Our experience with my wife’s car during the previous month makes me think it makes a lot of sense to install bigger batteries in these scooters - specially in countries like the US with very cold winters.
In short - a local battery dealer installed a brand new battery in my wife’s car (Ford Focus 2Liter Trend with EFI).about 10 months ago.
During the previous month the engine light suddenly started coming on, and on the same day it started coming on my wife phoned me in quite a panic - the power steering warning light, as well as the ABS warning light also came on by times.
I took the car for a short test drive that evening, and realized the lights were not as bright as usual. When I started the engine, the power steering pump did not work, but came on after a while. During the test drive it was clear that the engine was less powerful than normal.
The weak lights made me think the battery was not fully charged and when I got home I hooked the battery to a battery charger. It was clear that the battery was not fully charged.
The next morning I did a test and it was clear that the battery was charging normally when the engine was running.
So I took the car back to the dealer who installed the battery about ten months ago. After some tests they confirmed that the car’s charging system was working properly, and the battery was still “fine”.
During a discussion the branch Manager had a look at a manual which indicates the correct size batteries on all sorts of vehicles. He then had a look at the battery in my wife’s car and asked me “ Who installed this battery ?”. I told him “ You people did - I still have the paperwork”.
He then shook his head and told me “Well this battery is too small for this car, you need a bigger battery”.
Long story, but they installed the correct (bigger) battery under warrantee. Since installation the power steering and ABS warning lights never came on again. The engine warning ligh died after a couple of kms, and never came on again., and everything, including power steering works perfectly. The engine power is back to normal as well.
All problems solved just by installing the correct size (bigger) battery. The smaller battery simply could not handle the power feed to several systems on the car. The smaller battery worked well for about ten months, but could not handle the power draw any longer.