Battery Replacement - Economy Method

Thanks! Keep us posted how it goes.

I have 2006 model too and my 12V lead acid battery is still doing fine. I may need to replace it in 2 years.

Did you see the CCA rating on the OEM battery? I am wondering if it is also around 330.

 

Excellent job! Reminds me of the way I cut corners when I owned a Cessna 152. I needed a new alternator and anything for a plane is five times what it would cost if it were for a car. Anyway, I bought a rebuilt Ford alternator and it worked fine.

I changed the 12V battery in my 2004 last summer. My friend assisted (and did most of the work) and he did a great job. I bought it online from a Toyota dealer and paid $104 incl shipping. Your price sounds a lot better! It will be interesting to see how it holds up. I see no reason why it won't last just as long since the specifications are virtually the same. Good luck!!

 

All good, except that it appears the battery is the traditional liquid acid type instead of AGM (absorbent glass mat); and it probably does not have a vent attachment leading to a rubber hose like the original equipment battery. If your right rear fender gets nailed in an accident, you may have liquid acid all over the luggage compartment or worse. During normal operation, hydrogen gas is being produced by the traditional 12V battery and is just being vented into the hatch space, lacking attachment to a rubber hose that leads to the fender.

For owners who are not satisfied with buying a replacement Toyota battery, I suggest that you should look for a battery that is 1) AGM and 2) equipped with a vent attachment. Beyond those considerations, the AH rating should be in the mid-30s minimum, and of course the physical dimensions must fit the available space.

vertex pointed out a couple of reasons why the 12V battery must have a reasonable capacity. Another reason is if your inverter dies while you are traveling at speed. The 12V battery has to provide enough energy so that you can gracefully come to a stop and shut down the vehicle.

 

I just replaced mine with the elearn Optima Yellow Top which is rated at 38Ah, 575 CA and 450 CCA.

 

Quote from another site concerning AGM batteries
Deep Cycle Battery FAQ

AGM batteries have several advantages over both gelled and flooded, at about the same cost as gelled:

Since all the electrolyte (acid) is contained in the glass mats, they cannot spill, even if broken. This also means that since they are non-hazardous, the shipping costs are lower. In addition, since there is no liquid to freeze and expand, they are practically immune from freezing damage.
Nearly all AGM batteries are "recombinant" - what that means is that the Oxygen and Hydrogen recombine INSIDE the battery. These use gas phase transfer of oxygen to the negative plates to recombine them back into water while charging and prevent the loss of water through electrolysis. The recombining is typically 99+% efficient, so almost no water is lost.
The charging voltages are the same as for any standard battery - no need for any special adjustments or problems with incompatible chargers or charge controls. And, since the internal resistance is extremely low, there is almost no heating of the battery even under heavy charge and discharge currents. The Concorde (and most AGM) batteries have no charge or discharge current limits.
AGM's have a very low self-discharge - from 1% to 3% per month is usual. This means that they can sit in storage for much longer periods without charging than standard batteries. The Concorde batteries can be almost fully recharged (95% or better) even after 30 days of being totally discharged.
AGM's do not have any liquid to spill, and even under severe overcharge conditions hydrogen emission is far below the 4% max specified for aircraft and enclosed spaces. The plates in AGM's are tightly packed and rigidly mounted, and will withstand shock and vibration better than any standard battery.


Their greater efficiency generally leads to longer life another big positive . There are alternative AGM batteries that I'll look at when the time comes to replace mine.

 

Yes, some other owners have also reported this. I personally find this to be quite fascinating because I examined the original equipment batteries in my 2001 and 2004 and they both were AGM and "dry", no liquid sloshing around inside. The Toyota New Car Features manual points out that the 12V battery is AGM and must not be replaced by a different type.

Yet, some other owners reported similar findings as you. Their batteries are also made by GS and look exactly the same as my battery, yet they are different inside...

