What are the most common causes of a drop in battery voltage? Seems to have dropped from 13.5v to around 12.9 on cruise and even lower on boost.

Banny

 

Heated rear screen on ..... loose alternator belt tension

 

I take it you have tested the alternator Banny?? If so and it shows ok then i would suggest that the battery is fudged, prob these last few cold mornings have finished it off;-)

Mine did the same, fitted new one and sits at 13.8v constant.

 

yea could be alternator or alternator earth> it doesnt hurt to lossen the alternator and move it about the re-tighten belt etc to ensure a good earth

 

Need your help guys. Had my bugeye for about 10 months, no probs so far till now! Keep getting a flat battery. Now I don't drive it in the week, works van etc. But I take her out every 2 days for a run on the motorway. Bought a new battery, ok for two weeks or so then the same thing. No lights are on interior boot etc. Even left the alarm off but no good. When the engine is running the volt Reading is 14v. Am a service engineer so I know the basics of batteries. Any ideas guys. All help big or small is much appreciated!

Cheers Craig!

 

Well 14v is a good charge rate so nothing wrong there> it must have a drain on it. Maybe tracker>

Just cos the battery is new doesnt mean its any good. its worth having it tested< it could have sat on a shelf before you bought it for months or even years

 

Thats what i thought having 14v when the cars running. I've had the tracker on the car since i bought it. Only seems to have happend in the last couple of months.

In the last 7 days, i've had the car out Thurs Nite, Friday, Sat, Sun, and Monday. Went to start it tonight, Nothing. I thought it sounds like the Alternator, but with 14v charging it, it can't be can it! Any ideas what test on the Alternator i can do!

 

Switch the headlights on an engine running and check voltage 13.5 to 14.5 volts is spot on>

Leave metre connected switch engine off and switch headlights on breifly then switch off. this is to remove any surface charge> Should have a min static voltage of 12.2 volts. Disconnect crank sensor and crank engine while watching metre> Should be able to crank for at least 15 seconds with out voltage dropping below 9 volts> anything lower than 9 within a 15 second period and the battery is scrap. If that all checks out then you have a drain and can start look into other things

 

Thanks for the Advice Bud I'll print this off and try it after work.

Not sure what the Crank Senor And Crank Engine Is, But i'll find out. At the moment the car won't start. Used jump leads twice this month, it's a pain to push the car off the drive and block the road. Worse at night now. I'll ring the Breakdown and get them out with the Charger Pack.

Thanks again pal, let you know how i get on