I'll give you one other example of how I treat my customers too good. I rebuilt a gen 1 prius pack for a customer a year ago, he's happy, he referred his friend to me who had a gen 2 prius that needed the HV battery replaced. My friend got some modules from a 2016 prius with only 5k miles on them, I bought them for $1,000. I rebuilt a pack with them and swapped it into the customers car, took me about 4 hours total, I charged him $300 for the swap and another $50 for rebuilding, he was out the door for $1390 (I only charged tax on the swap and rebuild not for the modules, but my accountant says I shouldn't do that anymore) Please tell me thats not a screaming good deal, I really should've charged another $100-$200 markup on the modules but I didn't because I believe treating customers good will payoff in the long run because I can get more customers and business. Unlike the hacks your talking about I actually got the certifications, licenses, and pay $200+/month for garage keepers and general liability insurance. I do offer a one year unlimited mile warranty on rebuilt packs and even if it was 18 months after I put in the pack I would still do all I could to get my customer back on the road. I'm still learning, i'll admit that, this is something you can always learn more about, the learning never stops. And I don't just work on packs, I do full service, I did 2 brake jobs last week, even though they don't pay as much as battery jobs i'll still do it to keep my customers happy. I'm a matchmaker for people trying to sell or buy H/EV's, I do an inspection on the entire vehicle and give a printout of the health of the battery and an estimation of it's remaining life, I charge $100 for that from the buyer, and then I get a finder's fee from the seller, all very reasonable. I've been a mobile mechanic for ICE cars, motorcycles and boats for 10 years, started doing some EV training back in 2011, now i'm all in with H/EV's because I believe they're the future and i'm in this for the long run. NiMH is being phased out, so these rebuilding with used modules jobs will start drying up and we need to transition. I'm all for rebuilding with good new modules, I got a kit from newpriusbatteries.com and installed it in my prius and i've been driving it around testing it for the last month and it's been working great. If they start offering more kits for other packs i'm all for it, i'd be happy to never have to cycle individual modules or rebuild with used again. You can read right on my website I don't sugar coat used rebuilt packs at all, I say what they really are, a used pack, and actually imo a good used pack is better than used rebuilt pack, all I have to do is charge them up with the trickle charger to get some basic balancing, put it in my test prius, and do a load test while recording data with TS. I don't even bother buying used packs over 120k unless they are really cheap. I know the hacks your talking about, and I share your frustration, they try to tell people rebuilt packs are like brand new which is total bs, they aren't licensed, certified or insured, most of them aren't even mechanics they just found a little scheme to make cash, they take the money and run and the customers have no recourse. My company is a real company, I care about my reputation, if I make a mistake I will fix it. That's my little rant, i'll stop now

 

1) I didn't miss it. Techstream is a useful tool, and it's beneficial for you, but it is very limited in terms of the details needed to recondition a pack, and it's only applicable to a small range of the battery's total capacity unless you force Techstream to go outside that - even then, you're still limited. there are 168 cells in a Prius pack. On the block level, it's pretty much impossible to see issues at the cell level. At the module level, you really start to see things
at the cell level when you know what to look for.

2) Yes, I am saying that. 1A is way too high, and again, you believe that having all modules at the same voltage has any meaning whatsoever. It doesn't. Since you ignored my example of 28 different voltages, those voltages, which only varied by 0.06V had as-removed capacities ranging from 527mAh (yes, 527 - not a typo) to 3,832mAh. After reconditioning the total capacity range was 747mAh (again, not a typo) to 5,297mAh with 16 of them too low to be reliably used in a car.

3) Because he's either gotten lucky, or there's no follow-up, and he doesn't see the aftermath/pitfalls. In 2008 there was essentially zero demand for this kind of work, so the handful of packs he did for the first few years likely doesn't play much towards actual expertise.

4) and how do you propose to do this? You cannot purchase new prismatic modules unless purchasing a new Panasonic EV Energy made pack from a suitable dealership. (NEVER MIND. I GET IT AFTER READING YOUR OTHER POST... PLEASE DON'T DO THIS)

5) there is no logical reason for this, and you have narrowed your selection down to a tiny fraction of available inventory. Here in Phoenix, where you will never find a dealership that says, "we've never seen one fail." Every time I go to the dealership, there are ROWS of cores stacked for return shipment because they replace so many batteries. >90% of packs fail above 120K miles here. Some of the best modules I have ever seen come from 2004 and 2005 years with high 100K on them.

6) Right, because you acknowledge that your process is insufficient. In your case, the 120K limit is what is protecting you - until it doesn't. I've seem some real turds between 100 and 120K.

