This has been widely discussed on the Toyota Yaris forum: www.toyotaownersclub.com/forums/forum/49-yaris-yar.../

It seems fitting a battery of different manufacturer than what it comes with may be the solution.

Except Toyota confirmed that fitting a battery of a different capacity (as suggested on the forum) would affect the warranty.

We intend to use our smart charger every week and keep the starter pack handy.

We intend to use our smart charger every week and keep the starter pack handy.

For 18 years, I didn't use my car for work (not even for commuting). My car sat unused through the week and was normally only used at weekends. Never had any starting or battery issues. Never used a jump pack or charger.

Surely you shouldn't have this issue with a modern hybrid, even if it's only used a couple of times a week.

Agree you shouldn't but it seems its normal for all Toyota hybrids. Instead of the Yuasha battery they now fit one called the Mitlu which seems to be r******.

Never had an issue with our Superb PHEV in 3 1/2 years (fingers crossed) but when we went to look at a Kia Niro (hybrid) the battery only managed to unlock the car (demonstrator) and it was then dead. Salesman said press the button under to dash which transferred enough charge in about 3 seconds to get it going.

Apparently the batteries on these Toyota hybrids are small and not too powerful since they don't have to churn the engine etc, its only enough to get it to realise its a car. But after a few days the drain from car systems drains them enough to make the car a non-starter.

The "experts" on the forum say that fitting a higher capacity battery will sort it and from experience it has worked for me in the past but Toyota say fitting a battery with different capacities to the original will affect the warranty.

I tend to believe Toyota rather than an internet "expert" who assures people spending £120 is fine.

There is a "mode" on the car called "ready mode" which charges the battery with the car sitting on the drive, road etc without actually driving it. Trouble seems to be the cars needs to be turned on and in the hour it takes the engine will restart several times. IMHO not a great idea leaving your car in this mode, would be likely to go missing and insurance would almost certainly not pay out.