Gen II Prius Individual Battery Module Replacement

Ok, so I've been reading this thread for about 2 weeks now. Ever since I changed out a bad cell in my 2007 Prius. 3 days after the swap, all the lights came back on. I looked into it more and found this thread. Great thread by the way. But I have a few questions!

1. Is there a cheaper multi charger than the $220 Hitec X4 chargers? There are a few options, but they all seem to be about the same price. I'm considering buying a battery from a wrecked prius for $700, and if I were to buy 2 X4's it would be almost 500.. So for 200 more it kinda feels worth not having to spend the time and energy doing the job.

2. How long would it take me (approximately) to discharge/charge the batteries for a full 3 cycles with just one charger? From what I've read it'll take more than a month. And I don't really want to borrow my mother-in-law's car for another month if I can avoid it.

3. My father-in-law has a Schumacher Inc - 406A. Would this work to discharge/charge all the modules? If so that would be great, but I've tried looking into it and I just don't know if it would be able to discharge, or if I would be able to set it to the specifications needed to slow charge the modules correctly.

4. If anyone in the Salt Lake or Ogden area has a charger that I could rent, or borrow, that would be great also. (and some hands on guidance on how to use the charger would be nice too haha)

Thanks.

 

Here's a useful google sheet

Dchg3 has conditional formatting.

Conduct a single cycle of each of the untested modules and report back.

No and No.

Well, technically yes and no, but you'll likely destroy a module or several.

 

I've had 2 cell failures so far on my nearly 150k 06. This car has been used to tow, sometimes some loads it REALLY shouldn't have, so I'm not surprised. Being a daily driver, I don't have the down time to condition the cells, nor the funds to buy 14 or 28 charge circuits to do it quickly. So I've been doing it the "wrong way" - buy working cells, swap them in, and head down the road.

The first failure was 3/15, shorted cell, less than 6.5 volts on it while the rest were at 7.5. I bought 2 3G cells off Ebay for $80, swapped them in to 15/16, threw the car back together, drove it around town for about 50 miles, then took off on a 1000+ mile trip. No problems.

Last month, 1/16, after 11,000 miles, I had another failure in Block 04. Cell 7 was at 6.2V. I still had the old good cell from last year, still at nearly the same voltage as the pack, so I swapped it in place of Cell 7. THIS time, rather than just throw it back together, I decided to build an equalization harness to get all the cells as close as possible before bolting the buss bars back on. Left it equalizing for a day, threw it back together, drove it for about 20 miles, then set out on a 125+ mile trip with a 3x5' flatbed trailer on the back, 2 server racks on it on the way home. Took back roads so I didn't have to top 60mph. It did fine.

More importantly, watching on the Energy screen, it acted more like a healthy pack than last year. Last year, for several days, it stayed in the green zone for most of the time, dipping into purple occasionally. Not the typical SOC check, but not the green/purple/green/purple of a dying pack. After a few days, it went back to the normal of trying to stay in blue all the time. This year, with the equalization, it went immediately to the normal blue range, and only hit green when expected. So hopefully I will get another 9 months of usage (or more). If not, I'll deal with it again. I'm trying to eke it along for another year or 3, at which point I will find a really low mileage 3G pack and swap all the cells in. It will be cheaper than buying enough chargers for a quick cycle.

So here are pics of the positive equalization harness, and of both pos and neg installed. Just 2 harnesses, and I did them the most difficult way possible, stripping out sections of insulation, doubling over the wire, twisting it, and cramming it into the terminals. I trust that method over using 28 sections of wire for each , but it does take a lot longer. Yes, they are the same color - I used speaker wire. I was going to mark pos with a red marker, but just decided to leave the insulators on the terminals, and remove them on the neg harness.



BTW, the garden cart pictured (Harbor Freight special) under the pack is what I use to move it around and work on it, as it leaves easy access to the bottom bolts that hold the cells to the pack. When one is obstructed, I just shift the pack to the side a bit to get to it.

 

Tom,

While very crafty, I'm afraid your harness does little good besides establishing a very short-term voltage parity and making you feel good about the results. Even in parallel charging where there is an actual significant potential parallel modules will take charges at dramatically different rates.

