Gen II Prius Individual Battery Module Replacement

I have one question regarding rebalancing procedure. After last discharging when I achieve desired capacity (around 6000 mAh) I need to charge particular cell to the......what's the proper value? 7800mAh? What voltage? 8.5V will be ok?
Thanks in advance, greetings from Poland!

 

here is my test results so far.
It would appear the highest voltage isn't always the strongest cell.
My 3 highest had more drop under load.
I charged my cells till 10Pm last night, took resting readings twice today6am and 8pm, put a .56amp load on for 1 hr, and took readings 1/2 hr after the load test.
pic of the load 60watt bulb across the full voltage(all cells)

time “10PM” “6AM” “8PM” “9PM” “9:30PM”

Mod 4 8.26 8.16 0.10 8.14 0.12 7.63 0.51 7.74 0.11
Mod 5 8.30 8.16 0.14 8.11 0.19 7.15 0.96 7.39 0.24
Mod 6 8.31 8.15 0.16 8.11 0.20 6.85 1.26 7.18 0.33
Mod 7 8.35 8.18 0.17 8.14 0.21 7.10 1.04 7.25 0.15
Mod 8 8.24 8.13 0.11 8.11 0.13 7.52 0.59 7.63 0.11
Mod 9 8.26 8.14 0.12 8.11 0.15 7.50 0.61 7.62 0.12
Mod 10 8.29 8.14 0.15 8.12 0.17 7.23 0.89 7.41 0.18
Mod 11 8.24 8.12 0.12 8.09 0.15 7.48 0.61 7.58 0.10
Mod 12 8.20 8.11 0.09 8.09 0.11 7.49 0.60 7.61 0.12
Mod 13 8.19 8.09 0.10 8.06 0.13 7.47 0.59 7.58 0.11
Mod 16 8.18 8.09 0.09 8.08 0.10 7.49 0.59 7.59 0.10
Mod 15 8.20 8.11 0.09 8.07 0.13 7.47 0.60 7.59 0.12
Mod 18 8.18 8.09 0.09 8.07 0.11 7.47 0.60 7.57 0.10
Mod 19 8.19 8.10 0.09 8.07 0.12 7.57 0.50 7.62 0.05
Mod 20 8.18 8.09 0.09 8.07 0.11 7.47 0.60 7.59 0.12
Mod 21 8.20 8.11 0.09 8.07 0.13 7.49 0.58 7.60 0.11
Mod 22 8.19 8.10 0.09 8.08 0.11 7.48 0.60 7.60 0.12
Mod 23 8.20 8.07 0.13 8.08 0.12 7.39 0.69 7.61 0.22
Mod 17 8.23 8.14 0.09 8.12 0.11 7.59 0.53 7.70 0.11
Mod 14 8.20 8.10 0.10 8.06 0.14 7.32 0.74 7.60 0.28

columns
module #,10pm,6am,loss from 10 to 6,8pm,loss from10pm to 8 pm,9pm,loss from 8 to 9 under .56amp load, 9:30pm,recover for 1/2 hr

 

Correct, got it in one.

I would put a 10-15 Amp load on it for 5 min and take the voltage readings at that point while still under load.

Here is the data sorted buy module number in a bit more of a friendly presentation:

	module #	10pm	6am	loss from 10 to 6	8pm	loss from 10pm to 8pm	9pm	loss from 8 to 9 under .56 Amp load	9:30pm	recover for 1/2 hr
1	04	8.26	8.16	0.10	8.14	0.12	7.63	0.51	7.74	0.11
2	05	8.30	8.16	0.14	8.11	0.19	7.15	0.96	7.39	0.24
3	06	8.31	8.15	0.16	8.11	0.20	6.85	1.26	7.18	0.33
4	07	8.35	8.18	0.17	8.14	0.21	7.10	1.04	7.25	0.15
5	08	8.24	8.13	0.11	8.11	0.13	7.52	0.59	7.63	0.11
6	09	8.26	8.14	0.12	8.11	0.15	7.50	0.61	7.62	0.12
7	10	8.29	8.14	0.15	8.12	0.17	7.23	0.89	7.41	0.18
8	11	8.24	8.12	0.12	8.09	0.15	7.48	0.61	7.58	0.10
9	12	8.20	8.11	0.09	8.09	0.11	7.49	0.60	7.61	0.12
10	13	8.19	8.09	0.10	8.06	0.13	7.47	0.59	7.58	0.11
11	14	8.20	8.10	0.10	8.06	0.14	7.32	0.74	7.60	0.28
12	15	8.20	8.11	0.09	8.07	0.13	7.47	0.60	7.59	0.12
13	16	8.18	8.09	0.09	8.08	0.10	7.49	0.59	7.59	0.10
14	17	8.23	8.14	0.09	8.12	0.11	7.59	0.53	7.70	0.11
15	18	8.18	8.09	0.09	8.07	0.11	7.47	0.60	7.57	0.10
16	19	8.19	8.10	0.09	8.07	0.12	7.57	0.50	7.62	0.05
17	20	8.18	8.09	0.09	8.07	0.11	7.47	0.60	7.59	0.12
18	21	8.20	8.11	0.09	8.07	0.13	7.49	0.58	7.60	0.11
19	22	8.19	8.10	0.09	8.08	0.11	7.48	0.60	7.60	0.12
20	23	8.20	8.07	0.13	8.08	0.12	7.39	0.69	7.61	0.22

