Dorman HV Battery with a new lease on life.....

I don't believe there's a set value out there. Since each module has 6 individual cells, it's more important that the 6 cells are fairly well balanced, and then that all 28 modules are well balanced with each other. A module with 5 strong cells and one weak cell can still provide ~5400 mAh, but's it's voltage would drop to ~ 6.4 very quickly when the weak cell drops out. If you're able to monitor a modules voltage curve while discharging, you'd be able to immediately identify any with a weak cell.

For me, I think any module that shows 5800 mAh or better during discharge testing should be a good module. That's just a bit under 90% of rated capacity. Anything under that bears more evaluation to ensure a cell isn't dropping out.

A Prius will function normally even if the modules all tested at 2000mAh, as long as all 6 internal cells in each module are functioning equally.

Using modules from 2015-current year eliminates most of the worry about having a bad module sneak into a customers battery. A few quick charge/discharge cycles to test and document capacities is all that's needed.

 

I would say for a well balanced battery I would want all the modules to fall within a certain band for capacity.

Let's say you tested/cycled all the modules and removed two weak ones. The remaining modules average 5600 mAh. I think for a DIYer, with the goal of having the car back on the road at reasonable cost, with reasonable reliability, I would have a band of 5200-6000 that I would prefer to see all 28 modules fall into. The further you can stay away from the bottom of the band, the better off you'll be. I think that would keep the delta V at a reasonable value during heavy discharges. If the band is too wide, you run the chance of the strong modules holding a high voltage while the weaker modules drop to a lower voltage, increasing the chances of tripping the RTOD.

The tighter the band, the more balanced the battery will be. A better balanced battery will have a smaller deviation between the highest and lowest module voltage during discharges and charges.

If you look at the results from the battery in this thread, the average was 6891 mAh. Highest was 7117 and lowest was 6655. That's a band of only 462 between highest and lowest. Essentially the average plus or minus ~3.4%.

 

Look at the heavy gauge orange cables. Where they attach to the module, there is a lug crimped onto the copper cable. On an OEM cable, there tends to be a bit of corrosion buildup on the copper wire. Apparently Dorman lays on a layer of solder to seal this up, and then puts a layer of heat shrink over the area. It's no different than an electronics guy tinning a wire on a lug.

To do this well requires a good technique, decent equipment and a good heat sink to protect the cable insulation. A typcal DIYer would end up putting a tremendous amount of heat into the lug and cable, most likely melting the insulation 2,3 or 4 inches up the cable. This is probably why they also install heat shrink on the area to cover any melted stuff.

I'll look around to see if I have any photos of the lugs. If not, I'll get some photos next time I pull the cover off that battery.

 

I have a bench setup with factory Gen 2 ductwork and HV cooling fan. All the modules are mounted in the oem clamps and baseplate and attached to the duct. The fan is driven by a Prolong harness.

I do an initial discharge/charge at 1.5 amps (discharge to 5.8volts) and 2.0 amps charge to either 8200mAh max or default delta V detection. I do this to document the "as removed from car" condition of each module. This is followed by charge/discharge cycles as needed to establish actual capacity of the module. I do 2 cycles per day typically.

 

Yes. At that point, the module is essentially depleted and voltage is dropping fast.

 

Without a doubt, 19 cycles is extreme. That is, by far, the most cycles I've ever done on a set of modules to find the point where more cycles make no significant difference. I'm normally in the "8" range, about 4 days, which is probably even more than really needed.

What makes it tough to change my current sequence is the chargers I use are not fully "programmable" to change discharge or charge rates at specific voltages. I would have to set them to discharge down to 5.8v and then stop. Then when I get home from work, record the discharge data and then set them to discharge at 0.4 amps to a new voltage. Once they're done, record data again, then I would have to change them to charge mode. Once they were charged, start all over again. I would basically have to do every step manually and hope the timing matches up to my work/home schedule. The sequence I use right now was settled on after a bunch of test sequences trying to get the timing to match my work schedule. I wake up at 5 am, do my morning routine, record the cycle data and just press the start buttons to begin the next cycle right before I leave to go to work. I usually get home from work between 5 and 530pm and do the same thing. It ends up being almost a perfect 12 hr cycle for me. Each cycle usually ends within 1 to 1.5 hours of when I arrive to record data and start the next cycle. Allows plenty of time for the pack to fully cool before another cycle starts.

The only thing I hate more than doing yard work is having to make adjustments on all 28 charger channels. I've found that frequently making changes on 28 channels leads to errors being made on setpoints.

The other option would be to set them up to perform the entire discharge at 0.4 amps, but that would again probably be a schedule thing as each discharge would be extremely time consuming. This was the big problem I had when using chargers rated for only 5 watts.

One thing I have thought about trying is to perform a full 3 cycle sequence using the Prolong system I have, then using my 28 chargers to do additional cycles to get actual capacity measurements for each individual module. I would still end up doing multiple cycles with my chargers to determine if the modules were still improving. The only problem with this is that I won't have individual control of the modules for the first three days, like if I wanted to disable cycling an obvious bad module. And the three days of Prolong cycling would have been 6 cycles of my normal sequence, which would typically be near completion. I think I still want to try it though.

On another note, has anyone figured out why Hybrid Automotive changed their voltage setpoints?
A year or two ago, I received a brand new in the box Prolong Gen 2 Deluxe Package as partial trade for a battery job. The setpoints for the three cycles are 134v, 84v and 17 volts. Now the equipment they sell uses 192v, 120v and 24 volts. What gives on that? I wonder if maybe those earlier voltages are less healthy for the battery than the new ones? Wonder if they offer free upgrade/program changes to previous owners? The sad part is that I've been using this $$ system merely as a fan controller for my test bench. I need to put it to better use.