Optima - Toyota Prius 12 Volt Auxiliary Battery Installer

Any competent mechanic can install it. In fact, anyone who can follow simple instructions and possesses a 10mm socket wrench can do it. It's actually easier to do than say putting the spare on!

If you don't get any referrals here, and don't want to do it yourself, I'd look on Yelp for the closest shop with good reviews. They'll have it installed in 10 minutes once they get to it. Print out the instructions and take them with you.

 

I never owned a car while I lived in Seattle, so I can't help, but these guys can:
Car Talk | Mechanics Files

 

If you're having the inverter pump changed, print the service campaign dealer letter (provided in the genII general section) so toyota can pay that portion of the bill.

 

That is pretty good service from the original battery. If you are a little bit handy the instructions are pretty clear how to install the Optima and when you do it yourself you know it was done with care. I would also look into having the dealer replace the battery if the price is right. Regardless of what is said by Optima or others, I think the oe battery IS correctly designed for the car.

 

Of course it is "correctly designed", but it's expensive for it's size. For about the same cost, you get the Optima which has more capacity so why would anyone not want to upgrade?

Another example is the stock Goodyear Integrity tires, which of course are "correctly designed" for the car, but there are much better tires!

 

Interesting question. Just what does that extra capacity buy me as a Prius owner?

 

Well, given that the Prius has a smaller than typical battery and at the same time a higher than normal standby load (quiescent draw), it will reduce the chance of being stranded somewhere with a dead battery. It might make a big difference when you accidentally leave a light on, you might jump in and start up as normal. Whereas if you had the OEM battery, you'd be stuck.

It should also offer longer life, as the DOD% (Depth of Discharge) is less on a larger battery, thus it's less stress on it.

It's also highly likely that any replacement OEM battery you get is already significantly aged probably from sitting in various distribution and parts warehouses. Several times now, I've heard people get back from the Dealer with a dead or low battery after replacement! Lead acid battery life is reduced by DOD x Time, so if the battery sits low for a long time, it's not going to last long even after it's recharged.

 

Oh, another benefit is not supporting the Stealer network by encouraging them to keep charging ridiculous prices for something that should only cost $50. (what a size-comparable AGM battery costs anywhere else)

Maybe if people stop buying them, the prices will become competitive!

 

Interesting. I also know that a higher cpacity battery can help more in a cold climate, which I don't have here.

I never thought twice about changing in a higher capacity battery on any other car, but the layout of the Prius is a bit daunting for me to go in and change things...

I hopefully have a while before I have to think about it anyway.

 

Actually it's much easier and cleaner to change the Prius 12v battery than it is in a normal car. It's right there in the trunk. Pull the big spare tire cover, the spare tire tray, then the little cover on the right and you have full access. It will be clean and there's no oil or acid anywhere. The original battery is small and light, and even includes a convenient handle so it's super-easy, it basically is just a tall motorcycle battery.

You need minimal tools, a socket set is recommended, but could be done with an adjustable wrench in a pinch. As long as you follow the directions and the connections are tight, it's almost impossible to screw up.

The side-effect of doing it yourself is two-fold; You know it's done right, and the pride and sense-of-accomplishment that comes from knowing you've done it is priceless!

 

Well - maybe it's not quite that easy. You will have to remove the traction battery ventilation duct that runs over the 12V battery and move the brake power supply located next to the battery, for full access.

I would also say that it would not be easy for an owner who doesn't have the correct tools to replace the positive terminal connector which is required if an Optima or other non-Toyota battery is used. I would recommend that a DIY owner needs to have the correct metric sockets (10 and 12 mm) along with 3" and 6" extensions and a 3/8" ratchet wrench (I used those tools to remove the 12V battery on my 2007 today.)

The 12V battery on my 2007 just died yesterday, and I plan to buy the correct battery from my local Toyota dealer tomorrow. The price remains at $139 and the battery is made in Japan (not China) so the price seems reasonable to me.

 

Thanks pEEf, I might end up doing that when the time comes. I had already found the battery, but space-wise it looked a bit tight for something bigger...

 

Oops! You are correct, I forgot about the duct. (I don't have one in my car anymore so it was easy to forget!)

Personally, I would choose an Optima even if it was 2X the cost, as I routinely am in the car doing something and using 12v power w/o the car being ready. I still think the OEM battery is a tad undersized. The added piece of mind knowing that an Optima can run my (LED) dome light for several days and still start the car with no problem is worth it!

I advise you to try to decipher the date code when you get yours. I'm curious how old it is from your Dealer.

 

IMHO, Optima vs. OE is not so much a question of capacity as it is design.