NiMH work in a very narrow voltage range and OCV variations with SoC are VERY small. When you wire them in parallel, their voltages equalize very rapidly thus dropping the transfer of charge to near zero (tens of mA). Yes, it moves the modules slightly closer to actual charge parity, but unless you're doing this for days/weeks at a time, it's barely worth the effort, and since you say this is a daily driver, I doubt you're doing this. Success hinges on how far apart the modules are to start with and how long you leave them harnessed.

You can check the results of the grid charge/discharge I did on my friend's '08 in my sig. This was done without any module replacement, and it was done after a note in consistent mpg drop over the course of a few months before any other indication of problems. 145K miles in AZ heat, a single grid charge/discharge cycle and the useable capacity of the battery is nearly 2.5X the pre-cycle test as measured by a Techstream discharge test.

If you want to "eke it along for another year or 3," you should do something that actually "balances" the modules. In series, all cells flow the same current. Period. There is no variation. If you put 3A into it for an hour, they all get 3Ah. Do that in parallel, and you'll find wild variation... of course, you'll have to charge with 84A in an hour to get the same energy input. This is why grid charging works. You have most of the modules in your pack at 161K. They've never been cycled below 40% SoC and suffer from significant capacity reduction due to short-cycling.

I vigorously recommend you invest in a grid charger/discharger to restore usable capacity and prolong the life of your original modules. Individual module replacement without deliberate and effective efforts at balancing are a total crapshoot.

Good luck,

Steve

 

So like I said earlier, I can get a good battery out of a wrecked Prius for 700. Are there any options for chargers that are not hundreds of dollars? I really need to get this done as cheep as possible. If I had a grand to dump into this, then I would just pay for a new battery through pep boys for 1200 haha

 

Bobakanoosh,
You can build a high voltage charger that will do an entire battery for cheap. A couple of power supplies and some wire nuts.
It will be kinda unsafe and require caution when constructing and using, but it is doable if you are dirt poor and can't afford another option. Call me to discuss.

 

There is prudently economical and then there is cheap. With cheap, you usually get what you pay for.

For $1,100 invested in a battery and charger, you will do better than donating $1,200 to the pep boys get rich scheme.

The only better thing to do is buy a genuine Toyota Battery for $1,900-2,400 (which can be found by searching Toyota dealers that sell online) and install it yourself. I understand that you might not have the cash up front at this time, but depending on how long you will keep the car, it will work out cheaper in the long run.

 

What battery discharge/charger would you recommend? I am thinking about getting one from Hybrid Automotive for $399, but I'm not 100% sold that's the best way to go. Does discharging/charging the entire pack at once work the same, worse, or better than charging each cell individually with something like the Hitec X4? I know I need to balance the pack. But what is the best way to do that, or does it even matter?

Jordan

 

I vigorously recommend the HA charger. He has a long and very positive history with the IMA community.

It's a matter of what your time is worth. you can spend weeks cycling through sticks with an X4, or you can do a full pack charge and discharge in a weekend and get excellent results.

Steve

 

If you can detail a SAFE charger that can charge the pack with only a few days of downtime, and costs less than $200, I'm all ears. Otherwise, it's out of my budget for at least the next year.

While the HA charger is intriguing, it costs half the cost of a 10k mile 3G battery pack. If I am going to bust my budget, I'd rather get a pack that will last me 100k for $700ish than buy a charger/discharger for $450ish that MAY or MAY NOT keep my pack running any longer at all. And the discharge looks "fun", having to essentially monitor the voltage for most of a day for the right times to swap bulbs.

Besides which, on the HA site it notes:
"If the battery does not recover from the initial reconditioning treatment and the failure errors return (red triangle or IMA light), then one or more modules inside of the battery has experienced a hard failure. A hard failure cannot be repaired by reconditioning alone and physical replacement is going to be required.
...
For Toyota hybrids battery packs, the success rate of replacing only the failed modules is much higher. In order to identify the failed modules in a Toyota battery, a load test of each module must be performed. Our Prolong™ Battery Module Load Tester is a simple, inexpensive way to identify and replace failed or failing battery modules."

Which is what I have done - I have replaced 2 hard failures.

I'd LOVE the buy the complete HA system and a 3G pack and go to town on it. But there's this thing called a budget...

 

talonts,
You are not going to find a brand new, premade, safety tested, purpose built, consumer-grade, high voltage charger for under $200.

For now it sounds like you have more time than money...

Do you have the knowledge of how to safely work around 240 volts dc?
It sounds like you do.

