Memory keeper

I have seen people recommend using a ‘memory keeper’ to save radio settings,etc. when disconnecting the cars battery, they seem to plug into power port (cigarette lighter to us older folks)…but my '09 Mazda 3’s ports are only live when the key is on run or accessory position. so do I leave the key on when disconnecting the car’s battery? doesn’t seem right to me, any thoughts?

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There’s also a version that plugs into the OBD port. That’s the one you’ll want if your power ports aren’t live when the car is off.

Better yet, here’s an example of one that works both ways:

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You can also hook up a 9V battery to the ends of the cables to the + and - terminals. As with any such setup, don’t have anything electric running, even a door-open light, when relying on the small battery.

No offense, but I kind of doubt that

My sister-in-law has a 2010 Mazda 3 and the power port is hot 24/7

I know this for a fact because I’ve verified it with a multimeter

It looks the accessory plug is for connecting the unit to an external power supply, not to plug into the car’s accessory outlet.

This might be adjustable. On my 2007 Town and Country van, it can be set to be always live. It depends on the position of its fuse inside the under-hood fuse box.

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Quite right, I missed that. Thanks for the correction.

I took an old 12 volt power supply for a printer, attached a power point socket, making sure the positive went to the center stud, you could do a permanent splice if desired for the obd connector.

If you have another good 12V battery, you could clamp jumpers from it to the + and - ends of the car’s cables. When you unhook the cables from the battery you are are replacing, that car still has a good strong power supply that won’t be bothered by a dome light or door open chime, etc.

well, i’m not a complete dolt, I checked both outlets and neither has power with the switch ‘off’, also the electrical diagram confirms that…as does the owners manual.

I don’t know what to tell you except this . . .

My sister-in-law’s 2010 Mazda 3 has a power port which is hot 24/7

I’m not sure why yours is different. Same body style, but one model year difference

hers is an S hatchback . . . I don’t know what you have

I’m not arguing with you . . . I guess I’m just telling you that my sister-in-law’s Mazda 3 has the power ports configured differently

I checked the front and back outlets in the Acura and they are off when the switch is off. Maybe there is a hot one some place. I’ll be a little more thorough closer to battery time.

Did wifes subaru with jumper cables and lawn mower battery, those little memory savers will be pulled to 0v if you go key on and fuel pump tries to prime, also if your headlights are set for daylight driving lights, most headlamp fuses are 20a and up and fuel pump close to same, little memory savers will only put out about .5-1amp…subaru doors closed key off headlights off jumper cables and lawn mower batt worked fine for me, negative to bare metal on engine or frame, follow positive back to fuse block or alternator and clamp on there…be cautious, while your cables are off your terminals are still hot so dont let them touch anything or each other

Well that’s an idea. The one time I tried it, the clamps on the terminals liked to slip off. You can swap cables in a minute or two so doesn’t take much.