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Availability of the 12V battery in USA

5871 Views 4 Replies 4 Participants Last post by  bjsegel
I love my Prius. It gets great mileage, etc.

However: About three weeks after I bought it, I went out to start it and it would not start. That is, there was no power and the car would not start.

I had it towed to the local Toyota dealer. They told me the battery needed a recharge and they would have it for me Monday (It was Friday when it went in). I had left nothing on. It just went dead.

Monday I came in. They said that the battery was defective and they had ordered a new one. I figured it must be the big battery. They also told me that they battery was not in stock in the USA and it would take about three weeks to get a new one. This seemed unreasonable to me, but I had no alternative but to live with the situation.

As predicted, it was nearly three weeks, and I was told that it was the 12V battery that was defective. They told me that an ordinary 12V battery would not work in the Prius. It had to have a special 12V battery, only available in Japan.

My chagrin is now nearly over. The local dealer and maintenance staff were very polite and they were and they were as chagrinned as I was. My chagrin is not directed at them. They did their best.

My questions:

1. Why does Toyota sell the car in the USA and not stock the 12V battery?

2: What is so special about the Toyota 12V battery that an ordinary 12V battery would not suffice, at least for the duration of the wait for the one coming from Japan. This is not a rhetorical question. I'd really like to know.

As I said, I love this car. This is my only complaint.

Bill Putaansuu
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There was a recommendation on this board not too long ago for the Exide Select Orbital 12v battery as a replacement for the OEM 12v battery. See ... l_XCD.html . I can't answer your question about compatibility---maybe some of the technical-minded contributors to this site could address that issue. I gotta say, though, that what the dealer told you sounds a little fishy to me. There's a lot of misinformation out there about hybrids in general and Prius in particular, and dealers are not immune to this problem.
On second thought, I don't think the Exide will fit in the Prius 12v battery compartment! The Exide is 10.17L x 7W x 8.12H---larger than the OEM battery, especially in the "L" dimension, as near as I can measure it without removing the OEM battery.
Suitable replacements

Dealership service departments are an amazing source of misinformation. There is really nothing special about the Prius battery. It is a typical lead-acid gas recombinant battery. Exide, Optima, and now Delphi (AC Delco) make these "gell" electrolyte batteries. However, because they are sized for engine cranking, their 55 to 65 ampere-hour size will require modifications of the battery holder.

As an alternative, Panasonic, Yuasa, and Eagle Pitcher make smaller gell lead-acid batteries that will fit. However, their products that will fit in the present Prius battery holder will not have much more capacity than the OEM battery that has been estimated to have a 25 amp-hour capacity. I have attached a catalog page from Digikey Electronics (great company) with a listing of lead-acid batteries. A 28 to 42 amp-hour battery would certainly be affordable.

Even the more traditional liquid electrolyte or "flooded cell" lead-acid batteries will work fine. These batteries can, however, weep electrolyte under some conditions (for example, high under hood temps and overcharge). There are several new cars that have the traditional liquid electrolyte batteries in the trunk and run cables to the starter on the engine. This has been done because of space limitations under the hood and lower temps in the trunk increase battery life. However, these installations have a full perimeter battery tray. I have driven my Prius with a garden tractor battery substituted for the original.

Toyota probably made a mistake in using such a small battery. It is true that electrical loads while operating the vehicle are entirely supplied by the high to low voltage converter, and no traditional engine cranking of the battery is required. However, they did not consider that parasitic drains on the battery when the car is parked can quickly kill the small capacity 12 volt battery--and apparently a lot of electrical loads are left on unintentionally. Further, Toyota did not consider that their well regulated 14.5 volt system voltage will not recharge an ice cold lead-acid battery located in the trunk (winter conditions). I advised another Prius owner who thought he had a defective battery to charge it overnight with a small charger (about a 2 amp rate) while the battery was at room temperature. When he removed the battery from the car and did this, it has worked great in his Prius ever since.
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When I picked up my new Prius last month, the 12V battery was dead and the car had to be jumped before I could drive it home! A couple of days later my wife had to call Toyota roadside assistance when the car wouldn't start in our garage. They sent someone who jumped it. Last week I had my car in the shop to take care of another matter and I complained about the battery. They replaced it right away; no long wait, although your experience and what I've read elsewhere led me to expect otherwise. So its hard to know what the real story is and why some people have had to wait so long.

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