Re: How long to allow a car to sit?
If you want the battery to last for more than a few years, you should charge it before you attempt to start the car.
The engine may start with a significantly discharged battery, but it won't last long. Batteries have a sort of "chemical memory". If you commonly crank the engine with a significantly discharged battery, pretty soon it will never get back to full charge at all and fail early.
I have a friend with several cars, but he's not very mechanically astute. He typically only drives them once a month and he was complaining that his high price "premium" batteries only lasted a couple of years.
Once I convinced him to either charge the battery before starting if the car sat more than a week or leaving a battery tender on them, his short battery life "problem" went away.
A typical service type battery - the kind you have to add water to - losses about three percent per day at room temperature. Discharge rate is faster at higher temperature and lower at lower temperature.
A sealed battery has somewhat different chemistry and their discharge rate is only about one percent per day at room temperature, so a maintenance free battery is definitely the way to go.
I have two $39.95 Autozone (made by Johnson Controls) batteries that are closing in on ten years old and still going strong because I charge them before using the cars if they've sat a week or more, and I don't use battery tenders.
Duke
If you want the battery to last for more than a few years, you should charge it before you attempt to start the car.
The engine may start with a significantly discharged battery, but it won't last long. Batteries have a sort of "chemical memory". If you commonly crank the engine with a significantly discharged battery, pretty soon it will never get back to full charge at all and fail early.
I have a friend with several cars, but he's not very mechanically astute. He typically only drives them once a month and he was complaining that his high price "premium" batteries only lasted a couple of years.
Once I convinced him to either charge the battery before starting if the car sat more than a week or leaving a battery tender on them, his short battery life "problem" went away.
A typical service type battery - the kind you have to add water to - losses about three percent per day at room temperature. Discharge rate is faster at higher temperature and lower at lower temperature.
A sealed battery has somewhat different chemistry and their discharge rate is only about one percent per day at room temperature, so a maintenance free battery is definitely the way to go.
I have two $39.95 Autozone (made by Johnson Controls) batteries that are closing in on ten years old and still going strong because I charge them before using the cars if they've sat a week or more, and I don't use battery tenders.
Duke
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