2011 Prius Battery Reconditioning? - Sitting for 4 years

i would not assume anything. prolong is best for batteriesthat are just showing signs of age.
your going to have to pull every module, replace the bad ones, and balance the whole pack one module at a time with a hobby charger. lots of threads here with good advice

 

Fair chance that battery is landfill right now, nothing left to recondition.

You've got some good ideas but I think you're much too late.

It can turn into a heck of a lot of work vs. the one time cost of a new battery pack.

 

It depends on the mileage and where they were operated, in city traffic or in the county. Check the voltage on the blocks with a scanner (bluetooth adapter). If all the blocks are approximately the same voltage, even if it is 14.6 volts (7.3 volts per cell), then this battery will most likely work after using the prolong equipment. If some blocks have 14.6-14.8 volts, and others have 14.4 volts or even lower, then this battery will probably work if prolong equipment used once a year, it will lose its capacity very quickly.
If the battery has up to 5 modules with a voltage of 6.2-6.7 volts, then this battery can also most likely still be restored; the weakest ones have already died. By replacing these bad ones and restoring the capacity in the others, I think it will come back to life. If there are more than 5 modules with a voltage of 6 volts, then this battery is most likely junk. If the battery is full of modules with a voltage below 6 volts, then there is nothing to restore in that battery.
This is how it happens with batteries on second generation Priuses.
I would like to see the battery voltage numbers on a 3rd gen Prius that sat for 4 years.

 

@Carall
it's helpful to quote someone if you want a reply

 

On a Prius that has been sitting for 4 years and the voltage difference between the modules is 0.08 volts, it doesn’t look bad. For 4 years the battery fought not to discharge and the voltage remained ~7.3 volts. I've seen a battery from a 2005 Prius with 67k miles, purchased in 2011, that sat for 5 and a half years without charging and was still good.

The first thing I would do is make sure that the buss bars on the inside have enough contact. If this is the case, then the second step would be to use the prolong charger. If this is the only battery you are dealing with, then you can try using an LED driver with a constant (CC) low current 300-500mAh, the method described here on this site. You will also need a power supply for the battery blower. On 3rd generation Priuses, there is no need to install the battery cover because it is cooled from the bottom. I don’t know how well the led driver would work, but the Hybrid Automotive charger does work.
If you plan to restore more batteries, then it is better to buy a Hybrid Automotive charger, which is made for this, but do not rely on the voltage that the Hybrid Automotive charger shows, it lies, the more you use it, the more the voltage differs from the reality. I got up to a 30 volt difference until I installed a bluetooth multimeter on top of the charger and now i can monitor the voltage from my phone wherever I am in my house. I don’t know whether this problem is solved in the chargers that are sold now. Probably not, since I've tried to find another DC DV meter and i couldn't. It is not an easy task to find a DC DV meter that will work with a DC voltage of 250 volts.
I think it can be calibrated using the potentiometers located on it, but how long will this calibration last?

 

there isn't an exact process, but there are a lot of threads where people detail how they did it and how successful it was, or wasn't.

introduction-to-traction-battery-rebuilding-refurbishment.112868

search words like rebuilding, refurbishing, reconditioning, traction battery, hybrid battery, high voltage battery and etc

 

Hmm, good to know. The volt meters can be calibrated, but yeah, who knows how long they stay that way...I will definitely look into it.
And you're right, we haven't changed the volt meter; at least not that I know of. My name is Garrett and I was moved to manager position in July of 2022, so I will probably be the one who will be on PC for now. So I am relatively new to what components have changed before then, but I believe we have used the same part. Thanks for mentioning!

Garrett

 

One thing to add, you can test them to see if they hold charge by measuring the speed of which its volts go down.

Thats the only real way to know if charging/discharging cycles helped recondition them to new.

This could be achieved by simply putting a load on them like a 12v headlight bulb. And having a timer with a multimeter making a spreadsheet of volt drop within X amount of seconds or minutes. The ones that drop the fastest are the weak links. They either lack the proper fluid composition inside (in which case will never be reconditioned), or need more charge and discharge cycles.

Just make sure to balance them all at the end before placing them back if you dont want your mpg to be bad or have hybrid check engine light. I normally put all mine to sit between two metal bars for a day, all connected in parallel.

 

This method will only work on very weak modules, but to detect modules that trigger 1% delta soc will require much more time and greater load.

Using the Hybrid Automotive method, discharging the entire battery to 5 Volts or lower, the capacity will restore to 8000 mAh and the only question is how quickly this restored capacity will drop to 2000 mAh. For worn-out modules this will happen in 1.5-2 years.

There is no better way to balance the modules than to charge them with a low current for 20-24 hours. If all modules in the battery are original, the difference will be up to 0.3 volts.

 

When you say balance them by charging them with a low current for a day. how many volts do you recommend? Would 8.5V at 1 amp work? Assuming im charging all 28 at once.

 

... discharging all 28 cells connected together as a unit to 5 volts.

 

i charge all 28 modules at once with ~350mA for 20-24 hours.

 

And what volts do you put it at?

 

My chargers are adjusted to 245 volts for 28 module battery.