Q: New alternator, car not starting in the cold

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As the weather started getting cold this winter my car started stalling out, but once it warmed up it ran fine for the rest of the day. Then we had one severe cold day and it wouldn’t even start. My friend and I jumped it and I took it to WalMart to have them test the battery. He said the battery was fine but it wasn't receiving a charge so he thought it might be the alternator. I spoke with a few mechanics and everyone agreed. So yesterday, it won’t start again in single digit temperatures, and I change the alternator. It started after a jump and we let it run for a while. After it sat off for about six hours in negative wind chill I tried again and it started fine. Then it sits overnight and this morning it won’t start again. Is it possible that I just didn’t charge the battery long enough? Or are we looking at a completely different problem? Side note...I’m trying hard to not put a lot of money into this car and I only need it to last a few more months. Thanks!

My car has 180000 miles.
My car has an automatic transmission.

As you may know, cold weather is extremely tough on batteries. Depending on the strength of the charge, you may not have charged the battery sufficient to a point for it to hold a charge. Generally, for a battery to charge significantly, it will need to run for 30 minutes to an hour for the alternator to properly charge it. The other possibility may be that you could have a failing voltage regulator, which is the unit that monitors the charging of the battery by the alternator. If this is not working properly, the alternator will not properly charge the battery. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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