View Single Post
Old 07-24-2019, 04:16 PM   #28 (permalink)
S Keith
Master EcoModder
Join Date: Oct 2014
Location: Phoenix, AZ area
Posts: 311
Thanks: 19
Thanked 172 Times in 121 Posts
Originally Posted by vskid3 View Post
Yep, Prius battery took a poop a couple weeks ago followed closely by the Camry throwing a code. I swapped the good modules from the Camry into the Prius so I could get the Prius to pass emissions and to have a working car.

I'm considering rebuilding the Camry's battery with these new modules and then piecing together a functioning pack for the Prius using the stock modules from the two cars. It doesn't make a ton of sense to drop ~$2k into a car with 205k miles, but I figure if anything happens to the Camry, I can just swap the new modules into the Prius or pick up a Camry with a dead battery. I would be a few modules short if I did it the other way around and got the new modules for the Prius and then had to put them in the Camry.
I mentioned I have no experience with the BeeMax cells, but I have approximately 13 months of experience with the linked supplier's battery. I purchased a second hand pack from a hybrid service provider. At the time, it was around 4 months old and had about 4K miles on it, and it had sat for about 2 months before I obtained it. It is my understanding that it is one of the first, if not THE first, batteries he sold.

I conducted testing on the modules prior to installation. They all tested at about 6300 vs. 6500mAh of rated capacity. This is comparable what I see on very good used modules from mild to moderate climates. For Phoenix-only batteries, 10+ year old modules with 150K+ miles can yield about 5500 after reconditioning.

I installed the pack in mid-June of 2018. Of particular note was the wild discrepancies in internal resistance. There was a 0.007Ω spread, e.g., .024-.031. New Toyota batteries have a 0.000 spread, and an original Toyota battery typically has no significant spread (.000 - .002) except for any blocks with failed cells. Approximately 4 months later, I conducted a capacity test via Techstream and noted a 40% decrease in capacity.

At the 13 month mark in it's second Phoenix summer, it is performing worse than the worn-out reconditioned battery I removed to install it. When I have time, I plan to pull it, test the individual modules and report comprehensive results.

My biggest concern has been cooling. I recently conducted an experiment where I checked back every 10 minutes after shut down. At the time I turned the car off, the battery was at about 130F. One the 3rd or 4th trip back, I saw temperatures above 150F. This indicates that the core of the thick D cell is MUCH hotter than the surface where the probe is mounted.

On "D" cells in general, the reliability of the Honda cells, the premium "D" cells made by Panasonic vs. Chinese-made cells, has been notably inferior to the Toyota prismatic module. I have a lot of personal experience with Panasonic made Honda "D" cells.

The Honda data suggests that "D" cells are inferior in general, and my experience suggests that "D" cells in a Prius in a hot environment are inferior to Toyota prismatic modules by a large degree.

Aside from this experiment, I would never consider kits from that manufacturer for use in anything but a very mild climate.

Additionally, while the individual sub-packs are interchangeable, the supporting hardware is not. You can't take one for a Camry and put it in a Prius. The cables and harnesses are not interchangeable.
  Reply With Quote
The Following User Says Thank You to S Keith For This Useful Post:
MetroMPG (07-24-2019)