I need advice. I recently came across a 2002 Prius with 138,000 miles for sale for $5500 from a private dealer. The seller said it was a theft recovery he bought at an auction. When I went to look at the car, one of the techs at the Toyota dealership it was taken to for service took it out for a drive with me and the check engine light (and the "!" triangle) came on. We took it back and pulled the code: P3006: "Batteries Levels are Unusually Different" or "Battery SOC Are Uneven" The tech did a further diagnostic report on the battery. I won't type it all here, just the parts that I think might be important: Battery SOC: 42.5% Delta SOC: 42.5% Auxiliary Battery Voltage: 13.828 V Battery Blk Voltage 1: 17.56 V Battery Blk Voltage 2: 17.67 V Battery Blk Voltage 3: 17.62 V Battery Blk Voltage 4: 17.63 V Battery Blk Voltage 5: 17.73 V Battery Blk Voltage 6: 17.68 V Battery Blk Voltage 7: 17.68 V Battery Blk Voltage 8: 17.62 V Battery Blk Voltage 9: 17.61 V Battery Blk Voltage 10: 17.62 V Battery Blk Voltage 11: 17.62 V Battery Blk Voltage 12: 17.63 V Battery Blk Voltage 13: 17.59 V Battery Blk Voltage 14: 17.59 V Battery Blk Voltage 15: 17.71 V Battery Blk Voltage 16: 17.57 V Battery Blk Voltage 17: 17.60 V Battery Blk Voltage 18: 17.54 V Battery Blk Voltage 19: 17.47 V The tech explained that the modules within the HV battery could be abnormally variant because the owner had left the sitting for about a month on their lot. He though the modules may have discharged at a different rate and, if the car were driven and the battery used, the charges might even out. He said there was a 'stall test' that could be done to determine if the problem was the HV Battery or the Battery ECU and that either might need to be replaced. It's not my car and so it wasn't my place to ask him to do the test. He said if it was him, he'd take it on a long test drive and see if it got better once the battery was being actively charged and decharged. I decided to do that. They'd cleared the P3006 code before I picked up the car, so there wasn't a check engine light when I picked it up. About 15 minutes after I started driving it, though, it came back on. I pretty much expected this because if the ECU was going to be able to equalize the charges of the modules as the tech thought it might, I didn't expect that would happen before the same code got set off again. I drove the car about 70 miles (getting about 38 MPG, a little less than I would have expected) and paid some mechanic elsewhere $40 to clear the code so that I could see if it would come back on, now that I'd driven the car a bit. He pulled the code, P3006 as before. I drove away and not five minutes later, the "!" and check engine light came back on. I know $5500 is a good price, but I don't know if I have the money it would take to get a new HV Battery and/or a new Battery ECU (I was quoted $1500 for both, used and I'm guessing another $300 to have them installed) if the battery were to fail. The voltages of the individual battery blocks look fairly consistent to me, the highest being #5 at 17.73 V and the lowest, #19 at 17.47 V, for a variance of 0.26 V. But the Delta SOC was 42.5% (I've read it shouldn't be above 20%, which is probably what set off the P3006 code). Can anyone explain this to me? I thought the Delta SOC was a representation of the variation in charge of the different blocks? Also, from what I've read, each block represents two 7.2 V modules, so shouldn't a block's voltage be closer to 14.4 V (7.2 x 2) than the ~17 V I'm seeing? I need to make a decision quickly. The owner wants the car back now, says he's got an offer from someone to buy it sight unseen. I'd really appreciate it if someone could provide any insight into what might be going on with the car and how likely it is that I'll have to replace the HV Battery or ECU in the near future. THANK YOU.
