12V Battery Charging/Maintaining, Apt. Dweller Solutions

My daughter in CA will be the end-user (in a couple months?) of my new ’26 LE FWD, and I’m in the process of prepping it with a few add-ons for her. One small add-on from the maintenance side I want to do is enabling ease of 12v battery charging/maintaining. A Noco Genius2 or 5 is in her future.

Like many, she’s an apartment dweller in SoCal. So periodic overnight (or longer) charging of the small 12v Yusa 345LN1 is pretty much out of the question (too far from apt. 120v/15 amp outlets to parking area). At her workplace, no outside outlets. Although she does normally drive daily it’s usually short 10-25 mi.) trips, and she has the occasional 1-2 week trip somewhere w/o using her car. So need other solutions.

I read pretty much all this thread AGM battery for Gen 4/Gen 5 Prius/Prius Prime and observations on the 12-V charging system | PriusChat. Very helpful/interesting. I have been a believer in 12v maintenance chargers for many years, then and now use them on my non-hybrid gassers with 12v battery management systems that are more convoluted that apparently what the Prius LE HEV has.

My 1st thought – I put an eyelet terminal connector under the hood at the jump start terminal locations and (somehow) bring quick-connect to outside the grill area. Every couple of weeks or so, she goes to a friend’s place, uses their (garage, other) outlet, quick-connect the Noco and overnight (~12+ hrs) or longer charge it. Likely won’t hit full charge in that limited time but seems it could help and wouldn’t hurt.

So I popped the hood, removed the “exclusive” jump start terminals cover (aka Fuse & Relay cover). My hopes were dashed when I saw the + terminal under the red plastic cover wasn’t a nut or bolt but that flat plate thing. Fine for alligator jaw terminal clamp, not so much for trying to permanently mount an eyelet connector. So she’d have to pop the hood and use the clamps for charging. So be it.

2nd thought – do the same thing as (1) at the 12v battery (hatch) end. For anyone who’s actually done this, how’d you exit the eyelet connector from the trunk to the outside?

3rd thought – permanently mount the eyelet connector to the trunk 12v battery, and use a portable power station left in the closed & locked trunk area overnight to charge the 12v. Nothing exiting the vehicle. Just remember to unplug the Noco before driving off. She has a Jackery Explorer 500. Anybody try something similar to this?

Any and all comments/ideas welcome...….

 

Thanks, a valid suggestion. I did get her a small portable power jumper for Xmas last year for her Fit, verbally walked her through operating it, not long ago she of course had a ‘no start’ incident away from home, had to have a service call jump start. When she told me later about it I asked ‘why didn’t you try the jump pack?’ – answer was ‘because it was back in the apt. at the time’ (and uncharged to boot). So much for being proactive. I sadly got on her s*** list for a week or so when I mentioned, well I explained it to you but I can’t understand it for you – I won’t make that mistake again. But maybe she’ll remember to carry it again.

Yep bad batteries happen – had a 2017 Honda CRV OEM battery fail after less than a year from purchase, got a new one free, no questions asked.

 

Thanks. I did find that thread Battery maintainer install directly to 12V battery | PriusChat , very helpful. Good to know no hatch seal issues doing that. I think my little YUSA 12v battery is different than your Prime battery, I’ll find out soon enough, I do want to attach the eyelet connector to hopefully bypass the neg. side shunt resistor (assuming there is one on by Yusa cabling?) that measures battery current. Ran into this with my previous F-150 12v. battery maintainer install.

 

I’m still thinking about a potential under-the-hood solution. Bear with me and be kind (I’m new to both Toyotas and hybrids, the lingo/jargon is giving me some issues, and not strong on electrics):

My LE (HEV) has the ‘exclusive’ + terminal jump start copper plate under the Relay and Fuse cover. The plate threw me off, was expecting a stud/nut type arrangement.

There is a stud/nut in the box that comes from what the owner’s manual calls the Power Control Unit.

Can I use that stud for mounting an eyelet connection to enable use of a Noco Genius2 or 5 (or, with the proper adapter, the Noco Boost GB20 powerpack)? The copper jump start plate looks to originate at that stud.

 

Thanks Mendel. I did look at that video from NutzToBolts on that 3rd Gen(?), that bolt under the 'fussy cover' is what I'm talking about. What I'm thinking is that for my '26 LE, the stud/nut location in attached thumbnail is the same - where the DC-DC converter comes into the relay/fuse box. As I'm poor on electrics, didn't know if attaching the positive eyelet on the Noco to that stud/nut would cause issues (the 130A fuse block location appears to be downstream of the stud/nut, the 'exclusive' Toyota jump start plate is downstream of the 130A fuse block).