PSA: Change your 12 volt battery every 4 years

It could be worse. We could be talking about swamp coolers and the significance of lowering the temp 1-2 degrees inside the Prius in the great state of TX.

 

It started that way yes, however, I guess I will just start another thread since this is really good stuff

thanks for that observation. I was trying to find the delta SOC....the min max thing . I appreciate you.

 

no not really, just everyday freeway overpass spaghetti bowl ride. I saw HV BATTERY spike up and I thought I'd get a picture of it to look at after my drive into town. It kinda adds to the relief I feel when you guys post the great cherrie responses.
thanks again, I'll take it. yes I just purchased an ELM 327 from some guy in Australia..

 

okay so maybe I should start a new thread? ..
I've concerns over age of my 12v and one thing led to another.
there are just some really great pri owners ready to share commonality

 

Did your engine rev up when the HV Battery spiked? If your SOC goes above 80% the computer will normally spin up the engine to burn off the excess charge.

 

Not that I could tell. But it did.

 

Dave (and everybody!), I really could use some clarification.

(I'm in the process of buying a Prius, trying to get this right)

12v: Dave, what do you mean by "occasional charging, from the boost point is easiest"
To be clear, how often is occasional, and how exactly do I charge it? (other than driving an hour or two).
I do not know what a boost point is.

The car I'm buying was only driven line 10-20 miles per month for the last three months, I'm doing the paperwork in a few days.

Also, on the hv/traction battery:
On a test run it went up two bars in 4 minutes (two stop signs + a long downgrade using the brakes)
and lost a bar going on the freeway for one exit.
Just double checking whether that is concerning

Thanks very much,
PNB

 

Under the hood, on the right when facing the car, you will see a black plastic "box" with a removable lid (press in on the lines on the latch at the front of the box and lift up). In the box you will see fuses and relays, plus a red plastic "flip up" cover. That is the "boost point". It's there because it's difficult to open the hatch if the 12V battery is dead, but you can use the mechanical key to unlock and then open the drivers door, allowing you to open the hood. DO ensure if you use this boost point or boost the 12V at the battery, to get the polarity right! It can be VERY expensive if you don't!

If you leave a Prius without running it for a week or more, it's -possible- the 12V battery can get too low. Especially if it has been deeply discharged before.

So if you plan to leave the car parked for extended periods (more than a week) it's good to connect a "Battery Tender" (a device intended for motorcycle and ATV use to preserve their batteries) to the boost point.

If you live in an apartment and can't do this, you might consider removing the negative terminal connector/cable from the battery if you're going away for a few weeks or more. Be aware, if you do this then close the hatch, there are only two ways to open the hatch.

One is to connect a "temporary battery" to the boost terminal (I use an "alarm" gell cell battery), the other is to crawl over the rear seat, lift the rear hatch floor, and release the "emergency escape latch" to open the hatch. Instructions are in the owners manual.
Also be aware you will loose all radio pre-sets and you may loose some "programming" of the way the car responds to things like the backup beeper, door locking, etc. Nothing you can't redo however.

If the 12V battery is healthy, you won't have any problems. When the battery in Pearl S got "old", I noticed a problem after two weeks (was lazy and didn't attach the "Battery Tender" - hey, it was -15C in the garage and the cables don't bend at those temps ).

Your observation of the traction battery operation is normal. It's a low capacity battery and the car uses a lot of power when it switches to "EV" operation. Expect to see the battery "gauge" move up and down quite a bit.

 

^^^ In above post, it's important to understand that the red covered "boost point" or jump terminal is the positive terminal, +12v when making connections for charging or jump starting.

To the soon to be Prius owner above, I believe the manuals are available online on the Toyota website, and some are available for download.

 

Has anyone tried a solar panel trickle charger permanently hooked up to the boost point, or even directly to the battery terminals? Would there be any drawbacks to doing something like that?

 

A nearby VW dealership was doing that for a while; I noticed a lot of cars on their lot with roughly foot square solar panels on the dash. I don't see them lately though, not sure why.

Also @MSantos (hmm, he's moved on?) installed one on the rear shelf of a civic sedan. He also had one of those systems that gives the car a slight electrical charge, to hopefully reduce rust. Accordingly, there's more "ambient" demand on the 12 volt, this was at least in part his justification.

Guide: Installing a solar panel on the HCH-II (step-by-step) | CleanMPG

 

The drawback is having to run the wires -somewhere- to do it. Finding a place where the solar panel gets enough sun is also fun. They will work through the windows, but there can be shading problems.
Then there is the problem of how to regulate the charge. Those panels are usually rather low current so regulation may not be necessary, but something to consider/worry about.
I have one of the small panels but have never considered using it due to the above. Mine isn't one of the battery maintainer type, it's a commercial panel for remote weather stations. Most of the small ones put out around 100 mA, enough to maintain the 12V system, but not enough to overcharge the 12V battery.

Then there is the panel on the roof of some Prius (like mine), which -could- be equipped with a second regulator to charge the 12V system. Probably a little more practical as it is less likely to be shaded. Keep in mind the shade from a "stick" can upset the panel output, reducing it to almost nothing.

 

Well, I was assuming I could stick one or two smaller panels on the roof below the larger factory-installed solar roof panel and run wires through the hatchback and down into the battery compartment. I know that there are small solar panel regulators available, which would hopefully fix that problem. Since my commute is short, 3-5 miles at best, I'm trying to get a little more charge into the 12v battery while the car sits outside in the broiling Georgia sun - there's no shade at all in the parking lot at work.

Does anyone know if it would be better to run the panels through the OBD-II port?

This one, for example?
https://www.menards.com/main/solar-wind-energy/solar/coleman-reg-3-5-watt-12-volt-solar-battery-trickle-charger-with-obd-ii-connector/p-2737874.htm

 

is it a safe area? maybe you can pull them out of the hatch when you park and rest them on the hatch window.

 

Inside the car, atop the tonneau cover comes to my mind. I think they're nae heavy.

(Been watching the show Shetlands, on Netflix.)

 

This is a horrible way of checking your 12V battery!
New battery measures 12,8V, inverter puts out 14,3V so you will always see the speed difference in window closing.

 

My way uses no tools and takes no time. Let me know a better way that uses no tools and is quick.

 

I always use the FLUKE multimeter. Its very Quick. And accurate. I keep it in the compartment opposite battery and I check it every Monday. In anticipation of the time my Battery needs replacing. Thinking of dropping it off at Oriellys for a good chargeing up... but then again, I thinks it may just send the battery over the edge... Then again I may be over the edge, I drive around with a battery jump box in the back seat floorboard in what must be anticipation.

 

One thing, a multimeter can measure voltage, and that's a good measure, really what I use for the most part. But there's also electronic load testers on the market, can test Cranking Amps, and give a rudimentary assessment of the battery's "health". And regardless that the battery doesn't "crank" anything in the Prius, it's a good measure of where it is in it's lifespan, and if it could survive something like a couple of hours of door ajar.

 

.So neither toolless, nor as quick. When the pricey multimeter shows low voltage, try my test. You will see how clear it is that the battery is struggling to raise the window.