For consistency, stay with the same bulb-change schedule, just add the time elapsed from 224 to 204V.

 

Hi Keith,

Just got done with the second discharge. The Voltage on the charger was sitting at 289V this morning when I set out to do the discharge. As soon as the discharge started, one of the 200W bulbs blew. Made a run to Homedepot to exchange the bad one for a good one and by the time I came back and started the discharge again (about 1 hour later), the discharger started with 282V. Also, I was inadvertently late changing bulbs. Here are the numbers:

245V - 1 hour 43 mins (I had this as 1 hour 11 mins yesterday for the first cycle, but wrong math, it was actually just 49 mins yesterday, so this is quite a jump today!).

222V - 22 mins (Switched to 65W bulbs here a couple of volts late at 222V)

204V - 33 mins

163V - 31 mins (Switched to 25W bulbs here 6 volts later than yesterday)

102V - 3 hours 57 mins (Discharge cycle terminated here)

Total time: 7 hours 6 mins

Total time to 163V is 3 hours 9 mins, is this a BIG enough drop from yesterday that you suggested I should see with a pack that's responding?

Also, do you recommend I still stick with 102V for the termination point for the 3rd discharge or should I go lower?

Thanks.

 

No worries about the bulb blow. Doesn't influence the results significantly.

What was the approximate charge time? For a valid comparison, it's important the battery is charged to full each time. 24 hours of charge is a good number.

287-245V = 2.75Ah extracted vs. 1.31Ah (corrected for time error)
245-222V = 0.59Ah extracted vs. 0.61Ah to 224
222-204V = 0.28Ah extracted
204-163V = 0.26Ah extracted
163-102V = 0.79Ah extracted

Total above 204V = 3.62Ah
Total below 204V = 1.05Ah

3.62Ah isn't great, but it's a workable number. About 1/2 of the 1.05Ah (or more) should move above 204V.

Looking at the > ~222V results:

"Before" = 1.92Ah usable above 224V
"After" = 3.34Ah usable above 222V

That's a 74% increase in capacity - strong evidence that this is doing some good. The only thing it's not telling us is if you have a problem at the module/cell level, which is easily masked when looking only at the pack. You'll find that out when you run the Hybrid Assistant discharge test.

Personally, I don't see a point going lower than 102, but it's up to you. Once on the 3rd discharge, if the < 204V times look about the same as they did during the second discharge, likely very little to be gained.

It looks like you may be headed for a restored capacity of 4000mAh or so. That's very workable.

EDIT: Note that my estimates are likely conservative. They are based on the anticipated/measured current at the voltages typical of the bulbs used on a 28 module prius battery, so I would expect your capacity to be closer to about 10% higher than my estimates.

 

Thanks, Keith. The charge time was about 18 hours. I will go with a 24 hr charge before the 3rd discharge. Thanks again.

 

Yes, please do. What made you terminate charge at 18 hours?

At 18 hours, your max input is 6.30Ah input, which may not be sufficient to get all 204 cells to 100% charge due to charge inefficiency.

Were both charges preceding discharges 18 hours?

 

Yes, the charge prior to the first discharge was also for about 18 hours. The charging started at about 60% SOC and the voltage right before the time I started the discharges was about 289V which I took to mean it was already in balancing phase and towards the end of it, as the below mentioned 24 hrs for an empty pack:

"A completely empty pack takes just under 24 hours to reach a full state of charge and balance, depending on cell efficiency. At no time should the combined 'filling' and 'balancing' times exceed 48 hours."

https://hybridautomotive.com/pages/pc

And I saw in the reconditioning instructions:

"1) Charge the battery until the voltage stops rising. A full balancing is recommended, but is not required at this step."
https://hybridautomotive.com/pages/recon

So I had thought the pack was probably toward the end of the balancing phase before the first discharge and that it was probably done with the filling phase before the 2nd discharge.

Since I don't seem to have done it properly, I wonder if I should do a 4th discharge the day after tomorrow with a 24hr charge preceding it?

Thanks.

 

No additional cycle is necessary. Just make sure the 3rd charge is for 24 hours and do your best to hit the same times/voltages/bulbs for comparison purposes.

Since the first charge started at ~60% and ran for 18 hours, it's highly likely all cells were at or very near 100%.

Since there is evidence that your battery has deteriorated somewhat, the 18 hour second charge, while possibly not sufficient to get to 100%, was probably very close.

 

Hi Keith,

Here are the partial numbers for the third discharge.

Started with 287V with 200W Bulbs

245V - 2 hours 19 mins (It was 1 hour 43 mins yesterday for the second cycle, so some improvement).

220V - 19 mins (Switched to 65W bulbs here a couple of volts late at 220V)

204V - 34 mins

One thing I am wondering about is if it would worthwhile going down to 20V on this cycle considering the above numbers or if I should I stick with 102V.

Thanks.

 

You are certainly free to do as you please, but I have stated my position and recommendation multiple times.

 

Hi Keith,

Terminated the 3rd discharge at 102V. Here are all the numbers:

Started with 287V with 200W Bulbs

245V - 2 hours 19 mins (It was 1 hour 43 mins yesterday for the second cycle, so some improvement).

220V - 19 mins (Switched to 65W bulbs here a couple of volts late at 220V)

204V - 34 mins

168V - 21 mins (switched to 25W bulbs here)

163V - 36 mins

102V - 1 hour 10 mins

Can't wait to drive the car the day after tomorrow morning.

Thanks for all your help.