Rainbow Prius Hybrid Powered by Lithium!

Hi Jack.

Thanks for the update. Looks like your company is exactly 1.0 mi from my home!

(Got an email with those pics)...

moto g(7) power ?

 

Interesting project, but you base a few assumptions on ungrounded "facts". Not here to knock you or your work, good to see some one having a go.
The weight reduction leading to reduced fuel consumption distortion of the truth is the main issue I have. My '06 prius has the extended range LFP 76 x 40Ah cell battery in the spare wheel well. If we plug in and charge it from the solar each day, the fuel economy holds at around 2.5ltr/100km ..... no idea what the formula would be to get that into US gal/100mile. That 2.5ltr/100km only holds up if I'm not driving it mind you :lol: I'm a tad lead footed and drive like hoon on the country rds around here. The acceleration with a fully charged traction battery and the ICE on full song is outstanding for a family type car.
My Prius will do around 80km around town with lots of stop/start and hill climbs on pure EV using the ICE kill function so the ICE never kicks in. The extended range battery is 10kWh and basically keeps the traction battery topped up to around 65%, although I have recently discovered the Prius interpretation of SOC isn't even close. At 85% SOC using the scan gauge to show the computers interpretation, the factory traction battery exploded, fire and all the works ...... so unknown if the Scan Gauge reading of 65% SOC from the Prius computer is really 65% and not actually 80% or more.

Next issue is using pouch cells, they tend to rupture on high charge/discharge because they can not be fully compressed. I guess you have experienced the "gassing" of LFP cell chemistries and the way they turn prismatic cells into balls if not properly compressed to stop them from bulging. The case on the prismatic cells is reasonably thick yet it bulges when the cell gets warm if charged above 1CA or discharged above 1CA. All the members of the AEVA that have tried to build traction batteries using pouch cells have had serious failures requiring disassembly of the whole pack to remove the ruptured cells. I guess the climate here in Australia is a bit more severe than those seen in most of the USA ....... death valley is a summers day over here, not unusual to see well over 50*C around these parts .... but they don't put weather stations out there because not enough people live in these areas, they just transit through them. 50*C is roughly 122F, not unusual to see 55*C on some of the outback roads. The temp inside a car in the sun parked in a carpark can climb well over 70*C ... I guess you get the picture regarding heat and these pouch cells.

After destroying my traction battery I plan to do some experiments using the LFP 40Ah cells as a traction battery, but the high rate discharging and regen current I expect will destroy them, 120 amp regen would be 3CA for these 40Ah cells and that's hard on the LFP chemistry.
LTO on the other hand can handle 30CA, so when I'm rich enough I plan to build a 55Ah x 84 cell in series battery to give me an 8.4kWh nom. capacity traction battery that can absorb all the regen the Prius can produce as well as give as much current for that rapid acceleration that a good traction battery gives.

T1 Terry

 

One lot were LG pouch cells and another were A123, both well resected manufacturers and actually bought from the factory door I believe, so certified A grade cells as far as I understand it.
If you have found pouch cells that will hold up to the torture of vibration and rapid high current discharge and charging, then great, I hope it all works as designed because you have clearly invested a lot of time and $$ into this project.
I can buy the 55 amp LTO cylindrical cells I need for less than the cost of a new OEM battery (here in Aust) to replace the one I sent to heaven (or was it hell, there were a lot of flames) it's the freight and import duties and GST on everything to go towards supporting our politicians in the way they have become accustomed to that really ramps the price up. To buy one of your batteries would be a similar issue, getting anything out of the US and into Aust is prohibitively expensive.

T1 Terry

 

the suspense is kickin in...my body is ready

 

Ummm...... What ever it is your on, it seems to be doing the job yet you can still type :lol:

T1 Terry

 

I went to find Nexcell and their website notes an address in Taiwan. I wouldn't be surprised if they will drop ship direct from there for non-USA based orders. The landing then redistribution here in the USA seems to have developed after all of Trump's aggressive foreign trade policy.

moto g(7) power ?

