battery loosing charge

[barry1952]

Hi l purchased a new boot Battery  for my 2008 Pirus from main dealer £125.00 28 months ago. Last week went to start the car and it was dead. Jump started it but again after running it. Following morning it was dead. Nothing left on overnight, Not the first time it goes dead if l have been away for a week and need to jump start it. Main Dealer this is nornal, is this right or am l being fobbed off.

  

[Cyker]

It definitely should last more than a week, assuming you're using the car regularly and giving it time to charge up the 12v Battery!

My brother is having similar problems with his Mazda 6 - Something is pulling more power than usual when the car is off and it kills the Battery if he leaves it for more than a week, but he hasn't been able to figure out what yet.

I know some people here were having an issue with the boot light not turning off when the boot was closed, and this was causing the Battery to drain faster than it should have.

Another known problem is having a Keyless entry fob that is stored too close to the car (e.g. car in driveway, key stored near front door), so both of them are continuously pinging each other instead of going into power saving mode.

If you can find a good auto electrician, they should be able to track down what's draining the battery.

 

[Chris Dance]

What was the warranty on the Battery when you purchased it? I do think the dealer should be carrying out some checks to see if something is draining the Battery. Otherwise if there is no obvious reason for the Battery going flat ask for a new one under the battery warranty. Our 17 reg Prius battery failed after 3 years. I could not get it changed under warranty at the dealer because it was in the first covid shutdown and  all garages were closed. I therefore had no option but to pay for a new battery from the AA.

 

[Cyker]

Well, they should, but if they're anything like my dealer they probably don't care unless you pay them £150 for a diagnostic!

But that's a good point, might be worth checking the manufacturing date on the Battery as if it's old and has been sat in their parts shelf through all the lockdowns it might actually be a duff battery as I'm sure they don't give the batteries topup charges, and if it drained that would affect its life (Although it should still last more than a week!)

 

[BhxTrev]

I just wonder if the alternator isn’t charging the Battery properly for some reason. I’m sure some garage could check that out pretty quickly without charging you too much. At least you’d know that it was probably the Battery or some other cause as mentioned by others. 

[Catlover]

59 minutes ago, BhxTrev said:

I just wonder if the alternator isn’t charging the battery properly for some reason. I’m sure some garage could check that out pretty quickly without charging you too much. At least you’d know that it was probably the battery or some other cause as mentioned by others. 

Trevor, I can’t speak for the 2008 Prius (original post) but Gen3 and 4 don’t have a conventional alternator. I think the hybrid Battery charges the 12v Battery, a lot of garages wouldn’t know that.

[Cyker]

No you're right - no Toyota hybrid has a conventional alternator to charge the 12V battery; They're all charged by the high-voltage system via a DC-DC buck converter.