How I Recondition Cells

I have only ever written BAD on two modules, this is one of them, it did not work at all.
It has been filled with water, somewhat drained after soaking overnight, and here is where it is now
Put in 6 amp hours at 6.5 amp load got out 4.98 at 6.5 amp load
83% charge efficiency, not terrible.

 

Red 6 Ah in @ 6.5 amps
Provided 4.976 Ah to 6 volts @ 6.5 amp load
82.9% Charge Efficiency

Green 6.050 Ah in @ 6.5 amps followed by 2.150 Ah in @ 2.5 amps until EOC reached. 8.2 amps in
Provided 5.798 Ah to 6 volts @ 6.5 amp load
70% Charge Efficiency
4 min volts and resistance
7.343 volts 7.65 mU (both are too high)

 

Red is the worst and best of my previous modules from herein

Green is worst and best for the BAD module that was filled with water and reconditioned

 

The BAD re-hydrated module compared to a lot of other modules

SEALING MODULE
This is EASY to do, we have PROVED that my threaded brass insert (NEVER USE BRASS IN NIMH) will withstand the 90 PSI where the vent system activates, and it is merely threaded in with a lot of teflon tape to take up space in the threads and tighten it up.

To seal back up, ROUND PLASTIC ROD that has an sae pipe thread DIE used on it to create THREADS and some of my 3600 psi plastic weld glue. There is little doubt it will be stronger than the original case plastic and will hold just fine. Thread the rod, cut a piece about 3/8 inch long, run a dremel on it to make a slot for a regular screwdriver, and you have a threaded cap.

If needed, the cap can be drilled out using the same size drill, re-thread and re-cut a new cap, re-water, insert new cap.

Mr. LOL

 

Wheels have been reinvented almost daily since they first appeared...

 

Did another recharge, 2 amps until it detected end of charge, 8.408 amps in, almost exactly the same discharge graph, picked up a little Ah over the last run.

Provided 5.898 Ah to 6 volts @ 6.5 amp load ( 1/10 Ah increase)
70.1% Charge Efficiency

Next ???

Let's drain it, and fill it with a 30% KOH mixture and repeat the process

P.S. I just looked and found a very faint sharpy note i made on this module 1.8
So it was marked BAD cause all I could get out of it a few years ago was 1.8 Ah.
Now it's close to 6 Ah.

 

lol pretty sure that's canada

 

constant sniping
that's rich
go reread that past 10 pages

 

There was 9 ml of water in the vent hose, not a lot, this includes what "jumped out" under charge and what was "dumped out" by my lifting and rotating the entire battery assembly for that purpose. That 9 ml represented about 8 inches in length in the drain capture tubing, 3/8 inch inside diameter.

Upon removal of the module from the pack, a further 10 ml was evacuated by turning the module upside down and shaking it like a paint can in a sink with running water for 30 seconds, the liquid escaping was a dark almost black slurry.

Excess liquid must be removed or it will take up volume normally reserved for the end of charge gassing and pressurization processes.

 

Seems there is a lot of confusion on how to read these measurements, as well as what are good bad measurements.

"A standard Prius with a single NiMh battery pack will usually show about 0.25 to 0.29 ohms."
Quoted from a source with a proven knowledge base.

There are 28 modules
0.25 / 28 = 0.00893 ohms PER module (8.93 mU)
0.29 / 28 = 0.01035 ohms PER module (10.35 mU)

The prius monitors at the level of TWO modules
0.00893 x 2 = 0.01786 ohms PER monitored module pair (17.86 mU) or 0.018 in techstream
0.01035 x 2 = 0.02070 ohms PER monitored module pair (20.7 mU) or 0.021 in techstream

Resistance goes up with heat, upon placing the prius in service in the morning, these resistance numbers WILL go up, in minutes.

Refer to page 1 of this post and you can see that over 6 miles the resistance increased from 0.020 to 0.021 to 0.024 to 0.026

Thats a range of 0.010 (cold) to 0.013 (warm) PER MODULE

A reading of 0.001 (one / one thousandth) is one mU (little m) or milliohm or thousandth of an ohm

A reading of 0.024 is 24 mU or twenty four / one thousandths of an ohm

My BENCH tests show readings of 6.4 mU to 7.2 mU as cells are cycled with some spikes in the 10.0 mu range
These are
0.064 to 0.072 and 0.10 ohms

Once installed and placed in use I expect these to increase to the low 20's as reported by techstream (maybe high teens).

When I see techstream reporting ohms as 0.030 or higher I am looking at modules that may need intervention OR A CLOGGED UP FAN, check the temps in techstream

This was from an EXTREMELY CLEAN car, 2008, cleaned 2022, was showing high heat and high resistance on a freshly rebuilt pack during test drive. The car was one owner, basically, and operated in and around a university at a major inner city.

Spray it with windex or 409, hold under faucet in sink, flush it out clean.

 

Understanding why reconditioning modules and pulling out low performers (low Ah) helps to somewhat restore the car and its mileage, as well as make it even a car not a doorstop.



"during half-hour exploitation, the battery’s level of charge has varied from 41% to 75%, which
is narrower scope than the information announced by the car’s manufacturer,"

International Automotive Conference (KONMOT2018)
IOP Conf. Series: Materials Science and Engineering 421 (2018) 022041
IOP Publishing
doi:10.1088/1757-899X/421/2/022041


That's only 2.2 Ah on a good 6.5 Ah module
Using 5 Ah modules would, at best, result in 1.7 Ah but probably much less as the low-end and high-end voltage areas both exhibit a widening that intrudes on, and shrinks (by BMS decision), the Prius working area increasing the number and frequency of charge discharge cycling

One might think it is a wash, that running 3 minutes at idle with ac on versus 2 doesnt add up to any loss, but the increased charging frequency is the loss, due to charge efficiency of 80 to 90 percent creating a LOSS of 10 to 20%, less frequent charging (better battery) saved fuel in the ac idle test.