Ok, hypothetically, lets say someone accidentally left their lights on their brand new ~ two weeks old ~ smart fortwo and drained the battery. How would you go about charging the battery? Again, we’re talking hypothetically here, but let’s say for arguments sake, the said fortwo is stored in a garage, but it’s not heated and the owners manual says not to charge/jump start a frozen battery. Should I tell my friend to remove the battery and warm it up? Is that even possible? Is it better to jump start is and get out and drive it or leave it on a charger? The outside temperature in this “pretend” situation is about 20º F.
Ok, hypothetically, lets say someone accidentally left their lights on their brand new ~ two weeks old ~ smart fortwo and drained the battery. How would you go about charging the battery? Again, we’re talking hypothetically here, but let’s say for arguments sake, the said fortwo is stored in a garage, but it’s not heated and the owners manual says not to charge/jump start a frozen battery. Should I tell my friend to remove the battery and warm it up? Is that even possible? Is it better to jump start is and get out and drive it or leave it on a charger? The outside temperature in this “pretend” situation is about 20º F.
Any advice would be appreciated.
I would not attempt to jump the battery as too much current can flow into it and if it is frozen, it WILL explode.
and dead batteries, and given the car is inside a garage although not heated, it is unlikely but possible that the battery is frozen. Now...if the battery sat outside over nite in a totally dead state, then it may freeze up.
To be safe, I would read the battery voltage with a voltmeter and see if there is any residual charge there. If there is, the specific gravity will not quite be low enough to allow freezing solid. If that is the case, I'd disconnect the battery ground and put the trickle charger on the battery in the car and let it charge overnite or until the charger shows 3 or less amps. If the meter on the charger is showing steady 6-8 amps continously (thru the first hour of charging) then the battery is most likely shot. If it has tapered down, it probably will take more charge and should not be condemned.
As a 3rd option, remove the battery and do a load test on it after attempting to charge it as described above. These various options should tell you the true story.
I think it best to suggest to your "friend" that he bring the battery inside overnight to make sure that it is thawed out, than re-charge it. Can your friend get into the car with no juice available to operate door locks?
It wil help if when asking a question or requesting advice, to ALWAYS state the model (450-451). This is particularly important because the people who are most knowledgeable of the 450 aren't usually as knowledgeable on the 451 and vise versa.
If the battery is dead dead, and the car is locked, you will need to open it with the key, 451-left door, 450-tailgate.
A trickle charger will not blowup a battery ( even if it is frozen) and a battery, in a garage, in a car, at 20degree's is not going to freeze.
An auto, even one that can be 'roll started' ( Mercedes term), that has an alternator, cannot be roll started with a dead battery (alternator- electro-magnetic field Generator- permanent magnetic field). Plus because of the computer's need for power.
I would recommend a trickle (1-2 amp) charge for several hours minimum.
It should then have enough power to enable a roll start.
BTW: If your radio has been set to "Safe", you will need to reenter the code.
To remove the radio always set it to 'Code' first. this is also true when ever disconnecting the battery, resetting the computer to a new primary driver.
Remove the rubber plug on the lock and use the key to enter if the battery is dead.
Is it quicker to Florida?....or by train? Is it colder in Cincinnati or in the Winter? Pardon me for being a wise guy here but I just couldn't let this one go.
The issue was what to do with a dead battery....not how to get into the car if the battery is dead.
I meant no offense but hope others will get a laugh out of my reply. I am alittle giddy today as I am going on vacation for the next week and am really looking forward to some warm weather and sunshine for a change.....
Thank you for the advice. It wasn't locked, so entry isn't a problem. I called my dealer and they advised using a trickle charger and give it over night. I was most concerned about it being frozen. I didn't know that was even an issue until I read the owners manual. There was a water bottle in my other car and it wasn't frozen, so I'm guessing my battery shouldn't be either.
Another question, when I realized the battery was dead when I couldn't get the trunk open (which was locked). Is there a way to open it when it's locked?
I have a 2008 451 Cabrio, sorry for not including that in my original post.
I'm glad you are asking I don't have any idea were the battery is located in the 451. I quess you could put down the passenger seat and get to the back of the engine.
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Pardon me for being a wise guy here but I just couldn't let this one go. 
Today
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