OE is not designed for, and does not tolerate, deep discharge. Witness the countless stories on PriusChat of the hapless owners whose battery ran down and then no longer holds a charge.

Optima Yellow Top is a deep cycle battery. It is designed specifically for deep discharge applications.

In the Prius, the HV battery does the cranking. The 12V battery is there to keep the computers alive while the car is not in Ready mode, or if the DC-DC converter fails. When my inverter cooling pump failed, which disabled the DC-DC converter, I had no problem continuing on for 20 minutes to the house because I had a Yellow Top installed.

The Prius needs a sealed lead acid or AGM battery since it is in the passenger compartment. IMHO, the Prius also needs a deep cycle battery, since the quiescent current is pretty high for a car this size. While I am NOT a fan of using aftermarket parts in MOST cases, this is definitely one where Toyota could have done better, and a Yellow Top exceeds OE in all performance categories.

 

FYI: All modern car batteries are of a recombinant lead-calcium design and are "sealed" the same way the quasi-wet OEM battery is. (In fact, not sealed, but with a pressure-vent that connects to a tube that runs outside to car.)

AGM delivers better life in a deep-cycle application and can put out higher specific current for it's size. It also has a higher power density for the same weight (less "baggage" electrolyte). If you were to substitute a standard flooded design of the same size, it would have higher internal resistance and not be able to handle the current pulses present in the Prius without sagging. (EPS is a big offender)

I'm reasonably convinced the stock battery is semi-wet in any event. (Glass mat, but with at least some liquid electrolyte)

The only argument for safety is less dripping sulfuric acid if the car is hit in the right-rear.

 

I will do that. The 2007's original equipment battery was dated Sept. 9, 2006 (vehicle production date was 09/06.)

BTW when I bought a battery last year for my 2004, the battery date was reasonably current (although I don't remember the specifics at this moment) and the voltage out of the box was 12.9V.

I opened up the 2007's original equipment battery. If anyone wants to do that in the future to their battery, first remove the top label using a single-edge razor blade (note that the label contains a warning not to remove it.)

This exposes a clear plastic rectangular cover over the six cells. I used a flat-blade screwdriver to pry up a narrow side of that cover and removed it.

Now the six cell holes are accessible. Each hole is covered with a little black rubber cap. When I removed the caps, I was surprised to find liquid covering the plates in one cell.

I thought this battery was supposed to be AGM: when an AGM cell fails, does this release electrolyte from the glass mat?

When I first had the no-start problem yesterday, battery voltage was 8.5V. I charged the battery all day (and also drove the car 50 miles during the day.) Then I measured the voltage this morning and found it was only 11.8V, so I decided that the battery was not holding a charge and needed to be replaced. For fun, I made the car IG-ON for a few minutes to load down the battery, and the voltage dropped further to 10.5V.

I am using a lab power supply to maintain voltage on the 12V bus while the 12V battery is out of the car. The current reading is 0.00A to 0.01A (the digital readout switches back and forth.) It is interesting to open the driver's door and watch the effect on the current: it jumps up to ~2.5A for a while, then slowly drops down as the ECUs decide that they can go back to sleep. (I turned off the cabin ceiling lights before taking this measurement, since this power supply can only produce ~3A.)

My 2006 Highlander Hybrid has a conventional flooded 12V battery. The exterior dimensions are exactly the same as the 2G Prius (w/Smart) battery. The HiHy battery is mounted in the engine compartment. My guess is that the electrical requirements in that application are no less than with Prius.

 

In clarification of my previous post, I was merely saying the OP, who does not want to install the battery himself, and has received good service from the original, may find it simpler to have the dealer install one at the time other service is done. And be done with it likely until 2016. It is also reasonable that I said the oe battery is correct. It has been designed to fit with the holder, cables, and vent, and electrically also is right. Not necessarily the best, but it is not a starting type standard flooded cell unit. This article was referenced before:

VRLA battery - Wikipedia, the free encyclopedia

Being expert at none of this, I noticed some points they say. The Prius float charge voltage is right for the oe battery, The charge can be continuous, the oe battery appears to be the acid-starved type, the "disadvantages" list, and AGM batteries are more expensive. At $139 the Toyota battery seems right in line on price.

Lastly I have to add that if a dealer sees changed cables and a different battery, that will be an excuse for denying, true or not, any remaining warranty. Win or lose in court aside, I am pretty sure some dealers will cause grief.

Last after last, I reread the article and find I still don't know what the oe battery is. At first I thought they were saying agm and acid starved were related types but not the same. In any case Toyota makes a big deal about the charging of the batter, I believe, so it isn't a standard car battery.