You can build a charger that is as safe as you want it to be.
Your main investment will be time instead of money.

Some ideas that don't cost much money...
1) Read up on electronics and think about what other existing electronic devices you could use that has the input voltage/output voltage you desire. Buy one and adapt it to your use.

2) Scour the internet for plans for building a device with specs similar to what you need. Plenty of free schematics out there. Then all you need to do is buy the parts and assemble them.

3) Take your knowledge of electronics (or learn more online) and decide for yourself what kind of parts you want for the task and put it together .

Next step above these ideas would maybe cost you a small amount of money, but shave a little off the time.
1) Call someone who has knowledge about electronics and explain to them what you are trying to do. Pay them for their time and then follow their instructions.
2) Find an electronics person, explain what you want, and ask him to build a custom one for you.

There are lots of ways to tackle this problem.
Only you can decide what is best for your situation and budget.

 

And you have not done so in a fashion that ensures longevity. Modules will continue to fail as you've made no effort to restore capacity or balance. You prefer to deal with one failing module at a time rather than treat the whole pack thus ensuring a progressive march towards the next failure.

I congratulate you on your access to cheap G3 packs. Here in AZ we're lucky to find 10 year old G2 packs for less than $1,000.

Good luck,

Steve

 

So I do have another question. What if my computer is bad? How can I know? And is it hard to replace? But I think mostly how would I know or test if it's bad?

-Jordan

 

I just spent a week, going through each module in my 07 pack, with 2 Reaktor chargers, and I added a Hobbyking Quattro charger to speed things up. Each module was cycled 3 times, down to 6 volts (I would feel safer at 6.3), and we noted the increase in capacity in every module. Some started out with 1500mah, but after cycling, many were between 5 and 6 amps, not bad for 10 year old batteries. Now there were a few that needed more cycles to bring them up to par, and that really slowed us down a lot. Tonight, I carefully wired the modules in parallel with lashing wire, and will leave it sit overnight, and reinstall in the morning. The car has been apart for a week now, while my wife patiently waits for this charging and recharging, to finally be over. After this, I have my 06 to do (quickly replaced 3 modules, no cycling or balancing, lasted one week and the warning lights returned), but I ordered 2 more Reaktor chargers to help get the job done. I would love to have an HA charger, especially on a newer model Prius, so you could keep the pack in tip-top shape. On these older cars, where the modules are starting to go south, and more invasive procedures are required, a stack of Reaktors or even the Quattro / X4 chargers, are what you need. When I started this, I had two B6 chargers that served me well through thousands of 18650 cells, but when it came to charging the Prius modules, they failed me. S Keith posted his opinion along with suggestions, and I listened, so with any luck tomorrow will be a good day, and I can start on the other car.

Tj

 

I am half way through this myself, my B6's also went out the door lol, its all good fun! Steve (and a few others here) really know their stuff!

you plan on matching your pairs? or just putting it back in

Cheers

Matt

 

Most of mine are so close, there is no reason to match pairs. I have two that are above the rest in capacity, one is the eBay module I bought to replace the dead one, so I am just going to reinstall and ride. Just fixing to get started, so will repost later with results. Good luck with yours!

Tj

 

sounds great you have done well, nice to know there is some good modules on eBay

cheers

Matt

 

I posted a pic of my lashing wire harness on Facebook, it only cost $3 at the local hardware store, just have to be extremely careful not to short anything. Tommy Johnson | Facebook

 

Got everything back in, and took a 10 mile test drive. Pack shows blue bars, about 3/4 full, and did not move at all, not even when under hard acceleration. Mileage during the trip showed over 50mpg, at a steady 65mph, and that is way more than it got before. So far, so good! Now if I can get this TIS to talk to the car, and clear the codes...

Tj

 

Two steps forward, one step back. Wife took the 07 to work yesterday, after the test drive. A few minutes after she left, she called to say the warning lights went out on their own (I couldn't get TIS working), and the car was running great. One her way home though, they came back on, right before she turned into the driveway. I stayed up late, reinstalled TIS on an old XP laptop, and it worked perfectly. The entire screen was filled with DTC's, so I saved them, and reset. They stayed off for 5 minutes, I heard the HV relays click, and I got a code that bank 12 was low. TIS showed it to be the same as the others, so maybe I missed tightening a battery post nut? I'm tearing it back apart this morning, hopefully for the last time. How are these banks numbered?

Tj