Community / Ask a Mechanic

A car that starts fine but has flickering/dimming lights, or accessories acting up, while the engine is running usually points to the alternator, not the battery — the alternator is what's supposed to be powering everything (and recharging the battery) once the engine is running. A battery problem more typically shows up as slow/no cranking at startup, not flickering while already running. A shop can confirm in a few minutes with a multimeter (checking charging voltage at idle and under load) before you pay for either part — worth asking for that reading rather than just accepting a part swap on a guess, since alternator replacement is a real cost (commonly $400-$850 at an independent shop in the GTA, more at a dealer) and you don't want to pay it if a battery or a loose/corroded terminal was the actual issue.

0 replies

No replies yet.