Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004

We pack well!
(no damage or problems!)
We ship that day!
We email you with shipping info!

Want your order fast? Our official cut off time is 4 pm. If later you can call 818 364 9810 or 800-236-1831.

Click here to check our A+ Business Bureau Report.

We also accept purchase orders from organizations. Fax signed POs to 888 908-0801.

A 8 to 10 hour course caused reading gains of 1.29 years! Find out more!

What we are doing to become more environmentally frendly!

Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004, 2005, 2006, 2007, 2008, 2009, 2010 & 2011

If you need a battery for a 2000, 2001, 2002 or 2003 Prius click here.

In stock! We also now have the direct replacement battery (same battery with smaller connectors and Toyota style vent hole) in stock at the same Price! Less work! Click here!

Price includes:

Optima D51 (D = Deep discharge, yellow top; 51 = group size) battery with full 3 year replacement warranty!(We expect this battery to outlast the Prius because the Optima red top [more crank amps, fewer deep discharges] batteries last 10 years in cars where they have to crank the engine and are exposed to engine heat! The yellow top [deep discharge] should last even longer especially in a Prius! (no engine heat, no engine cranking) We have been selling the batteries for almost 4 years and they are going strong in the Prius! [We asked!]) Here is the reply from one customer who bought the battery 8 November 2007: "No problems whatsoever. I have one red Optima that is 10 years old and still works fine!" P.G., Cherry Valley, CA
our installation kit(included), that includes 8 pages of instructions with 8 drawings and photographs plus data on maintaining voltage to the car so you do not loose any settings + many refinements based on feedback from many users!
Free shipping to all 50 states and US territories via Air Mail or ground whichever is faster.
You should have your battery in 1 to 3 days! (1 business day for all of California and the metropolitan areas of Phoenix, Tucson, Flagstaff Reno and Las Vegas. Anywhere else in the US and Territories the battery FLIES TO YOU!)
JUST SELECT FREE SHIPPING IN THE SHOPPING CART!

While you are waiting for your new battery we suggest you turn off smart key; if you have it. (Switch by drivers left knee.)

"Unbelievably good service!!!! I ordered the battery after 4PM and it was sitting on my back porch by 8:30AM the very next morning----just about 16 hours after ordering. WOW!!!!! Installation with the included instruction was a snap.

Thanks. Great to know such service still exists in today’s world." H. S., Santee, California

"Just to thank you for extra fast delivery, I got it on Wednesday [He ordered on Monday.] - picked up in local post office and replaced old one." R. M., Franklin Park, Illinois

Hobbit talks about his Optima battery in his 2004 Prius.

In stock.

For customers not in the US or territories we recommend you just buy our installation kit as it is too expensive to ship the battery outside the US. Outside of the US you also may not need the installation kit. The Optima YT S 2,7J (available in Europe, the middle east and parts of Africa) has Japanese electrical posts and will work if you Prius has them. You can tell by looking at the battery. If it has electrical post that are only a little bigger than pencils (Japanese posts) the battery will work without a kit. battery The installation kit will work in Canada or Australia but not in Japan a Prius made for Japan has a battery with American electrical post.

The 12 volt battery provided by Toyota is a pretty ordinary flat plate sealed battery. We hear far too often about it failing within two years. Here is one example: "I'm going thru my 3rd Toyota Aux. battery in 6 years. Toyota replaced the others under warranty... Their/Yuasa batteries still STINK! I even had a "Battery Minder/Tender" on this entire winter to top off the Aux. Bat. It still stinks!" [and fails] K. B., Talent, Oregon The Optima does fail usually within 6 months but only at about at .5% rate and we have been selling this battery since Oct 2007. The batteries are holding up just fine! WE ASKED! We expect the Optima to last longer than 10 years as their batteries last that long when they have to crank the engine and are exposed to engine heat. (Neither of this occurs in the Prius. See chart below)

We have helped Prius owners install this battery in over 700 Prius!

"I want to say that the battery, kit, and instructions were excellent. I had no problem performing the installation, and am very satisfied and glad that I took the chance that I'd be able to do this myself rather than paying a Toyota dealership through the nose for an inferior product." D. P., Lafayette, California

What makes this a longer lasting battery?

