Prius plug in battery only getting 8 miles per charge. Help!

it's not that, it's that no one understands what you're trying to explain.

if you can tel us what chemistry it is, we're interested

 

Ahhh.... I see the problem. John Kelly (Weber university) doesn't even say what chemistry the cells in his battery tear down and rebuild video, he simply refers to them as lithium ion.
It doesn't help that in some interweb article they are refered to as 3.6v cells, but others refer to them as 3.7v cells. That 3.7v nom. covers a huge number of lithium based chemical combinations, but they all seem to have a common upper end voltage of 4.2v and they all seem to require that 4.2v to be held in an absorption style charging regime that stops the charging when the current falls to a given % of the advertised capacity.

This is where these 3.7v cells loose some of their capacity and this compounds with each recharge, the fact the charging regime uses the well known 85% SOC upper charging cut off makes things even worse.
A full saturation recharge to 100% capacity resets this problem and the capacity returns .... LFP and LYP cells suffer a similar problem, but they don't have the fireball problem if someone gets it wrong by attempting to charge to greater than the safe upper voltage.
To make it even harder, there is a ZVW30 model with the 4.4kWh battery that weighs 80kg, and the XW50 with an 8,8kWh battery and weighs 120kg .... double the capacity but not double the weight, so a chemistry change?

T1 Terry

 

probably. it came 5 years later, and tripled the range with only double capacity.

the big problem for amateurs trying to rebuild a plug in battery is the size and weight.

 

I believe the pre-production model built in 2009-2010 used 96 3.6 V cells (346 V total), about 600 of these were made as demo vehicles. The production ZVW35 Prius Plug-in from 2012 uses 56 3.7 V cells (207 V total). The Toyota documentation doesn't seem to go into any details about chemistry unfortunately, but it's probably the pre-production vehicles that are the source of confusion regarding cell voltage as they used different batteries.

 

This claims they are Lithium nickel cobalt aluminum oxide (NCA) batteries: https://elib.uni-stuttgart.de/bitstream/11682/10977/1/PrasadMalya_MT_print.pdf
Which makes sense as IIRC Panasonic are the battery supplier, and they produce this type of chemistry.

 

nice find. that should make things easier, i'd love to goose mine back up to 16 miles.

 

Great find, I think this is probably the best reference section from that paper

A bit of a Google search turned p info from here right back in 2012 Prius PHV - Production battery cells | PriusChat
Got some reading and reference stuff to follow up just in that thread, but great to see this battery pack question has already been explored here

T1 Terry

 

Many if the members posting to that thread were still active a couple years later when I was a newbie trying to figure out how my 14 PiP was put together. I learned a whole lot about Prius from all of them and very mush miss their driving and posting style as well as the amount of data they pumped onto this forum daily.,,,,

 

I commented this thread last December. The ev-range on our Prius Plug-in 2013 had come down to 8-9 miles. Now it's spring and the range looks to be about the same. BUT i just went to our local repair shop a week ago. A peg on the left brake caliper was totally stuck. It was bent. The brake pad was really worn but so that it could not be seen without taking all apart. The brake disc was still pretty warm when the guy removed the wheel. So there has been definitely BRAKE DRAG. And this could have happened for quite some time. Also on the other side one of the pegs was not moving that well. After changing all the discs, pads and the bad pegs, the gas consumption came down noticeably. The warmer weather probably had an effect also. I'm curious if I should now disconnect the 12v battery to reset the range readings...

 

glad to hear they found something. it never hurts to reset everything, but it's not necessary.

just try the test again. charge it up, and see how far you can drive before the engine comes on.

i'm getting 11.4 right now on the gauge, and sometimes able to go as far as 12.5 or so under the right conditions.
temperatures are averaging around 50f.

 

i wonder id anyone has figured out how to reenergize these cells

 

I have had success with about 50% of the old Prius NiMh modules by refilling the electrolyte and steady recharging, stopping over night at 7v, them 7.5v, then 8v and now 8.5v ..... aim is for 8.8v, close enough to the 9v max and allows for a cell or two being a bit out of spec.

It would be interesting to get hold of one of these Prime PHEV batteries to see if the cells can be recovered or if an LTO cell battery could be built to retrofit the original battery.

T1 Terry

 

the problem with these buggers is, they're large and heavy.

 

LTO cells tend to get the heavy tag attached to them, but the fact they hold their voltage so well under load, it might come down to comparison of energy/voltage/time when comparing one chemistry to another.
The NMC (lithium nickle manganese cobalt) chemistry was supposed to be the latest and greatest, yet they don't seem to have very good voltage sag properties, so not really suitable for EV use. I believe Toyota is about to deliver an SUV that uses the LTO chemistry Toyota's New e-SUV Comes Equipped with Toshiba's LTO Battery Tech. so maybe the pendulum is finally swinging back towards the LTO chemistry being the better option .... time will tell I guess

T1 Terry

 

Caliper slide pins seizing on the rear brakes are a common problem on these, especially in climates that get salt on the roads in winter. I already had to replace all the pins on mine a few years ago as they were badly corroded and some seized. I'd recommend inspecting and lubricating them at least every two years.

As to your range estimation, just use the car normally and it will change over a few days. Disconnecting the battery doesn't do anything useful in my experience except show a higher number for a few days - it quickly went back down to normal for me.

 

I just had a quick Google search to see if anyone close by here had a PHEV Prime .... it seems like they aren't even actually available over here yet, even though the headlines say they went on sale in 2022 in Australia .....

It would be quite a task to disassemble one of those batteries to condition charge each parallel cell group and then test them to see if they all have the same capacity .... basically looking for poor performing cells ...... Anyone have a lot of time on their hands that would be willing to take on this project .... with guidance from the brains trust here, and photo log each step?

T1 Terry

 

What kind of equipment (besides the batteries) would be suggested for cycling?

I've only seen one reference for the Gen 3 12-15 Prius Plugin 3 bank packs someone posted a few months ago (forgotten exactly how many cells / bank and chems - and other specs) and I don't know the chem used in the Primes 5 bank setup either although I seen it referenced a few times.

 

The Prius PHV been a poor seller in a lot of markets, they've already dropped sales of it here in Ireland and are ditching the Prius altogether in some countries (Corolla, Yaris/Yaris Cross, RAV4, C-HR hybrids are selling better). It was way too expensive in countries that have import tariffs on Japanese-built cars and any substantial taxes on new cars (i.e. not the US ). Mine was an ex-dealer demo from the UK, I imagine actual orders were very low.

There's much more interest in the RAV4 PHV (Prime in NA), but again it's expensive and compares poorly on price to the Koreans.

 

Oh drats - there are the chems right up there in this thread.

 

I would recommend testing each set of cells in parallel, so a charger that would stop charging at 4vdc and a headlight globe would do for the load test with a voltage cut off at 2.6vdc. The NCA (lithium nickel cobalt aluminium oxide) cells used for these battery packs have an upper voltage of 4.2v and lower voltage of 2.5v, but no value in pushing them to the very edge of failure.

It would take quite a while to do the testing because each set is being tested separately

T1 Terry