Prime 2023 12V battery integrity on EV

Mr. V: which battery monitor do you use?

 

There is a complicated battery sensor and a computer that optimizes the 12-V-battery charging to extend the lifespan of the battery. It probably doesn't always charge it to 100% SOC because the battery is too hot, too cold, etc.

I have never had any issues with my 12-V battery in my 2021 Prius Prime Limited, despite leaving it undriven for more than six weeks once and having the full Toyota Connected Services subscription for three years. I never trickle-charge it. If you follow the precautions I listed in my previous post, the OEM Prius Prime battery will probably last for more than ten years unless the car sat undriven at the dealer for a long time.

 

Toyota says the original battery was defective and the charging system was fine - hopefully I will not have an issue with its replacement. I do drive the car most days, so I don't really see why it would have died without some sort of defect. My son't car (my gen 3 2013 Prius) did sit undriven for almost 2 weeks, in the cold, and appears to have taken a charge fine, and the car is putting 14v or so into it, so I suspect that is OK too.

 

You don't leave it plugged in for longer than overnight, right?

Did they put a Toyota TrueStart DIN H4 as the replacement battery?

 

It is probably more accurate to say the 12V isn't drained during charging. There are systems that monitor the charging process that run off the 12V system, which is powered from the wall when charging is active. With the plugged in, and charging not happening, those systems are still active to a degree in case charging starts up again. At those times, the 12V is powering things. Unplugged, those systems are off.

What Level charging do you use? Level 1 could mean not enough available energy to actively charge the 12V up.

 

Defective parts in new cars do happen. Starter batteries aren't immune to this fact.

 

How is this relevant to my post?

 

Your first question was one insinuating user error, which is something you imply in all these bad 12V threads I've seen.

 

What was the voltage after 6 weeks? I have battery temp also, not an issue.
To have a set of data, maybe get a battery monitor to see what is actually going on. Looking at the threads, 12 volt is a recurring topic. How many 12 volt discharge threads would be in a Toyota truck forum?
I saw your previous post. I already know long trips charge the battery. I am not making unnecessary long trips to charge the 12 volt. But a person doesn’t really know what the 12 volt is doing anyway, it’s guessing. It would be interesting if you could report state of charge and voltage value as your car sits and drives. I think you would be surprised.

 

I asked him a simple question. There was no "insinuation."

Moreover, I mentioned in my former post the possibility of the battery degrading because the car not being driven at the dealer for a long time.

Factory-defective battery? That is a very small chance. GS Yuasa is very reputable company, and they wouldn't deliver batteries without testing them. I hope you are not claiming that all 12-V battery problems in new cars are caused by factory-defective batteries.

I did have a 12-V battery failure in a brand-new 2009 Corolla XLE once, and I knew it was my fault because I had stopped regularly driving the car and was driving my old car instead. The Toyota dealer still replaced the factory OEM battery with a Toyota TrueStart battery under warranty with no questions asked.

 

I didn't check.

Interesting, yes, but I want to have one less thing to obsess about.

 

How many Amps does your monitor show are being dumped into your 2020 Primes 12volt when it's being charged? What are you calling fully charged?

 

It doesn’t show amps. I got a clamp meter for that and Weber Auto shows where to measure it.
It’s something to bring friends over on New Years Eve to watch.
I have the charger going right now. When I got home the soc was 79%.
Get one on Amazon and try it, don’t like, return it. Otherwise it is too much writing describing.

 

You can organize them on a schedule.

 

I'm not a big fan of verbose posting, but you are at least still writing about only the 12 volt and not both the 12 volt and the 351 volt batteries, right?

 

With 3000 km on my 2023 PP, I have just had on-warranty replacement of its defective 12V battery.

The discovery I want to report is that Toyota does not use flash (non-volatile) memory to store the owner's configuration choices, so now I have to go through the menus again, re-indicating all my options. My advice is to take notes.

Following Mr. Vanvandenburg's excellent example, I will be installing a monitor for the 12V battery.

 

The topic was 12 volt. I am charging the 12 volt now, which was at 79%.

 

Interesting! I just had a 3000 mile defective battery replacement (hmm, not suspicious at all) and ALL my settings were there! I was wondering if the Toyota app saved them? Or maybe my dealer uses a memory-keeper when changing? Or meybe they didn't change my battery at all?

I think I'll be getting a monitor too!

 

I don't know if the Toyota app saves them. It does not (as far as I can tell) give the user access to them (for example, I can't use the app to see what blind-spot-monitoring options I've chosen, let alone change them).

If your defective battery was not quite dead when they replaced it (mine was quite dead), then they could have

1. used a memory-keeper, or
2. changed over carefully. Instead of just disconnecting the old battery (as my dealer must have done with mine), your dealer might have first connected the new battery in parallel to the old one, then disconnected the old one.

Since

1. the built-in instrumentation gives one no way of monitoring the 12V battery (a design error), and since
2. these are new-technology batteries, with a non-trivial observed rate of defects, and
3. they self-discharge more rapidly than most owners expect, and
4. they are charged only when the car is powered on. In particular, they are not charged while the traction battery is being charged (a design error)

a battery monitor is, I think, an essential accessory.

The monitor I got plugs brainlessly into the 12V power socket (once called the cigarette-lighter socket). Mine is from Motomaster, C$20 from Canadian Tire.

Once I've had it for a week or two, I'll post some data here.

 

The only reason I thought that was for a fleeting second when I first started the car I thought the display flashed "restoring settings" but I sure could be wrong.