How I Recondition Cells

My reconditioning process does not care about cell temperature or cell swelling. If they swell or get hot, they have issues to begin with and probably wont recover during the process.

My process uses a 1C charge and discharge, 6.5 amps.
I discharge at 6.5 amp load down to 6.0 volts.
I charge at 6.5 amps to delta voltage end of charge, that signal being a 400 millivolt drop in voltage.

I ignore voltage completely, some go 8.84 volts, some go 9 volts, none ever go over 9.25 volts.

During the initial charge, I will check the cell near end of charge and if there appears a lot of swelling I may disconnect the charger but it has been rare that I see this, some swelling is ok with me, excess is when it looks like it is really distorting and may gas.

On subsequent charges I am unconcerned, if it swells or gases it had issues to begin with and salvaging it will probably just put a bad battery in a pack that will fail early.

I use one charger and one discharger, it takes about 36 hours to get through a cycle just due to charge times of about an hour a battery. That provides any rest period needed, I discharge as soon as charge is complete.

When I started this a decade ago, I used a VECTOR brand 2, 6 10 amp 12 volt lead acid battery charger and a meter, and that worked just fine, I would just check the meter and look for end of charge and prepare to stop the charge when I saw voltage stall and wait for the pending drop in voltage.

I used 6 amp charge and sometimes 10 amp, I never saw any reason not to use 10 amp in my use of that charger, the only reason I stayed with 6 on that charger was a fluke in the software in that charger that turned it off exactly one hour into the charge if it was set at 6 amps, so I took advantage of that fluke, I could not use 10 amps as that would be way overcharged before it would cut off in one hour.

I went to an automatic charger just to free me up from watching the process. I have never had a mishap explosion rupture or fire.

I take a half inch square of paper towel and lay it on the relief valve, I press it hard so it makes a circle print on the towel, but i do not insert it, if the battery gases it will blow the towel off and I will know it gassed. They rarely ever gas.

Three cycles is usually enough and the returns on additional cycles are usually not worth the effort.

Packs I have built this way last for years. I have yet to intervene on one installed in a prius.

I use a Hitec X1 Pro charger with optional power supply to charge (it can discharge too but not at 6.5 amps)
The Hitec is no longer available.

I use a West Mountain CBA II for discharging, and optionally, to monitor and graph charging of the Hitec.

 

Yep, thats why I go to 6 volts, 1 volt per cell

 

lol how many years does that take ?

I can usually get a dead pack back in the same week and so far they last many many years, with a few hundred in equipment

 

I'm charging one 7.2 volt battery at a time

 

So I decided to apply PriusCampers algo to mine and see what happens
I chose battery 22

It had the following over 3 cycles using 6.5 amp charge discharge to 6 volts
1- 2.682 AH
2- 3.81 AH
3- 3.399 ah
So it actually lost capacity on the third cycle.

I then further discharged it at 6.5 amps to 3 volts. It had a surprising runtime of 1 AH until it finally knife edged and went over the cliff

I recharged it at 6.5 amps

Then discharged it to my 6 volts.
It had a resulting AH capacity of 4.727

So that indeed does seem to release some hidden capacity back into the working area of the battery.

I have a few more operating below the minimums in this pack so I can test further and see what happens when a single additional discharge to 3 volts at 6.5 amps is applied to them

Thanks camper

 

I made a copy of the google sheet and linked it in case anyone wants it for their use


Go to bottom and click...
Sheet 1
Copy To
New Spreadsheet
Click Open Spreadsheet on the dialog that pops up

 

So, this is kind of cool...

Supposedly, as I make changes, while I am conditioning these, the data in this link which is a pdf will auto update. So you can follow along lol.

docs.google.com/spreadsheets/d/e/2PACX-1vSx-WW7K8mTj9YxoQQauVHKokyvHNWENl7WH8VD_i-Z5Fano87mN5itP7M-acQUpMnqNuMlrNzj9sS7/pub?output=pdf

when i paste it in my browser it works without the required part I stripped off the front, if i leave that on their it gets wacked out by the forum software, you know the ache tee tee pee stuff

 

This is the first 8 odd numbered batteries on the 4th cycle (starting at 3 not 1)

 

In the end, only cell 2 is bad, and it is real bad, all the others came up nicely and once i replace cell 2 they will be ready to be placed in their new pack.

When I get them ready to go, I discharge at 6.5 amps to 6 volts, then charge right up at 6.5 amps for 10 minutes and note the voltage

I will use that to PAIR the cells up into banks so there is no aberrant behavior between banks and no codes.

Another method I have used to pair them was capacity testing, and I would use excel and pair the best module with the worst, then the 2nd best with the 2nd worst, etc etc. and that worked so far over 130k miles on my 2005.

 

I discharged each already discharged module to 6.5 volts at 1/2 C 3.2 amp load.
Then I charged them based on time, 15 minutes, at 1C 6.5 amps.
27 of the 28 cells are in serial number order from the same 2008 car are factory original unknown mileage,one of the cells, number 2, replaced one of the bad original modules, it is a 2004 with about 150k miles on it.

 

the csv file for the aforementioned 15 minute chargeup

 

Just test drove the new pack....
Went over the mountain and just prior had to pass a car from 30 mph to 75 mph.
Here's what the battery looks like now

Passing the car then slamming on brakes to turn right to go over mountain







Now Going Down the Mountain - Regen



And now cruising straight and level

 

Follow along, these are the cells pulled from the 2008, they are 2012 dealer installed replacements.

docs.google.com/spreadsheets/d/e/2PACX-1vSx-WW7K8mTj9YxoQQauVHKokyvHNWENl7WH8VD_i-Z5Fano87mN5itP7M-acQUpMnqNuMlrNzj9sS7/pubhtml

 

docs.google.com/spreadsheets/d/e/2PACX-1vSTiKNgzc7gyAROwq3FCgvNarkLEqL4nj4v6EDuwEUcnmeNmPZr5uU98X95s5qLIdw-Fgn1St1NUmIH/pubhtml

docs.google.com/spreadsheets/d/e/2PACX-1vS2nXlg9ijcSNTZxMIuagRbj3nPCNDpNs_rTgmnMjgJO-CXgPjm16PA07j7Tyt4JJtVpAFQyiti8NWt/pubhtml