HVbattery techstream diagnosis of the hybrid battery pack

If you're not that familiar with balancing the entire pack by itself, individually, you can buy the grid charger that's at the Prius shop. That will enable you to balance the entire pack at once.....and you can do it every few months to keep up the condition of the battery.

1. Replace the 2 bad blocks with good modules. You'll need a total of 4 modules to replace the 2 blocks.
2. Buy and install the harness for the grid charger, then balance using the grid charger.

The harness remains in the car so if you need to balance with the grid charger again, it'll just require you to plug in the charger into the harness.

 

It is not quite that simple. A quick search of the PC archives will find a rich set of experiences gained as many Prii owners have rebuilt their HV batteries, some successful and some not. The basic steps of a full rebuild are:

1. Obtain a number of low mileage modules from a "good" source (there are few good sources). You will need some spares as the replacement modules need to match the existing ones in capacity and series resistance. I am assuming that about 24 of your existing modules are in good shape as you live in a cool climate (heat is the enemy).
   
   Another option is to get a low mileage Gen3 salvaged battery that has not sat in storage for a long time and start with the 28 modules from that battery. They will fit in your existing Gen2 HV battery shell.
   
   
2. Obtain some battery rebalancers and a digital voltmeter (I have a SuperMate DC6 and a 12v power brick but many equivalent ones are available). You wil)l want more than one to cut down the elapsed time as the rebalancing process takes over a day per module.
3. Rebalance each module (3 discharge/charge cycles with the proper settings). Make certain that modules are clamped under pressure to avoid bulging the sides as they heat up during the cycles.
4. Check each charged module under load to see a uniform voltage drop in a fixed amount of time. One minute with both filaments of a halogen headlamp will suffice.
5. Put all 28 modules in parallel for a while to equalize their voltages.
6. Install the matched modules in your battery (similar capacity,, preferably over 4.5 amp-hours each and pair them so that the measured voltage drops during the load test add to a common amount).
7. Install your rebuilt HV battery remembering to slide the safety plug to the locked position.

Remember at some of these steps there is a dangerous level of DC voltage (200+) that can kill. So be careful and wear safety gloves.

JeffD

 

JeffD's method is a little cheaper. But you'll need to have a little more experience and a lot more time in doing it his way.

$400 is not expensive if you hear about what people are spending for refurbished batteries nowadays.

 

I actually have a few good modules I can sell you from my 2005, that will better match the capacity from your 2005 battery. Send me a message and we can set that up.

The grid charger also has a discharge function for a little more. I highly recommend you get that option. Then you would just charge and discharge 2 or 3 times and you're done. You'll be good in 1 weekend.

Also another Jeff from Hybrid Automotive is on PriusChat and he's always helpful if you have any questions in charging and discharging using his grid charger.

Even with the grid charger, you probably will not be able to keep the battery for the life of the car......it'll help tremendously on a DIY basis to keep it going, but with all batteries, they will need replacement over time.

 

I don't know of any. I had 27 good ones but sold out a while ago. Take JC up on his offer.

As I said before, do some research on this site.

One option is 14 Gen3s each paired with a Gen2. The Gen3 modules have a lower series resistance than your Gen2s, but the resistances add so pairing one of each should work.

You will need to separately charge and test the replacement modules first unless you are replacing all 28 modules with a known good set.

No, you do each module separately to balance them. Putting them all in parallel just equalizes module voltages.

You might get by with swapping the 28 Gen3 modules (assuming the Gen3 is in good shape) into your Gen2 shell without going through the rebalancing process. Getting the in-car charger to slowly rebalance the HV battery in place after that is a good idea.

Good luck. JeffD

 

After you install the new modules, you would need to use the grid charger to balance the entire battery pack.

I guess if you wanted to save money, you can see how it works in your pack as is. But from past user experience, that may or may not be a lasting repair. Best to balance when finished.

 

Me?

I would just replace the existing with a new battery. Just can't see replacing modules and balancing - waste of time and labor. Remans, currently, FWIW, don't hold up like a new HV battery.

Just my .02 cents.

DBCassidy

 

You might be able to get somewhat of a "goodwill warranty" from Toyota. Your mileage is not that high. They "may" cover 1/2 of the repair, just have to ask. Your out of pocket cost will be in the 4 digit range, but at least it'll be a new battery.

 

Yes it'll involve their diagnostic fee first, that's always the case. But if it's reduced from $4000 to $2000, I think it's not a bad deal.

I don't think you can register in CA and get the warranty. If that were the case, everyone would do it. There are many threads on here that discusses this topic.

 

If Toyota eats half the charge or more, fine.
If not, buy the battery and install it yourself.

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The problems with solitary module replacement(s) just make it a poor choice IMHO unless you expect to the car to last less than a year regardless. And please do listen to Jeff Denenberg when he tells you that balancing from a grid charger is insufficient.

 

When did he mention this?