Quick HV Battery Reconditioning – DIY Grid Charger Results & Analysis

Re how the ecu measures SOC is something that I would like to know more about; if it uses coulomb counting, I would assume that it is using the pack current sensor such that it would be normal for the modules to be at different SOC since each module has different self discharge, capacity, and discharge curves. I suspect that if you can obtain close SOC by a method, once time passes they will migrate apart again

 

So are you saying to discharge the pack to 140v, 5v/module? Can you please elaborate on the expected "better result" ? ie, capacity improvement, discharge signature, lower self discharge, etc?? Thank you

 

One other model to consider is a HJS 480-0-300, a little difficult to find the correct model but it has an adjustable output voltage (max=300) and most importantly, has adjustable current limiting from 0-1.6A and has built in voltage and current display. I ordered one from aliexpress for $82. I like having the capability to set the desired current limit to control battery heating.

 

A really healthy battery can drive 3 km or 2 miles in EV mode on a flat road.
As for the charge to the green bars. It all depends on your driving style. During normal driving, the battery charges at ~5-20 amps. During braking, the charging current is highest.

 

I'm saying to discharge the pack to 5v, 0v/module, if your pack has lost its most capacity. This is when your battery pack is old or has high mileage. That is, you already see the symptoms of capacity loss: the charge level drop from 6 blue bars to 3 or 2 bars in the morning while you driving. Loss of power. Engine kicks in very often with the air conditioning and heating turned off.
The improvement will be in increasing the capacity.
In order to tell how healthy the battery is, I check the residual voltage after discharging it to 40%. I let it sit for 10 minutes and measure the voltage. The lower the residual voltage, the worse the condition of the battery is. You should see 7.7v-7.8v, but not 7.5 or even 7.4v.
The #1 test i rely on is the weight of each module. If the weight is 1030 grams or less, this module is already dry and you should not expect longevity from it. Such modules usually begin to leak. 1038-1043 grams is a really healthy weight, but such weight is rarely found on Panasonic modules. This is the weight for Panasonic modules. The Primearth modules with the flat top are lighter.

 

Perhaps an even better result could be achieved. Depends where this battery has been used during its life, city traffic or province and how many miles it has driven.
I've seen 2004 batteries with 90k miles, still in a good condition, but most of the time it's time to go for 2004-2005 batteries like it happened to gen1 prius batteries.

 

I have a couple of Panasonic modules that appear to have a bad cell or two, dropping from 8.x to 7.0 immediately upon load test, the weights are 1034, 1036g. I’m assuming that there is not a fix for these. I am curious how long do modules that appear to have close (.2v delta) discharge voltages down to SOC 40 remain fairly equal, ie, after the common methods of conditioning, how long before the SOC’s are quite different again? This is mainly a food for thought question and a ROI for the purchase of one of the popular conditioning devices and your time value.

 

I have about a hundred such modules. They're trash. I tried to do something to them, but it was no use. If all modules are original in a battery and after being sitting for a week or two there is module(s) with a lower voltage than the rest, those module(s) are garbage, I replace them before reconditioning. One cell has already degraded in such module(s) and if such module(s) sit without charging for several months, that bad cell will fail completely and the voltage will become 6.x volts.

 

I just purchased one of C1050A units for only $53 shipped, which at 1.05 amps will hopefully make this a 1 or maybe 2 day reconditioning project! Super excited to try it.

 

What is the output voltage for this unit?

 

1,050 mA at up to 241 volts. It has a built in potentiometer to dial it back too. But no display

 

I should mention it can only be turned down to 525mA with the built in potentiometer. In case you wanted to charge at a lower amperage.

 

Sounds good, what is the complete model number? Will you control the temperature of the modules as needed?

 

Mean Well HLG-240H-C1050A

I haven't quite figured it out yet but yes, charging at a higher rate I will watch the temperature and voltage closely, especially since I am still very new to electric cars and batteries. As far as I can figure out, the whole idea is just charge the batteries up to maximum voltage (8.2v/cell?), then discharge them to minimum voltage, watching the temp closely and taking care to make sure they don't drop below 7 volts per cell (196 volts).

Dr Prius said my batteries got up to almost 100 F yesterday during the tests I did, so I assume that's a safe place to stay below.

I'll probably wait til the holiday break to get the conditioner built. I'll still need to source parts. I'll need to get a higher amp diode as well, or maybe wire several diodes in parallel since they are only rated to 1A and they don't really look like they'll hold up to 1.05A for hours at a time. I'm aiming to get some surplus DIN rail and terminal blocks to make the wiring easy and sturdy and professional looking.