P0A80 and my big hill

My 2007 sat for a while while waiting on a wheel bearing repair. ( Axle stuck in bearing and too busy/tired to bother, but seem to be better now ).

TLDR: running up and down a steep hill seems to have helped the battery.

After the repair, the HV battery was not in the best shape. The SOC on the dash would drop from two or three bars down to zero just after starting the car. It did not have teh power it normally has while backing out of teh drive in EV. When I drove it a short distance to walk teh dog, on some short hills, I would get P0A80 regularly. Then that stopped, but I got P0A80 when I would go down, or sometimes coming back up, our big hill, which is enough to almost fully charge the HV from just about any SOC on the way down, and can drain the HV pretty well one the way back up, with just how much depending on how briskly one drives back up.

My first desire was to recondition the battery enough to wait for Lithium packs to come back in stock, but since buying a rig to recondition the battery would cost almost as much as a fully installed reconditioned battery and take time I do not have to install teh harness and perform the reconditioning, I called for an appointment to get a reconditioned battery. It is from the same place I bought this one from four or five years ago. Before I decided to call , I had erased the P0A80 code to see when it would come back.

The gas tank was pretty low, so I thought I would kill two birds with one stone by getting some gas, as well as get the P0A80 back so they could see it for themselves, rather than just my screenshot. ( It was on two bars, and the car has run out of gas when the guess gauge has displayed 3, so it needed some gas just for the technician to run it for the repair, and for us to test drive it after the repair )

I was running Dr. Prius to watch the battery monitor.

Getting gas went fine, but the P0A80 did not come back. The SOC went to 97% or so on the way down, and to 26% on the way back up. The voltages difference was 1 volt for maybe one scan during that time, but never more than 0.1x except near that one peak of 1V. And that 0.15 is generally block 6. with all others pretty close together.

So I went back down and up the hill a few times, getting the SOC up high ( 80 to 100% and generally above 90) and low after going up (in the 40's and 50's). Never got P0A80 again, as the max volt differential stayed around 0.1x, and often 0.0x. During the hill runs, the battery temps did get up to 99-109F on a 79 degree ambient day with the AC running full inside.

By the way, Dr. Prius battery monitor has always not liked ( a lot of red ) when I go down my hill ( about a 250 foot change in elevation in a quarter mile or less). First in the overall voltage reading, then the voltages of the packs themselves, and then in the SOC going above 80%.

Before the hill runs and heating up, the block resistances were always exactly the same, around 25 or 26 milli-Ohms, with battery temps at then ambient of about 84 degrees F. After the hill runs and with battery temps around 100 to 109 degrees F at an ambient of 79F, the resistances varied some, with 6 of the blocks at 28~29, 6 at 30, and the two blocks that had previously been problematic, 6 and 14, at 31 and 32 milli-Ohms.

I really wanted to wait until the project Lithium batteries were back in stock, ( for obvious reasons considering my hill and the hilly terrain nearby ) but ordered the replacement battery at about $1000, since I felt the Prius needed it and it would be easy and quick.

But now I am thinking that the battery might be ok to go a few more months until the lithium packs might be available again, and I should cancel the rebuilt battery install.

What do ya'll think? Might my hill have reconditioned the battery enough to postpone replacement? It seems to be driving just fine for now, and this was clearly not the case before.

I still do have one concern with the lithium packs, which is why I did not pull the trigger on them just before they went out of stock. ( They were in stock one day, and I was going to ask about it, and they were out of stock the next. ) What did they do to address the charging at temps below 32F? Is it just that we would want to keep the actual pack temperatures above 32 before running the car? That is not impossible in my area, but I just need to know.

Thanks,
Doug

 

I was out giving it a test drive while you answered. The improvement in pack 6 did not last. It started to go higher than the other cells during charging and lower during discharging.

Changing 6 and 14 would be a good idea, if I had the time, but I have too many other things to get caught up on.

I will just let them swap it, and then see what happens when the lithiums come available.

 

Hometown Hybrids is the company I used last and the company that I have an appointment with. The current battery is from them, and lasted a number of years, I don't remember how many, but I am guessing 4 or 5. (edit: just looked and it lasted 3 and a half years. I am sure it was partially to just sitting, but I had noticed a decrease in capacity before it sat.)

It looks like Houston Hybrids does have a better warranty, though. On rebuilts, both are 2 years, but Houston Hybrids is unlimited miles versus 50k for hometown hybrids.