7.5x or more deep discharges

15X Superior vibration resistance! - The tightly wrapped spiral design (see cut away image toward bottom of page.) provides superior vibration resistance so you battery is less effected by pot holes, construction projects, drainage ditches speed bumps and rough roads.

Pure lead! - Because of the spiral design the lead plates do not have to be strengthened with an alloy and are 99.99% pure. This results in lower voltage drop as the battery discharges and contributes to the longer life of this battery!

More capacity: 2 ampere hours more capacity and 2 pounds lighter than the larger Toyota (GS) Battery for cars with Smart Key or Navigation.

Battery ampere-hours pounds

Toyota with smart key 36 29.5

Toyota with out smart key 28 Note: Tray size is still the same and Optima fits great!

Optima D51 38 27.5

The Toyota GS Battery has free liquid acid that is not absorbed in the glass mat. Consequently, it can not be easily shipped to you. So if you wait till your battery is completely dead you might have to go to the Toyota dealer near you and pay whatever price they charge. PLEASE DO NOT WAIT! HOWEVER, WE DO SHIP Ground (Next Bus. Day if you are in CA, Western AR or Western UT) and PRIORITY MAIL so we often can GET A BATTERY TO YOU IN 1 to 2 DAYS!

Also Prius owners have told me the Prius acts very strange when the 12 volt battery gets weak they get error messages like: "P LOCK MALFUNCTION WHEN PARKING, PARK IN FLAT PLACE AND APPLY PARKING BRAKE SECURELY." Your MPG can also deteriorate for reasons we can not explain but this has been reported by several Prius owners.

This is the ideal battery for the Prius. We have sold them for over three years now and the battery has a less than 1% failure rate! On a Prius the 12 volt battery does not start the engine the high voltage battery does. You do not need the RED TOP battery which is chemically configured to provide a lot of starting power. Instead you need a battery that can handle the slow stead drain than occurs when the car is parked from: the clocks, the memory chips, the security system and the remote entry and key less starting system. THIS YELLOW TOP BATTERY IS DESIGNED FOR THE DEEP DISCHARGES THAT THESE SYSTEMS CAUSE WHEN THE CAR HAS BEEN PARKED FOR A WHILE. (See comparison chart below!)

How much work is this to install?

You pop hood, disconnect battery terminals, unscrew hold down bracket replace battery and then attach above and close hood.

Prius 2010 +: it is just two extra bolts plus the vent tube connections.

Prius 2004 to 2009:

So it is more work than a traditional car but very doable if you have the tools!

Minimum tools needed:

Flat screw driver
10 mm wrench or 10mm deep socket
10mm socket
socket extender
12mm wrench or socket
1/2 inch wrench or 1/2 deep socket (13mm will do)
vise, large adjustable wrench or vice grips
tape
a small battery or jump start battery to maintain the 12 volts in the Prius so you do not loose any presets. (Optional but recommended!)

Our free shipping is next day ground (to the California and western Nevada, including: Las Vegas & Reno & Arizona including: Phoenix, Flagstaff & Tucson ) or Priority Mail (2 to 3 days)! If you need the battery as soon as possible let us know in the comments or call us at 818 364 9810. We will do what we can to get it to you as soon as possible!

The three main contributors of premature battery failure are:

Vibration which causes distortions in the plates and eventually shorts.
Repeated deep Discharges
Heat!

If you want a battery that lasts longer. This is it! You will pay about the same at a Toyota Dealer but this is a better battery! We offer free shipping on this battery via UPS to the Southwest and or Priority Mail to the rest of the 50 states Hawaii, Puerto Rico and other US territories! You should have your battery in 1 to 4 days!"

_____ is Optima red top battery _____ is Optima yellow top battery

soc-% state of charge ocv - open circuit voltage for deep cycle

soc ocv
100 13.18
90 13.01 The 2004-2009 Prius has a drain of approximately 12 milliamps with smart key turned off (Thanks hobbit). After two weeks the battery would still be at 95% soc and the battery good for 10,000 cycles. However, age and heat also effects batteries.
80 12.83
70 12.65
60 12.46
50 12.28
40 12.08
30 11.89
20 11.68
10 11.48
0 11.27 Look at the graph! A battery chemically configured to take deep discharges (yellow top) has 7.5x(300/40) the life compared to the red top!

