Prius Battery Replacement Kit (GenII/GenIII) with NEW custom cells

The Hybrid Assistant app has the ability to manually control the fan.
That app has tons of other great data.
Plus can be used with Hybrid Reporter app.
Nice visual cues for stages of warmup.

 

Wow, totally cool. Not so easy to set up in the beginning.

 

I'm I wrong or does Internal Resistance seem a bit too high for a New battery pack?

 

See post #258 of this thread.
It explains why the numbers are different.
"An extra 8-10 mOhms is basically just the metal you see exposed on the welds."

 

Ok, without finding my data cable for downloading screen captures, here's a quick rundown on some numbers from Battery "A". I'll try to find my notes on Battery A history IRT mileage. (edited here: Battery A was a 6 month warranty battery from a rebuilder local to the previous owner, installed in her 2005. More info on the "experiment" battery is in my thread "Just another HV battery thread and experiments"). These numbers were captured with the Hybrid Assistant app, as I ended up being on my own this evening. After running it through a bit of heavy throttle and heavy brake. Heavy throttle means pedal to the floor from stopped condition. Heavy brakes means hard enough to activate anti-lock system on dry pavement. Much fun was had.

Minimum voltage 178v
Maximum voltage 268v
Minimum block voltage 12.34v
Maximum block voltage 19.33v
Maximum delta 1.67v
Average delta 0.22v
Minimum observed current -106.00 amps
Maximum observed current 168.00 amps
Minimum observed SOC 54.9%
Maximum observed SOC 65.9%

I also sat in the car for about an hour today while my wife was at a doctors appointment and perused through techstream screens. About 48 miles driven before we arrived at the office. About 5 minutes after parking the car, I was online with it. The blocks were 0.024 through 0.027 ohms. Blocks 6 and 10 were the 2 blocks at 0.027 ohms. Those are also the 2 bottom performing blocks when looking at the voltage curves from the above throttle/brake test drive done later in the evening. The IR readings are mohm in order of Block 1 to 14:
1------24
2------24
3------25
4------25
5------25
6------27
7------26
8------26
9------25
10----27
11----25
12----25
13----25
14----25

 

2k1Toaster,

Those numbers provided by Eric look very good (promising) to me.
I agree the larger ir numbers are probably due to extra metal or possibly variations in tack welds.
I am wondering about the buss links lengths (resistance) between module rows 1 2 & 3. could there be some ir loss (.001-.002ohms) there? And the external buss straps between modules (maybe .0001 ohms) ? ir lossed on external module buss will not be visiable on torque app.

I would like you to examine the tack welds using only two cells tacked together with a 100+ amp load in a darkened room.
I want to know if those tack welds glow red in the dark for a 1 or 1.5+ second 100 amp load (indicating ir drop that could be improved with extra tack welds)? You might be able to construct inexpensive spot weld machine with merely a 1 farad supercap. Any heat developed due to high current on tack welds will be conducted into the battery cell unnessarily.

Do you know what the single cell fully short circuited current might be (100,200,230 amps?)
The auto-stores sell a magnetic coupled amp-meter that is nothing more than a magnetic compass (with somewhat calibrated scale) placed over an insulated battery cable. Probably reads up to 1000 amps and very inexpensive ($6.00-10.00?) you would probably need this device and a huge set of pliers (to short circuit single battery cell) to answer this question. I'll keep my fingers crossed here.

I believe I have an inexpensive solution for battery temperature management.
Something like a thin plastic cover with double-sided stick tape placed acrossed the top of all modules. Striving for an air tight seal within all modules. And small stratigicly placed holes placed directly over the top row of cells and strategicly placed holes between modules to direct air flow to the second row of battery cells. And a third set of holes placed further away from second set of holes (row 2 cooling holes) aimed at row 3 cells.

Sounds pretty crazy I know.
Here is my interpetation of how the orignal hv battery cooling air flows.

The top part of the battery case seals (very porly) with single-sided foam strips to the top of the battery modules.
Air from the cooling fan at say fan speed 3 flows at lets say 100cfm (cubic feet per minute).
The battery modules (original) are tightly fitted together with a very narrow gap between cells. An purposefull air restricted gap indeed. Through this gap, lets say 3cfm of, air flows. To sum it up The top of the case is the input air plentum where back pressure is developed across the cooling fan.

I measured this back pressure successfully (on my prius) using an aircraft altimeter plugged into one of the top holes in battery case). displaying units (inches of mercury) I determined my plentum was not sealing properly due to the many times of opening and closing my hv battery case. Oakridge laboratory did a technicial paper on the prius (gen1 I think) and stated that there cooling fan backpressure was something like .06 inches of mercury. Mine had about half that say .03" These numbers are from memory of 6 or 7 years ago so don't hold me to them . I know my numbers were about half of what the Oak ridge Lab numbers were.