And again, but this time sorted by "loss from 8 to 9 under .56amp load":

	module #	10pm	6am	loss from 10 to 6	8pm	loss from 10pm to 8pm	9pm	loss from 8 to 9 under .56 Amp load	9:30pm	recover for 1/2 hr
1	19	8.19	8.1	0.09	8.07	0.12	7.57	0.5	7.62	0.05
2	04	8.26	8.16	0.1	8.14	0.12	7.63	0.51	7.74	0.11
3	17	8.23	8.14	0.09	8.12	0.11	7.59	0.53	7.7	0.11
4	21	8.2	8.11	0.09	8.07	0.13	7.49	0.58	7.6	0.11
5	08	8.24	8.13	0.11	8.11	0.13	7.52	0.59	7.63	0.11
6	13	8.19	8.09	0.1	8.06	0.13	7.47	0.59	7.58	0.11
7	16	8.18	8.09	0.09	8.08	0.1	7.49	0.59	7.59	0.1
8	12	8.2	8.11	0.09	8.09	0.11	7.49	0.6	7.61	0.12
9	15	8.2	8.11	0.09	8.07	0.13	7.47	0.6	7.59	0.12
10	18	8.18	8.09	0.09	8.07	0.11	7.47	0.6	7.57	0.1
11	20	8.18	8.09	0.09	8.07	0.11	7.47	0.6	7.59	0.12
12	22	8.19	8.1	0.09	8.08	0.11	7.48	0.6	7.6	0.12
13	09	8.26	8.14	0.12	8.11	0.15	7.5	0.61	7.62	0.12
14	11	8.24	8.12	0.12	8.09	0.15	7.48	0.61	7.58	0.1
15	23	8.2	8.07	0.13	8.08	0.12	7.39	0.69	7.61	0.22
16	14	8.2	8.1	0.1	8.06	0.14	7.32	0.74	7.6	0.28
17	10	8.29	8.14	0.15	8.12	0.17	7.23	0.89	7.41	0.18
18	05	8.3	8.16	0.14	8.11	0.19	7.15	0.96	7.39	0.24
19	07	8.35	8.18	0.17	8.14	0.21	7.1	1.04	7.25	0.15
20	06	8.31	8.15	0.16	8.11	0.2	6.85	1.26	7.18	0.33

One of the experts here could suggest where the cutoff point should be, if they think there is sufficient data. Again they maybe able to suggest changes to the methodology.

Hope this helps as a start.

 

@TMR-JWAP has done a lot of module comparison in his testing.

 

I will figure out how to load with 10 amps or so with multiple lights to test for 5 min this weekend.
So far I hope I may have a few good cells to use as replacement when I test the pack out of the car.
I hope to remove the pack from the car soon.
I will attach a picture of the dash.
I have the red triangle and a check engine light.
I have an elm327 unit and have downloaded Torque pro for android.
It has an option for the 2005 prius, but I still get no errors from mcu?( but I have a check engine light).
I also get the battery going from full charge all bars to moving down 3 bars after moving the car forward 10 ft and the battery fan is on full after a couple of minute of turning the car on.
My car has a hymotion plugin battery option installed(I dont know if that stops me from getting error codes)
If so should I figure out how to disconnect the hymotion before I remove the battery to try to get error codes?

I am excited about the car I have bought, I just hope I can get it working as a plugin hybrid, My commute is 4km and this car seems just right.

thanks for everyone's help

 

2005pluginhybrid, you mentioned 4 modules with 0 V and the 20 modules you are working on, what is the story with the 4 remaining modules?

In regard to the 4 modules with 0 V, you shouldn't assume they are bad/dead. Put them through a couple of charge/discharge cycles and see what happens.

In regards to the Hymotion, you should start a separate thread specifically about that in the Prius PHEV Plug-In Modifications forum which you will find under the Gen 2 Prius Accessories & Modifications forum. You should find anyone with expertise with the Hymotion there, but the knowledge is fast disappearing.

 

Any voltage between 7.92 V - 8.16 V. Pick one and do them all the same.

 

I look forward to your new post about your Hymotion system. I've worked on them and the sobering reality is that it is orphaned system that has little to no chance of being operational. It can cost several thousand dollars to make it operational if it is currently not working properly. Most parts are basically unobtainium. But maybe you'll be lucky and yours in an exception where it is still working.

 

Most parts are basically unobtainium.

Sounds to me like it could be less hassle (and money would flow in the good direction) if there's an opportunity to part it out and just put it back to OEM.

