Question: Can you recon a hybrid battery by connecting them all in paralle

i don't think so, sounds like trouble. but what do i know? welcome to priuschat!

 

Theoretically yes. But first you need to charge/discharge every module so that they have exactly the same voltage. Then you need to connect them parallel in a way that every module has same serial resistance between it and the power supply or load. I would say that it would be simpler just to do this while the pack is still connected in series.

Charge and discharge currents and voltages depend on lots of things.

 

This is going to sound really negative.

All of your assumptions are wrong. You are still getting a code because there is a weak module in your pack. No amount of discharging and charging is going to bring it back. Static voltage difference of .08 volts is of no importance. Load test all the modules to find the weak one. Buy a Mini VCI cable!

It does equalize the voltages but it does NOT equalize the SOC. The matching voltages are just surface charge. Once the surface charge matches there is no push (voltage difference) to move Ahr from one module to the next. I have tested this. Voltage and SOC can be two different things. Modules in a good working pack will be at the same State Of Charge and the same voltage

A load capable of draining 34 modules in parallel would be a great load test for individual modules. What are you planning on using? That is allot of power to drain a whole pack at once.

Parallel charging NiMH is a fire danger. NiMH have voltage dip (delta V) when charged to full. Depending on the charging rate, "full" and the delta V will happen between 8.4 and 9.0 volts for a Prius module. When one module hits the delta V first all the rest of the modules in parallel will happily dump all their energy into it.

I hope you are open minded enough to listen.

No, it will do no good at all. Only a proper load test of each individual module will find your weak modules. The "b" word gets thrown around so much on Prius Chat that it has no meaning.

Most members charge the modules individually. Here is a link for a $3 charger that could do half of you pack in series. 3 Dollar Battery Charger It has no safety features. I use an Electrophoresis power supply to slowly charge a whole pack in series. The only thing charging modules is good for is setting a uniform full starting point. It is the discharge that tells the story.

Again, this is a good way to start a fire.

It is easy to spot the modules that have already failed.

That is because you still have weak modules in your pack. A proper load or capacity test will show that some of the modules will have 4000 mAh capacity and others will have 2000 mAh and at least the one that is now causing the code will have close to zero capacity. No amount of charging and discharging will "b" a 2000 mAh and a 4000 mAh module. You need to identify and replace all of the weak modules. Lost capacity can not be regained by cycle charging and discharging. Not replacing all of the weak modules leads to wack a mole as they continue to die one at a time.

Arrrrrgh! Static voltage and the "b" word again! This is all meaningless! Read this short thread on charge and discharge testing using a Mini VCI cable without having to take your car apart. Unable to determine the cause of the triangle warning | PriusChat

One other critical test of module health is self discharge. Modules that can not hold a charge while sitting idle for weeks or months are junk.

None of this is meant to beat up Carmry Mark. I have rebuilt some where around a hundred packs and have lost track of the total. I do not want to see any one head down the wrong path trying to get their car running.

Brad

 

Yes, Torque can be used to look at module voltages while under load and charge.

Yes, just make sure you are counting from the right end of the pack. Opening a Camry battery is a nightmare compared to a Prius. That makes playing Wack A Mole even less fun.

 

A Camry has 34 modules for 17 blocks or pairs. A Gen Prius has 28 modules for 14 pairs. I have not yet tried Torque but plan to.

I have rebuilt just one Camry battery. The way the case is set up is a nightmare compared to a Prius. I would replace both modules in a block before opening the pack up twice. But what you should really do is test all the modules.

I test capacity by slow charging a whole pack at 500 mA until full. At full a 28 module Prius pack will peak at 240 volts and then drop to about 230 volts. The pack will also start heating up at this point. The only purpose of the charge is to bring the modules to a uniform full starting point. I then discharge each module separately at a 20 amp rate to 5.4 volts. To do this with minimal investment you could use the $3 charger and time a headlight discharge on each module.

Here are the results from a 2007 with 200K miles. There are 26 modules as the two real clunkers have been removed. The best module has nearly twice the capacity as the least. Shown is the date and mAh capacity,



This is a 2006 with with 300K.



This is a junk yard 2009 with 164K. No modules have yet failed on this pack.


The point of all that is that your pack and every pack will follow the same trend. 3/4 "good", 1/4 weak and a couple failed.

There is disagreement. The majority opinion believe in the "b" word. I and others believe that there is nothing that can be done to recover lost capacity. I really need to start a thread on simple alternative battery rebuilding.

Brad

 

I used to parallel batteries. I kept getting weird results that did not make any sense so I tested to see if paralleling batteries brought them to the same State Of Charge. Paralleling batteries does bring them to the same voltage. My test used five modules closely matched at about 4000 mAh capacity. They had all been discharged to 5.4 volts at a 20 amp rate. Two of the modules were then charged to full. All five modules were then connected in parallel overnight. This brought all five modules the same voltage. All five where then again drained to 5.4 volts at a 20 amp rate. It has been awhile since I ran this test and I did not save the exact numbers. The two modules that had been charged had about a 3 amp discharge capacity. The three modules that received charge only through a parallel connection had about a 1 amp discharge. I repeated this test charging the other three modules with similar results. Paralleling the batteries did not evenly distribute their energy. Once the surface charge voltage matches there is no push to move energy - Ahrs - from one module to the next. Paralleling batteries accomplishes nothing.

I have some really nice old no longer made chargers that can discharge at a 20 amp rate. They auto stop at 5.4 volts and record the total mAhr discharged. For doing just one pack you could substitute a car headlight and a timer. A high and low beam wired together should have about a 10 amp draw. The exact amount does not matter, you just want a high rate to save time and to give the batteries a real test. Discharge each module exactly 10 minutes and record the ending voltage. Running two headlights on two batteries at the same time will make it go quicker and be less like watching paint dry, Higher capacity modules will have a higher ending voltage. For this test to have good results the modules have to start at a uniform full charge. If you added an amp meter then you could calculate mAhrs.

Not an easy question. I have about ten packs worth of modules to chose from and can select very closely matched (200mAh) modules to build a pack. For you it will come down to cost. Get rid of the outliers. I am planning on building a pack of well matched weak (2000 mAh) modules and running it in my own car. I will not use any modules with excessive self discharge.

 

Numbers please! What was the spread in voltages after the load tests? Did you use your amp meter to test the draw from the headlight? What kind of headlight did you use?

Brad

 

Couple of comments......

1) If you think Camry is bad you should try a Highlander
2) Agreed. You need to test all the modules individually.......there is no short cut on this, sorry OP
3) Agreed. Balancing is only done at the end to keep the hybrid ECU from having a fit over differing voltages in the pack at startup, it plays no role in discovering the current health of modules.

4) Op, you should have bought a mini VCI setup and looked at the battery resistances and voltages under charge/discharge before pulling it all apart (often you can tell exactly which ones are bad before you even get in there)
5) Load testing is the most important test and will usually highlight any bad modules very quickly (headlight/stopwatch test for 2-3 mins works great and post your test results if you want anyone to help verify your findings)
6) Capacity testing is important in the overall performance of the pack (higher the capacity and the closer matched they are, the more MPG you should get from the pack.....if they are mismatched too far it can throw codes while in use, best to aim for no more than 20% max difference between the smallest and largest capacity and pair them together to smooth out the differences between blocks)

 

Find attached custom Pids for the camry hybrid. I've modified it to include the extra banks found on the TCH. Works perfect