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12 Volt (12v) Toyota Prius Auxiliary Battery for 2001, 2002, 2003 with installation kit

Availability: Usually ships the same business day

miata+kit  US$153.95  

The Optima Battery has performed so well in the 2004 (less than 1% failure rate in the first 2 years) and later Prius that we now recommend the Optima D51R for the 2001 to 2003 Prius. Optima: 23% more capacity, spiral wrapped plates for extreme vibration resistance and made with thicker lead plated for deep discharges instead of cranking amps (the high voltage battery starts the engine on the Prius) It cost more but will last more than twice as long!

If you car is only going to be used for a few more years any way this may be a good solution and our customers insisted we keep selling it for this reason.

No core charge - turn in your old battery at many auto-parts stores for a store credit.

Are you just replacing this battery and do not need the kit? Go here for just the battery!

Price includes A write up on how to significantly reduce engine oil consumption.

Battery ships free to all 50 states and US territories.

Join hundreds of other Prius owners how have installed this battery with our kit! It is easy! (This is a battery and installation kit for a Prius 2001 to 2003.)

Prius owners: Why pay an outrageous price at dealer for a 12 volt battery? I did not and you do not have to also! Just say no and replace it yourself! This battery is almost the same size but a little shorter, has American electrical posts instead of Japanese, and has two vent tubes instead of one. Our kit with instructions handles these differences so it is an easy replacement and everything fits!

From a customer:

"I just wanted to express my appreciation to you for making the auxiliary battery replacement in my Prius one of the most successful do-it-yourself projects I have ever undertaken...!

I have to admit, it was unexpected to find a "hybrid parts" link on your website for educational resources. But I was desperate for a better solution than what my Toyota dealer was offering: $362 for the battery, and another $100 to install it. I have owned my Prius for 15 years now, and am pretty much done with paying outrageous dealerships costs for maintenance. But when the local auto parts store told me that company policy did not allow them to sell me a 12V battery for a hybrid, I realized that eLearnAid was probably my last, best hope for a reasonable solution.

And: wow! 30 minutes start to finish. All the parts were included, great instructions in checklist format, and the car started right up again afterward. 1-2-3 done!

Thanks again, W. Y., Franklin, WI

PS: My girlfriend is a high school teacher. When I told her my positive experience with eLearnAid as a parts supplier for hybrid cars, she felt a kindred, entrepreneurial spirit with regard to educational resources. So I am sure she will be perusing your website in the near future!

Our free shipping is ground(to the Southwest) or Priority Mail (2 to 3 days). If you need the battery as soon as possible let us know in the order comments or call us at 818 364-9810.

In a hurry? You can call us at 818 364 9810 up to 5:30pm. If we are in and can get your products out for you we will!

Now available in Canada go to bottom of the page.

  • Voltage 12 (12v or 12 volts)
  • Amp Hour 31
  • CCA* 320 (Cold Cranking Amps at 0 F.)
  • Shipped fully charged ready to install
  • Maintenance-Free
  • Valve-regulated absorbed glass mat (AGM) eliminates acid spills and terminal corrosion.
  • Vent hose attachments for emergencies in case the battery is heavily overcharged.
  • Resists vibration and heat for longer service life
  • Length 7 1/2"
  • Width 5"
  • Height 7"
  • Weight 25lbs
  • Warranty: 18 months replacement excludes damage due to misuse or neglect, improper charging or improper application of battery. If you are over 25 miles from us call 800-237-6126 Click here for full details.

    We ordered one other Prius battery and had it replaced under warranty. Wanted to let you know we found the cause of the drain - we had an aftermarket car stereo causing steady drain even with the ignition off. That's finally fixed, and we're replacing the weak battery for what we expect will be the final time, and we don't expect warranty coverage. Thanks for your excellent support in the past! R.T., Fort Collins CO

  • Made in USA
  • Free shipping to all 50 states and US territories. Battery ships from Los Angeles via UPS ground or Priority Mail so you should get your battery in one to three days!

    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 battery is designed for the Mazda Miata and fits any Miata from 1990 and later. This battery is has more electric storage capacity (takes longer to discharge) than the original Miata or Prius Battery. This is because the battery is made with machines that insure the chemicals are evenly mixed and that the battery is completely packed so there are less air pockets that robe the battery of it's performance.