DTC P3006 is a serious trouble code. The traction battery really has failed. You will have to replace it immediately. The relatively low mpg that you noticed is evidence that the battery is not holding charge from regen braking as it should, assuming that you were not running the air conditioner as max AC where the compressor is continuously running. When you were driving the car did you notice if the gasoline engine would go off when driving at slow speeds under light load? If the engine kept running that is further evidence that the battery is bad. When looking at the traction battery SOC indicator in the MFD, did you see the charge level jumping up and down quickly? If so, thats more evidence of a bad battery. You've come up with a reasonable estimate of $1,800 if you were to use a salvage battery as a replacement (assuming you can find an independent to install for $300; a dealer will not touch salvage parts.) Would a price of $7,300 seem like a good price to you for a 2002 Prius with 138K miles and other possible problems that you haven't noticed yet? If this seems OK then buy the car. If it doesn't seem OK then let it go. Also note that a salvage battery comes with no guarantee beyond an offer to return if the battery does not work immediately upon delivery. So one year from now or one month from now you could be facing the need to replace the battery again. Don't forget the other potential service issues that the Classic Prius is known for, such as having to replace the catalytic converter, the engine ECU, the electric steering gear, an occasional transaxle or inverter failure, etc. None of these are inexpensive repairs. As to your question about why the module pair voltage is reading 17V instead of 14V, this is because the battery pack is normally operating at a voltage of around 320+V when properly charged. 273.6V is the nominal rating for the battery pack with 38 modules, 7.2V each.
Thanks, Patrick. As I was driving to work this morning (a 10 minute drive), I kept a closer on the energy flow and the SOC on the MFD. The SOC did seem to fluctuate a lot (was fluctuated between 75%, 50%, and 25% as represented the display every couple minutes, was at 100% for a moment, then back to 25% within a minute or two). The engine only turned off once or twice for a second or two. I don't have any other experience driving a prius, so it's a little hard for me to gauge, but it would seem that what you were describing as indications that the battery is going bad is what I was seeing this morning. I'm going to pass on the car. He said he'd bring the price down to $4700 so it'd be about $5000 with tax, but I just don't think I can afford to take the gamble. The problem with buying used cars in the $3000 to $5000 range (where I'm at with my Grad School budget) is that they're all a gamble, really. Thanks again, Patrick. I feel more resolved in my decision to not buy the car now.
What catches my eye is that the battery ECU is looking at a charge state of ~ 17.6/block, 334 total, and calling it a 42.5% SoC. And then it's reporting the exact same number, 42.5%, as the Delta SoC. I confess I have no numbers of my own to compare them to, as I am still trying to cobble together some scanning solution (short of having a used Graham scanner fall in my lap) to get numbers on my own car. But do these numbers even make sense? They push my 'weird' button, to the point where if I had a spare battery ECU (which of course I don't) I'd be tempted to swap it in and see if it reported the same numbers, and -then- look at the battery itself. Somebody who's familiar with normal readings may with complete justice tell me I'm off the track here. -Chap
Yup, Chapman, those numbers pushed my weird button too. The one case I was able ti find online where someone listed the Battery Blck Voltages was in a situation where the battery definitely was going bad and the voltages varied between ~8V and about ~14V. The voltages on the report from this car are pretty consistent. And yes, it's very strange that the Battery SOC and the Delta SOC are the same number, 42.5%. It could be that I don't understand the Delta SOC. From what I've read, it seems that it should be a representation of the variance of charge of the individual modules within the battery. It could be that I've misunderstood; That it actually is some representation of how much the voltage has fluctuated over a period of time, or maybe some combination of the two. There's a battery ECU on Ebay for $80 too, so if it was that, that wouldn't be too expensive a fix, either. The stall test is supposed to be able to determine if the problem is the ECU or the battery itself, but I don't think I want to spend the money to have the test performed on a car that's not mine. Not to mention the owner wants the car back.
