12v Battery Is Discharging, Re-Charge Now !

Would a regularly connected smart charger be practical for your situation? That's us, often only using the car about once a week. Works a treat.

It took me a while to come around to that, but it was getting to where I was despearately looking for excuses to drive, and thought "this is nuts...".

 

Thanks. I will look into that!

 

Edit nvmind, wrong thread

 

Well, this thread, and others like it is certainly an informed read. Love the "car in READY Mode" for a few hours trick. Being January as I type this, and in Chicago, where it is often -5F to 30F, I find it a bit scary to use the physical key to lock the door(s) for vehicle security, with all the carjacks and whatnot. My car is always just 5 feet from the street. What I'm worried about is the physical key breaking off in the door at such chill temperatures. I mean, even warm, it doesn't go in or out of the lock very easily.

My PiP is an early 2017, which means 5 years on the OEM 12v lead acid battery. Even last winter, I noticed it took up to 5 seconds for the MID to light up (at about 20F) after pressing the Start button, and even then when it lit up, made some horrible low tone beeping sounds. It wasn't happy, that's for sure. Didn't take that long years earlier. Now as we start the new winter, I am more apt to just have the 12v replaced before I experience serious problems. We have a few straight -5F days ahead of us. I will sure try the parked in READY mode trick but the cold key locking worries me. Perhaps some silicone or graphite spray in the lock first, or is that a bad idea?

Got a quote today for an Interstate brand replacement battery at $215 and $275 total + tax installed. Don't know if that is in line with what a Stealership might charge. Anybody have experience with replacement 12v battery installation costs to help me compare? Thanks!

 

Do more search. Toyota OEM battery is MSRP $180 and I found it as low as ~$135 online price (plus shipping and core deposit if purchasing online) direct from dealer parts dept. Search for Toyota TrueStart brand battery (Part Number: 00544H4052470).

00544H4052470 - Vehicle Battery - Genuine Toyota Part

The aftermarket battery should be similarly priced or cheaper. I have read in another thread that some regions have a shortage of the particular LN1/140R/H4 size group battery that can be used for replacement on the PP or Gen4. That might be driving the price up. As far as installation is concerned, most auto parts stores install 12v batteries free of charge. It is a simple swap, most people can manage DIY.

That being said, before jumping the gun and replacing the battery, try charging the 12v battery with a battery charger and do a load test to see how good your battery is. The cost of a charger and tester together would be cheaper than your quoted cost of the new battery and installation. I see you are parking on a street. But if you can charge the traction battery, then you can certainly charge the 12v battery.

 

@DavidA I found one - Truestart H4 (En) - online in winston salem, nc for $146 local pickup only. Might want to search for a local dealer that has online pricing for local pickup, as the shipping of lead can be substantial. toyota retail is listing currently as $181 for the part.
https://www.oemgenuineparts.com/oem-parts/toyota-battery-00544h4052470

 

That's a great price. Too bad I'm not local to NC. I will be calling a few Stealers around here soon, as I should have today, but didn't. I have found amazing differences in DIY service parts at local Toyota Stealerships. The difference can be huge; air filters, wiper inserts, etc. I have never shopped for a battery that way. I won't be awapping it myself. I'm too old and too lazy for stuff like that anymore, and I swear out loud a lot whn things go wrong. And installing it outside in single digit temps is not fun. I will definately shop for the combo of battery and install.

Meanwhile...
Today was the first time I put my car in READY mode to charge the 12v at the reported 14.4v. I drove it up onto my back patio, away from the street, turned off everything. It was 14 degrees, and I had just returned from a semi-short outing. I had 66% left on the traction pack. Duration was one hour. I didn't want to do this for 3 hours like suggested, at least not yet this first time, as it was an experiment.

I was, and remain concerned, that locking the car with the teeny tiny physical key at these temperatures was risky. I sprayed a little bit of WD40 (I couldn't find my Dry-Slide can) into the lock, and the key turned nicely, which amazed me, as I've never inserted it in the lifetime of the car.

As far as I know, the engine never started during this. Perhaps EV READY mode does some pack heating, even when not charging? do not know. The one-hour READY trick used 7% of the tracktion battery. When I'm off to work tomorrow, it will be about 3F out, and the pack will have cold-soaked at -2 overnight. Then worse than that on Friday. I'll see how it all starts and re-starts at work again at 10pm after cold-soaking all day and evening. No option to charge at work.

 

I'd be concerned with buying a relatively rare lead acid battery that has sat unloved on the shelf for (?) 6 months - 1 year without a trickle.
Lead acid have a self discharge. That would be a hit to it's life expectancy right there.
And they usually have a date of manufacture sticker on them.
It's a round colored sticker with month and year.

 

Those battery tenders/trickle chargers are important to have with a Prius. In the winter months you want to use them at least once a month. If you battery is over 4 years old, probably 2x a month. I remember a few years back my battery was in the moderate range at the dealer. Since getting the trickle charger, it registers in the good range.

 

I agree for all Lead Acids that are not used daily.
Look for a 'Tender' with the antisulfation function. Those definitely help with the life of a lead acid.

It's still sad that you have to baby sit this car because having it plugged into a EVSE is not adequate....

 

The original battery in my 2018 (bought 2019 Feb) is CCA 295A. Tested as 271A which is good.

 

how was the resting voltage?

 

Drove 4 hours ago, it’s 12.37V now.

 

I've found "good" batteries are invariably higher than their spec'd CCA. If I test a battery and it's lower than spec, I start researching new batteries, keep a close eye on it.

I'm using a Clore Solar BA5, btw.

 

I use TOPDON BT100.

 

12.37 is fairly low

 

Has anyone else found that charging the 12v battery with an external charger with the 12v battery still connected to the car does not fully charge the battery? It didn't on my Prime and now experienced the same issue with my Tacoma. This is with two different smart chargers (CTEK and Schumacher). I had no problem fully charging the batteries when disconnected from each vehicle.

Also, it seems to me that battery voltage is only an indicator of the state of charge of the battery, and not its health. Even a weak battery will fully charge to 12.6-.7 volts when put on a battery charger. Any thoughts here?

 

Never had a problem fully charging the 12v battery without first disconnecting. In fact, I have never disconnected the 12v battery from a car to recharge it before. Always worked on my PP, Pathfinder, and CRZ, all of which have a battery monitor installed so I know it was fully charged.

True. That's why it is recommended to do a load test on a battery to assess the SOH (State of Health). Digital load testers are cheap and easy to use, but testing the battery in-vehicle may give a different result than out of the vehicle. I also have read that carbon pile load tester is the gold standard. I now have three different load testers, two digital and one carbon pile. The last test I run on the old 12v battery I replaced gave a similar load test result using all three testers.
Preemptive 12V Battery Replacement | Page 2 | PriusChat

 

how are you measuring it, to decide if it is fully charged or not?

 

Solar battery tester, multimeter, Schumacher charger


iPhone ? Pro