4.6is Battery Voltage of 11.97v when Car is alarmed - Help Please :)

[james8whippy]

Hey Guys,

Been having some issues with the battery going dead after a couple of days.

I have connected a multimeter to the battery and have alarmed the car and it went to 11.84v at first.
I left it 16mins for it to go asleep and then the voltage is now sitting at 11.97v is this too low?

I have a new spare Bosch sitting in the garage that came in the car when I bought it but I had a Optima Yellow top which I used for car audio in my previous car and I hadn't long paid £250 for it so I took the original out and put the Optima Yellow top in as I couldn't bare letting it go to waste http://www.optimabatteries.nl/upl_files/File/OPTIMA_YellowTop_S5,5L.pdf
it's been fine for nearly 2 years in the X so I really hope it isn't the yellow top.

The bosch battery which isn't connected to anything gives a voltage reading of 12.98v So as a last resort I could always put that in the car but I'm just hoping it isn't my yellow top that's knackered

Does anyone know what the voltage should be at when the car is alarmed I understand the alarm will drain a bit of power so is 11.97v to much of a drain for sitting locked and asleep or do I have something else that is draining the power do you think?

I only use the car at weekends so at the moment I just leave it connected to a charger but I would like to resolve this as I can't trust it at the moment

Any help would be appreciated?

Thanks
James

[james8whippy]

Update:

Just disconnected the yellow top from my car and the voltage is showing 11.84v with nothing attached.
Whereas the Bosch is showing 12.98v

Looks like some cells might gone in the yellow top

Just found the invoice bought it in Dec 2010 so under 2 years just. Lets see if they will replace it as I personally don't think that's acceptable.

Thanks
James

[X5Sport]

Current drain on a parked/asleep car should be less than 120mA, and could be as low as 60mA.

A fully charged, off-load battery should show at around 12.6V.  A dead battery (open circuit) will show 11.7V, or 10.5V connected.  Each cell produces 2.1V (6 in a car battery).  From your figures it sounds like a dead/near dead battery.  These figures are for a calibrated meter.  Allow for errors in the meter, and don't check a disconnected battery within 4 hours of last charge (it allows the battery charge state to 'settle').

Your charger needs to be putting out 13.4V for a gel, 13.5V for a mat (AGM Type) or 13.9V for a wet battery if you are using a conditioning charger.  Modern batteries are either Gel Electrolyte, or Advanced Glass Mat (AGM) batteries as they are much safer to handle than a wet battery - no electrolyte/acid sloshing about!!

With the engine running you should see 14.4V typically.

Hope this helps.

Richard

[jaynana]

if your car doesn't run during week days (like mine which does a total of about 5 miles during the 5 week days , in 5 trips - that is 5 cold cranks!!) u can expect the battery to be low.

mine's a new bosch S5 from last year autumn, i've tested the charging voltage from the alternator to be good, but if i don't do some weekend running, by next fri it comes to about 11.8v.

the battery simply does not get to replenish the energy it spends on so many starts.

plus in my case it is worsened by my gsm remote attached to the webo, which itself drains about 60ma!!

[Raj]

Tbh I've always been told that yellow top aren't really ideal for normal car use. They are really designed as an additional for powering HUGE systems.

[james8whippy]

Thanks for the replies guys,

It's seems after changing the battery it seems to be much better.

I'll try send it back as it's still within the 2 years warranty.

Next time I need a battery I'll just stick with the Bosch standard one as my big audio system days are over.

Thanks
James