    This Mazda Miata battery also fits in the original Prius battery holder of the Prius 2001 - 2003, when installed with our kit with instructions. This battery also exceeds the storage capacity of the original Prius Battery (Toyota Part number 28800-21050 - GS S34B20L) which has 28 Amp Hour rating compared to 31 Amp Hour for this battery. Since the battery is a sealed battery, it has the same electrical characteristics as the original Prius battery but it has more capacity. It has been put into over 200 of classic Prius (2001 to 2003) cars with no problems. When I took mine to the dealer for service their only comment was favorable regarding the bigger grounding cable we supply with our kit.

    This sealed battery is designed to go in a trunk and utilizes absorbed glass mat technology. This advanced battery has no free liquid because it is absorbed into the glass mat. Consequently, there is no acid that can spill into the trunk. 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 13.75 volts. 13.75 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. If gassing does occur the gas passes through the vent tube. Our Prius kit extends the original vent tube because the connector is on a different side of the battery.

    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.)

    Because this battery does not start the engine in the Prius it can be used after it's output has seriously declined and at least three users have told me that their Prius now gets better mileage with the new battery. One told me that getting a new battery restored his mileage back to the original mileage he was getting when the car was brand new and another told me that he is now getting better mileage then he did originally. Here is the third owner's comments: "All installed and working GREAT! My mileage has jumped amazingly (>10 mpg). Would have saved considerable amount of money by replacing earlier. Thanks again for being there." (for another similar story go to the bottom of this page.)

    So if you 12 volt battery is weak it could also be affecting your gas mileage because your Prius is wasting energy trying to recharge a battery that will not take a charge.

    Another user had let the 12 volt battery degrade to a point that he had to turn the ignition on and off four or more times to start the car. He told me his gas engine would never shut down when he was driving.

    In short, if your 12 volt battery is four or five years old we recommend you replace the battery. The normal battery life is four to five years.

    Prius battery test procedure for all Prius Cars 2001 to 2008

    Here is a battery test you can perform on a Prius battery that is easy to do.

    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, clock, memory chips etc.

    The original Prius Battery GS S34B20L (Toyota part number 28800-21050) has Japanese electrical posts, which are smaller than the American posts, which come with this battery. This new battery is also shorter and has two vent hoses instead of one. For the Prius you can not buy off the shelf parts to make this battery work. So we recommend you save the time and trouble and also get
    our installation kit which includes all the parts you need and installation instructions. Our kit has has everything preassembled as much as possible to save you time.

    We bought a number of things that did not work quite right in developing this kit. Save yourself the trouble and purchase our kit. You will not save much buying and making the parts yourself. We make the battery riser because we could not find one on the market after a lot of research and the positive battery connector is also custom made.

    You will need a vise, a large crescent wrench or vise grip, a 10MM wrench, some tape, two flat edge screw drivers and a 1/2 inch wrench. You have to follow the normal precautions of disconnecting the negative battery connector first and connecting it last or your can short the positive connector to any exposed metal in the car. If you follow the instructions, that come with the installation kit, you will not short out the battery but you may want to buy the kit and have your battery professionally installed.

    You will save money and get a stronger battery!

    Note: If you dealer replaced the original GS Battery with a Panasonic 12 volt Battery he also replaced the battery hold down brackets and this battery may not fit securely in the new tray. Compare the top of your battery with the picture below to be sure. (The battery is located behind a cloth coated plastic panel in the left side of the trunk. There are three plastic snap down holders. Depending on the connector you push in the center button to let it snap out or if no center button you pry them loose with two flat edge screw drivers on each side.)

    GSOriginal Nippon Denchi GS S34B20L battery - Toyota part # 28800-21050

    Customer comments:

    "Thank you very much for the Prius battery and conversion kit. I had no problem installing it, and the car is now running great. I really didn't expect to get better mileage, but it appears that your claim is true. Prior to changing the battery, I was getting 45.5 mpg. Since changing it, I have put 500 miles on the car, and so far, I am getting 48. Very impressive!!

    I was very pleased with the fast shipping, as I ordered the package late Tuesday and received the battery on Friday and the conversion kit on Saturday. Thanks very much for providing this service, as it is a real cost saver!!

