Gen II Prius Individual Battery Module Replacement

if u shop around and maybe wait, a used pack maybe had for $400(-100 for core trade in) , u may have to drive 2 hours or so to a remote boneyard,, but to have a 'non-fooled-with' pack , even a 130k+ mileage unit , pull out of a wreck will get u 30 or 50k miles ? (10 times more than you'll get out of whack-a-mole module frustration ! )

 

Self service yards are much less than that in my experience. 150 or 300...and the 300 place sometimes has half off specials. Core charges at both are 30 dollars.

 

i have serial number " 119R6S09533Y " on HV battery . how old is pls ( Toyota AURIS 2013 )

 

It's been years since I replaced my Gen2 modules with Gen3 ones, but I occasionally check in to this thread. I would take chronon's advice to heart and start looking for a replacement pack. You'll be miles ahead when it's all said and done. I hear you when you say that reading all 122 pages is daunting. My first post was on page 45 and it took me weeks to read all of the posts that came before.
Good Luck.

 

Yes, I know from experience, mix and match modules may get u by for a short while, but -- something about all having sequential codes, (made at same time), experienced same heat, loads, etc., -- they will respond in kind, u throw 1 or 2 older/newer in and that 1.2v change will easily occurr throwing your red triangle ...

 

The fourth character is the year. The R in your serial number indicates 2016.
A = 1999
B = 2000
C = 2001
etc
R = 2016

 

That is true for the decode of a module.

If the poster really does mean on the outside of the HV battery and he is not mixing the terminology and calling a module a battery.

There is a two-year difference with HV battery pack serial numbers.

A = 1997
B = 1998
C = 1999
D = 2000
E = 2001
etc
R = 2014
The R in this serial number indicates 2014.

 

A 2016 battery in a 2013 car? That's something you don't see every day.

 

I have got to the stage where I cycled my modules and replaced one bad one and now want to get it all back together. Car is 2005 with 108k miles.

My hobby chargers have given some inconsistent results but i think have been affected by changing weather- I have been doing this out in the shed. I will post the results shortly and would appreciate some feedback from you knowledgeable lot.

My question now is what is the best way to prepare the modules before reinstalling so they don't throw a code? Is the generally accepted view that there is no need to rig them up in parallel to equalise voltages?

At present the open circuit voltages are over 8 volts, having been gently over charged during the cycling. I read that this could cause the car to throw a code. Is this right, and should I discharge them down to a set voltage using my hobby chargers? If so what level should that be?

Many thanks
Mike

 

Here are my results hope you can read them OK

 

Attached are some screenshots from hybrid assistant before I took out the pack. I couldn't do a very satisfactory load test in the car because the aircon doesn't work- not usually a problem in the UK! Module 20 turned out to be bad so have bought a 2007 module from ebay which seems strong, currently doing some cycling on it.

 

I should add that the question marks mean the charger didn't store the results. I quickly found out it was better to do the cycling manually but unless I was standing over the chargers when they finished the charge cycle it wouldn't store the mah figure if it reached the limit set. I tended to set this at 8200 at 2A.

Discharging was usually set to 5.6v at 2A though it rarely went over 1.4A. Sometimes I would do a couple of extra discharges at 0.4A down to 3v on a stubborn module.

 

A couple more screenshot of the report before pulling out the pack

 

Last one

 

I would say yes to rigging them up in parallel to get them to equalize. You can charge them together to, say 8.4V.

I don't see why being slightly "overcharged" would make a difference to the ECU. These modules can hit voltages of nearly 9V or even higher I've heard, during normal operation. And then when left alone they self discharge back down to around 8V.

That's what I did. I hooked them all in parallel, charged it up to 8.3V, then put it back together and threw it in the car. So far no codes, it just works.

 

Thanks a lot for your reply. I've tried to include a quote from a different thread in which there seemed to be consensus that no need to equalise the modules. What are your thoughts on these comments?

Thanks

 

In the big picture, if the modules are healthy, it wont matter a lick if you equalize or not.
---and---
If any of the modules are unhealthy, guess what? Equalizing or not equalizing will still not matter a bit. It will code out.


A healthy module will hold a good charge for months. As long as a charge cycle was performed on each module as the last step of your cycling, you should be good to go. (assuming the modules are fairly well balanced in capacity.)

 

Well, I generally agree with the post you quoted, but now see three different ways of trying to do the same thing.

1. You quoted a post referring to just wiring them up in parallel and leaving them there. I see some benefit in this, but do agree that it's still not an ideal way to balance the modules and cells. Due to internal resistances the lower voltage modules theoretically won't charge up to the same SOC (state-of-charge) as the higher voltage modules and viceversa, the higher voltage modules won't discharge down to the same SOC as the lower voltage modules. And in the end, it only balances modules, not the individual cells.
2. There's a reference in that quote to "the right way" of balancing the cells, that is, to have the battery all wired up normally (and even installed in the vehicle) and then taking a high voltage "grid" charger and then "overcharging" the battery as a whole. Since individual cells can't hold more voltage than their maximum charge they just dissipate the extra charge as heat and eventually all cells reach 100% charge, or top balanced.
3. I did a combination of the two. I wired the modules all in parallel and then charged them. Thus each module reached the 100% charge.

However, you apparently already "balanced" the cells by overcharging each module. The only problem, and this is what I found, is that unless you have 24 hobby chargers you have to charge only a few at a time. NiMH batteries have a high discharge rate which means that by the time you get to the end of charging each module your modules are now out of balance again.

This is why I finished by putting them all in parallel and charging them up together. This way they all had to charge up to about 100% and then finished with the same voltage. This is the only way I could figure out how to do it with a single hobby charger and not having a "grid" charger. After taking the modules off and putting the battery back together the modules were able to self discharge down to the nearly the same voltage levels.

On the other hand, the car may eventually balance them out as you drive.

 

No, this is not correct, it is the voltage difference and the difference in the capacity between the modules that cause codes. Fractionally just under 8.2 V will show as 8 bars (green) on the Prius' energy screen and is as high as you would want to go. You could go as low as 7.6V and still be ok.

This is an incorrect interpretation. Whether you charge all 28 modules in serial or each one individually, the 'right way' is to get each of the 6 cells within each module to 100%. This is achieved both with a grid charger or a charger doing a single module.

The voltage being lower does not mean the modules are no longer balanced. If they are self-discharging so quickly it is more likely the modules are in a poor condition.

A final charge prior to assembly to 8.2 V will not take very long per module and with most hobby chargers you could wire two modules together in series and charge two at a time so should easily be achievable in less than a week (for the final charge.)

 

Thanks! That's what I thought. I was just quoting the reference @Moshy had mentioned.

I can't remember exactly the difference. All I know is that there was sort of a scale with the last modules being charged having the highest voltages and the first ones having the lowest voltage. It may have been only .3 or .4V. But being the perfectionist I am I wanted all to be exactly the same. So I charged them in parallel. It was very easy to do with two pieces of of solid copper bare wire. It also didn't take long since they were already mostly charged up from cycling.

My $20 hobby charger only charges up to 6 cells in series. So I'd have to get a different hobby charger.