Gen 4 12 Volt battery.

Hi all, I've read all of your posts in this thread since I have had problem with my 16 Prius' 12v battery. Just want to contribute the quote price from my dealership I got this morning: $350 for the 12v battery with only 1 year of guarantee, and they don't even have it. As far as I know, most dealerships in my area (San Diego, CA) do not have those batteries in-store. So as you can imagine, it's a pain in the butt just to find one, let a lone finding an affordable battery. But thank you for all of the good information, I am going to look for an EverStart in my local Walmart.

 

Re "... I can't tell how fast the battery is spinning the starter ..." - that's because it doesn't spin the starter ever.

I'm very well aware that ".... it doesn't spin the starter ever", that's the point I was making.The reason batteries have a CCA rating is that a battery's condition can often be determined by how rapidly the starter cranks a cold engine, but of course this is not possible in light of the way the ICE starts on the Prius and why I could not determine how the battery responds to a heavy load like spinning a starter.

I did a bit more testing today and have determined that the 12 vdc battery is most likely defective as after a full charge it immediately drops below 12 vdc simply by bringing on the headlights which is a relatively low amp load.

I'll see what the dealer says when they do a test with their equipment to determine if they will replace the battery under warranty.

 

Electronic battery testers still test CCA, and regardless of the car not using the battery to turn the engine over, CCA is still a good indicator of the battery's health.

 

In my experience with testing batteries, which has been professionally over the past 35 years, the only reliable way to test a battery is to put an actual load on the battery, which electronic battery testers do not do.

 

Great video, many thanks Alan.​

 

After watching the video that Mendel posted, (thanks Mendel), I'll have to reconsider the value of the new generation of conductance testers. However, in the video it shows the use of an inexpensive load tester similar to the one rated at only 100 amp that can be bought at Harbor Freight for about $20. What I was referring to was a high quality load tester that can put an actual load of at least one-half of the CCA rating of the battery. Since a quality load tester with this capability will be much more expensive than what most of us want to spend, the new conductance testers may be a good alternative and something to have, at least for those of us that are somewhat obsessive/compulsive about monitoring our batteries and charging systems.

 

Maybe someone can tell me.... If a 12 volt battery physically fits the space, and you can hook the cables to it, wont that suffice ? In both my F150 truck, and in my Hyundai Accent, I have been using very cheap ($49) but not bad at all Wal mart batteries. Couldn't the smallest of those be made to work ? Whats the problem ? Terminal placement ? Bet I could adapt them.... In fact you better bet I will, if it comes to the difference between using a $49 battery, vs a $350 one.

 

since the 12v is now under the hood, my only concern would be that it is designed to accept the specific charging parameters of a prius.

 

@Elektroingenieur has researched compatible 12 volt batteries for fourth gen; here's some links he posted earlier in this thread:

Gen 4 12 Volt battery. | Page 2 | PriusChat

 

Is there any reason, other than form-fit, that would prevent you from installing a long-life battery with GREATER Amp-Hour capacity? If not, then I would think you could install one with modification of the mounting hardware.

 

Gentlemen; thanks for all of your input(s) on battery life for the 2016 Prius 3 (under the hood) battery. This is my third Prius (2010, 2013, and now 2016). My current 2016 would be old enough for me to upgrade, but I like this one so well, that I'm going to keep it for a while longer (only 25000 miles, and I prefer CD the player on the top of the line stereo/speakers). But, my neurosis is this: I want to be proactive on the battery. If it's a six year battery, I want to replace it a five years. In my experience, batteries don't "show signs of going bad". "They just go bad!" And they just go bad at the worst times possible. And they look up at you and they say, "Dude! I've just gone bad, and there's not a goddam thing you can do about it"! So, enough of my poor ability to portray comedy/drama. My conundrum remains: If my original is a four year battery, then I'll replace it now. If it's a five year battery, I'll replace it next year. I've delved deeply into the bowels of the bureaucracy of Toyota Inc. as I care to; and I cannot find an answer. Surely in the fraternity of owners there is someone who can point me in the correct direction.... Thanks brethren!!

 

When my son had his 2005 Prius he chose to proactively replace the 12 volt battery after 8 years. He never had a problem but did not want to be stranded because of an old battery.

 

I'm not so sure that it will go suddenly - it's a wet cell lead-acid battery, not gel or AGM. It's one of those things in life which you can never be certain of - but replacing it at 4 years just in case is something I'm not considering - just in case. As I said previously, I sold my previous car, with a 5½ yr old battery going fine in winter, the car before, I know the person who bought it at 4¼ yrs old and it lasted about 18 months - idle for up to 3 weeks at a time.

