I understand that to change out a battery in today's cars/trucks it is important to keep a constant supply of power to the CPU amongst other components.
I'm interested in a gadget that plugs into a cigarette lighter and powers these devices by way of a 9V battery.
I'm a little vague on how to connect it up. Question: Should the memory saver be connected while the battery is still connected to the vehicle? If yes,what is the chance of "blowing" up the 9V battery?
Does your car owners manual have any special instructions to follow when replacing the battery?
I would think that disconnecting the battery completely before inserting the "keep alive" gadget in the DC power socket would defeat its purpose since you could lose whatever settings would need preserving in the small interval of time the system is totally without power.
Does the gadget have any instructions?
I doubt the CPU in the car ECM would need a constant supply of power. The memory in a car's computer isn't like the RAM in a desktop computer where the memory is cleared when the power is switched off.
You would need to keep the circuit powered only as a convenience to prevent the car's radio from going into anti-theft lockout mode. Many radios, if not most, these days, will require you to enter a code after you disconnect and reconnect the battery before you can use the radio. There may be other settings that depend on a constant supply of power, like seat memory settings, etc.
If you don't know the radio code, but the radio is currently working, using the gadget you mention will allow the radio's security circuit to stay alive while you replace the battery. But you can just go a dealer for the make of car you have and prove to them you are the legit owner by showing your registration, and they will give you the radio code (if it's the original radio).
Service shops use a similar device when replacing a car's battery. It prevents them from the hassle of having to reactivate a customer's radio, and keeps the clock from losing time. I would suggest asking a friendly service garage about this, and get their input.
I've seen similar gadgets that use a dedicated battery pack.
I searched the web for you, and happened upon this idea (use at your own risk): hook up the new battery in parallel with the old one before you remove the old one. That would accomplish the same. Sorry, but that sounds like a hassle to me.
Thanks to LAVESH,Larry,and Everett for your replies.
Great info and references.
I guess i'll get one of those little gadgets in case i need to change out a dead battery, and my local Mechanic is closed.
Thanks again,and Happy New Year.