2007 Prius. Hybrid battery (original) failing...

Danica · Aug 7, 2025 at 7:32 PM

pasadena_commut said: ↑

For those of you not familiar with Coachella, it can get ridiculously hot in the summer. National weather service forecast for today is 116F (47C), probably close to that yesterday. A marginal HV pack is not going to do well under those conditions, with the AC running full blast, or the pack running very hot if it isn't. It may run OK once the car cools off to something more reasonable, like 75F, although it might not get that low. Palm Springs is nearby, but Palm Springs is not where you would look for a good deal on, well, anything.

So for the OP, here is the situation. If that code is correct you probably need a new HV pack. (Does the OP have a dog, does it ride in the car, has the pack fan ever been cleaned? The pack fans are notorious for jamming up with animal hair leading to batteries overheating. Look on youtube for videos.) The price of the pack varies by hundreds of dollars from dealer to dealer. To find the best price one must check the Toyota Dealers "nearby", and that means well into LA. Some of them have Web sites which will give the price, others you need to phone. Price can vary by hundreds of dollars, and supply varies, there are periods where they have so many they drop the prices low, and at other times it is hard to find one. Then you need to get somebody to install it. (Not something a person should try who does not already have tools and at least some experience working on cars. It isn't all that hard, just not a job for a complete newbie.) Note, the pack comes in a shipping case which resembles a coffin - it is very big and very bulky. It won't fit in a small car like a Corolla (unless it is a hatchback), but it will fit in the back of a Prius with the rear seat down. Dealers will not ship them, one must take delivery at the parts counter. There is a core charge as some parts of the old battery must be returned. The core charge is refunded when they get the core back - in the big shipping crate.

The primary advantage of going to a Toyota dealer is that the warranty on the pack would be longer. However, I would suggest looking for independent shops in Riverside and San Bernadino, and if necessary working west from there. The installation cost should be lower, and if it is an OEM battery, it will be the same battery as from a dealer. Experienced mechanics can get one of these packs in and out in like an hour (maybe a little longer if it is 116F!), it isn't rocket science, and practice makes perfect. (It took me much longer as I had never done one before.) See if you can find somebody who can pick up an OEM battery at a dealer, bring it to you, and install it. Or you might have to have the car towed to them. Possibly you can drive there if the car still works late at night when the temperature is low. You do have to look at the pack first and see if it is the OEM battery because you need some of the parts from inside, the replacement battery does not have the electronics and some of the air control bits, those need to be moved over. If the pack is painted a bright color it is not an OEM pack, if it is a metallic gray it might be (but without a full history no way to tell for sure without opening it.)

I don't know where GreenTec gets its "all new cells". In fact, I don't think I have ever seen a picture of the inside of one of those packs. It might not even be the same technology. Toyota NiMH batteries use Prismatic modules (rectangular) whereas Honda and some others used cylindrical sticks. The Toyota OEM modules were a better technology and their packs lasted much longer than the Honda packs of the same age. There have been people who sold packs for the Prius using those cylindrical cells, perhaps it turned out well for some people. There was a Lithium based pack available, now I think a Sodium one, I do not recommend those unless you are into experimenting on your car. Not a good choice if this is the only car you have. I don't recommend any of the options with used modules.
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Thank you for the response. To answer your question, no I do not have a dog. I have a couple cats, but they never ride in the car unless they are going to the vet, and then they are in a carrier up front with me.

Yes, the summers here can be brutal. I've been trying my best to protect the car from the summer heat ever since I bought this Prius in 2017. I try to do all my driving in the early mornings, unless I absolutely have to go somewhere in the middle of the day. I keep the car garaged, with all the windows open. And I seek out shady parking spaces whenever possible, and put a reflector in the windshield. Until yesterday, the car had seemed to be doing well.

The dealer I spoke with said that as long as the car still has the original core I will not be charged. I got an estimate in writing, and it contains an instant rebate for the core, as long as it is original. I bought the car used in 2017 (from a dealer) and was told it was still on the original hybrid battery. I also got a printout of all the mechanical work the previous owner had done on the car, and there was nothing in there about the hybrid battery being replaced. I remember being told that the previous owner was the same person who had bought the car new, which I believe was confirmed in the printout.

The car might be drivable in the early morning, the coolest part of the day here. But after what happened Wednesday, I'm afraid to risk it. If the car flaked out on me while I was driving on a busy street, or worse, in the middle of a busy intersection, that could be dangerous. I'd rather pay for the tow than take that risk.

Thanks again.

