Hi, I'm going to leave my car for three weeks, what are some steps I can do to ensure the battery wont be drained when I come back.
I have a capacitor and LED alarm blinker.
The weather will be warm.
I do not want anyone starting the car while I am gone.
Should I remove the negative battery terminal?
Empty or full tank of gas?

thanks

 

This is just my .02; I think someone else should reply for a better answer, esp. if they've done it before.

But, I'd let my car sit before when I had to travel somewhere and couldn't take it, and I left it in the cold. For 21 days, you shouldn't have to disconnect the battery. You want the tank to be around half and 1/4 full. If it's a manual, make sure you shut it off in gear. If it's on flat surface, you shouldn't need the E-Brake up.

Just make sure things are unplugged in the car, like an IPOD or something. I let my car sit before and it was fine.

 

well some alarms use power all the time. paging lcd alarms use alot more power and can drain a battery in afew weeks. so if in doubt simply take the negative cable off and just be sure to lock it all up.

 

I'd personally pull the battery cable to be sure. Theoretically, parasitic draw shouldn't drain a battery that fast, but with an alarm system, your parasitic draw is going to be a lot higher.

Also, full tank of gas, definitely. If the tank isn't full, the cool mornings will make condensation form in the tank, diluting your gas. It probably won't be enough to do any kind of damage to your engine, but your fuel mileage over the course of that tank when you get back will be terrible.

 

o ya if your worried about the gas simply buy a small can of HEET gas treatment. it simply pours into your gas tank and helps burn any posibly water in the tank. simply dump a bottle of that stuff in your tank either before or after doesnt matter.

 

Unfortunately ECU reset from pulling a cable will make for horrible mileage as well until it relearns fuel trims, but I agree, pull that cable to be sure you don't drain your battery.

 

If you know someone who has a trickle charger you can borrow. those are nice and save your battery. All it is basically is a 12v solar cell that VERY slowly adds power to the battery, much like your alternator does while you drive. Buying one new is quite an investment though.

 

Not necessarily. Assuming the PCM has adaptive memory, the fuel trim will only get worse if he drives like a grandma. Adaptive memory adapts to the driver's driving style; they take the driving style (grandma driving, constant WOT accel, etc) into account and adjust the fuel trims, shift points, etc based on that (assuming there's nothing wrong with the engine like a leaky fuel injector, injector stuck closed, o2 sensor failure, exhaust leak before the primary/secondary o2's, etc). Otherwise, it'll resort back to its base fuel map, which will give decent fuel economy, negating engine wear and tear, tire pressure and condition, etc.

I finished the Engine Management Systems courses here at wyotech a few weeks ago... if you want me to, I could argue my point further

 

typically when i unplug my battery the motor doesnt run to well at fist, i just hop on the gas a bit and drive afew miles then i cut the motor off and start it back up and it runs just fine again.

 

I left my old jeep sitting in my driveway when I went to the UK for six months and when I came back it started up with no problem, but its probably good to disconnect the negative terminal on the battery to be on the safe side.