Battey keeps flatting

[CeriUK]

I have a UX 250e h 43 k miles driven

and during a recent cold snap my 12v Battery did not have enough charge to start the car. 
 

I jump started it easily and done some motorway journeys 

However if I don’t use or start the car for 4 days or more it flats again 

do I have a dead Battery or is it a symptom of something else please?

the hybrid Battery is fine and had a perfect health check during my last Lexus service 

 

 

 

[steve2006]

Hi Ceri and welcome to the LOC. 😀

At 4 years old and with temperatures now falling the prime suspect, I agree, would be the 12Volt Battery.

Personally I would take it to the dealer for a check and not one of the “Free Battery Check” places where one of their “load tests” could create additional issues with the car’s computers if the voltage falls excessively.

Basically if Lexus mess it up the car is already there and they will have to sort it.

Although I have a petrol V8 the fact it spends more time in the garage not being used than driven plus mainly local trips when it is usually kills my Battery in 3-4 years.

[Lexusjim]

Ceri

Welcome 

 

I agree with Steve. Most  likely a failing 12v Battery. 

Once the car returns from the dealer (hopefully with a nice new Battery,  I recommend  fitting a Battery monitor such as: 

https://www.ancel.com/products/ancel-bm200

that way you can easily keep an eye on it to ensure it stays in top condition.  You are probably aware that it is a big no-no to have the car in accessory mode....it can flatten the Battery in 20 minutes...always ensure it is in ready mode if you are in it. 

Additionally,  if the vehicle is not being used for days at a time, you might consider a trickle charger, such as https://www.amazon.co.uk/gp/product/B07JLX9J15/

(Other makes are available) 

A jump starter such as

https://www.amazon.co.uk/NOCO-GB40-UltraSafe-Lithium-Starter/dp/B015TKUPIC?

is also a useful purchase. Lots of arguments on the forum along the lines of 'you shouldn't have to buy these items for a car that costs  £xxxxx' however I prefer to be 'looking at them rather than looking for them'

It's a lovely car....don't let this put you off

 

[Pauly C]

Notwithstanding the above, I am (very) reliably informed a driver does not need to go out for a thrash up and down the motorway to charge up a half dead battery…..having the engine idling (if you can get it started) will charge up a Battery just as quick, and will use less fuel😉