 

Some things of note : the Nissan Leaf uses pouch cells, and they work well (aside from the Leaf has no cooling for the battery whatsoever, resulting in degradation). It also used Li Fe PO4 lithium pouch cells. So they can work well in an EV.

My main question : balancing. I’ve read a few pages of this thread and I may have missed it - but - how do you manage the balancing of the cells?
I imagine the internal balancing of the cells that make up one module is managed by the circuitboard inside that module. However, how do you keep the modules synchronised with each other? It could be something as simple as an I2C type controller, and a single wire that clips to each module to ‘talk’ to the next one using ‘serial’ comms - to prevent the modules ‘drifting apart’ over time?

 

I don't think anyone is saying pouch cells or LiFePO4's can't be used in vehicles. But the difference is they have a BMS meant to work with them. Not strapping a NiMH BMS to a Li cell.

 

All DIY EV's have some form of BMS to stop charging if a cell goes high voltage and some sort of balancing device. The not so flash units use a resistance circuit across the cell terminals driven by their proprietary programming, the good ones actually transfer some of the excess capacity from the high cell to the low cell.

Cooling is the big issue with pouch cells, they only require a very small area localised hot spot to melt through the pouch and then the electrolyte is lost. One of the more common failures is a poor connection at the tabs creating localised heating.
You can be certain, if cooling was easy to do Nissan would have done it with their early batteries, but they chose to limit the discharge/charge current in an attempt to keep the pouch cells cool. You can't do that with the Prius, the regen is savage and the discharge current can be quite savage. LFP handles high discharge current reasonably well, they just suffer voltage sag and increased internal resistance due to the heat generated, but they don't handle high current regen real well and that causes the majority of the heating and resistance increasing within the cell. If you can keep the cells cool they with do a much better job for a longer period than if they are not well cooled.

T1 Terry

 

active cell balancer. My diy pack has acb, it’s the newest thing in bms.

 

How many cells in the battery? What active balancer/s do you use. Active cell balancing isn't actually new, it was out there 11 yrs ago when I first started building lithium house batteries. Not something that is really needed with a 4 cell 12v battery, but 8 cell 24v and 16 cell 48v batteries it is a must have. For a 67 plus cell battery it would need quite a bit of microprocessor control to get the excess charge from say cell 67 to cell 1 .....

T1 Terry

 

And one of the most widely used IC's in the automotive industry for lithium active balancing has my work in it.

 

Is this the best replacement battery for Gen3 Prius as of the moment?

 

Without a doubt.

 

Guys I got the lithium battery from projectlithium!

I did the replacement myself, carefully following all the instructions and video (it took morning + afternoon), it's not hard but not even easy.

What can I say... My old pack was 100.000km old, so not that bad, but I really feel the difference in all the characteristics:

• Acceleration is better than ever
• EV only mode does more than 2.5km with ease
• The mpg(km/l) looks really promising but I want to test it more and get a real average (i have both gasoline and LPG).

Moreover, it's summer, 40° Celsius here in south Italy. I used the car two days both within the city and traveling 30km in highway.
It looks like the battery is really getting less hot than the previous, the fan kicks in less frequently and the charge is maintained while parking.

So far so goooood. And thanks Jack for all the support!

 

congrats! keep us posted

 

Yes, keep us posted @Giugrilli

If these prove to be reliable batteries over the longterm, I’d definitely consider these lithium packs if and when I need a replacement for my Prius C.

Looking forward to more feedback and reviews from early adopters.

 

Welcome to the Elite club of the Lithium Prius

http://www.RedBullet.net

http://www.ProjectLithium.com/?ref=mG0GE

http://www.Pulstar.com

http://www.PlugOutPower.com
Use code 7373

 

Pretty interested. Curious to see what the long term will be for these.