS
Recently acquired (Feb 2011) Aiming to get running and return all parts/configurations to original.
First BSA. Have 1970 Honda CB750 too.
Support Your #1 BritBike Forum!
Membership Type! Free
Member
Premium
Member
Premium Life
Member
Vendor
Member
Site
Sponsor
Recognition No Premium Member Premium Life member (5 years) Vendor Member Site Sponsor Membership
Post commercial threads No No No Yes Yes
Custom title No Yes Yes Yes Yes
Upload avatar & photos No Yes Yes Yes Yes
Link avatar & photos Yes Yes Yes Yes Yes
Private Message Storage: 10 100 100 100 100
Length of signatures 255 600 600 600 600
Removes this very advert island between post 1&2 No Yes Yes Yes Yes
Price Free $12.90/year $105.00 No End
$55.00/5 years
$210.00/year
($17.50/month)
Email
Click on button >>
  Premium Member Premium Life member Vendor Member Site Sponsor Membership
Re: First Run Squawks - Voltage [Re: DaveOfTexas] #438243
06/04/12 4:22 am
06/04/12 4:22 am
Joined: Aug 2001
Posts: 1,799
Christchurch, NZ
Kevin (NZ). Offline
BritBike Forum member
Kevin (NZ).  Offline
BritBike Forum member
Joined: Aug 2001
Posts: 1,799
Christchurch, NZ
The Zener diode controls the voltage. What did the voltage drop to with the lights turned on. How about readings at low rpm and then again with a good rev..

I would be thinking the meter, - is it reading correctly?
There will still be a little ac ripple but you are measuring at the correct place, - across the battery itself.

Next would be checking the Zener earth. Are there any floating voltages in the system ? ie some components not earthed correctly or linked to a common ground point.
Is the Zener indeed connected to the rectifier output and battery live correctly.

It may be a fauly Zener, you could put the meter over that and see if you get similar results. The voltage should obviously plateau at the Zener operating voltage.

At least you have too much charge. Easier to fix than too little.
To prevent boiling the battery you could run with the lights on... or even pulling an alternator ac lead off the input to the rectifier.

It shouldn't be too difficult to work through and fix this one.

Last edited by Kevin (NZ).; 06/05/12 12:26 am. Reason: shouldn't

Why, Y, Dash Y..



Re: First Run Squawks - Voltage [Re: DaveOfTexas] #438274
06/04/12 10:04 am
06/04/12 10:04 am
Joined: Jun 2002
Posts: 9,469
Scotland
S
Stuart Online content
BritBike Forum member
Stuart  Online Content
BritBike Forum member
S
Joined: Jun 2002
Posts: 9,469
Scotland
Hi Dave,

Originally Posted By: DaveOfTexas
The voltage across the battery terminals reads 15v

Agree with Kevin.

1. Have you tried a known good battery in your multimeter? As I found out just yesterday, even when measuring Volts, my multimeter's reading was high due to a failing internal battery. frown Or try just another multimeter.

2. Do you always have battery Volts at the Zener's tab terminal?

3. Have you checked for any resistance between the Zener's stud and battery +ve?

However, as long as the Volts don't go higher than 15V, you might be stuck with that limit unless you change the Zener; that's what many new ones have been working to for some years. And, if you change the Zener, there isn't any guarantee that another one won't regulate until a similar Voltage. frown

Originally Posted By: DaveOfTexas
That will surely boil the battery.

Ime, it won't. But, if he doesn't understand already, you need to impress on the bike's owner that 43-year-old Britbike electrics aren't fit-'n'-forget like his car's or modern Jap bike's; he needs to check the battery water levels regularly, then he'll notice if the levels are dropping. wink

Hth.

