12V battery low or?

Yup, five years is a reasonable time for a battery to last. Time to go shopping.

 

In an ICE vehicle, it's easy to know when a battery is going low because cranking it will become more and more difficult so you can easily plan ahead and change it before getting stranded on a very cold morning. In an EV, things are quite different. All is going well until suddenly, nope, dead battery. I'm keeping a small lithium booster in my Model 3 frunk (that's the only thing you can pop open with a 9-12V battery when the 12V battery dies) so I can boost the car to make it come alive. Looks like I'll have to buy another one for my Prius Prime since the same thing can happen to it.

 

Was the car just sitting for a long time?
This is the scourge of the Prime. You need to keep that 12v battery from getting too low. If you plan on letting the car sit for a while invest in a battery maintainer/trickle charger. There are numerous stories like yours in the forum posts.

 

Sorry. Somehow I was thinking this happened prior to your trip. I see you have a 2017 PP. 6 yrs is probably time to replace. The traction motor only charges the car in READY MODE.
I wish the Prime would at seast give you a LOW 12V BATTERY ALERT. But 99% of the time this happens is after the car has been sitting and the Telematics drains the battery. in your case in the hot conditions I wonder if the electrolyte evaporated?

 

It has to do with the fact the hybrid battery is 200+ volts and the under hood battery is 12 volts, and the circuitry to allow the big battery to charge the 12V battery when in READY mode is controlled by “the computer” which is booted by the 12V battery. There is no mechanical switch to connect the circuitry if the 12V is too weak to boot “the computer”.

If you’re shopping for a new 12V, I’d recommend this one from Walmart: EverStart Maxx Lead Acid Automotive Battery, Group Size H4 12 Volt, 480 CCA - Walmart.com

 

Yes, you are, guessing that is. Do you have a multimeter? That’d give you a rough idea; an electronic load tester (Solar BA9 for one) would give a good idea. Automotive retailers selling batteries tend to have the latter these days, and will test for free.

 

As a 12 volt lead acid battery ages its ability to accept a charge is diminished. Your short trip was not sufficient to recharge your battery (especially if you were using multiple 12 volt devices). Your battery had enough energy to start the car initially, but not enough to do so after a short trip. End of story and the story will repeat itself unless you replace the battery. Personally, I’d look at having your dealership install a new Toyota battery simply because the warranty on it is very good.

 

Yep, I've been waiting to buy one of those new battery jump starters...hoping for a good Black Friday deal....actually the one I've been watching just went down 40%...bought!

To know how "healthy" a 12-volt battery is, there are some excellent testers out there. I've had a TopDon BT100 tester that tells me the percentage of battery life left...anything around 50% or lower should be replaced. In my 2014 Tundra, the tester told me the battery was at 62% in Sept 22 so I'd test it almost weekly. In May 23, it was at 41% and the tester said "Replace". (Old battery was 5-years and 3 months old and the truck is parked outside so gets temps from -20 to 100 here.)

 

Short trips may not be long enough to charge a battery back up after the start up drain.

Some Hyundai hybrids don't have a separate 12V. They use a small portion of the traction battery for 12V duties. If it gets too low, you push a button, and the main battery portion charges the 12V one back up.

 

Good price, $160 vs. $210 for the same battery at O'Reilly. The similar batteries from O'Reilly and NAPA with 445 CCA will do fine, cost less, may have a slightly shorter life. These are made by EastPenn (DEKA), one of the 3 auto battery makers in the U.S. My choice is the ACDelco LN1 AGM battery from Summit Racing, $152 including shipping. But...if your local Walmart has this in stock, you can get it today.

Batteries don't "suddenly" fail. They deteriorate slowly over years. One day it doesn't quite have enough working electrons to get the job done, in our case to power the car's electronics.

 

The TopDon BT100 needs to bring the RPM to 2500 to test the charging capacity, I'm assuming this test is not necessary since the battery isn't charged by an alternator (what is being tested I think) but the inverter, right?

 

Right, but there's no telling if the test meter will show something meaningful in this non-standard system.

 

As I understand, Tesla does something similar.

 

As I understand, Tesla does something similar.

 

As I understand, Tesla does something similar.

 

No, they do have a low voltage battery, albeit, now it's a 16V Lithium battery (much smaller and lighter) instead of a 12V Lead Acid one. The difference is whenever the car is On, the battery voltage is maintained. There is no concept of Ready/On/Acc in Tesla.

 

When parked, Teslas would wake up when the starter battery measures low to charge it back up. Seems Bolts will also do so, but maybe only when plugged in.

A Tesla can also call the service center on its own when those charge ups become too frequent.

 

What? I didn't know that.