Battery or Alternator issue

My car started this issue 2 months ago. The battery sometimes dead for no reason after I park for 8 hours at work. I've got to jump to get the battery work. I bring to Autozone to check and they have only 8-10v. That meant my alternator needs to be replaced? My car is civic 2016 EX and 40,000 miles. Anyone has this issue?

tisuanhoc said:

My car started this issue 2 months ago. The battery sometimes dead for no reason after I park for 8 hours at work. I've got to jump to get the battery work. I bring to Autozone to check and they have only 8-10v. That meant my alternator needs to be replaced? My car is civic 2016 EX and 40,000 miles. Anyone has this issue?

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First I'd get a load test done on the battery, before you jump to the alternator conclusion, my first suspicion would be a 4-year old battery going South. I'd also make sure the battery connections were good and clean. A couple of high resistance (shorted) battery plates will draw down charging voltage.

Yeah I hardly doubt it’s an alternator issue. Your battery is more likely to go out than your alternator. Your battery simply just isn’t holding its charge anymore. Did autozone run a load test on the battery?

+1 for the battery being the issue.

Your Civic is 4yrs old now. All the stops and starts, etc have worked the strength of the cells down. Time for another battery.

These batteries may test fine too, but they are essentially too small for our cars and have been a known issue even from day 1. In your case, definitely would say the battery has reached it's end.

I've been driving Hondas since the 80's, driven Civics, Accords & Preludes, only outright battery failure was in an 89 Prelude (actually failed at the dealer!) Have replaced a few Civic batteries, usually when my mechanic indicated some weakness during a Multi-Point inspection, the Prelude got a Interstate battery, the few others were always Honda batteries that they warranty for the life of the vehicle. I live in the Midatlantic area, winters are typically not too extreme, sometimes going below zero, but have never noticed a capacity problem. Worked at a hospital for 25 years so car had to start, always did, never let me sit.

PhilF said:

First I'd get a load test done on the battery, before you jump to the alternator conclusion, my first suspicion would be a 4-year old battery going South. I'd also make sure the battery connections were good and clean. A couple of high resistance (shorted) battery plates will draw down charging voltage.

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I cleaned the connections and It worked. Voltage displayed full. And I'm going to replace the battery soon. Thank you guys for your help.

Just had to do my battery after 20 months. Probably the battery

Easiest way to check if the alternator is working fine is if you have a charging light on in your cluster(the one that looks like a battery) there is likely a charging system fault. Which is almost always the alternator. Also if you can turn the car on and then put a multimeter between the two battery terminals while it's running it should show between 13.5-14.5 volts. That will tell you the alternator is charging the battery. If the battery tests ok on a load test you may have a parasitic draw(something is putting a draw on the battery) and if that happens to be the case you may need to have a mechanic do an electrical diagnostic.