Your Prolong charger is a high voltage trickle charger and pumps less than one amp into the entire pack (all 28 modules wired up in a series). When the pack is fully charged it's at 240v and then the balancing phase to get all cells fully charged will push that voltage up into the 245v range, which is why a cooling fan and not charging on a hot summer day is really important.
@Bunce Glad to hear the earlier project worked out well. Now you can tell all the naysayers to take a hike... Good luck with the new project. I'm sure any and all knowledge learned on the first one will come in handy for this one. My best advice?.....Be selective about the advice you heed.
I just checked the charger and switched over to discharge at 245v. Here's the reconditioning data so far. Date Hrs Voltage Charge 01.25.2020 15.00 227 01.25.2020 18.00 242 01.25.2020 22.45 243 01.26.2020 _8.30 245 Discharge 01.26.2020 _8.30 240
The top end balancing is key to the process. If you don't get them stable at the top balancing, bad things happen when you drop voltage out. Prolongs recommendation is to have the voltage relatively stable at plus / minus 1-2 volts and be that way for 4-6 hours when you too end balance. They are the experts and I listen. Good luck with the discharge cycle and keep us posted.
The discharge must have ended and bounced back to 155v. I reconnected the charger, it seemed the amperage was bouncing around between 0 and 0.569 and jumping to everywhere in between. I don't think I've noticed that before. Is it like those 12v smart chargers that pulse charge to break up crystallisation? I only watched it for a couple of minutes and will check on it before I go to bed.
Not according to Jeff, it is just a by-product of the components used. It settles once it reaches 202 V.
That rapid fluctuation in amperage is what makes it better than all the other grid chargers. The fluctuation is based on a unique NiMH charging algorithm, as is further refined by feedback regarding how the battery is accepting the charge in any particular moment. It's a highly efficient way to trickle charge compared to most other grid chargers which tend to just pump out at 1/4 amp without any fluctuation, which takes longer and can be problematic if you charge the pack for too long.
Here's the data so far : Date Hrs Voltage Charge #1 01.25.2020 15.00 227 01.25.2020 18.00 242 01.25.2020 22.45 243 01.26.2020 _8.30 245 Discharge #1 01.26.2020 _8.30 240 01.26.2020 12.00 187 01.26.2020 17.00 156 Discharge ended and bounced back to 155 Charge #2 01.26.2020 22.15 155 01.27.2020 _8.30 230 01.27.2020 10.30 233 01.27.2020 17.30 244 01.27.2020 22.30 245 Discharge #2 01.27.2020 22.30 245 Charge #3 01.28.2020 10.30 155 I feel like it might be charging and discharging a little too fast. Any thoughts? Having said that, I'm not monitoring it, and I don't want to try and beat an extra volt or 2 into it on the charge cycle, it's already in delicate shape. And I usually miss the end of the discharge session.
It would not be good if it was charging and discharging quickly, but at they don't look bad from what I can see. Are you doing progressively lower discharges? First discharge to 134 V; second discharge to 101 V and last discharge to 84 V? As you are documenting the bounced back voltage, it is hard to tell. It would be better to make a note of the voltage every hour (or more frequently if you can be bothered) during the charging stage until the voltage plateaus. It is really difficult given the data whether you are leaving it charging long enough. I think you may not be getting the point of the top balancing. It needs to go for at least 4 - 6 hours after the voltage has plateaued, to do any good. You can get away with only doing the top balance on the first and last charges if pushed for time, but really you will get the best results doing the top balance on all charges. Look forward to the next update.
Unfortunately, between college and sleeping, I'm unable to monitor it. More of a case of plug it in and let it do its thing, the discharger is fine but on the charge side of things I'm usually away when it would have topped out. This is more of a "can I work with this battery as is or do I have to replace any cells" kind of deal. If it's somewhat healthy, I can do a better job next time. If not I'll replace the cells and do a proper job. Discharges so far are 134v, 84v and it's on the 17v now, but I think I'm going to switch that to 84v and then when I come home from college, discharge a bit further for a few hours and switch to charge before bed. I'm a bit scared to take it all the way down to 17v.
It can be hard when time is a premium, so no worries. Yes, it might be better initially to just do another discharge to 84 V. That is the new low now. The voltage targets I gave in post #34 are the current HA recommended targets.
Something seems off... Date Time Voltage Charge #1 01.25.2020 15.00 227 01.25.2020 18.00 242 01.25.2020 22.45 243 01.26.2020 _8.30 245 Discharge #1 to 134v 01.26.2020 _8.30 240 01.26.2020 12.00 187 01.26.2020 17.00 156 01.26.2020 22.15 155 Discharge ended and bounced back to 155 Charge #2 01.26.2020 22.15 155 01.27.2020 _8.30 230 01.27.2020 10.30 233 01.27.2020 17.30 244 01.27.2020 22.30 245 Discharge #2 to 84v 01.27.2020 22.30 245 01.28.2020 10.30 155 Discharge ended and bounced back to 155 Charge #3 01.28.2020 10.30 155 01.28.2020 18.00 227 01.28.2020 22.00 231 01.29.2020 _7.30 245 Discharge #3 to 84v 01.29.2020 _7.30 245 01.29.2020 16.30 166 Discharge ended, bounced back to 166 Discharge #3 cont. lower. I didn't mean to go to 27, that happened fast. 01.29.2020 16.30 166 01.29.2020 17.30 27 Charge #final 01.29.2020 22.00 227 Look at those numbers for the final discharge. I discharged down to 84v while at college. When I got home I put in on discharge again and thought I'd go to maybe 50ish v. In 1 hour it discharged from 166v to 27v. And then when I put it back on the final charge it went from 27v to 227v in 4.5 hours. I think I may have exposed the weak cells and may have some work ahead of me. Oooof. We shall see though. It should be done by the time I get home from college tomorrow.
It should be ok, and yes the last 199 V down is very fast. I wouldn't worry. That's actually pretty normal. It shoots up to 219 V within 1.5 hours. If you can, let this charge go for 36 hours in total. When you have done that do a short discharge down to 225 - 227 V. Wait until you have an hour that you can supervise it. It will (should) only take about 45 min. After you have finished, do you have Dr Prius or something like that to do the hybrid health evaluation? it would be good to see what each block voltage is like after a drive.
Normal behavior. But why do 2 discharge cycle back to back? Always do a charge cycle between them as you could damage what were the weaker ones. Good luck and keep us posted.
I wanted to bring it lower than 84v but didn't want to go down to 17v and am unable to babysit it. I did not expect it to drop so fast on the second one.