The US Prius models come with batteries with Japanese size electrical posts. We provide an installation kit with new electrical connectors and a connector and plug to allow you to connect the vent holes in this battery to the vent tube in the Prius. This Optima battery can replace the Toyota 12 volt battery for the Prius with Smartkey or navigation system Toyota part number 28800-21170, now 28800-21171 (GS Battery # S46B24R) or for a Prius without the Smartkey or navigation system Toyota part number 280021050.

Comments from customers who have used this battery in the Prius for over a year!

"The battery has performed absolutely flawlessly and is one of the best improvements you can make to a Prius . Easy to install, everything is included.

In general, I am totally sold on Optima batteries; I use them for my cars and boat, my oldest one is about 10 years old and still works.

Toyota puts so much emphasis on how the Pruis main battery lasts the life of the car; but what they don't tell you is that the accessory battery is a cheap ass lead acid that, even in a best case scenario, will be dead after 5 years. The Optima should correct this issue and bring the accessory electrical system to the level of the rest of the car.

My factory battery died when one cell failed; the car was 1 year old at the time. As you know, Prius, with all its electronics does NOT have a simple circuit to shut down the interior light! It is therefore only a matter of time until one does not shut the door all the way and the next morning the battery is completely dead. This is what happened to me twice. When I charged the factory battery for the second time it failed. The symptoms were somewhat strange as it would still run but after sitting a few days it would not.

It is good to know that with the Optima kit the chances of recovery are much better . And I don't think I'll ever have to worry about having to replace it due to age.

Regards,"

P. G., Cherry Valley, California

"I just wanted to let you know that the Optima battery in my '04 Prius has been great. We had a few sub-zero mornings last week -- the kind that in the past, with the OEM battery, had me running a long extension cord and portable charger out to where my car is parked overnight to get it started. I had been taking to turning off the keyless entry system to try and avoid a cold-morning dead battery. I found the OEM battery to be the car's achilles heel, because when it is weak, you have to resort to the physical key to get in the car, and even then you can't get the back hatch open to access the battery.

But this winter with the Optima battery in place, not an issue. No matter the temperature, the car 'boots' properly, so all other systems, including the gas engine, start up without problem. I've always been a fan of Optima batteries, and adding one to my Prius brings up the 12V traditional electrics up to a quality level commensurate with the rest of the car.

Thanks for a great kit to install the battery."

M. A., Fort Collins, Colorado

"I've had no problems since I replaced the battery. The sound system sounds great. I haven't let the battery discharge deeply (I've learned to turn off the wireless key when I'm on vacation), but I trust the yellow optima is the right battery for a deeper discharge and a good choice for this application."

J. G., Monte Sereno, California

From the manufacture:

optima spiral technology

The unique design of the SPIRALCELL TECHNOLOGY. provides many features not available in ordinary batteries. The following is a summary

SPIRALCELL TECHNOLOGY PROVIDES: More plate surface, closer plate spacing, ability to use high purity lead. RESULTING IN: Low internal resistance. This low internal resistance gives you more power in a smaller box, ability to recharge much faster and higher cleaner voltage characteristics during discharge

Immobilised plates (locked in place). RESULTING IN: Improved vibration resistance, no shedding of active paste material, lower gradual loss of power and capacity as the battery ages. This gives you a battery that lasts longer and performs better throughout its life.

Voltage 12 (12v or 12 volts)
Amp Hour 38
CCA* 450 (Cold Cranking Amps)
Shipped fully charged ready to install
Maintenance-Free
Valve-regulated absorbed glass mat (AGM) eliminates acid spills and terminal corrosion.
Vent hose holes for emergencies in case the battery is heavily overcharged. (You need a connector and plug that we provide with our installation kit)
More than 15 times the vibration resistance of an ordinary battery.
Last up to twice as long
Length 8.9" and 9.15" at top cover
Width 4.5" and 4.9" at top cover
Height 9" including posts
Weight 28lbs
Warranty: 3 year exchange, excludes damage due to misuse or neglect, improper charging or improper application of battery
Free shipping to all 50 states and territories: Ships the same business day you order via UPS ground or Priority Mail! Just select the shipping method "Free to 48 states for $50 order"

The Federal Magnuson-Moss Warranty Act of 1975 prohibits a manufacture from curtailing warranty coverage due to after market parts unless it can be demonstrated that they caused the problem. (For more information click here and scroll down go to paragraphs under "Tie-In Sales" Provisions.)

