Gen II Prius Individual Battery Module Replacement

But are you sure they are numbered starting at the computer end?

 

I would think it wouldn't make any difference how they were numbered if you start from the computer end and pair them by twos from the left to right. My numbering scheme is for my module identification and tracking.

 

So, in receipt of a replacement battery module & a charger ( SKYRC QUATTRO B6AC BC580 Professional Balance RC Multi AC/DC Charger Discharger | eBay ) which bears a remarkable resemblance to the products everyone else is using, but with a different name, I have swapped in the replacement module & begun battery cycling.

Thanks for the posts above regarding how to replace the module, that all went very well, it was number 20 is the stack so not too many to take out.

Now charging & discharging has begun, I began with the recommended settings above...

5.0A charge
7500mAh cut off
0.7A discharge (charger max)
DeltaV 4mV/cell
Discharge 6.0V
3 cycles, discharge --> charge.
Delta Peak 2

Initially I had some teething problems with the cycle stopping with a 'Charge Limit Reached' alarm. As I was home all day today & doing some other DIY (painting a lot of doors white) I ran the process manually, with the charging limit turned off but monitoring every few minutes during the charge.

I watched the charger reduce the charge to 1.7A during the final charging. It also paused to rest several times before resuming. In total, the charge was between 7560 and 7820 mAh delivered - hence the cutting out previously.

I've also noticed that the charger tends to read low on the volts - 7.6V against 7.8V on my flukes.

Question is - has anyone else had this problem? These modules are 8 years old & high (262,600) mileage.

I'm minded to carry on with the overcharging limit set at 8000mAh to get three decent unattended cycles.

Any views?

Thanks

Matt

 

1.7amp at high SOC is not necessary and simply not a good idea. Why does everyone want to make this a race?

What kind of cooling and pressure did you have on the module?

I am 100% certain your 6590mah cells did not accept 7800mah of charge. This means you are overcharging them way too much and generating a lot of unproductive (and destructive) heat.

You will likely find differences in voltage readings between a precision measuring device and a hobby charger. Don't sweat it. Just note the difference and either recalibrate the charger, or account for the difference when programming the charger.

 

Hi Eric,
It's interesting because it is what the internal program of the charger when set to NIMH, 4mV DeltaV cut off chooses to do. Is it safe to use this approach with these modules?

I did have a good feel of the modules (there were 4, each 7 modules apart) during the latter part of the charge. They did not feel hot or even very warm to the touch. Would you expect the heat to be very evident? These feel significantly cooler under charge than, for example NIMH AA single cells in a standard charger?

There was no forced cooling applied, but a lot of free air - temp was 22C in the shade today. The pack is assembled with the covers off but the cross pack clamping in place. It is standing on it's mounts in the car with the boot & windows open & the seats down for ventilation all around & underneath. The car is in a garage with the doors open, hence the steady temperature & free air supply.

Unfortunately there doesn't seem to be any way to calibrate the charger. I don't have any sort of logging ammeter to record the actual current delivered. Question is, with the modules not becoming hot, would you expect this to be metering error in the charger?

Thanks

Matt

 

At this point just keep doing what you are doing.
Sounds like you can't make any adjustments anyway.

Some cost-conscious shops use charging protocols that end with 1.5 amps, so I guess everyone has their own way of doing things. But since a hobbyist is not bound by the same time/labor cost constraints as a shop, I would prefer to see more gentle charging.

Some cooling is better than no cooling. Forced cooling between the modules is best.

 

Looks like I have been beset by metering error - putting a fluke into circuit & watching the current during charging, it seems that 5A on the charger is 4.4A on the fluke. Assuming the error is linear, 7800mAh recorded on the charger would be more like 6864mAh on the fluke.

Anyone else experience this with a hobby charger?

Thanks

Matt

 

Have you factored in the reduced capacity, I am sure it will be reduced on such high mileage cells and as for the metering I wouldn't trust either unless recently calibrated

 

Many, many times.
Their cost is too low to have quality components.

Even if you have several of the same model/brand it's likely that there will be variations.

 

It does matter what order they're in, when you pull the code from the OBDII scanner it tells you what "block" is bad. The blocks start at the computer end and each "block" is two modules. So the first two modules next to the computer make up block 1, the 3rd and 4th make up block 2 and so on. There are 28 modules and a total of 14 blocks. The cars OBD system doesn't narrow the problem module any more than one of the two modules, but you should be able to figure out which one of the two is bad.

 

Thanks for the info. I assumed that was the way it was numbered so I lucked out and guessed right however I was not sure how they were paired. I have a battery that has 86k miles with no codes. I was just trying to learn the process of testing, evaluating, and reassembling the pack according to the outcome of my determination of the capacity. I have been doing my process in the living room of my motorhome while on vacation and will install my battery in my 08 Prius when I get home in Oct. My car has 260k miles on it and my thought is that it should show a fault at some point in time so this exercise is just preventative maintenance. Thanks again.

