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Replacing a car battery without losing the radio code

Maintenance/Repairs
#1

Hello,
I read that in order not to lose the radio code while replacing a car battery, the leads of the battery should be connected to a secondary power source. I have a booster/jumper pack which I would like to use as the secondary power source. While using it to jump start my car, i was advised to connect the black clamp to the chassis of the car but not to the black terminal of the battery. Should I do the same when I replace the failing battery? If so, will the radio code be kept? I am just concerned that by leaving the black lead, which connects to the failing battery, unconnected until i mount the new battery, the radio code might be lost as the electronic parts of the car won’t be powered with the jumper pack

Thank you

#2

If the battery is discharged below 5 VDC, not only will the radio presets be lost, but also the adaptive memory in the computer, and any learned programs in modules can also be lost.

So, once the battery is dead, it’s a moot point.

Tester

#3

Thank you Tester for your prompt reply. The battery is not yet dead but failing to start the car without a booster, that’s why I bought a replacement to it. I have edited my original message using failing instead of dead battery

#4

Does the radio in your vehicle require a security code?

#5

In that case, go to a local auto store and purchase one of these.

Just plug a nine volt battery into it and plug it into a cigarette lighter or a power port that has constant power.

This will keep the memory for the radio, computers. and modules while the battery is replaced.

Tester

#8

Thank you. I thought I could use the booster/jump pack

#9

Yes, it does

#10

A jumper pack works, until you try to connect to a GM battery with the side mount terminals, and remove them at the same time.

Tester

#11

Well you can use that but why bother for $10? The black cable for the battery is the ground. That means that it is connected to the metal framework of the car. So whether you connect black to metal or to the cable makes no difference. The red positive is different.

If you do use the memory saver, make sure you plug it into an outlet that is powered all the time even when the car is off.

#12

If you use the ones that plug into a poerpoint, you have to make sure it is live when the key is off. I got one that plugs into the obd2. It has a powerpoint adapter, I rigged it to a socket with an old ac to 12v dc adapter.

#13

I have replaced a few batteries and not lost the radio codes or computer memory. I think they have enough storage/memory/charge or whatever to stay live for a few minutes. I had enough time to clean the terminals too. Did not waste any time but got lucky each time.

#14

Connecting that device to only power the radio could present problems b/c the jump pack is probably designed to be connected to an automobile battery. The battery it is connected to has massive capacitance which will reduce or eliminate current and voltage spikes produced by the jump pack. The gadget mentioned above powered by an ordinary 9 volt battery is a better choice imo.

#15

The jump pack contains a battery, only smaller than the common vehicle battery.

#16

https://www.tayna.co.uk/tutorials/change-car-battery-without-losing-radio-code this guide is pretty good and is a very good step-by-step instruction.

#17

Don’t know where you live, but the last couple of battery replacements were done by the local auto parts store, who used a memory saver. I had no problems with the replacement and didn’t have to buy anything else.

#18

I’ve done what you propose, and it has worked. And I have not fried anything.