Hayslayer · Aug 7, 2025 at 9:46 PM

Danica said: ↑

Thank you for the response. To answer your question, no I do not have a dog. I have a couple cats, but they never ride in the car unless they are going to the vet, and then they are in a carrier up front with me.

Yes, the summers here can be brutal. I've been trying my best to protect the car from the summer heat ever since I bought this Prius in 2017. I try to do all my driving in the early mornings, unless I absolutely have to go somewhere in the middle of the day. I keep the car garaged, with all the windows open. And I seek out shady parking spaces whenever possible, and put a reflector in the windshield. Until yesterday, the car had seemed to be doing well.

The dealer I spoke with said that as long as the car still has the original core I will not be charged. I got an estimate in writing, and it contains an instant rebate for the core, as long as it is original. I bought the car used in 2017 (from a dealer) and was told it was still on the original hybrid battery. I also got a printout of all the mechanical work the previous owner had done on the car, and there was nothing in there about the hybrid battery being replaced. I remember being told that the previous owner was the same person who had bought the car new, which I believe was confirmed in the printout.

The car might be drivable in the early morning, the coolest part of the day here. But after what happened Wednesday, I'm afraid to risk it. If the car flaked out on me while I was driving on a busy street, or worse, in the middle of a busy intersection, that could be dangerous. I'd rather pay for the tow than take that risk.

Thanks again.
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You are making a wise choice. The only other thing that may come up at the dealer is the battery computer. The gen 2 hybrid battery has an ecu module inside. The voltage sensing wires connect to that ecu. Sometimes, there is significant corrosion on the ecu pins where those wires plug into. It's unfortunate, but it happens. If it's severe enough, it will cause battery faults and can even cause a high voltage short circuit and start a fire at the ecu connector. The new batteries do not include the electronics section of the battery, which includes the ecu and relays and a bit of wiring. Those original parts are transferred to the new assembly. IF IF IF your ecu has corrosion, they will likely tell you a new ecu is needed. These are about $1000 new from Toyota, about $100-150 for good used ones on ebay. Even I keep several in the shop.

You could also call Greenbean and ask them what style battery modules are used in their "new module" packs. If it isn't new Toyota/Panasonic/PrimeEarth prismatic modules, I would stay away. Now, if it is Toyota/Panasonic/Primeearth prismatic modules, the good thing about Greenbean is they show up at your door with a COMPLETE battery, with the ECU fully inspected and repaired if needed, so there's no tow required and no surprise $1000 ecu charge there.

Although Toyota doesn't sell these modules separately from a battery assembly, for DIYer's it is possible to buy a less expensive battery for a different model car and install those modules into a different case, for a different car. The same modules are used in dozens of car models. For example, I can buy a battery for a gen 3 for about $1500, and put those new modules in a Gen 2 pack.

You will have no "must drive every day" problems with a new Toyota pack. When new, these packs can sit in a car for a year or more without being used and they will be perfectly fine. The 12v battery will be dead, but the HV battery will be fine. They don't start having self-discharge problems until several years of use. Based on your usage description, that will work great for you.

pasadena_commut · Aug 7, 2025 at 11:40 PM

Hayslayer said: ↑

You could also call Greenbean and ask them what style battery modules are used in their "new module" packs.
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One can always ask. Since they make a big fuss about new cells, but say nothing about what they are on their web site, it seems super unlikely that they have access to the same modules that Toyota uses. They might have modules that look like, and are spec'd like Toyota's, but that doesn't mean they will actually last as long. (Just like all "AA" alkaline batteries look about the same, doesn't mean they have the same longevity or capacity, far from it in fact.)

Hayslayer · Aug 8, 2025 at 12:17 AM

pasadena_commut said: ↑

One can always ask. Since they make a big fuss about new cells, but say nothing about what they are on their web site, it seems super unlikely that they have access to the same modules that Toyota uses. They might have modules that look like, and are spec'd like Toyota's, but that doesn't mean they will actually last as long. (Just like all "AA" alkaline batteries look about the same, doesn't mean they have the same longevity or capacity, far from it in fact.)
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You nailed that and I agree 100%. That's why I had this statement about manufacturers: If it isn't new Toyota/Panasonic/PrimeEarth prismatic modules, I would stay away.

Panasonic was the original manufacturer of the prismatics used in Toyota hybrid batteries. Not remembering all the details, but they later split off the battery division into some partnership with Toyota, iirc, and renamed it PrimeEarth.

I've seen Chinese "prismatics" online a few times over the last couple years. They probably work as well as their "Denso" imitation sparkplugs....

2007 Prius. Hybrid battery (original) failing...

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2007 Prius. Hybrid battery (original) failing...

Danica New Member

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