 

GS is known as GS Yuasa, and I've seen Honda and Yamaha generators use a similar battery - but it's not a sealed nor AGM type but it uses the small JIS posts than SAE ones.

 

After I replaced the 12V battery in my 2001 with the larger Panasonic battery that Toyota recommends in a TSB, I removed the labels on top of the original equipment GS battery (which are marked, "do not remove"). Then I removed the translucent plastic covers over the six cell holes. Looking into the holes, I saw the fuzzy white glass mats between the lead plates. I tipped the battery over and it was completely dry, no free liquid inside.

 

I have no doubt that as the GenII Prius fleet ages, a lot more owners will refuse to pay for an externally vented battery, and will put in whatever battery they can make fit

At a certain level, a battery is a battery. To meet modern safety requirements, the internal location of the Prius battery really limits the choice for correct replacement items. There is no doubt that as long as the battery fits, it will work, but perhaps not be safe under all circumstances

These owners must accept full responsibility for any damage (Eg, battery acid eating out the bottom of the tray area) or injury (Eg, buildup of hydrogen gas resulting in a fire/explosion) that occurs.

I can only imagine news headlines in a couple of years: "2006 Prius explodes, 12 volt battery to blame." Then the fine print reveals an incorrect, aftermarket 12 volt battery was used

Personally, if I had to replace the 12 vdc battery in a Prius, I'd go with either the OEM or the Optima conversion

 

In my climate, I have seen batteries crack and leak acid, making one hell of a mess. In bitter cold temps, a low battery will actually freeze. If you then attempt to boost it, it will explode

No, I do not invent "campfire stories"

The Optima battery kit from Elearnaid is actually the Mazda Miata battery replacement. It has the correct vent tube connection. A couple of our forum members provided detailed installation photos

http://evnut.com/prius_battery_optima.html

Prius 12V swap

You can clearly see where the vent tube plugs in

 

Ambient temps don't have to be particularly cold or hot for a battery to leak acid. I owned a 1988 BMW 325 convertible many years ago. When the original equipment 12V battery needed to be replaced I bought a Sears battery of the correct physical dimensions and speced for that car.

The battery leaked. I took the battery back and got a replacement. That replacement also leaked. Sears paid a few hundred dollars for the battery tray area to be repainted and I bought a battery from the BMW dealer which did not leak.

Is it so impossible for you to visualize a scenario where a battery is overcharged? In the case of a regular vehicle, the voltage regulator on the alternator fails and the output rises to 16V or more. In the case of the Prius, the DC to DC converter output regulation fails and a similar result happens.

 

The Optima battery specifically intended as a replacement for the Mazda Miata battery, has the vent tube provision. I am unaware of any other battery that has this provision

When I was a teenager in St George, Utah, I briefly had a 1972 Chevy C-10. I'm sure you're aware how crappy the voltage regulators of that vintage were. Combine a failed/crap voltage regulator with the extreme summer heat, by September the battery tray was rotted right through

Yes, I actually do carry a large commercial-industrial quality fire extinguisher in every vehicle I own. That allowed me to save a person in Utah from being burned to death following a severe crash.

I've never needed a fire extinguisher for my own use, but have needed them several times up to this point, to help others. Fortunately, my first aid kit has never been needed

Much like the Canadian Tire jump start box I carry in my vehicles. If worse comes to worse, and something is seriously haywire with the vehicle needing a boost, all I'll fry is a $100 booster box

I don't have to worry about frying a $4,000 inverter/converter in a Prius, or the electronically controlled alternator in my FJ

Over the past 5 years, I have used the booster box an average of twice a year. It works, I help somebody who is potentially stranded in dangerously cold weather, and all with no risk to my personal vehicle

Some of us are comfy with accepting a certain level of risk, and some of us prefer to practise Risk Mitigation

As far as your economy battery replacement, all I can suggest is keeping an eye out for any evidence of battery outgassing or seepage. A lot of those cheap batteries will seep a little bit of acid, so keep an eye on the area where the battery is sitting