Going to buy a 2005 with a dead hybrid battery

I'm sure you'll get replies from the people here that know FAR more than me but from what I know the hybrid battery can't be dead if the gas engine runs. From what you say it sounds like the gas engine is running if the car moves. The Hybrid battery is actually what starts the gas engine, the 12volt battery just powers up the computers. If the car moves just on electric you won't get far at all before it really is totally dead.

 

As @jeff652 can confirm the Prolong system is designed to prolong(!) the life of the battery, not resurrect a bad one. It appears you are DIY so your best choice would be a kit of new cells from @2k1Toaster here for $1600. You will end up with a much more reliable vehicle than having to periodically replace modules & re-balance the pack.

The Gas engine can run in "limp mode" with an unbalanced battery pack.

 

There are usually a few levels of death on the battery. When it first fails you can drive it almost normally, it is just sluggish. I drove mine at full highway speeds for months like this (DO NOT ATTEMPT!). Eventually the modules will get so bad, that almost any current draw will collapse them and that's when it can barely get above surface street speeds and it really sluggish and hesitant. It is definitely not safe at that point, but can be moved around with extreme caution. Then the next level is dead dead. It doesn't really do anything other than turn on, give you the middle finger triangle and refuse to move. You have no warning or knowledge of when it will switch from one to the other state. It sounds like you're in the second state, it may switch to the third state during your drive, you don't know. So just be prepared. Sometimes with a code clearer you can nurse a few minutes out of a dead-dead by clearing it and making the car think everything is OK, and then you can move a bit until the car figures it out.

This is like putting a terminal patient on life support on a healthy diet and moderate exercise routine. That's good advise if you're still healthy enough to do it. When the battery gets to this point, you're really not going to gain much. Get a new battery, and then prolong it, and that's a winning combo.

No.

Kind of. They generally have mountains of cells and can match your other "good" cells with cells sitting around that are also close to what you have. They build a pack from closely matched modules from all over. With you, you only have the cells you start with, you'd need to buy a few hundred cells to pick out a pack of good ones, then sell back the few hundred extra cells.

If you're budget tops out around $1500, you can also check out my kit.

 

2KtToaster works with batteries for a living He knows how to specify good cells.

 

I traded in my 2008 in November and got $3,000 for it with 108,000 miles. I may have been able to get a little more out of it if I sold it myself. A 2005 isn't worth much even in excellent condition and one with problems is well a problem. You can buy one that runs for the money you will have in it and your time is worth something. I have a saying, "Never play another man's game".

 

To the OP....DON'T DO IT!

If you are just getting into Hybrids, get one that actually works. They have depreciated to a point where a working Prius and a non working Prius is very similar in price (after you spend the time in repairing the broken one). So why bother getting a broken one?

Working 2005 Prius - $3000-$4000
Broken 2005 Prius - $1000 - $1500
Prius battery - $1000-$2500

With a broken Prius, you won't know if there's any other damage until it's too late.

 

some have better knowledge. it is painstaking, but can be done. the car you are looking for should be almost free. maybe $500. at most?

 

I have a 2005 Prius with <$200 in repair items in the 285,000 miles on the car. That includes one module for the traction battery as well as the sensor wiring and battery ECU inside the traction battery..

I'm not as skittish about buying a Prius with a bad traction battery. I own 4 of them. Because of that, I opted to buy a high-end Denso Hand Held Toyota Teste II and a grid charger. So far, those two pieces of test equipment have been first class. Recently I purchased a SuperMate DC6 charger. I have a 2002 and 2005 extra traction batteries in the garage sitting on the shelf that I've been fixing up as money and time permits. Now I cans start to better balance the modules on the extra replacement battery.

Your question about "a lasting fix" is a very good one. Truthfully, no one can really tell. IMHO, all you can do is replace the offending module(s). Then once you have the battery fixe and running, take note of the module voltages every once in a while. If they start dropping, you may have a problem The good thing is that with a 2005 the modules are sealed and don't exhibit the problems in the Gen 1 traction batteries.

The downside of a Prius is it's learning curve. It is very a steep curve as you've been finding out. But, with a little elbow grease, time, some mechanical and electrical knowledge you can be dangerous in no time at all.

