05 Prius Code P0A80 and P3018 Good Battery

Have an 05 Prius we bought in August of 2017 with 210k miles, wouldn’t start or do anything. Was told it had a new HV battery put in two years prior. Ended up being the inverter pump-I pulled one from a scrap 06 prius that I was told was just replaced, been running fine but no great MPG numbers. Probably high 30s to 40s.
Car is now at 226k miles as of June 2018. This car has made me a believer in the little Prius! The other day the HV battery was at a full charge and 3 minutes later after sitting in a fast food line with the air on, it was down to 2 red bars and the engine kicked on. Later that evening, I got the red triangle, VSC, check engine light, and orange circle exclamation point. Started it up a little later, and only the triangle was on. I pulled the code with a Bluetooth ELM327 and Android, and it was P0A80, so I pulled the HV battery to check voltage on cells and every cell was between 7.85 and 7.96. I also cleaned the battery fan just in case, but it didn’t seem bad. Put the battery back in the car, checked all fluids and coolant levels, drove it to work but the battery still wouldn’t charge much. Took it on the highway and all of the lights reappeared, and two minutes later it beeped and I lost all power, HV battery is sitting on 1 red bar, appears to be limp mode. Got it home, pulled codes and got P0A80 and P3018. It seems to be some kind of overheating issue. I pull a small 4x8 trailer every once in a while with nothing more than a couch or couple pieces of plywood.
Thoughts? Suggestions? I know I did not load test the cells, but the voltages were all very close. I am willing to learn or try anything on this car, not scared of much on vehicles. I plan to buy a computer cable to check the systems better. Please give me some direction to get this car back on the road!

 

I assume rebuilt/reman battery. The case looks just like a stock case. I yanked on the wires pretty good to make sure everything is hooked up. I find it hard to believe a wire just broke, or that the battery is bad enough to completely not run, given that the voltages are so close.
12V battery seems to be good, never had to jump it and all of the accessories have worked fine-no problem with radio, lights, or anything along those lines.
I can definitely hear the battery fan running.

 

What is the best way to put some load on the battery or the cells with general tools to get a better read when testing?
The wires going to each cell and the plugs around the computer seemed to all be tight and in good shape. Would there be any specific wire or plug to check? I did not completely inspect the cells to check their serial numbers to see if they matched.

 

I plan to start pulling the battery apart again this afternoon and tomorrow morning and run a load test on each module with a DIY headlight load tester for 120 seconds for each. I hope to find some low voltage cells, I will post up my results. I understand there are many values to test for in an ideal rebuild, but I am hoping that this basic load test will give me some answers without having to do a long term slow load test on each individual module.
I have been reading around about different options and requirements to rebuild/recondition an aging HV battery. From this research, I am looking at purchasing a reputable grid charger to keep this vehicle running well, and to do some side work on a small number of hybrid vehicles that I buy and sell.
When it comes to reconditioning a used pack, most people suggest/require that the entire pack must be charged and discharged three times for the repair to be worthwhile. This requires investment in equipment, time to set up/customize the equipment, and time to run the process. I see some different thoughts on this "requirement" and would like input of those that know the results and have done the work the less popular way-without taking the time and energy to charge and discharge each individual module. I definitely want to do the work correct, but also don't want to spend more time or money than what is necessary. From working on cars myself and seeing car work in foreign countries, I know there is a "best practice" way of repair, a "good" way that will get the job done, and a "jerry-rig" bubble gum and ducttape that has no guarantee of how long the work will last. I usually try to end up with the "good" way that works, but might be frowned upon or argued about by other people.

Please give input on the discussion between requiring charging and discharging individual modules, and any more time efficient approach to make the battery still work.

 

Update:
I bought a HybridAutomotive charger and charged and balanced it a few times, it worked OK but still had a red triangle show up twice during a two hour drive. Stopped and disconnected the battery for 30 seconds and it went away each time.
Car sat for a few weeks through travelling, then I pulled the battery apart and replaced three bad cells after sitting for that length of time, all of the rest were within 0.1 volts of each other. Put it all together, did two of the three cycles for the charge/discharge over last weekend. Car seems to be driving well, battery cycling like it should and holding a charge.
Last night I hooked up a trailer wiring kit to pull our small 4x8 trailer with some cabinets and when pulling out of my neighborhood the display went down to 1 red bar, but then recovered after normal driving. After restarting the car from being parked the red triangle light, VSC, check engine, and few other lights lit up. Car still ran, drove, and charged/discharged normal.
Starting to think the 12V batter needs replaced, it doesn't have a date and the car sat for a while before we bought it last August. Learned how to enter the maintenance/diagnostic screen on the display and with the car on the battery reads 13.8 volts. With the car in READY the battery reads 11.9 volts.
I am pretty confident the HV traction battery is in decent condition at least. Does any of this sound like the 12V battery could be the culprit? Thank you all for the advice and help!

 

I have an ELM327 reader and tablet, will get a good app for it.

 

Wife has been driving the car back and forth to work, Sunday afternoon the red triangle and check engine light popped up again. That day it went down to red bars but this evening drove it a good bit and it registered between 3 and 5 blue bars-not charging up as much as it should but also not discharging completely. Got home and read the codes with Torque Pro Lite and got a P0a80 and P3017. Cleared them and they went away for now.
Guess i’m going to take the battery out again, load test each module with a headlight to see if any other have gone bad, then replace and charge/discharge/balance again.
At some point it would probably be better to buy 28 modules and just rebuild the entire pack but I’m not quite in a place to do that right now.
Also, does anyone have any good suggestion for a scan tool app for iPhone?

 

Update for anyone that has searched or kept up on the thread:
-Have been driving the car regularly and September through December would have the triangle come on average of once a week, would ignore it and let it turn itself off after a few cycles of driving. Fun fact-cruise won't work with the VSC light on, but will work with the triangle and check engine light on.
-Drove the car 2,800 miles in December for family holiday trips, about half way through to now (late January) the code has not reappeared, don't know if it finally balanced itself or not.
-Sometimes when coasting a long distance at a decent speed (long highway off ramp) the battery will get full up on green bars and then the engine will rev high for 60 seconds or so when at a standstill. Anyone know the cause of this?
-Still love the car, keeping an eye out for a <200k 08 or 09 for a good price that should last for a good long while. No plans to get out of owning a Prius anytime soon.