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AC o r Headlights Causing Faster Battery Drain?

AC o r Headlights Causing Faster Battery Drain?

Whenever I drive at night with AC and headlights on, the battery performance seems to fast, especially if I make short trips.
Does this indicate the alternator isn’t charging properly under load? What can be done to stabilize voltage levels?
Zarnish asked on 05 Aug 2025 17:55:58 pm
2 Answers
26 views |
Car Mechanic Expert - on 05 Aug 2025 18:01:53 pm
If voltage s significantly while running AC + headlights, it’s a charging system issue.

Likely causes:

Weak alternator output under load

Failing voltage regulator

Underrated alternator for electrical demands

Fix:

Test battery with and without AC/headlights on

Upgrade alternator if possible o r battery to higher amperage rating

Check if the engine RPM is too low, reducing alternator output
Car Mechanic Expert - on 05 Aug 2025 18:01:55 pm
If voltage s significantly while running AC + headlights, it’s a charging system issue.

Likely causes:

Weak alternator output under load

Failing voltage regulator

Underrated alternator for electrical demands

Fix:

Test battery with and without AC/headlights on

Upgrade alternator if possible o r battery to higher amperage rating

Check if the engine RPM is too low, reducing alternator output
 

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