Regards,

Re: First Run Squawks - Voltage [Re: DaveOfTexas] #438296
06/04/12 12:37 pm
06/04/12 12:37 pm
Joined: Aug 2010
Posts: 205
Texas USA
D
DaveOfTexas Offline OP
BritBike Forum member
DaveOfTexas  Offline OP
BritBike Forum member
D
Joined: Aug 2010
Posts: 205
Texas USA
Oh, boy this reminds me of a thread I started a while back!
http://www.britbike.com/forums/ubbthread...true#Post425359

I do have that Pacifico thing sitting right there!


1969 BSA B44VS PC8113
Engine PC8113B44VS
Recently acquired (Feb 2011) Aiming to get running and return all parts/configurations to original.
First BSA. Have 1970 Honda CB750 too.
Re: First Run Squawks - Voltage [Re: DaveOfTexas] #438328
06/04/12 3:01 pm
06/04/12 3:01 pm
Joined: Oct 2008
Posts: 1,659
Canada
L
LarryLebel Online content
BritBike Forum member
LarryLebel  Online Content
BritBike Forum member
L
Joined: Oct 2008
Posts: 1,659
Canada
The Haynes manual says that at 15.5 volts the Zener diode diverts all the current from the alternator, about 5amps, to the heat sink, thus insuring the battery is not overcharged. So apparently you seeing 15v is OK.

Re: First Run Squawks - Voltage [Re: LarryLebel] #438335
06/04/12 3:43 pm
06/04/12 3:43 pm
Joined: Aug 2010
Posts: 205
Texas USA
D
DaveOfTexas Offline OP
BritBike Forum member
DaveOfTexas  Offline OP
BritBike Forum member
D
Joined: Aug 2010
Posts: 205
Texas USA
Larry that almost sounds like doublespeak!

The battery is seeing 15V but it is not being overcharged?

If I leave it, you all agree to send me a new battery in a month?!

Just funnin' ya.


1969 BSA B44VS PC8113
Engine PC8113B44VS
Recently acquired (Feb 2011) Aiming to get running and return all parts/configurations to original.
First BSA. Have 1970 Honda CB750 too.
Re: First Run Squawks - Voltage [Re: DaveOfTexas] #438337
06/04/12 3:52 pm
06/04/12 3:52 pm
Joined: Dec 2004
Posts: 9,077
Scotland
kommando Online content
BritBike Forum member
kommando  Online Content
BritBike Forum member
Joined: Dec 2004
Posts: 9,077
Scotland
15V is at the top end of what a battery will tolerate but it will shorten its life eventually, I have a digital car battery charger and it charges the battery until it sees 16.3V and then stops and use it regularly and my car batteries last fine. For the moment until you csn get it down to 14.5V switch your lights on.

Re: First Run Squawks - Voltage [Re: DaveOfTexas] #438347
06/04/12 5:09 pm
06/04/12 5:09 pm
Joined: Aug 2010
Posts: 205
Texas USA
D
DaveOfTexas Offline OP
BritBike Forum member
DaveOfTexas  Offline OP
BritBike Forum member
D
Joined: Aug 2010
Posts: 205
Texas USA
OK I will watch it closely during the trials and run lights etc, see if it comes down, if the battery heats or boils.
Thanks.


1969 BSA B44VS PC8113
Engine PC8113B44VS
Recently acquired (Feb 2011) Aiming to get running and return all parts/configurations to original.
First BSA. Have 1970 Honda CB750 too.
Re: First Run Squawks - Voltage [Re: DaveOfTexas] #438354
06/04/12 5:52 pm
06/04/12 5:52 pm
Joined: Oct 2008
Posts: 1,659
Canada
L
LarryLebel Online content
BritBike Forum member
LarryLebel  Online Content
BritBike Forum member
L
Joined: Oct 2008
Posts: 1,659
Canada
Dave. I'm just the messenger .... don't blame me.


Moderated by  Allan Gill, Jon W. Whitley 


Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | "OLD" BritBike Forum | DVD- Manuals & Parts books | BritBike Stickers & Decals
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.6.1.1