Battery keeps failing Aygo

[Rosiesb]

My Battery keeps draining down to 0 After new Battery was kept running every day then missed a day and it went flat

[Guest]

Is the alternator charging? Measure the Battery voltage after fully charging the Battery, then monitor the voltage while driving - if the alternator is working then you should see a voltage closer to 14V than 11 or 12V.

[FROSTYBALLS]

Interior light not being left on? As the car should still be under warranty, have you sought the opinion of a Toyota dealer? If it is the alternator, that should be covered under the warranty.

[Rosiesb]

AA man out today said alternator fine, no drains, and nothing on when key out. Toyota have already had a look but found nothing wrong. I’m taking it to a car electrics guy on Fri.

[Wiz201]

19 hours ago, Rosiesb said:

AA man out today said alternator fine, no drains, and nothing on when key out. Toyota have already had a look but found nothing wrong. I’m taking it to a car electrics guy on Fri.

just be aware any work undertaken by someone else other than Toyota can void your warranty, despite the fact they've already looked at it.

[Rosiesb]

Well fine, they were pretty disinterested and wouldn’t pay for my new Battery so I’m pretty disinterested in visiting them again at all. 

[Mooly]

22 hours ago, Rosiesb said:

My battery keeps draining down to 0

Has it actually been measured at 0 (zero volt) at the terminals? To do that over a couple of days needs a pretty substantial and constant current draw. That would be very unusual. There is a world of difference between a Battery that is just discharged and one that is showing '0'.

In that condition nothing would work, no central locking, no dash lights, no nothing. Is that what is happening?

Taken at face value and if the Battery is 100% flat then I would suspect something like a leaky diode pack in the alternator. Any shorts in equipment and wiring would blow a fuse.

 

 

  

[Rosiesb]

Yes, that’s what’s happening Can’t even unlock doors/boot unless by manual.

[TPMC]

Hi 

Im also having a very annoying Battery drain issue. I have a black box installed, resulting in a constant draw of 0.25a (0.13a when the black box is unplugged). I had to replace my old Battery (45ah) after both this issue and a bad alternator ruined it. Now with a new Exile Battery (50ah), by battery died after 10 days of having it. I take my car for almost daily drive, for durations of around 20mins. Hovever, the one day I decided not to drive it, the battery died. My electrical mechanic told me to get a bigger battery (70ah), even though it isn't recommended by any battery dealers. Should I get a bigger battery or/and should I unplug my black box overnight?

thanks.

[Guest]

59 minutes ago, TPMC said:

Should I get a bigger battery or/and should I unplug my black box overnight?

Do the insurance terms allow you to unplug the black box?

I fitted the largest Battery I could into my 2008 petrol (cold climate diesel battery) with no adverse effects (I ran it for 10 years only selling it in October 2020).

BTW even 0.13A with the black box unplugged sounds unusually high?

[Rosiesb]

AA man told me a bigger amp Battery is ok. As long as it isn’t below recommended amps.

[TPMC]

1 hour ago, Rosiesb said:

AA man told me a bigger amp battery is ok. As long as it isn’t below recommended amps.

I heard that if your Battery is larger then recommended, and your alternator doesn't output enough current,  then the Battery will never be fully recharged, and hence damaged. Is this true? 

[Guest]

17 minutes ago, TPMC said:

I heard that if your battery is larger then recommended, and your alternator doesn't output enough current,  then the battery will never be fully recharged, and hence damaged. Is this true? 

No the output of the alternator is more than enough to fully recharge the largest Battery that will physically fit an Aygo. A larger Battery will take longer to fully recharge but will also take longer to fully discharge.

Before I retired I had been Electronics Manager for a well known automotive consultancy 

[Mooly]

5 hours ago, Rosiesb said:

Yes, that’s what’s happening Can’t even unlock doors/boot unless by manual.

Interesting. So it is pretty much discharged then... and that takes some doing in just a couple of days. Without proper diagnostics it is all guesswork but I would still suspect something like the alternator as possible cause.

The car is standard I assume and has no additional equipment fitted such as alternate audio systems, sat navs and so on?

Once you start getting upward of 50 to 100 milliamps current draw on a 24/7 basis then that can start to cause problems over weeks and months with the Battery reaching less and less of a full state of charge each time you drive it.