Just Started Prolong Reconditioning

From a data scientist point of view without knowledge of electrical chemistry , I’d guess you would want to do two discharges at the first two levels so that when the more risky 84v discharge happens the cells are more in synch with memory effect on the low end.

If you have three cells after first 134v discharge ending at: .75 .8 .85, I’d guess a second discharge to 134v would end up like .79 .79 .83, which would be less delta on low end when you go to 101v level on a third. Just thinking math wise , maybe with how the chemistry works it doesn’t end up like that.

given ecu reports the total of voltage of two blades (and we can’t turn it on and measure at either high or low end can we? ) and opening up the battery and measuring each blade gets you a six cell total we can’t ever know what the exact distribution of voltages across the 168 cells is after each charge and discharge. Seems like to make a more scientific choice on how many discharges, to what level and how long to let balance you’d need to know each cell voltage at both ends

 

Thanks for adding that, I hadn’t thought of it that way, while the ice may be fine the MGs are in danger.

I think the end result of this is now that I have the prolong kit, I should find a low mileage g3 and pass on my g2 to a family member on flat ground where it should last a lot longer than with me here.

 

Is it possible to monitor rpm of the MGs with that app ? That would make getting an android device worth it for me I think.

 

The idea I was trying to convey is that when the cells discharge past the point where memory effect is in play wouldn’t they will discharge at different rates based on how healthy the cell is? As the deeper discharges happens it seems that the effect would increase. In the 63 page thread Jeff talks about failing cells don’t like the deepest discharge, it could be that with as discharge rates between cells changes at the low voltage that some cells go past the target voltage because it goes until the entire pack voltage reaches the target

Without being able to see the distribution of voltages at the end of each cycle for every cell we will never know.

In models on things I work on I see this effect happening all the time. The condition on the discharge cycle is discharge until total pack voltage = x with no control on exiting it based on individual cells so anything could theoretically happen, one cell could stop discharging and a other keep going.

 

@dolj right we’re doing this because the discharge rate when a cell’s state of charge is at the memory effect level is near zero

Based on the exit condition of the discharge and not being able to look at the distribution of voltages at the end of each discharge, I don’t think I’m ever going to go that low until the pack fails. It’s an equation we don’t know and can’t construct.

if I was building a program to do it it would be something like this in pseudo code

level1=134
Level2=101
Level3=84
Delta =.025

x=1

Do until x> 3
Charge
Discharge(levelX)
If min (c1-c168) = 0 then x=5 (test if a single cell is dead)
Else if max (c1-c168) - min (c1-c168) <= delta then x=x+1 (make sure max delta between cells is low
before going to next discharge level)
End
If x= 4 then charge

 

@edthefox5 thanks for the input, I will be getting new device so I can monitor and avoid “low hv battery MG and inverter screaming mode “

 

haha yeah.. as long as soc is between 41 and 79 everything is great, account for that or face the rath of an ecu that was programmed before millions of people drove the car millions of miles

 

Oh that reminds me of an idea I haven’t ever taken to the time post.. the late 2000s phev conversions would send a signal to the ecu that spoofed the state of charge.. how hard would it be to do that so that we could control our range of battery to use?

Like for me it would be awesome to change lower bound to 20% when climbing and 90% on way down.

 

I’m nearing the end of charge four and the end of my journey. Pack charge is flickering between 246/247 after 23 hours at 10 am, a winter storm is coming so whatever it is at 4:00 is what I’m going with so I can get supplies.

general thoughts after immersing myself in this for a few days from point of view of a data scientist.

- Since the cells in the pack don’t receive the same amount of air cooling , the distribution of cell capability/capacity after a decade of use wouldn’t be normally distributed around the midpoint of capability between best and worst cells. Say for instance if cells 1,6,163,168 (the likely best cells at the ends of the pack) have 90% capacity remaining while cells 81,82,87,88 (the likely worst cells in the pack in the middle ) have 60% capacity remaining, the mean cell capability/capacity wouldn’t be 75. The mean of the pack would likely be lower and skew the mean of the distribution below 75.

Given the reason we are doing this is cell capability / ability to discharge at lower voltage is very low for a cell with large memory effect, we don’t have the ability to monitor individual cell level voltage and the discharge process end condition is based on the sum of voltages of all 168 cells - it creates the chance that better cells in the pack discharge way lower than the target mean voltage of each discharge level.

I’m not an electrical engineer so I don’t know what that means good or bad, I just know how the math could work out when you have 168 cells with different levels of memory effect and varying discharge rates at different voltages. If there is a way to do it, I would potentially sacrifice a few end and middle blades to look at individual cell voltages to see if that is an issue.


What I would like to see in the deluxe package to improve the product:
-The charger display should go to at least one decimal point, during balancing phase that would give a better idea of what is happening when you check it
- would be nice if you could set a max charge point or had some sort of timer. I would use it every day to warm up my pack if it had that capability.
- why doesn’t the discharger just have a dial/ plus minus button to set the target voltage instead of having the three set levels?

Thanks to all who answered my questions @SFO @PriusCamper @dolj @edthefox5

 

Update for the thread: I’ve driven 2500 miles in the 4 1/2 months since doing the reconditioning

I purchased an android device to run hybrid assistant , prior to doing this I had a 2007’ish scan gauge before the xgauge update so I don’t have knowledge of exact soc and amps before doing the reconditioning other than the bars on the mfd so some of my benefit is attributed to having visibility to more info.

since reconditioning I’m able to drive all mountain passes around Tahoe without getting into “empty battery mg1/2 angry and screaming mode” when there is no traffic and I drive 40-45 mph depending on steepness. Biggest problem on ascent of the steepest road is there aren’t well designed pull outs where you can maintain speed and let people drive by. Stopping to let people by and getting back to speed eats up 5-10% of charge.

if you’re monitoring amps in and out the key change in behavior is when you ask for more power it reads as sending charge to the battery, if you increase ice rpm when this is happening you get the mg1/2 angry mode. Keeping ice around 3000 rpm and whatever speed you get is what you get is what I’m doing to keep it out of angry mode.

on descents biggest issue is getting ice to shutoff when water temp gets below 70c and soc is 72 or above. After I pull off the main highway usually have to come to complete stop to get ice to shut off as I can’t get EV mode to turn on. Below 50% soc can’t get EV button to shut it off so I coast in D until 50% then pull over to stop and get s4 idle check then restart and coast in neutral until approximate point where coasting in D will end up at around 75% when I brake to turn that lands me below the “ soc is too high... spin the ice to burn off charge “ point when I park

Below freezing tank averages were around 42 mpg, I just finished a tank today in 70s air temp at 51 mpg same starting and ending elevation filling up.

overall I’m satisfied that the process has helped and that I did it. Assuming I can sell the kit for $400, it is certainly worth the $300 net to do it and of course the satisfaction of doing it yourself.