I my alternator dying or battery? I've checked with multimeter
Hallo Mazda 2 users 
I got 1.3l 2011 Mazda 2 - I do not know if my alternator is dying - I got about 12.8V while charging when engine is warm and has about 600RPM or about 13.5V when cold engine when about 1500RPM - sometimes even 14V when bit higher RPM.
I've bought new but the cheapest battery about 3 months ago and not sure if it is its problem.
Currently I got battery at 12.2V (when engine off) when I turn lights on and fan at 1 speed (when engine off) - I got about 11.2V
Does alternator charges battery slower (lower Voltage) when battery is low (12.2V)?
I got battery charger at home and my old battery which had 11.9V it was charging it at about 13V - but when battery reached about 13V - it charged it at 15.1V.
100% I've cleaned metal clamps and poles with sandpaper and tighten clamps as thigh as possible.

I got 1.3l 2011 Mazda 2 - I do not know if my alternator is dying - I got about 12.8V while charging when engine is warm and has about 600RPM or about 13.5V when cold engine when about 1500RPM - sometimes even 14V when bit higher RPM.
I've bought new but the cheapest battery about 3 months ago and not sure if it is its problem.
Currently I got battery at 12.2V (when engine off) when I turn lights on and fan at 1 speed (when engine off) - I got about 11.2V
Does alternator charges battery slower (lower Voltage) when battery is low (12.2V)?
I got battery charger at home and my old battery which had 11.9V it was charging it at about 13V - but when battery reached about 13V - it charged it at 15.1V.
100% I've cleaned metal clamps and poles with sandpaper and tighten clamps as thigh as possible.
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GopherInWI
Mazda Protege
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Oct 11, 2025 08:51 AM



