How I Recondition Cells

I just finished the 3 charge/discharge cycles for each module. I have them all hooked up now in Parallel to balance them. All balanced at 7.23.

Sorry if this sounds like a dumb question. My question is, some modules 3rd cycled was charged and then discharged and some were discharged and then charged. Does this matter before putting them back in the car how they ended on their 3rd cycle as long as they all balanced were at 7.23 before putting back in car?

Or should be ending all of them on the last cycle as a charge and then dropping the voltage down to 7.2 individually and then balance?

 

Ideally you should be doing C -> D -> C -> D -> C -> D -> C doing a 4-6 hour balance charge on that last charge.

I don't know where you got that 7.23 V number from, but that will leave you with the battery installed below the 40% charge level and that level is below the minimum the car likes. You may not be able to start the car at this charge level. You should be aiming for 7.9 V for each module which will have you install the battery with a 60% level of voltage.

Yes you should but as stated above you should be aiming for 7.9 V as a final voltage. I would leave them for 24 hours after the final charge before checking the voltage and making that final discharge as required.

 

Thank you for the quick response. I thought 40% to 60% fell between 7.2 and 7.6. I guess i was wrong. So...

1. End with a Charge.
2. Balance to 7.9 V is ideal.
3. Final Discharge?? Could you explain this part please.

 

Your final balance charge will be in the region of 8.4 V, Remove from charge after 4-6 hours (from the point no further increase is recorded) then let it sit for 24 hours. Measure the voltage then if needed discharge to 7.9 V. An alternate option is if your voltages all equal each other after the rest and fall in the 40% – 80% range you could just leave them there and not do a final discharge.

40% – 80% range roughly equates to 7.68 V – 8.16 V, all things being equal.

 

7.23v per module is only 202v total, which seems low enough to be problematic... Especially because NiMH modules are top balanced, as in fully charged. I'd want to have the pack up to at least 220v and with a high voltage trickle charger I'd get the pack up to 240v range overnight to make sure all modules have the same charge.

But It'd be interesting to see how well this would work as is. Of course what's interesting to me may well be lots of hassle for you if you have to pull the pack to charge it again.

Main point is, I don't understand why you aren't fully charging the modules? Did you do this with each round of conditioning too? That might reduce the effectivness of your reconditioning efforts. But you can always work on it again later once you enjoy your Prius being back on the road again.

 

Every cycle i fully charged it. I only discharged to 7.2 per 6 cells after the 3rd cycle. This is my 1st time messing with this so im just learning. In fact i might of killed one lol. The voltage did drop down to 17 by the time i saw it(40 min after it ended). So that would make it 8.5 since this double the voltage, cylinderical block, which is actually okay i think. Normally i only get to see the discharge information since i been doing CHG -- DCHG cycles. This is 1st time im seeing the CHG info.

 

So i have cycled all 3 times and final chg dchg to 8.4V. Currently letting them rest and hoping they fall inside 7.7 to 8.15V range before i do a parallel balance and put them back in.

I do have one more question. My last dchgs for all, 1 was 5850, 2 were 5950, 1 was at 6200, rest were pretty set near 6000. I been reading on this forum about a *capacity balance* as well? Is this a step I am missing? Or is my dchg to 8.4V suppose to have them all fairly similar capicity levels? Is this what you(priuscamper) meant with a high voltage trickle charge to 240V?

 

Maybe "capacity balance" is reference to trickle charging the pack overnight via Prolong, Maxx Volts or DIY system? Or at least that's how nimh modules are balanced, from above, where fully charged cells dissipate excess charge as heat while less charged cells catch up. I've always had better luck with rebuilt packs that I have an opportunity to do this to.

More important. You've done enough work!
Put the pack back in and enjoy the ride.

 

So I balanced all of them and did a quick load test for information sake. I marked the voltage drops at 1 min and 2 min. Keep in mind these are cylindrical blocks so double the voltage.

Starting balanced voltage on all 14 blocks were 16.57. 55watt headlight bulb. D1, D2, D3 are the 3 discharge cycle results.

1min. 2 min. D1. D2. D3.
1. 15.38. 15.21. 5160. 5950. 6000
2. 15.39. 15.21. 5750. 6080. 6100
3. 15.39. 15.20. 5670. 6000. 6000
4. 15.31. 15.14. 5470. 6000. 6000
5. 15.39. 15.20. 1265. 5640. 5924
6. 15.34. 15.17. 5127. 5950. 6000
7. 15.38. 15.20. 5520. 6070. 6100
8. 15 20. 14.97. 4560. 6200 6200
9. 15.32. 15.15. 5294. 6000 6000
10. 15.31 15.12. 5200. 5822. 6000
11. 15.33. 15.16. 4351. 5978. 6000
12. 15.33. 15.12. 2300. 6172. 6200
13. 15.37. 15.21. 4870. 5780. 5850
14. 15.34. 15.17. 5280. 6070. 6100

I thought about doing another cycle on #8 but wasnt sure if that would help or make things worse. Since most modules are around 6000 and #8 is more at 6200 but not as good on load test results.

Decided to just pair #8 with #5 and the rest seem rather similar results. Will be putting it back in the car tomorrow morning and posting final results. Pass or Fail it has been a good learning experiance.

Any final thoughts based on this information before i put it back in?

 

So my nickname is the one mistake wonder. It is always one thing i screw up. I was using 48 inch lb torque but not sure what happen here. Is this weldable? Any suggestions? Im thinking about cutting the remaining small portion screw left on battery off and soldering a full screw that i cut off a bad module. Is it safe to solder onto a battery though?

 

If you have old, bad cells to experiment with you can see if you can remove the stud from a cell without destroying the cell. If so you can remove the stud you broke and install one you remove from a bad cell. IMHO soldering will a)introduce too much heat, b)not hold - laser welding might but that would make it cheaper to get a new cell.

 

You could also try to find a "long nut" - one which you can tighten onto the remaining part of the broken stud and into which you can also screw a "salvaged" stud. This will create an alignment challenge, but that should be easy to solve.

 

I didnt think of this. I can technically put the same long nut in the module next to it to fix the alignment issue. But the rectangle piece that connects the 2 modules would both be touching only the nut and not flat against the battery. Would that cause an error?

 

You'll get different opinions on this, but in my life experience as long as you have a strong metal to metal contact there is no relevant measurable effect on conductivity with "extra metal" in the path. Now with microelectronics it's different..

 

So i put in for the time being like so and drove for 40 mins with no codes popping up. So I leave it be like this until a code pops up or better to do the long nut thing. Did some Dr Prius test too but i dont know if they are accurate, mean any thing, and i feel like i get mixed results with 101%(somewhat understandable as it was a new battery bought 2 years ago before sitting for months due to Cadillac theft) but a weak module 11, err idk how to process both of that.

Please share your thoughts everyone.

 

dr prius 101% capacity seems to be a good sign, are there any lights on the dash from that weak block 11?

Also, what charger/discharger did you use and how much was it? (need to get ready for when my time comes)

 

No lights or codes for the block 11.

The charger i used was Tenergy T180. I got 2 of them off amazon for $85 each.

 

Is that terminal connection secure, or just wedged?