7) You have likely learned that it wouldn't have mattered. I can be a real d!ck.

Again, to kinda give perspective on all this, so you don't think I'm some emo-rage tool, I acknowledge that you're making an honest effort. If you keep the process in place without deviation including restrictions on source, you'll likely be fine and put out a decent product. Based on your claims, I believe you are charging a fair price. Cost + tax on materials + $75-100/hr is very fair. If you're value focused and tell the customer that a new pack is going to get them a permanent fix in contrast to your work, then that's ethical.

 

First, Toyota has cut their Gen2 pack list price down under $2000. Consider that and what you would pay with your shop discount. for barely 2 hours worth of work.

If that doesn't turn you off those cylindrical cell abominations, you have to understand that the WORST hybrid batteries ever made have been the "D" cell batteries used by Honda - literally the worst. And those cells were made by Panasonic - good cells but bad implementation. They were not some sh!tty Chinese made garbage. They've been sued on almost every model they made for battery issues. The only reason they didn't get sued on the 09-11 is because they gave ALL states the CA warranty.. You've taken cylindrical cells and installed them in a cooling system designed for prismatic modules. Before you think that wider spaced cells or cylinders are somehow good, simply do some research about aerodynamic flow around a cylinder or sphere. Look at what honda did to their packs to address cooling characteristics around cylinders. They are either using baffles or they are staggering cells to move them into the air path of the previous cell. The Prius cylindrical cell pack makes zero effort to provide adequate cooling flow.

The prismatic modules are allowed to run pretty hot. You've likely seen this on Techstream. They really don't start getting cooled in earnest until > 120°F. Cylindrical cells have less surface area for cooling, airflow characteristics mean even less surface area is used for cooling (a tiny amount), and they have a thicker cross section than prismatic by almost 2X, which means the center of each "D" cell is going to be notably hotter than a prismatic module. Note also that the thermistors used at the bottom of the pack in the cylindrical design read artificially low due to airflow bias - less heat is being absorbed by the air (meaning it runs cooler than it should) as it passes over the cells, and the thermistors are located in a region of maximum airflow. Artificially high airflow + air that is cooler than it should be = artificially low temperature readings = the car thinks the battery is MUCH cooler than it is.

They may be fine for very cool climates, but in summer temperatures in most regions, these "D" cell packs are going to be very short lived, and they do not represent any value whatsoever to a customer when you consider that at a shop price, you could now install a brand new Toyota battery for $2100 and make **** good money while providing a the absolute best value for your customer.

Don't get suckered by 2k1toaster. He's selling snake oil. Most of his claims of positives are actually negatives. If you desire to provide value for your customers, you can't even consider offering those packs. They exist for one reason... sales of Chinese "D" cells are slowing as Hondas are starting to be taken off the road permanently. They've shoe-horned them into a Prius case to find a new home for them. They are over-priced, and they will underperform as has already been demonstrated by Chinese Honda packs - yes... better than almost all rebuilds, but inferior to the old Panasonic cells.

I realize there's a lot more in your message, but frankly, your mention of the cylindrical cells has drained me of any ability to focus on anything but that.

 

Yes I have been told that the cooling of the cylindrical cells in any pack is an issue because of the exact reasons you mentioned, we know this from the Hondas. I think if there's any region you could make it work, it would be here in Michigan, we don't have mountains, some really big hills but no mountains, and our temperatures rarely exceed 90°F. I've never seen the cooling fan go above low speed, even with rapid acceleration and deceleration and 90°F, once you have temps above 100°F cooling becomes critical. I just wanted to try out one of the packs and see how it works in my region, so far so good but it's only been in for a month I guess we'll see how it does when summer comes. Perhaps there are a few things that could be done to improve cooling, like some baffles like your talking about, relocating the bottom thermistor to the side or top maybe.When I replace a pack I always use some electrical tape to seal up air duct connections because they don't have a good seal at all, gives a little better airflow, clean the fan and filter or replace filter with a new one. I wish somebody had good aftermarket prismatic modules, that'd really be the way to go. There's a local Toyota dealership that said they can get me the new modules for around $2,000-$2,100 they said their price is $1,800 and their list price is $2,564. Only a 1 year warranty on those packs though but it's OEM so we know it's gonna last a long time. I scanned that Tahoe today and it is showing a block voltage is low. They are thinking about trading it in to the dealer, so I might just replace the bad modules with the best matching ones I have and do some balancing with my whole pack charger, I quoted them $485 to do the job including the modules. The truck has 210k and they've had a lot of problems with it so they are reluctant to put a new pack in. They did put a low mileage engine in it about 50k ago and the truck is actually in great shape, the dealer offered $10k for it which is probably the best they could hope for. I'm going to make some calls tomorrow to verify what price I can get a new pack for but it sounds like just getting the thing rolling and code free might make the most sense for their situation.

