BritBike Forum logo
BritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorThe Bonneville ShopBritBike Sponsor
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
ShoutChat Box
Comment Guidelines: Do post respectful and insightful comments.
Buy BritBike staff a coffee
Buy BritBike's staff a coffeeStill here since 1996 serving BritBike enthusiasts..
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Member Spotlight
MotorEddy
MotorEddy
Lancashire, UK
Posts: 39
Joined: August 2011
Show All Member Profiles 
Newest Members
Alex Lynch, B Mac, Lenz-a-lot, UncleYeti, harold2019
10774 Registered Users
Top Posters(30 Days)
franko 128
NickL 66
MarcB 53
Popular Topics(Views)
947,603 mail-order LSR
Forum Statistics
Forums34
Topics67,493
Posts675,613
Members10,774
Most Online14,755
May 5th, 2019
Who's Online Now
68 registered members (Al Eckstadt), 448 guests, and 834 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Voltage drop key on #772925 05/07/19 6:09 pm
Joined: Oct 2017
Posts: 241
N
Nick H Online Content OP
BritBike Forum member
OP Online Content
BritBike Forum member
N
Joined: Oct 2017
Posts: 241
My 12 volt battery is fine with no load. Reads 12.8 or even 13 when charged. When i turn the key on it drops to around 10 volts. A tail light and points are the only things in the circuit. If I disconnect the points, the voltage goes back up.
Do I have a bad battery?


1966 BSA Lightning
1967 Triumph "Choppa"
Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK
British motorcycles on e-Bay North America
Re: Voltage drop key on [Re: Nick H] #772930 05/07/19 7:19 pm
Joined: May 2013
Posts: 5,705
Allan Gill Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: May 2013
Posts: 5,705
Yup!


beerchug
Re: Voltage drop key on [Re: Nick H] #772973 05/07/19 11:45 pm
Joined: Oct 2017
Posts: 241
N
Nick H Online Content OP
BritBike Forum member
OP Online Content
BritBike Forum member
N
Joined: Oct 2017
Posts: 241
Thanks. They don't last long do they?


1966 BSA Lightning
1967 Triumph "Choppa"
Re: Voltage drop key on [Re: Nick H] #773005 05/08/19 6:25 am
Joined: May 2013
Posts: 5,705
Allan Gill Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: May 2013
Posts: 5,705
If your not using the bike regular no, they don’t and it’s important to keep them charged up. Once they have failed it’s usually the end for most batteries. The other thing is if the charging system on the bike isn’t getting the battery up to full capacity then this will also shorten the life. But crucially, disconnect the battery and put it on charge soon as it’s not in use. They can then last a very long time, it only if the battery is at full charge.

Is it a dry cell (AGM), or traditional lead acid?
(Both above are similar but AGM has matting between the plates and are totally sealed, unlike the traditional battery where you can top them up.

Gel is different again and most people who think they have a Gel battery... often dont


beerchug
Re: Voltage drop key on [Re: Nick H] #773311 05/11/19 1:17 am
Joined: Jan 2018
Posts: 18
S
Sinical Offline
BritBike Forum member
Offline
BritBike Forum member
S
Joined: Jan 2018
Posts: 18
A standing charge of 12.8V with the bike not running is very good. After turning only the key on, it's normal for a gradual voltage drop, sometimes dropping to 11V or even 10V. If it's not dropping below 10V with key on, I wouldn't condemn the battery based on that alone.

Once the voltage drop stops and you turn the key off again, does the voltage return to 12.8V ? Does the bike fire-up without any problem ? Once running, does it idle at between 13.5V - 14.5V ?


1966 TR6R (stock)
1970 TR6R (chopped)
"Obsession Is What Lazy People Call Dedication"

Moderated by  Alan_nc 

Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | DVD- Manuals & Parts books
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.7.3