Rebuilding HV battery. Limited success with used modules.

So, are you saying you want to arrange a group purchase so you can get a few new modules to install with your old ones, or you want to arrange purchasing a 1000 modules so a bunch of guys can get 28 each? And what price do you expect this to happen at? Think it would be competitive with just buying a pack out of a wrecked 2014/2016/2016?

And in my neck of the woods, I've never seen techstream show less than 19 milli-ohms (0.019 ohms) on ANY block of any age...what production date modules have you seen 13 milli-ohms?

Oops, my bad, as you're talking individual modules and I'm talking blocks

If you actually have 24 milli-ohms on individual modules, then your pack has significant problems.

 

If you can arrange to get brand new toyota/panasonic/oem (not chinese knockoffs) for $10 each, I will buy a few thousand myself, right now.

 

You won't get them at $10/ea. Not going to happen at such a low volume of 1k units. $30/ea would be a good 1k volume price.

And that is exactly why I have done what I have done. You can't buy the new Panasonics anyways, they won't sell them to you because you aren't an OEM. I can actually buy them since a company I am part of is a rated supplier for Toyota which gives us access to their supply chain for various testing. And no, that can't be absued.

My solution is to make an alternative new battery for the reasons you mention. It doesn't make any sense to just keep putting 10+ years old modules in a 10+ year old pack. Makes even less sense to spend $800 on eBay for a bunch of "reconditioned" cells that are also super old or double that for the same thing from Autozone...

 

Have never seen 24milliohms too

 

what if we bought 10,000?

 

If you could buy 10k units from Primearth, you would still be very far away from $10/unit.

 

100,000?

 

Not to be harsh but that's just a pipe dream for many reasons; some have already stated. Add in the fact, this eventually involves potentially deadly voltages and a company would be foolish to sell to the general public.

Besides, they already sell them completely and safely packaged with a warranty through any Toyota dealer. Why would they want to undercut themselves to save you a buck while also screwing (one of) their best customers?

Your efforts would be better served in trying to get Toyota to lower their pricing.

 

Your primary goal should be figuring out how to keep the batteries from exceeding around 100F while inside the car. Your best bet is to get a high heat rejection tint. They make clear tint and dark tint. The best tint on the market is the Prestige Spectra Photosync which can block 58% of solar energy with 75% VLT (mostly clear) and 71% of solar energy with 35% VLT (pretty dark) . I suggest putting dark tint in the rear and light in the front so the pack doesn't heat up while driving.

When the batteries are brand new, they can handle the high heat but it's obviously very bad for them. These older batteries on the other hand can't handle the heat because the delta in resistance between the cells grows not only as the pack warms up but as the pack ages. As the internal resistance goes up due to faster aging from being hot, the cells warm up faster and the pack quickly gets out of balance. I experienced this issue first hand a few weeks ago where I have a professionally rebuilt pack (I was told by last owner anyway) but because I left my car parked in the sun all day and decided to drive the car on a 102F day, red triangle and cel for a weak cell block 9 showed up. Using techstream, I figured out that when the pack was starting to overheat, the car didn't want to charge the pack, and since I ran the A/C in an attempt to cool the car, it was draining the pack more than was being replenished by the engine. Pack reached upwards of 164f and I don't know what the temperature threshold was before the car started becoming undrivable that day (very weak acceleration, driving with 1 pink bar). That evening when things cooled down, after about a mile and some computer recalibrations, I was able to drive the car home without resetting anything, leaving the triangle light on. The next morning or so, when I started up the vehicle, the CEL and the triangle light went away on its own.

Today was another very hot day (102F) and because I had to drive a very long distance (100 miles), I was deeply concerned I'd have a repeat of that other day. I took several precautions like using the cargo cover, then putting a reflective windshield cover over the cargo cover to reject heat from entering the trunk. I also parked in the shade as much as I could, put the A/C on floor and max fan speed 65F, started my journey at 9am when it was 70F outside. As I was coming back, it was already 80F+ and 102F for about 20+ minutes of the journey. Recorded the pack temperatures and voltages both on the way there and back and the none of the temperature sensors exceeded 105F. Car's fuel economy was perfectly inline with what I expected on this trip and car drove normally. Having a temperature balanced pack is really important and not allowing external heat to influence the pack temperature I can see is really important.