 

$485 sounds very fair, and your solution is appropriate for the situation. However, this situation is a perfect example of where your 1A charge system is inappropriate. A LARGE number of those modules are likely seriously deteriorated and have less than 2000mAh capacity. Charging at 1A is 0.5C. Balancing should be done at < 0.1C. Overcharge at > 0.1C runs a high risk of cell damage as well as inducing voltage depression/capacity loss - which is the opposite of your goals...

Go buy this:

https://www.ebay.com/itm/EC570-90-El...0AAOSwonBZ~jKh

0-2.5A, 0-500V, 350W maximum. It will charge a Prius pack at about 1.2A. It will charge the 40 module pack at about 900mA.

You'll need to fabricate some leads with 4mm bullet connectors AND you need to put 3A/600V diodes in the charge leads (one is adequate, but I prefer one on each lead, strip to battery on (+) and stripe to PSU on (-))... a battery pushing back on the supply will kill it.

Seriously, check with your Toyota dealership again. On 1/1, they lowered the list price of the Gen2 Prius pack by more than $500. You should get a shop discount on top of that. They did not adjust pricing on any other packs.

Concerning your understanding of temperature, I recommend that you collect some additional data. Techstream will suffice, but it's bulky. I recommend a decent ELM327 OBDII bluetooth adapter and Torque Pro or Hybrid Assistant. Start monitoring your prismatic pack temperatures during normal driving. My 13 mile drive home on Friday in 70°F saw the battery at 111°F with the fan on 2 or 3 (I can't remember, I used Hybrid assistant to force the fan on full blast). This was flat land 70/30 surface street/freeway. You may be very shocked to find how much hotter the battery can be than mild ambient temperatures particularly after sitting in the sun all day.

Electric tape isn't a bad idea, but I personally find it unnecessary due to the way the cooling system works. It's demand based with an active feedback loop, and it really only matter when the fan is on 6. The amount of leakage I've seen is minimal compared to the total air flow even on 1. HOWEVER, the seal on the top cover is CRITICAL. I find I am replacing that seal more often than not with a more dense foam strip moved slightly inwards. Note also that brand new packs from Toyota can have seal issues. Watch for these.

Lastly, the exit duct - it's likely more critical than the inlet as getting that heat away from the battery is pretty important. I've seen these jacked up from the factory. I get that duct aligned and fully seated before I tighten the deck bolts.

 

Thanks for the information, I'll take a look at that charger. I got that DC PS off ebay for $350 so it was a pretty good deal, I just wanted something to be able to charge any pack, but it would be nice if it had lower amperage for balancing. That's interesting the temperature can be that much higher, I guess I do need to log some more data on that. I will check back with Toyota because the last time I spoke with them was in August or September, that would be great if I could get a gen 2 OEM for $1,500-$1,600.

 

The EC570-90 will charge any hybrid NiMH pack on the planet. I've used it to charge a 250 cell Mariner Hybrid.

It also acts as a constant voltage supply. If you set a peak voltage, it will taper current once that voltage is reached. Handy for quick charging at lower voltages, but having a safety as it nears full. You can then intervene and dial down the current to something near 0.1C and increase the voltage to above the expected peak to have it just keep pumping current.

I can neither confirm nor deny your proposed price point, but I know the answer. I can tell you that you have correctly identified all digits of the price in that range, i.e., of the four different numbers used in your price range, each one is used once...

 

Wow that EC570-90 is only $89?! Man I should've waited on buying that other power supply, this is a lot better, thanks for sharing, I think i'm gonna have to order that tomorrow.

 

+30 shipping. It can be hit or miss on if they work or not. Make sure you have some leads ready to go.

If you're looking for a low current option to trickle the questionable packs (like the GM), you can string together LED power supplies. My favorite is the Meanwell APC-35-350, 28-100V, and they can be put in series. $12 each or so.

 

Another data point on temperature...
About 4-5 miles into my morning drive (about 1/3 of the way), I decided to plug in and check it out.
Car parked since 11am on Saturday (about 44 hours).
50°F ambient according to car. Weather services report 52°F for my zip code.
64°F pack temperature.
About another 9 miles to finish the drive:
50°F ambient
82°F pack temperature
Fan on 0 during all monitoring.