Install 12v battery maintainer under hood?

Post#10 is really good. Although I am not which battery it is referring to. Is the 12V battery under the hood is also called the Traction battery?

 

No, the 12v battery just starts up the electronics in a Prius. The traction battery is a collection of battery modules in series that add up to about 200 volts.

JeffD

 

the 12 volt battery is called the Auxiliary Battery in the Owners Manual and the techstream documentation.
the traction pack or traction battery refers exclusively to the high voltage battery.

 

@Sid786 -

OK, just got back from 6 months out of state. Left the 2018 Prime (original battery) on a Noco Genius 1 battery maintainer for the entire 6 months and the car started right up. After warmup I ran it in Charge Mode while driving it around for another 10 minutes just to run the engine. No codes or any other issues.

I did put some gas stabilizer into a full tank of gas just before I left. I also washed, clay-barred and put two layers of sealant on the car before I left (but that's a whole 'nother level of crazy).

 

@QUOTE="Pdog808 .... thanks for the update and this is really a great news for long-term storage, that Noco Genius 1 worked. I didn't had the option of the power outlet, so I bought the solar charger listed below. I had left my keys with a friend and after 3 weeks I did ask a friend to start the car and it started. So this product is working or 3 weeks is a short time for this test. Next time we will check after 4 weeks. Only issue is that the solar panel is outside the car. Another friend told me about an OBD-2 to MPTT converter, which plugs right into solar charger cable.

20W 12V Solar Battery Charger, Waterproof 20 Watt 12 Volt Solar Panel Trickle Charger & Maintainer, Built-in Intelligent MPPT Charge Controller for Car Boat Marine RV Trailer Automotive https://a.co/d/5tBVjNu

 

I've got a Noco GBC007 cable hardwired into one of my other cars. I can use the Noco Genius to trickle charge it or the Noco Boost to jumpstart. Very handy

 

People seem to be talking about 2 different things in this thread. The title of this thread refers to the 12V battery, yet some people are talking about the traction battery. On a Prius, the traction battery can only be charged via regen braking during the operation of the vehicle. On a Prius Prime, the traction battery is charged the same way BUT also by plugging it into a Level 1 or Level 2 charger - there is a receptical for this.
Back to the topic of the 12V battery. On pre-2023 cars, this battery can be located under the hood or on the trunk. It looks like a typical "normal" car battery except that it's smaller and very low cranking amps. I've owned a 2017 Prius and just recently added a 2023 Prius Prime to the garage. A couple of years after we purchased the 2017, a routine visit to the dealer service resulted in us being told the 12V was "bad" as it didn't pass their tests. They wanted over $500.00 for a new one. No thanks. I left it for a couple of years and the car never failed. Since that car was used only a couple short trips each week, I periodically checked the resting volts of the "auxilliary" battery. Some days, it was just below 12V and other days (after a drive, it was about 12.5+V). Because the car was now getting a few years into its life, I installed a Black and Decker fully automatic battery charger/maintainer. It puts in a trickle charge when necessary and shuts off when the battery is "full". A "trickle" charger may not be a good idea if it doesn't know when to shut off. A "smart" charger is the way to go. Everytime, (especially in winter) the charger was plugged in whenever the car came home from being used and unplugged at the start of the next trip. Sometimes, the car would sit for many days. It's been about 2.5 years since I started doing this and the 12V battery has performed well without fail and the car's operation has been flawless. At each service, there is no longer any mention of the 12V battery failing any tests. (I can't be sure, but I still think this was the service department's way of selling another $500.00 battery for their parts dept. It was completely unnecessary.)
This winter (first one for the Prime), I will install another B&D maintainer on the Prime and plug it in when I don't foresee driving it for many days. On the 2017, I use the positive and negative terminals on the battery that's in the engine bay. On the '23 Prime, where the battery is in the trunk, I'll use the recommended connection points (like when "boosting") as per the manual. There is one positive charge point in one of the main fuse panels under the hood. The negative can be any metal point on or around the gas engine. A smart charger for these types of cars is a no brainer.
As a side note, I have a voltmeter built into a USB adapter that plugs into the power port (cigarette plug, if you will). Anytime the Prime is running, whether it be in EV mode or HV mode, the 12V battery is being charged. Early in any trip, the voltage goes up to 14.2V. After it's been "topped up", it goes down to a more normal 12.6V.

 

I returned after 5 months and the solar trickle charger from Amazon was awesome and did it's job. During 5 months a friend did started the car for 10 minutes once a month. 12v battery is still working great and I have taken it off the trickle charger.

 

I'm sure that you provided some good information in your post.

It would be easier to read and comprehend if you would include a bit more white space.

Like this.

 

Yeah there's no way I'm wading through that second paragraph.

 

Granted its not the same since we aren't running an AGM in the Prius but I was previously using a NOCO Genius 10 with a Northstar AGM in my Tacoma. The NOCO's charge cycle just didn't cut it with the AGM batt. I ended up switching over to Victron's Energy Blue Smart IP65 12-Volt 15 amp Battery Charger and haven't looked back.

I have to revisit the specs of the Victron but as long as its fine with the Prius (and I don't see why it wouldn't be - 12v charger/maintainer), I'd recommend it over NOCO. Victron has always been a solid performing and top notch brand. The remote connect via BT is a neat feature as well

Take a look at the specs of the Victron. Google search -

blue-smart-ip65-charger

and you'll see the Victron product page as well as the amazon product page for the 15A unit.

 

My 2 NOCO battery maintainers both have AGM settings; maybe they're newer chargers than Mitch's. I just put a 12v AGM into the Prime, and I have a couple of AGM batteries on some small equipment.

 

The Genius 10 does support AGM however what I found was it did a piss poor job with the Northstar I have in my Tacoma. It would never complete the bulk charging state.

Once I switched over to the victron, no issues whatsoever.

Other than what I encountered with the Northstar, the Genius 10 did fine with my other (non-AGM) batts. Unfortunately, it's now sitting on a shelf in favor of the Victron