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New battery dead, is it the alternator

2003 Ford Explorer XLT with 110K. My wife left the lights on SUV and drained the battery. I could not jump it. Noticed it had the original battery in it so I replaced and it drove fine for 1 day and died again(lights were not left on). I checked voltage of battery and it was 7.6V. Is it the alternator? If so, after I install new alternator how can I recharge my new battery…it’s only 2 days old?

Get the charging system checked. Some auto parts places do this free if you want to avoid the diagnostic charge.

Have the battery and the charging system tested. Most auto parts stores (or wherever you bought the battery) will do this free. It could be a defective battery or it could be something else. Don’t guess. Test the components and be sure.

Remember a free electrical system test is worth just what you paid for it,have a real mechanic check you FORD out.

It does sound like the alternator or the wiring to it has a problem. Use a battery charger that can deliver 8 to 10 amps to charge the battery back up. Don’t use the alternator as a battery charger, even if it is working like it should be.