This sealed battery has little free liquid electrolyte because it is absorbed into the glass mat. Consequently, there is little acid that can spill into the trunk even if the case cracks. It also has attachments for a vent hose so any gases are vented outside of the car. The battery does not normally emit gases but can do so with heavy over charging with pressure building up and the valves in the batteries releasing. This should not normally never occur because the Prius high voltage to low voltage converter puts out around 13.8 volts. 13.8 volts is the voltage the battery puts out at no load and at that voltage the battery can not be overcharged and it is the maintenance voltage for the battery. However if one cell shorts out or the voltage unexpected goes high gassing can occur.

The 12 volt battery is not used to crank the gasoline engine in the Prius but it does supply all the 12 volts circuitry which includes all of the computers in your car. If this battery fails, the computers will not start and the Prius will not start. A weak battery can also pull the 12 volts power down to a lower voltage. This can cause problems with all of the computers that control your car. (When I had a problem with my car the first thing the dealer insisted I do was replace the battery. The problem was caused by something else but the battery was weak.)

Since the 12 volt battery does not start the gasoline engine you can still use the car with a very weak battery. So much so that at least three Classic Prius users have told me that their Prius now gets better mileage with the new battery. I am now starting to get these stories from 2004 + owners also for example:

"The MPG skyrocketed in my car after the battery replacement. I was getting 37mpg on the freeway and now its over 48mpg. Thank God!"

So if your 12 volt battery is very weak and your MPG has deteriorated a weak battery could also be affecting your gas mileage. (Possibly the voltage is lowered on the 12 volt system and this is effecting the engine computer and the sensor data it relies on. But this is only speculation we have never done test on a car with this problem.)

Prius battery test procedure for 2004 to 2010 Prius Cars

Here is a battery test you can perform on a Prius battery that is easy to do. It will not always detect a weak battery that does not allow you to park you car for long before it is drained down by the security system.

However, this test requires no tools, is easy to do and will give you some idea of the state of your battery. You can also perform this test after the car has been parked for a while to see how well the battery holds up under the drain from the security system.

Do this test after you have driven the car for at least 30 minutes. This will give the battery a chance to be fully charged.
Put the transmission in Park.
Engage the parking brake
Push in the power button. (if not already on)
Press and hold the "Info" button on the MFD while turning the headlights on and off 4 times.
Push on Menu in upper right of display screen.
Push on Display Check
Push on Vehicle Signal Check
You will see the 12 volt voltage displayed. In accessory mode the voltage should be 12.6
With no electrical accessories on including lights the voltage should be fluctuate between 12.6 and 11.9. The lower the voltage, the less of a charge your battery currently has. If the voltage is low do not proceed as the load test might totally discharge your battery. (If you see a voltage around 13.8 you are seeing voltage from the high voltage battery being converted to around 13.8 in an attempt to recharge your battery. This normally does not occur till after you start the engine but might occur earlier if the battery is very drained.)
You can also test the battery by turning on the headlights, rear window heater and the heater fan. For a new battery the voltage would be around 11.3. If the voltage drops below 10.2 it should definitely be replaced. For voltages in between the lower the voltage, the lower current charge of your battery.
Push on the break pedal and push start. You should see Ready in the Speed display. The voltage should now read between 13.8 to 14.2 and higher in winter. This is the charging voltage!
Note: If in doubt disconnect the 12 volt battery completely (start with the negative post to avoid shorting the battery) and hook it up to a battery tester.

Included is our installation kit which includes all the parts you need and detailed installation instructions.

2004 to 2009 Prius Customer comments:

"The new battery is perfect. Thanks for the kit. Installation was easy. On the OEM battery when I'd close the windows after shutting off the Power switch the battery voltage would drop to 11.8 or less. The new Optima only dips to 12.4 volts.

Also the shipping was perfect. The cardboard container is very cleverly designed. Thank you for sending such a heavy item without charging and arm and leg for shipping." C. M., Bainbridge Island, Washington

"I installed your Optima battery kit tonight in my '04 Prius. Shame on Toyota for making battery replacement so hard, and Kudos to you for making a nice replacement kit and good instructions!

J. H., Minneapolis, MN

Please Note: California Proposition 65 Warning Battery posts, terminal, and related accessories contain lead and lead compounds, chemicals known to the State of California to cause cancer and reproductive harm. Wash hands after handling.