Guide: manual reconditioning high voltage battery. (long)

[MeeLee]

So, my mechanic had left the car with the ac on full blast, and my car ended up with the high voltage battery completely depleted, and roughly 33% rechargeable. MPG aslo dropped by quite a bit. 

 

My model is a 2019 with lithium battery pack, and only has 95k miles on it.

 

They supposed to come with automatic reconditioning, but occasionally this doesn't happen.

 

I researched what this 'reconditioning' procedure is, and some mechanics may have tools to charge and deplete the battery pack several times, and restore it to much of its former glory.

 

I don't have the tools, but I can do the charging and depleting from the car, as the "Empower" window shows the state of charge on my car, as well as the energy output to the electric motor.

 

First I tried fully charging the battery for longer time, but that didn't do anything to recover the cells.

 

Then I used the Empower window, to make sure the battery got completely depleted, by running the car on electric only.

In Empower, a fully charged battery reaches about 2.25 bars (equals roughly 22kW or 30HP on electric motor output).

I kept the motor output at 2 bars on the Empower indicator, where it struggled to reach even 50MPH (where as before it could easily do 70MPH at 2 bars).

 

Once the battery level lowers to 2 bars, lower the motor output to stay below the state of charge indicator. If the output exceeds the state of charge, the engine will start, and you want to prevent this from happening, as you don't want to charge the battery just yet.

At least not until the state of charge is below 0.1 bar (roughly 1-2 hp motor output).

You'd have to have a fine foot, to keep the motor output under the state of charge the entire time, and a large safe space, where you won't hit anything, and won't bother cars behind you, as the car will slow down going on all electric.

 

A good place to do this, if you don't own a dyno, is on a long straight road, without any side streets, preferably at night or late in the evening, when there's no traffic.

And put lane assist on, as you need to switch your focus between keeping the car on the road, just not to end up in the ditch, and keeping the motor output below the state of charge on the indicator.

 

Once the state of charge reaches nearly zero, the engine will automatically engage. You'll want this to happen with the SoC being as low as possible.

When recharging, I find the battery charges fastest between 2.5 and 2.75 bars in eco mode, as less power is transferred to the wheels in eco mode, amd more power is harvested by the generator.

 

You don't really need to fully charge the battery, but at least let it run up to 1 of 2 bars.

The bms just needs to trigger the dead cell to charge. Once it charges, it can later figure out how much charge the cell can hold as you're driving normally, during its automated reconditioning procedures.

Hence, the phase of emptying the battery cells during a manual reconditioning, is more important than the charging phase.

 

Then repeat the process (completely empty the battery, and recharge) for a few times.

Sometimes you can recover a significant amount of battery. Other times, only a little, as cells have lost even more voltage potential over the course of time when the bms bypassed them.

 

Charging from a depleted state, will trigger a 'try to charge the cells'-action in the BMS, for those cells that are considered dead. The BMS will never charge these cells when the pack is charged up, because the charge current would be too high for the 'dead' cell  (the dead cell would be charged from the other cells in the pack, and could overheat).

Instead the BMS just disables the cell it sees as not functioning, until the rest of the pack has a similar low voltage. Then it'll try to charge the cells, just like the other cells, with a low current (divided over the other cells).

The BMS will only try to charge the dead cells, when the rest of the pack is relatively balanced with the dead cell in terms of charge.

 

I've repeated the process of charge discharge, about 5 times, and while I haf lost nearly 2/3rd of the battery charge before manually reconditioning, due to the error of my mechanic, I estimate that roughly 1/4th has been recovered since then, to a SOC between 50% to 66% of new (estimated).

I'll probably need to redo the procedure again to about a good 10x charge/discharge cycles to have it working good again. Should take roughly 2 hours time (estimated).

 

The procedure is nowhere explained, which is why I created this thread.

If your battery has recently died, it should work without any expensive tools.

 

I recommend to do the manual reconditioning procedure only when you've recently noticed a significant drop in mpg, and electric range.

For me, that didn't happen until 95k miles.

 

You apparently also can manually charge individual cells in a pack,  when the above procedure was unsuccessful, by opening the pack, using a 1,2V charger, some crocodile clamps on each pouch cell cathode and anode pins, and bringing individual cells back to life through directly charging them (without bms).

This procedure is significantly more tedious, but could save you thousands on repairs, if you have the time.

That's also how battery repair shops repair a battery pack. They first recondition, and only replace the cells when necessary. 

Edited May 7, 2022 by MeeLee

[mwr]

4 hours ago, MeeLee said:

So, my mechanic had left the car with the ac on full blast, and my car ended up with the high voltage battery completely depleted

How could that happen? Shouldn't  the car automatically start running the ICE to charge the battery when the charge is low enough? Or, is there some setting that allows that to happen? Thinking about it more, in my 2015 FFH (with a key, not a no-key fob), I suppose I could just turn the key only one "click" and run the electrics (radio, AC, etc) without the ICE starting; but I never do that so don't really know.

Edited May 7, 2022 by mwr

[MeeLee]

On 5/7/2022 at 10:10 AM, mwr said:

How could that happen? Shouldn't  the car automatically start running the ICE to charge the battery when the charge is low enough? Or, is there some setting that allows that to happen? Thinking about it more, in my 2015 FFH (with a key, not a no-key fob), I suppose I could just turn the key only one "click" and run the electrics (radio, AC, etc) without the ICE starting; but I never do that so don't really know.

Yeah, the engine will go on shortly, just to get a minimum charge.

Apparently the AC allows the battery to run below the minimum levels.

 

Apparently shock charging isn't really working well. I've tried multiple times to drain the battery and charge it, but I've not been able to increase range.
The best range I got, was after a long highway drive.
I presume that the voltage of the pack doesn't drop low enough to re-charge the disabled cells.

I did recover about 15% in total, resulting in roughly 55-65% of factory range.
But I now think my mechanic won't aknowledge he did it.
What's worse is that our local Ford dealerships don't recondition the battery packs either.

 

Because the battery still starts the engine, and helps acceleration (although roughly at half it's previous power), my gas mileage has suffered only by roughly 2MPG from 44.9-45.5 average to 42.5-43.9 avg.
Basically the cruising time on electric battery that's gone.

The motor accelerates slower, and now can do only up to 50-55MPH max (where as it could do 75MPH before), and the car as a whole doesn't feel as smooth anymore as before. Only when the battery shows it's fully charged, does the engine feel smooth.
All other moments, it's the engine trying to propel the car, while trying to charge that battery pack.

[Waldo]

The state-of-charge graphic in the cluster isn't a 0-100% gauge, it's more like a 30-70% gauge.  So just because the graphic shows low battery charge, it doesn't really mean it's as low as you think it is.

[MeeLee]

I know, it still shows 50-100% charged when driving, but the motor output is now closer to 15-20HP (55-65MPH) max, instead of the full 30-40HP (75MPH) max.

 

The charge meter also goes well below the '0'-line, in to that I have to drive quite a few tens of seconds to a minute before the blue charge line reaches the first indication level.

 

The reconditioning of the battery is for NiMh batteries or Cd batteries or whatever other batteries that are non-Li batteries.

Apparently it doesn't work on the FFH Lithium battery.