    H. F., Basye, Virginia

    "I don't write recommendations (you have to read all of this one), I try to work with people I know or have known for a long time. I am a people person so ordering a car battery online was very odd for me (the free shipping was huge for me since the company is in LA and I am outside of Washington DC in Virginia). I did call eLearnAid.com on a Saturday and got the owner (like the rest of us, I think he needs a life). He assured me that the product was an upgrade and that the install kit made the job more than reasonable for the car owner to perform (I was very impressed with all the details he shared with me off the top of his head, he too owns a Prius). My #1 incentive was when I called my dealer before I made the purchase, they wanted over $300 for the battery and install, call your dealer and price compare, I am sure it will shock you like it did me, I now have far less trust toward them. I also called about 6 to 7 other places and they all did not stock this battery (including Sears), because of the venting tube it is a unique item. I highly recommend you buy both the battery and the install kit as one package, I'm sure you can play around for a week to build your own kit with about 4 trips to HomeDepo and a car parts place but why do that when you can save all the fuss and failures, just get the pre-made install kit with a set of very detailed instructions. The first thing I did when I got the battery and install kit was read the instructions, the first time I kinda got the idea, two weeks later I started the project (I like to upgrade or replace things when its a good idea to do them but not when its an emergency, so I did not need to rush to get this project done, I highly recommend buying this product if your battery is 5 years old or older) and the second time I read the instructions they seemed reasonable to follow. Once I got my head in my trunk and into doing the work I read them again and the instructions were a dream, you just don't know how good they are until you put your face into your trunk. The best part was when the instructions told me to write down the radio stations programmed into the radio system, my wife uses our Prius and re-setting them for her was a big payoff that night (this made me look thoughtful ... us guys need all the help we can get when it comes to being and looking thoughtful ... LOL). I have to say it took me a few hours to do this project, I was working in the sun and it was hot and I had to play with the dog from time to time. Then there was the battery harness bolt that Toyota stripped when they installed it, so when I was taking it out it broke in the body, I had to drill it out and insert a bolt with new washers and a nut (if this happens to you get stainless steal parts from HomeDepo, no need to do it twice in a few years due to rust), this was the only issue I had to overcome and it was the fault of Toyota when the car was built. I only have three more things to say, buy this product now if your car is over 5 years old, buy it now, buy it now."

    G.M., Springfield, Virginia

    "Thank you! I received and installed the Miata battery in my 2001 Prius in the first week of December, using your kit. For the past three winters I've faced a constant struggle to start my Prius in temperatures below 20F, which are quite common in Chicago. My Toyota dealer recharged the original battery, replaced it and recharged the replacement twice over those three winters. Those solutions never lasted more than a few weeks, and after one recharge my problem was back within a couple of days. I was resorting to one of those Black & Decker portable, cigarette lighter based jump starters and I typically had to recharge it every other day and wait 3-5 minutes for it to work in the car, each and every time.

    Anyway, to make a long story short, after nearly two months with the Miata battery my car starts as quickly at 0F as it does at 60F. If not for this product I would have traded my Prius in by now (I came extremely close to doing so just a day before I found your website). The very reasonable cost of your battery and kit will probably save me thousands of dollars over time, as I'm hopeful now that I can keep my Prius (which is in excellent condition otherwise) for years to come.

    Cheers, J. M. Evanston, IL

    "Well I received the battery today and it took me about 30 minutes to install it. The wood block [battery riser] worked fine. I would like to suggest that if possible, make a kit with a switch to disconnect the battery when the Prius is not going to be used for three or four weeks (like when I am on vacation). If you make a kit for the on - off switch, let me know."

    "Thanks for the battery and the part kit. Most of all, thanks for coming up with the idea to market it, it saved me a lot of time and effort.

    Best regards,


    We have added a disconnect switch! See below.

    "I had been seeing a slow, consistent drop in my mileage (mid 30s during cold weather) over the past few months. I was suspect that the 12v battery was going bad (I have a 2002 Prius) and found your site on the net. I ordered one of your replacement batteries and install kit, which arrived in just a few days. Installation was straight forward, except getting the nut loose from the positive side terminal, that thing is on there! I saw an immediate jump in my mileage, back to the low 40s. It amazes me that the 12v battery was taking so much energy from the system. Anyway, I just wanted to thank you for the great service and a great product." J. B., Eugene, OR

    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.

    Availability: Usually ships the same business day

    12 Volt (12v) Toyota Prius Auxiliary Battery for 2001, 2002, 2003 with installation kit miata+kit  US$153.95  

Optima battery and installation kit for Prius 2001 to 2003
Optima battery and installation kit for Prius 2001 to 2003

Mazda Miata 12 Volt Battery in Canada


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