Who do you listen to? That's only a question you can answer. IMHO, if you can get a good low mileage Prius for a song and a dance that has a failing traction battery, you're money ahead. Then fix it, and run it into the ground, fix it again and repeat. But, that's what I'd do, and am doing with the four that I own.

 

Great, don’t buy a reconditioned battery, buy a new from Toyota battery, good for 150,000 care free miles, 2500-3000$, just make it part of the initial expense, then just own a Toyota, if it needs rubber or brakes or front wheel bearings, so be it. 50+- mpg for a year then a little drop, beats anything else out there for the money.

Used batteries are used batteries, they are a throw away item....

 

Sorry I don't agree with your thinking here. With a running Prius you get to see how the rest of the car runs. Even if you think you might have to replace the battery in the future the car runs now so you can see how the CVT, inverter, the different water and cooling pumps ect. work. With the Prius not running you can sink money into the battery and now it's running only to learn the inverter overheats, the CVT is shot or something else that was hidden from you because the car wasn't running and didn't allow you to check for other things. In other words the battery could be just the start of your problems.

 

I admire your tenacity and resolve, but to minimize costs and the Wife needs a car...suggests to me you might consider other options. A 2005 Prius will be in need of more than just a battery. Just my friendly.

 

Bunce,

Do what you're comfortable with. Every member on this forum has different levels of ability with regard to electrical and mechanical. Some of us like to tinker and some of us just want to buy a new car every few years. If you're a DIY kind of guy and you like to tinker and learn, buy the car and enjoy it. I've been fortunate enough that I've had (2) 2005 Prius(es), one had 235k miles the other had ~260k miles. Both were bought when they had bad batteries. Repaired both myself. The 235k car now has 280k and unfortunately, the 260k car got run off the road around the 285k mark and totalled. The only other work I've had to do was putting new bearing hubs on the 235k car when it hit ~275k. My son has been using it for college for a couple years now. The 2007 I have now, I purchased with a bad battery at 143k miles in Feb 2017. I'm at 165k now. No other work required except fixing the battery. Obviously, no two cars are the same and your results may vary. Which ever way you go, good luck.

 

The last 2005 I bought with a bad battery for $1400, came with additional problems. Needing a 3 way coolant valve, water pump, Maf sensor, and a little body work.

But I've had owned a few before and know the symptoms and have the knowledge to DIY.

These cars are really reliable but can be very expensive to fix when they break. With a non running car, you could be lucky with just a battery issue, but you could also be unlucky to have many undisclosed issues as well.

 

IMHO one huge problem with just replacing bad modules is that the only replacement modules available are used and of unknown history or longevity. I only know of one credible source That would end up with a new pack other than Toyota OEM.
If I had that car I would not expect it to be reliable enough for somebody else to depend on. If I drive a hobby car and get stranded it is different than somebody else getting stranded expecting me to come out and fix onsite.

 

When the guy says dead he means dead. You wont be able to start the engine with this one so its a tow home and then you have a 3500 lb paper weight in your yard while you play with the battery and that may take a while because all you've done is watch youtubes. After that you may after alot of time and money get the battery together and it may run for a while....even guys who know what there doing usually resign themselves to whack a mole repairing it and you get it on the road and find out the motor is blown or the trans is blown or the ac doesn't work. And maybe with a boatload of luck, time and $$$$ you get it running and then the wife gets to drive this thing. Yeah great plan.

 

Alas it's not that simple.
Without a working HV battery, you can't tell what ELSE might be wrong with it.
This will be a HUGE gamble.......the cost of which might go WAY beyond just getting a working battery in it.
Consider this move carefully.

 

Tomorrow I have an appointment to look at one and it sounds like the battery is totally dead. He said we wouldn't be able to drive on the highway as it can't get up to speed.

That was quoted from post #1. That means the car probably does move. Therefore, the battery is not "totally dead", just failing.
"It can't get up to speed" is a symptom of a failing battery that significantly impacts the ability of the car to accelerate. I've been through this, and I've taken cars with this symptom for test drives. Each time, it has been solved by replacing/repairing the HV battery. I'm not saying it's guaranteed the car has no other problems.

Why do we feel this possible purchase is such a huge, potentially devastating gamble? Everything has a price. If the man is comfortable with the price, compared to what he may be getting into, what's the big deal? Is he paying 10k for it? Is he paying 1k for it? Does it have 300k miles or 30k miles? There's a lot of variability here. It's up to him to determine his comfort level.