12V Battery Replacement Recommendation

It’s 2025, but just wanted to let anyone who might need it, Amazon has OBDII memory savers that hook into OBDII and a 9v transistor battery for ~17 dollars. Search using this on Amazon:
9V Battery Powered Memory Saver for Car Battery Fit for All OBD ll 16-Pin Interface

 

So you attach this device to the obd2 port while you are changing out the 12V battery? Would it not create excessive charge briefly when both the battery and this device are connected? Is that ok?

 

It doesn't: voltage sources in parallel do not add. 12 volts ∥ 12 volts = 12 volts.

 

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Speaking of 12V chargers, has anyone used this Bosch charger?

 

Mendel Leisk has experience using the obd2 port for memory saving. I’m new to this forum and not sure how to contact him. I haven’t tried (or purchased) it yet. The amazon page has user reviews on using the product I’m looking at, which may also be a good source.

 

Yeah I posted this the other day.

That said, if I’m going to take brake calipers off the rotors, first thing I do is disconnect the 12 volt battery’s negative cable, without using a memory saver. It’s no big deal. I don’t really care about radio presets though.

 

To me, radio preset loss is a trivial side effect of disconnecting the battery. One annoying side effect is the resetting of calendar date in the display dash. I still don't know what the thinking was behind it. Perhaps the most important items in memory are learned parameters which can impact gas mileage. Still, it's a no brainer that one should disconnect the battery (and not use any memory saver tricks) when repairing brakes.

 

You have to disconnect the battery to replace brake pads? Is it because of an electric pump for the brake booster?

 

Mostly, yes. There’s been multiple reports here, someone has the caliper off the rotor, opens drivers door inadvertently, system pressurizes, and piston pushes out of caliper.

also, if you’ve pushed/screwed back caliper pistons to accommodate new pads, there’s a chance that a “sentient” brake system will detect excessive brake pedal travel, throw code.

battery disconnect is a blunt tactic for DIY’rs, just “better safe than sorry”, but it works.

 

Thanks I had to ask. I've replaced a fair number of pads and rotors on 'regular' cars over the years, and have never disconnected the battery. Here's hoping the brakes last a long time on my '26. There's a lot to learn.

 

Toyota USA “seems” to be recommending a tri-yearly or 30k mile brake inspection. It’s easy to overlook, due to the format of the Warranty and Maintenance Booklet, doubly so due to vague wording. Usually the pages say to “visually” inspect brakes (every 5k miles, presumably during tire rotation), but at 30k, 60k and so-on miles, the visual inspection statement is omitted, and a statement to check calipers and rotors (paraphrasing, it’s something thus) is added.