Sorry to quote old replies.

I'm not qualified nor has sufficient knowledge on this matter. Just stating my observation, usually this happen to local and japanese cars. i.e. at the red light, can observe their brake light/headlights getting slightly dimmer and brighter cyclically.

I've seen it happen to some P1, P2, H and T brand cars. Yet to notice it on continental cars (even the old ones don't really exhibit this phenomenon), I guess it has something to do with how they designed the car's electrical system. Might not be something that can be easily solved with aftermarket modifications.

On more recent iteration of these cars, most of them have full LED lights all round already, hardly notice

From my observation, 5 years++. More obvious ones, just keep an eye out for Myvi, Bezza, Axia at night while stationery and idling.

It's not like a huge difference whereby the brightness suddenly reduce by 50%, but noticeable that it is not constant.

Hahaha, I don't really look into the headlights directly, will go blind. Unless from inside the cabin

Looking at rear brake lights at night is easier to spot (Traffic light/traffic jam). Not sure is it because high current draw (headlamps 55w, fog lights, radio, brake lights etc), when the ac pump switch on and off might have contributed to that. But so many of these cars OTR, and people around me usually cite them as reliable cars, likely not a functional/reliability issue.

Just to chime on on a recent battery change.

2015 Mazda 3 2.0 came with Delkor Q85L EFB battery, dated July 2023. A new to me car, noticed the car started cranking a bit slower in the span of 2 days and seem to get worse gradually.

Ordered a new battery through Century ResQ, very quick response. They only had Century Excel Q85 EFB in stock nearby me, RM535 installed with trade in. Within one hour of ordering, their dealer rep showed up. Tested the Delkor with 44% SoH only, luckily I caught it early. Aanyway, gonna turn off the i-stop from now on.

Initially ordered a Varta silver through BateriHub on Shopee for the same price, their branch is literally 5 minutes away from me. Kept pinging them also no response through Shopee after 2 hours, also gave them a call through main hotline, no one picked up. Cancelled my order instantly, it's not worth it to put my money with a dealer like this. Take it for what it’s worth with this info

If the date written on the battery is genuine, 2 years and 3 months is about alright.

So far yet to detect any other anomaly, still have a list of preventive maintenance to do in near future.

I have a friend with new FL CX-5, 1 year old with 21k mileage. Car couldn't start last week, after jump start works again. Tested today at SC 79% SoH, SC told to continue using. On the second year, claim warranty on battery owner need to bear 50%