Cell Balancing

Disappointed that nobody responded to me above, but ... the saga continues, and I could still use some advice. My first charge after getting a new module went 36 hours -- constantly showing that charging was active before I interrupted it because I needed the car. When I started it, the CEL came on. But, when I got it over to Corey (my CSP) and restarted it, the light had gone out. He checked it and the new module was registering higher than the other cells, so he thought I should try to do more balancing.

I drove it and got down to 9 miles when it dropped to 0. That was about 4 (uphill) miles to my house, so I put on the Sport mode. However, for the first time ever, my car made an extra "chime" a mile from home and gave me Red Empty Battery level warning (but NOT the Reduced Performance" message). But, I got home ok.

I've had it on the charger now for 20 hours, and it is still showing that the car is drawing charge. Should I leave it? Or has that been long enough to try it again? Will the dumb thing be satisfied sooner or later and turn off the charger if I leave it long enough? Or, is it possible that it might keep trying to cell balance indefinitely? Just looking for some additional opinions.

Sorry for any delay. I've been crazy busy. I will PM you my # to call me tomorrow. The module he put in shouldn't have been installed with a higher voltage than the remaining 14 modules. The balance strategy is such that when charging once any module hits peak voltage, charging stops and it then goes into balance mode to bring any stragglers up to peak very slowly. The difficulty is that the modules are series so how do you balance only a couple. It pulses voltage a little at a time to bring up the low ones. The problem with most of the CSP's is that they have no means to match the module to the rest of the battery at install so they just put the new module in and hope it balances. However if the one new module is higher state of charge than the other 14, it will stop charging first and leave the other 14 behind to balance which may take days, weeks or even never. I had a special 24v Lithium charger built (wasnt cheap but worth it)to do this on the bench and I match the new module to the measured voltages of the other packs within 10 milli volts and bam, balances immediately every time, no light and 100% on first drive cycle with no range drop.
I will talk over the phone tomorrow
Joe

Ok let's see if we can figure out what was done . First off if the battery let to zero goes into the red that's not a good thing . The HV battery always keeps a % of battery that isn't used itS there to maintain systems that use the HV battery like the AC .
Did your CSP install a new module purchased from Fisker is the big question here . Myself and Joe I feel do the most battery repairs . I have a car in the shop now that I've spent at least 30 hours trying to repair the battery .
Anyway it's important that we know if it was a used module or a new one . I have good used modules that I install it saves money. It's possible that the battery has more then one bad module that's why the battery doesn't balance out . Joe and I both purchased a charger and power supply made to charge modules this way we can match the voltage of the new module with the ones in the battery . I've been told that it can take two weeks of charging and discharging the battery to balance it out.

When we build a battery the only way we have to test out the battery is actually install the battery into one of my demo cars and drive the car and charge the battery . I do this for at least five cycles that's usually long enough for the defective modules to show if they are useable or not . I then remove the battery and scrap the bad modules and the rest that aren't showing bad I use them in my next battery repair . A lot of times even after all that work ones we thought were good end up junk .
Like I said I have over 30 hours into a battery repair Fisker wanted me to replace the battery but I'm trying not too . The problem this battery has is two faults bad modules and a isolation fault . With that fault voltage is actually leaking into the battery . The battery sees this voltage and shuts the car down . The best way I can describe it is a dead short to ground . In this case it was 117 volts . So far I've replaced three modules the isolation fault is repaired and the car has been driven but I still think I have another module that has bad cell . This battery is also having a hard time to get to balance .Sorry I went off subject some but just wanted you to know it's one of the hardest repairs to get done right. A123 has test equipment that test the battery out of the car but I've been trying for three years to get this tester that can be shared by all the CSP dealers that repair batteries. Not ever tech do battery repairs .
We need to know some details about the module replacement. Right now continue driving and charging the battery .

I don't know if this will help in the understanding of the system but here goes.

We seem to have forgotten the term "trickle charge" these days what with intelligent battery chargers and inexpensive power supplies. Back in the day when silicon was pricey, you had the option of an expensive fast charger or a cheap trickle charger on anything high-end with a rechargeable battery.

Once any cell is fully charged, any current drawn (by its internal resistance) just gets emitted as heat.

Trickle chargers are simple power supplies, but crucially support a power transfer that is so low that once the battery is charged, can safely be emitted as heat without causing any problems.

Most modern chargers switch down into trickle mode once the battery is near full.

What happens when you switch out one cell in a battery and that cell is more charged than the others, and the charger can only charge the whole battery? Once the one cell is full, the charger has no option than to switch down to trickle charge to ensure that one doesn't overheat, but all the others will now charge at a snail's pace as a result, but if left long enough, the rest of the pack will approach full and a "balanced" state - but this could take days depending on the initial disparity.

Does that help?

Martin