And PRIUS Battery doesn't actually start the car - hence it isn't subjected to the high amperage load that a normal battery encounters many times a day.

 

I’ve posted before about the warranty period: like most other parts of the car, the originally-installed auxiliary (12 volt) battery is covered for up to 3 years or 36,000 miles, whichever comes first.

I’m sure Toyota had design objectives for battery service life and imposed requirements on their suppliers to this end, but those standards are proprietary, and more importantly, they don’t translate directly into the warranty period, which is also determined by the acceptable cost of warranty and other commercial factors.

Indeed, I wouldn’t assume that there are any differences in design or failure rates between “four year” and “five year” aftermarket batteries, as much as sellers might like you to believe otherwise. Batteries with longer warranties sell at higher prices, allowing sellers to absorb the cost of replacements further into the cumulative hazard function and still make a profit. It’s a classic price discrimination strategy.

 

Pay me now or perhaps pay me later.

 

If it ain't broke, don't fix it.

 

Not sure if I should start a new thread or not, so I apologize in advance. So my car has been garaged since March from the whole COVID thing here in San Francisco. I run the car every few weeks, but during the last time, I neglected it for about 6 weeks. Last week I found my Prius Two Eco 12v battery fully drained (26,000 miles). I put a portable pack jump starter at the terminals, started the car and let it sit running for about 20 mins. This week, I found the car in the same situation. After jump starting, I drove for about 35 mins. After 2 hours, I checked the battery while off at the terminals with a multi-meter and found 11.5v. I read through this forum and one other one but I don't understand all the technicalities. Can someone confirm the following?

-I'll likely have very little use out of this car for the next 6-12 months. If I bought a new battery, I'm afraid It will drain again due to my lack of memory to drive it. Are there any issues with just taking the 12v battery out for several months at a time until I need to drive it?
-Do I need to replace the battery, or do I need to check the electrolyte levels as suggested somewhere in this thread, and if so, how do I do that?
-I see Elektroingenieur's comment saying any H4 should be fine. My O'Reilly has a SuperStart Premium 140R H4 Part #140RPRM. Will this be ok? Any cons to getting this instead of factory?
-I saw another this post Definitive guide to find the 12V Battery (june 19’) | PriusChat where Sam Spade 2 commented that if I got one of those AC Delco or Napa batteries, I'll have to check electrolyte levels every month. If I bought this cheap battery, would I need to check the electrolyte levels every month? If so, I'm curious why?

Thanks!

 

If you don’t run the car at all for a long time, the larger, hybrid vehicle (HV) battery will eventually self-discharge, and recharging it requires specialized equipment.

In bulletin T-SB-0028-14 Rev1, “Long-Term Vehicle Storage Guidelines” (PDF), and similar bulletins for later model years, Toyota tells dealers to run new hybrid vehicles in their inventory for 30 minutes, at least once every 60 days. A similar statement, with “every few months” instead of “60 days,” appears on page 80 of the Owner’s Manual (PDF). The car records internally when it hasn’t been run for more than 60 days.

Maybe, but I’d give it a fair chance to recover, first. Use a charger (at a rate of 5 A or less), or drive for a longer period, so that the auxiliary (12-volt) battery voltage, with the car off, is at least 12 volts. If the auxiliary battery, having been properly recharged, then won’t hold enough charge to start the car a week later—and there aren’t any aftermarket accessories draining it—I wouldn’t feel bad about replacing it.

In principle, you could check the electrolyte level, and if it’s low, open the battery to add distilled water, but sulfuric acid is nasty stuff—see the warnings in the Owner’s Manual, page 599—and I wouldn’t bother. In your photo, the battery type is “345LN1-MF,” in which “MF” almost surely means “maintenance free,” that is, designed to last its useful life without such attention.

I haven’t seen one, myself, but the specifications appear to be correct, and a customer review mentions that it worked in a Prius Prime car, which uses the same auxiliary battery as fourth-generation Prius cars.

No. As far as I know, the original auxiliary batteries, as installed at the assembly plants in Japan, aren’t sold at Toyota dealers in the U.S., who instead offer an equivalent TrueStart battery with a different part number.

No. Just run the car—even parked, if there’s adequate ventilation—for at least 30 minutes. The engine will run as needed to recharge the HV battery, and the hybrid system will recharge the auxiliary battery.

 

Thanks, that's very helpful. I'll try charging it today first. Do I have to remove the 12v to charge it, out can I just hook up directly to terminals.

 

The manual recommend removing the 12v battery to charge it for safety reason, but I don't see it necessary to remove it since it is under the hood not like Gen3 and earlier. I have been charging my PRIME's 12v battery without removing it. No problem.