Re-hydrating the battery modules.

Here is a very good paper on NiMH failure modes and the remediation of said issues.
The gear I am developing already includes sonic cleaning of the plates.
Upcycling of Spent NiMH Battery Material—Reconditioned Battery Alloys Show Faster Activation and Reaction Kinetics than Pristine Alloys - PMC

 

Its acceptable to me because it is a normal part of the process to recondition the modules at 6.5 ah to delta voltage end of charge

What are my real world results on the modules I have fixed over the past decade
Astounding , and still in service.

Here's the latest pack I worked on for a few days, modules are all from one 2008 and are almost ready to be installed in another 2008 that has hv issues.

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

Also, that discharge to 3 volts, only ever did it on this pack, wont ever do it to another cell, did nothing beneficial

 

Maybe
I am charging to delta voltage end of charge, which is prolonged voltage at say 8.85 to almost 9 volts for several minutes until the voltage starts dropping due to saturation
I place a cut off q tip wrapped in plastic into the vent, then, using a sharpy to provide a balance point, place a can of beans on top to help prevent the qtip from rising up and leaking.
Nothing bad has ever happened, and none of my end of charge gases are lost.

 

I use Delta Temperature as the end point with a current throttle to 1.5A charge rate as the blade passes over 8V. 3.0A under 8V.
Usually the charge terminates at around 42°C with an ambient of 30°C. I have 3 temperature sensors array across the blade. Centre temp. is always about 4 to 5° more than the ends. My custom gear handles the charge/discharge (up to 16A) and the # of cycles while tracking the AH in, Discharge AH out, and internal resistance & Voltage and times.

 

Because Panasonic/Primearth/Toyota don't have enough experience or invest enough in R&D to know what they're doing............unlike the rest of us battery scientists in this thread. Maybe they just figure the tops will blow off if it gets bad enough.

 

Thanks for sharing that pdf on your reconditioning data set. Would have liked to have seen the internal resistance outcomes as well for pack balancing.

 

I use 6.5 amps up and down, discharge to 6 volts (why 6.5? anything less takes longer and 6.5 is 1C and thats just fine for these modules)
I use a fan if the ambient temp is 85 or higher, otherwise, no fan cooling i never see any heat from the modules.

In Jan 2015 I paid 1,000 for a 2005 and got a trailer and hauled it back to virginia from nyc, it had 142,000 miles on it, a month later it had one of my packs in it using my rebuild methods .

My wife drove and abused that car for years with a long commute and no oil in the engine constantly

I have been using the car a year now.

It still has the pack from 2015 in it, it has 279,673 miles on it, the only codes we ever had were for the trans when a fuse under the hood was taken out by road salt. The pack is still running today with no issues or codes.

That pack is the original 2005 cells with a few replacements in it, I dont recall how many but one day I will pull it out and then I will know.

It went 142k with the factory pack, the I bought it, so far it has gone another 137,455 with mostly the same pack after i rebuilt it in 2015

Also of note, in 2015 I did not have my fancy NIMH charger, instead I used a VECTOR 12 volt lead acid battery charger and a meter to find end of charge, that charger had 2 6 10 amp charging, I used 6 amp using that charger, it worked just fine.



Why did I get a fancy NIMH charger, cause you have no idea how much time it takes to watch a pack using a meter for eoc instead of using the right charger that sees it and shuts down automatically lol

People can question me about my charge rates, pack swelling and on and on
The car above proves what I do works, and it is prius number 4

 

I dchg down to abt 5V with a throttled Dchg rate as low as 0.3A as the voltage drops. I write the code for my charge/dcharge gear so i can customize the charge/discharge profile based on temperature, Voltage, current, time and Int R. Make it all automatic.

 

My 2 cents, no reason to go below 6 volts.

 

Yes... it does seem so. The new gear I am designing to do the whole pack of blades at once won't waste time by discharging under 6.

 

This may be the most interesting thread I've read in a long time....I may have learned enough about reconditioning to feel comfortable tackling a battery myself pretty soon.

 

Glad that works for you.

 

I dont have a fancy resistance meter for batteries. i haven't looked for one for years but when i did they were expensive.

I dont think the prius does REAL resistance reporting, i think it uses MATH to produce those numbers, and I have seen HEAT effect that math it produces. I have taken 19ohm modules and blocked the fan intake and they went to 30ohms real quick. heat and math.

I may take the time to look at and post the resistance reported by TS after I install them to see what it reports on the banks.

Are there any GOOD resistance battery meters out there now that arent a fortune that dont use math and instead send a signal through ?

I use the graphs produced by the process to determine, yeah, that looks good, if the resistance was off the graphs voltages also would be off from module to module

 

Yes... SM8124.
https://www.aliexpress.com/item/32431050637.html

 

lol last time i looked stuff like that was over a thousand dollars

 

I have 3 of em...been using them for about 5 years.

 

Just heard the pressure vent on a blade I am processing make a loud 'pop' . No heat..31°C, Charge rate at 1.5A. V at 8.6V. Everything else normal, blade is clamped and can't swell.

 

yep, thats why i plug em up so i dont lose that precious gas lol

also, thanks, i just ordered that meter, may be here this year sometime lol

 

Why are 3 of the Blades highlighted in red during the 4th cycle?