I'll just chime in and say what I think you've already deduced. This would be a great deal for someone who has the funds available and/or tech skills to go ahead and fix some things up. The car still books for ~$8-10k, so at $4700 theres plenty of margin there for repairs but if your budget is only $5k then that doesn't help you. On top of that you are always taking a risk with a car that needs work, as you never know what other problems could lurking. Rob
$11,810 - Kelly retail price, excellent condition $9,710 - Kelly private party, excellent $7,840 - Kelly private party, fair ~$4,600 - Toyota price to replace battery $7,210 - retail price, broken $5,110 - private party, broken $3,240 - private party fair, broken $5,500 - offered price, broken Off hand, it looks to be what Kelly Blue Book would consider to be close to a fair price for a battery broken 02 Prius. However, you need an extra $4,600 for Toyota to get it repaired. In my case, I have the maintenance manuals, tools, spare parts and knowledge to make a battery repair. However, knowing what it would take and the utility of the vehicle, it is only worth ~$2-3,000 to me. I would have to travel to Denver to inspect the car and make 'field repairs.' Then I would have to drive the car back to Huntsville assuming the car has a tag that would let me drive it back. Then there would be the maintenance when I arrived so the costs would look like: $1,846 - Delta weekend $102 - gas for 1277 miles $80 - two nights room $50 - meals ---- $2,078 - just to pick it up $300 - new tires $30 - transaxle oil $120 - alignment $20 - ICE oil change $10 - wipers ---- $480 - standard repairs $200 - battery repair ---- $680 - vehicle repairs (assumes no body work) ====== $2,758 - to get and fix-up vehicle $5,500 - offered price $2,758 - my expected expense ====== $2,742 - net worth of car to me in HSV I might be able to get better ticket prices and bring it up to $3,742 but we're getting to the limit. This assumes my labor is free. Is your labor that free? Now if someone has an extra ~$5k and can get the purchase price down to say ~$4k, they would have Prius whose battery should last another 6 years. Personally, that car doesn't look attractive until the price gets closer to $2k but I've seen salvage cars in terrible states sold for $4k on Ebay. IMHO, you pays your money and takes your chances. GOOD LUCK! Bob Wilson
I really like this detailed evaluation. I could follow it all until the last step. Are you getting a post-repair net worth by subtracting repair expense from asking price? Would it be off-base to subtract repair expense from one of the non-broken-condition Kelly values for a post-repair net worth, and then compare that number to the asking price to determine the attractiveness of the deal? -Chap
I was trying to take my expected expense to fetch the car and fix it up to my standards. Even if I cut the air fare down using some of the 'low cost' fares, it still winds up being expensive. In some accounting systems, my repairs would be treated as an optional, value-added improvement of the base car. I could see someone thinking I've boosted the car value by this expense. However, I see it as my expense to bring the car up to my standards, an additional expense. If you want, you could take the offered "$5.5k" and add my "$2.5k" and state that the car would cost me "$8k," which only brings it into the lower range of the Kelly value. That makes the car at $5.5k still too expense for my taste. I need some profit. Bob Wilson
Here's my question: How do you determine which cell block is bad? Normally there will be a much greater difference in cell block voltages (at least 1 volt but more likely >1.2V to account for a bad cell w/in the block). What I see is a good battery and a bad ECU. Like Chap, I would like to swap out the Batt ECU because in reality, there is no error in the cell block voltages. With that in mind, the wandering SOC and constant ICE run are clear indicators of a bad/weak battery. Normally I would say try to buy the car for ~$3000 and try to replace the ECU and if that fails, replace one cell with a matched cell from Ebay. These weird symptoms clearly do not allow me to advise this. I've never heard of these particular symptoms.
The first thing to do before replacing batteries is to replace the wiring harness, with the control wires. This costs around $110. Mine had corroded several control wires, and rather than attempting to fix, I bought a new one. Take the other side off (without control wires), and clean, very thoroughly, the copper connectors. I mean shiny clean, by sanding with emory cloth or similar. Then reassemble. It took me twice to get it right, since I didn't clean the connectors properly the first time. Torque to the required inch/pounds, meaning tight, but not overly tight, which might break the battery stud. Yes, this happened to me too, and I had to replace a battery cell. I chose to replace two, thinking they needed to be somewhat similar in voltage. I think the "matched cell" hypothesis is a bit of overkill: it is the connections that need to be extremely clean and tight. The P3006 error never came back, well over 1000 miles. Good luck with this, it is a lot cheaper than a new or rebuilt battery.
If you sand down copper you must treat it with an anti corrosive. Lots of stuff out there, high quality grease will work fine but sanded raw copper left exposed and especially the sanded connections that have current going through them will quickly corrode around a battery. Current, heat, battery fumes, and a little humidity will make a mess out of your hard work.