 

Couldn't agree more Eric and that's why I lowered my charger inputs at your suggestion when I did the actual rebuild on my pack. I found that heat seems to be less of an issue than pressure in the modules when they are overcharged. I destroyed one module with well over 10000 mAh (estimated) by accident and while it never got hot to the touch, the case was completely toast as was capacity. When rebuilding less is more because once you cross the line you can't unbake the cake so to speak.

The block order is based on how they are wired to the hybrid ECU. In the Prius they are completely linear but in the Highlander they are actually wired so that #1 block starts on the inside portion of the passenger side battery pack. So if you numbered all the individual modules 1-30 in a row from passenger side to the driver side, electrically block #1 would start at 11/12, block 2# would be 9/10, etc then once you got to the end it restarts in the middle so block #7 would be 13/14. Took me a while to figure this out but once you look how it is wired you can understand how it works reasonably easily. I actually didn't understand the wiring myself until I found the bad block 1 module and was surprised at the location where it was physically in the pack.

 

Interesting statement. Close to what? Close to each other? If you measure individual modules with cheap multimeter, which displays it plus/minus 0.x V - I guess that is where you discover the difference - i.e. "close" not "the same"

However - FYI amount of capacity (or energy) battery provides in between, say 6 & 7 volts (even less in between 6 & 6.5) is a tiny fraction of what it provides in the range of say 7 to 8.5 Volts. Meaning that you do not have to be so much "presize" - around that area and the difference could be neglected.
Discharging under load (e.g. 6 amps or whatever you load and wiring can handle) with the auto stop when the module have reached preset voltage on a module - is what our tool does among other things like measuruing capacity of all modules simultaneously. Fast, easy and renders all that parallel hook up unnessesary. Same with the charge - stop at preset voltage or capacity level.
On that note - all that parallel balancing whichever method you use only make sense if you compiling the pack from the modules with similar capacity. To measure that quickly (all modules simultaneously) - is where you need our Battery Analyser. Ther is no substitute for that...

 

Interesting Kiwi. I've just replaced. 2 modules in my Gen II. My next step is to start balancing. I was thinking about a grid charger from Hybrid Automotive.
I'm in Australia and would be interested in what you have but your web site doesn't seem to mention anything about your product for sale. Maybe I've missed something.
I would possibly be interested in such a product .
Oh yes - go the Waratahs on Sat night.

 

I have had my Prius down for a couple weeks now and am starting to cycle the pack. Here is setup. I got the chargers from lamtech.


I noticed that no one has talked about outgassing from the modules. Since starting the cycles, I notice a distinct smell. I attributed it to the chargers, but seem like the smell kept getting stronger. I concluded that it must be the batteries themselves and went to buy a 6' vinyl hose and connected it to the pack. It solved my odor problem. I have some pics below exhausting outside.

 

That's because we try not to overcharge the modules too much (and keep the charging rate below 1C).

JeffD

 

I would get gas even with 1A and 7250 mAh limits. I still needed the hose to remove the outgassing. Maybe my nose too sensitive. I also try to keep the modules below 80F during the charge, but I have seen it go as high as 89F

The setup allows me to charge 12 modules at one time so that maybe cumulatively the gas is coming from up to 12 modules.

 

Look at "Contact Us" page - it gives options. Custom Build is available - planning to put more photos in a few days time as quite a few boxes were designed and built. Should we add subscription button to the site?

Re: Charger - are you planning to charge NHW-11 - 38 Modules? HA from my understanding - they do not have chargers for that voltage, but you may charge 1/2 of the pack with those aimed for honda. Their chargers deliver less than 0.4 A - you will wait > 10 hours to charge... :-(
We would normally charge 38 modules with 2Amps 160-170v stabilised, isolated, voltage/current/temperature controlled SMPS charger. i.e one half at a time. Have built two of those to play with NHW-11/10 packs or Honda packs. Those are not for sale. It is much easier to sourse industrial SMPS modules 1.2Amp nowadays to build charger for 28 modules - build 4 of those as complimentary for the Analyser.
Now experimenting with special microcontroller based chargers - inspired by folks in Russia who had positive experience in the past, and also by the guys from the Gold Cost who were kindly asking me to build one as they are obsessed with idea but have no skills to build or tools to test the results.
Just finished experimental box. In simple terms - it allows to pump in more power keeping modules cool. Too early to jump to any conclusions yet - but last weekend tested the old NHW-11 modules. Tested in controlled environment, graphed, documented, timestamped. The test demostrated measured capacity raised from 1,3 to 1,5 and then to 1,7AH in the 3 consecutive tests with the idle period between charging of 24 hours.What helped is that the ambient temperature was the same 15C all three days at our place.
Conclusive results of course could be obtained with the other sample from the same pack charged with the conventional SMPS charger in the same controled environment to the same level of charge and discharged in controlled environment to the same voltage level - we can do that with or Complex. It is fun and has never been done before on Prius batteries...

 

It's a GenII - 28 modules.
I'll have a look at web site again.
Thanks