DFOR

Put the car away for the winter in December. And, stupid me, never but the battery tender on it.

Obviously DEAD battery a few weeks ago. Got it charged it a few days later. Started right up.

Will I have problems with the battery this season, or did I only shorten its life. Replaced it about 2 years ago. Thanks.

DetroitPlac

My battery is 7 years old. I've drained it twice this year now in getting my car back together. Still seems to have plenty of juice. I wouldn't worry about it.

vettpapaw

I have done the same thing several times and it didn't seem to have any effect on my battery.

c4cruiser

How cold did it get in the garage or wherever it was stored? A fully discharged battery may not survive extremely cold temps.

If the battery did get back to a full charge (what is the voltage after disconnecting the negative cable?), it might be a good idea to have a load test performed. That will tell you if the battery has been hurt.

tbrowne

Generally, starter battery life is halved each time it is completely drained. Marine batteries are built to be regularly discharged without damage but they don't provide the cranking amps that a starter battery does.

TrackAire

It really depend on multiple things, but my main business is 12 and 24 volt dc motors and batteries are our number one issue because we can't control what is in the customers vehicle.

Never let a battery go below 10.5 volts as it will diminishes its reserve capacity. Regardless of what the construction is or what the marketing materials say, deep discharging a battery is the worst thing you can do to it.

Deep cycle batteries also fall into this same situation. Deep cycle does not mean deep discharge.....so don't let that marketing jargon fool you. A standard sized deep cycle battery likes to give 20 amps per hour and absorb 20 amps per hour and it can do this multiple times. That's why they don't make great starting batteries and RV use 4 to as many as 8 batteries in parallel to give the amps needed to run high amperage inverters, etc.

A fully charged 12 volt battery should be at 12.7 volts. 12.5 volts is already at 90% capacity and 12.0 volts means 50% capacity....you can see how ugly the discharge curve is to performance.

The main issue you will find when the battery gets damaged is lack of reserve capacity and the ability to maintain a charge. So for example, if the battery was fresh and not abused, you could park your car without a battery tender for over a month and it would start up no problem. Once the battery starts to have issues, you often can't start the car after only 2 weeks, then 1 week, then 3 days, etc.

Sometimes you get lucky and the battery survives deep discharge and can give you years of service. But conditions such as sulfation, acid levels, temperatures, vibration and G-forces, etc can drastically alter the performance of the battery. Batteries are like milk, eventually they will go bad just due to time regardless of how you treated them....add in deep discharging and this accelerates the process.

Nyt_Muves

I did the same this winter. I have a red top optima. Seems ok now but I'm tempted to replace it anyway so I don't end up stranded.

3sACROWD

If there is a chance the battery froze replace it. The case may have been compromised. Battery acid and C5s don't mix!

Years ago I had a battery freeze (non Vette) . Took battery out to thaw and to get to an outlet for charging. Looked fine. Put back into car and worked fine. Days later my clothes had holes in them from the acid. I replaced the battery.

rrwirsi

How old is the battery? I change mine in every car after 4 years. Never had starting problems since doing this procedure.