 

The reality is people are mainly interested in known-good parts.
If the Hymotion system is not working, most people would be better off simply removing it, or paying to have it removed. Including the harness that goes from the back of the car up to underneath the dash.

 

re :
2005pluginhybrid, you mentioned 4 modules with 0 V and the 20 modules you are working on, what is the story with the 4 remaining modules?

In regard to the 4 modules with 0 V, you shouldn't assume they are bad/dead. Put them through a couple of charge/discharge cycles and see what happens.


I had picked the 20 highest voltage modules, because that was the most I could connect with the power supply voltage I had built.
the other 4 had lower voltage but may still be good.
I will try a hobbie charger on the 0 volt ones and see how it goes.
Once I have used my best ones in the prius, I plan on using any good ones on a custom battery for a boat.
I have tested a pair of modules connected to a minn kota electric boat motor and they seem to work fine.
This way if I need modules for the prius in the future, I should have good modules available.
My boat is small and I dont go far on a small lake, so I don't need a real big battery.

I also started a new thread titled
Hymotion Plugin modification for gen 2 Prius testing
and I appear to have put it in the wrong section.
I will be delayed in removing the stock battery, because I want to make sure I understand the safety required to disconnect the hymotion from the stock pack.
Safety first

Thanks for everyones help and ideas.

 

I was able to disable the hymotion and run my prius as a regular prius and get codes from the mcu with torque pro.
I seem to have bank 2 at a low value. 13.5 to 14 volts, while all the other banks are about 17.5 and within about .1 v of each other.
If I leave it idling, occasionally bank 2 jumps up to 17 or 18 volts and then drops back to 13.5 or 14.
The fan has quit running continually so far at idle.

Would it be reasonable to be able to remove the cover of the battery and use a hobbie charger on the 2 batteries on bank 2 and try to recover them?

 

Yes, it would as you will need to get in there anyway to check the condition of the cables and buss-bars, etc.

No, it is pretty much a certainty that at least one module in block 2 is past redemption. Contact @ericbecky, Jeff at Hybrid Automotive or @TMR-JWAP who can see you right with a suitable replacement.

 

removed the battery today.
I do have some corrosion on the bus bars, but overall I think the pack looks clean inside.
26 of the modules are 8.25 v +or - .01 V, except the 2 in bank 2. they were both 6.88 volts.
at least the 2 bad ones are near the end I will remove them and test them with a hobbie charger, just for interest sake.
I feel the general opinion is that they are bad. Since all the others are so close, something must have gone wrong with these two.
The next step will be to decide which of my other cells to use as replacements.
they are all resting between 7.5 and 7.8 v at this time, sitting idle since last thursday.
I will measure the pack tomorrow, as I expect a loss overnight, because the pack had charged in the car before I removed it.

 

removed the 2 bad modules, was hard to do, found out why, they were both swollen a bit.
Don't think there would be any good reason to test them.
I think I will wait a day or so, to let the modules from the car loose a bit of voltage. Then I think I will use cells 4 and 17 from my spare pack, as they had the least loss in my 1hr load test.

 

While the would be a reasonable assumption, you should repeat the charge and load test with your existing modules, because what you are looking for is two modules that behave in the same way as your remaining 26 modules. That is, charge up to the same voltage (+/- ~0.3) and take the same time to discharge to a given voltage (say 6 V) using a 10-15 A load. These modules would have similar capacities.

Using modules that are much better when compare to your existing modules will give you as many problems as using modules that are much worse.

 

I used a 60 watt incandecent bulb to provide a .56 amp load at 168V(for 20 modules). To make a 10 amp load at 240V, I would need alot of bulbs. Probably 20 or so. I was thinking of setting up bulbs and switching them into the load one by one to reduce inrush currents. But this would take a long time to build. Is there an easier way to provide a 10 to 15 amp load at the full 240 vDC

 

It sounds like you are trying to design this.
Light Bulb Discharger - Hybrid Automotive

The user guide is here,
Light Bulb Discharger - Hybrid Automotive

 

Exactly. Even if you could get a 5 A load it would be better than 0.53 A.

Rather than use light bulbs, have you considered using a 16-24 Ohm resistor rated at 240 VDC? You might have to build in some kind of inrush protection, though, unless you have some pretty robust wiring that could take the initial load.

If you are using light bulbs, you will need to wire pairs of 110 V bulbs in serial to spread the voltage over the two bulbs, otherwise you could blow a few bulbs in quick succession. These pairs could be then wired in parallel to increase the resistance. But that's an awful lot of bulbs.

The problem you will have, in any case, is that as the voltage drops, so will your current, unless you change (to lower resistance) bulbs/resistors to keep the current at the desired rate.

 

That is exactly the principle behind the light bulb discharger I linked to. The process it described in the product guide but my link was incorrect.

Prolong Simple Discharger User Guide - Hybrid Automotive

EDIT: The Prius uses a 2 bulb charger and there is a useful chart in the guide showing what bulb watts for each voltage stage of the discharge.
Their intelligent discharger automates this process.