In any case to keep the cooling air flow from taking the path of least resistance (in your case flow across only the first two battery modules) we/you need some well engineered air restriction to insure the more distance cells get good air flow.
The first cooling fan speed (speed one) kicks on around 96F. All ecu initiated fan speeds 1-6 are all variable fan speeds dependent on the speed that the prius is traveling down the road.
Fan speed 1 which is barely audioable (sound wise possibly highly desireable in a luxuery car?) while sitting still is only about 100 rpm. While the prius attains higher road speeds the fan speed (while still in speed 1) increases to maybe 275rpm? (still inaudioable to the driver ). it seems to me prius designers intended that the cooling fan should never be heard by the passengers of the prius?
Cooling fan speed 2 is initiated by the battery ecu around 100F which varies from say 200rpm when prius is stopped to say 375 rpm when moving.
Cooling fan speed 3 is initiated at around 104F and is maybe 300rpm when prius is not moving to say 425rpm.
Ok enough of this you get the idea. (manual speed initiated from torque app is constant speed only. not variable anymore)
The gen II battery cooling fan motor has a label says 12 volts. The fan control relay applies 13 volts to the motors positive lead while the ground is supplied from the fan speed control module located in the plastic battery exhaust vent (for speed controller cooling). The fan voltage gauge from torque app show only volts of ground potential applied to the motors negative terminal (not total voltage applied to fan motor) I changed the math for that pid to display motor voltage instead of ground potential.
Anyway the highest fan speed 6 speedcontroller applies only about 8 volts max to the 12volt fan Motor.
when cleaning my fan motor I applies various voltages with an adjustable power supply. At 12volts the squirel cage blower produced about 10 pounds of thrust at about 4.3 amps of current.
I used this variable power supply to aid in determing the backpressure in my hv batter case.

Anyway at fan speeds of 100-200rpm I doubt there is any backpressure exerted on the cooling fan.

Getting back to my idea for sealing the top of your modules. The strategically places holes should increase in diameter as there distance from the cooling fan increases.

For high quanty orders of your pack you might just simply design a circuit board with only finalized sized via through holes. probably $10.00 each on small orders.

If you can keep all ir buss drops below .0001 ohm each I will be purchasing one of you packs.
Hope all this mumbo jumbo helps a little toward a 10year+ prius battery pack.

 

There is a bit too much credit being given to the OEM cells. While the OEM pack allows for more conductive heat loss the temperature still spikes in the middle of the pack and failures still occur in the middle of the pack. Toyota was not so much concerned about this in the original Prius and you can see how the Gen 1 cells have plastic (a very poor conductor) and only switched to a metal siding after revision. Basically right from the start, you can tell that Toyota engineers heat loss concerns did not fall on conducting it through the pack, even though that may be a good idea.

As some of you already pointed it out, you can calculate the heat generated from the simple P= I^2*R or V^2/R equation. This does not point to anything significant right away concerning the structural integrity of the materials involved.

Since the heat is not conducted across 2k1Toaster's pack, you can reasonably treat each cell in an independent manner and you are more likely to have a pseudo-uniform temperature profile. Of course there will be some transfer from the air and busbars, but it is minimal compared to the prismatic modules. The heat loss from convection will increase but the overall temperature will still be higher do to a lack of conduction heat loss. I think that Is driving the concern from this.

Worst case with 2k1toaster pack is that the internal temperature of the cylinders is too high to maintain structural stability. My calculations show it's probably not (I have 15 years of background doing this type of analysis), I'm willing to bet on it being the case for decent amount of time. Of course time will tell.

 

Has anyone figured out that 2k1Toaster is not your typical hobbyist when it comes to batteries? His knowledge of testing and evaluating batteries is impressive.

Plus he has access to equipment that even many of the rebuilders would be envious of. I know I covet it.

Fun stuff for sure.

 

Ericbecky

There is another gauge you should add to you torque screen that is even more important.

Nimh volt delta It displayes difference of max module voltage and min module voltage
Choose the first round gauge which has two needle pointers the red one records the highest reading obtained.
Touch and hold guage (set up better resolution as you did before with Ir guages)
select Display configuration then select set-maximum-value 3
make sure set-minimum -value is 0

The Nimh volt delta should already be in your extended pid list. If not here it is.

Nimh volt Delta
pid:21do unit:volt max/min:3.0/-30
equation: ((2.56*M)+(0.01*N)-327.68)-((2.56*J)+(0.01*K)-327.68)

 

I hope you are paying him handsomely for all this work. Perhaps you should buy a battery from him.

 

Prodigyplace
I didn't know Ericbecky sold batteries.
I thought he was only a purchaser of batteries?

 

He has said he has purchased new batteries from a dealer to resell to his customers. You would need to ask @ericbecky to be sure, though.
He might even sell you a thoroughly tested battery that has cylindrical cells.

 

Ha, ha!
Right! Have I got a deal for you. $1,800 delivered to your door. Fully inspected system.
Be a part of history.

Seriously though, thanks for the Delta SOC PID. The one in Torque never reads properly and I never bothered checking it.
The screen is running out of room.

The system works well enough for me that I am satisfied at this point.

And if you do ever need to make some purchases let me know.
I can drop ship packs to customers or work with your local dealer to try to get a pack for you.
Also used, tested OEM modules.
Call any time 608-729-4082

 

Hey, I tried to get you some business...

 

Oh. Wait. I thought you were posting the PID for Delta SOC.

Nevermind. I'll leave that for some other day.

 

I've figured out why ir10 reading is lower than the rest of the cells (shown in Erckbecky's torque app posts).
The high voltage safety plug seperates battery block pair 10 in the orignal battery pack.
The safety plug disconnect say #4 awg say 10 inches in length is obviously approximately .002-.003 ohms.
This would be factored into the ecu battey analysis programming when displaying module 10 internal resistances.
Since 2k1toaster cannot seperate block 10 cells. The block 10ir will be off when using his pack.

This brings 2k1toaster pack into a much more favorable light for me (more equalized module resistances).

It should be noted here and forever after that. Removal of the high voltage service plug many times will result in more ir10 resistance being displayed. For battery rebuilders high internal resistance in ir10 is not nessarly bad module but
worn/loose safety plug spade/blade connections.

But even better infomation for battery rebuilders STOP REBUILDING WITH USED BATTERY MODULES

.

 

How do you mean Nimh delta in inaccurate? I've been using it for more than 4 years.
Its very good reference. There is possibly decimal point error or unclear on the units displayed?