dr prius lithuim modules problems

in response to highmilesgarage post: thank you for posting the excerpt from next power . it appears you solved my quandary to some degree, number 3 clearly says the prius will overcharge the pack in an attempt to balance the pack so for any reason if one of the cells has a problem and the voltage sensor reports a voltage fluctuation out of line with the pack it will over charge the pack thus killing that cell and eventually the rest and making the pack totally unusable in a fast downward spiral. it fits my situation temps under 30f is about when it started having problems and my # 10 module is sometimes over a volt higher or lower than the pack when high current charge or discharge happens. so unless i replace it soon , the whole pack is doomed. and then it is only a matter of time before it happens again if i drive it in below freezing temps.
this could have been solved if they basically put in a pack battery microcontroller to have a separate monitor for the pack that gave a driver a display of the actual pack v/a/ohms ah ,temps etc. and could add or decrease resistance , heat the pack , regulate voltage input and output and was in between the sensor wires of the prius system and the pack so it could lie to the prius computer to manipulate the prius to do what it or the driver wanted .
also this exposes a fundamental flaw in almost all battery pack designs that are compromises to make the battery packs less weight , size , expense ,they rig the cells in series where one cell going bad degrades the whole pack even if the computer doesn't destroy it even faster. if the cells had individual flow and temp controls and heaters etc that were connected in parallel then stepped up to high voltages you would not have these problems , you could completely lose half the cells and you would just have half flow rate and capacity , it would be immensely more reliable and resilient and long lived and maintainable. however the up front cost of the extra equipment , and greater bulk and weight would add a few thousand to the price tag and hits to cargo capacity and curb weight mpg etc.. which would hurt sales , for manufactures it is far better to sell more cars now and worry about battery problems 10 years later and up sell improved replacement parts.

 

apparently there has been a whole lot more going on since the last time i researched replacement packs a few years ago , and i just learned a lot and most of it is not good . there are a lot of relatively cheap chinese replacement packs with dubious looking set ups that are a gamble and after you factor in shipping ,customs and time to get to you , etc are probably not worth it . an electrical engineer tore appart one of nexpowers new sodium battery packs and there are a lot of flaws . still in semi prototype / customer as beta tester mode. and he tested the packs performance and looked at the hardware and and engineering of the pack and pointed out a lot of problems with it consistent with problems and flaws of the previous lithium versions and indicating the sodium packs unless seriously redesigned will be another disaster in un ideal conditions. also the useable power from sodium is far lower due to voltage drop profile . so due to only being able to cram so many cells into the original prius case , the pack will have a lot less capacity . the electrical engineer basically said a lot of the stuff i had said about nexpowers lack of good power or cell management and protection and a smart/ programmable system to integrate well with the prius programming . it seems they do not pay enough attention to the important details and fix the problems at hand but launch onto a different chemistry with the same flawed process . sad , because if they just fixed the flaws with the lithium pack it would be a great pack and value for those that buy it ,

so unless i want to start my own company and proto type an expensive universal hybrid pack that would work better than what is already out there ( which i know i could do , just a matter of time and money that i don't have ) , i am back to oem hydrides for the foreseeable future.

 

almost tempting.

 

this is reportedly a dr. prius sodium cell early pack

 

i tried to get a greentec oem pack but it turned out to be new yabo 6.5ah round cell sticks of i think 4 cells , since their refurbished packs only had a 2 year warranty , i got the new yabo pack and installed it myself. it did have that wierd staggered voltage difference every 4 sticks but once i started using it they balanced out and typically stayed under .1 v difference . it runs good , little lesser but similar performance to the lithium's so far . the cells are supposed to have more capacity than the oem cells , that is disputed by others , but may not be the same cells as there is another chinese manufacturer that puts out the same round cell sticks that get put into other companies prius packs. there is definitely more surface area of the cells exposed to much more airflow , a lot more space around the cells etc. so heat dissipation and absorption should be much faster ,although the cells are fatter than the blades so more material per surface area will slow thermals , so i do not want to calculate or even guestimate the physics / math involved , but i do think it will come out more favorably than the oem blades on thermals but there is also no openings or drains for gas off of electrolyte so they may explode or pop if they short . but you should not have electrolyte induced corrosion until then. hopefully i can get 8 years out of the pack . i will post updates possibly every 6 months on performance etc. or at milestones or problems etc.

 

generally i am under the impression that oem new cells lasted about 150 000 miles on average , and there are various gradings of refurbished blades all depending upon the people refurbishing them , charging them up etc. and testing them , which you are totally relying on them getting low miles packs and doing it right , i can do that myself , i swapped modules / blades before and have a power supply that i can charge them with whatever amps and volts i want , but i do not have the time for that . the prius is my primary driver minimum 80 miles a day just to go to and get back from work . the 1st gen honda civic hybrid that is my back up car has a slippy cvt that i don't trust , i just wanted to get it done for the winter. also the fact that the refurbished oem cells are a crap shoot and last on average 2to 3 years for the 1 year warranty one and 4 or 5 for the 2 year warranty one i just decided to gamble on the new cells which are supposed to last 8 years or more . i am tired of pulling apart the back of the car every so many months to replace the pack. i don't like dealing with dealerships as i have had many bad experiences with them and so have many others i know, and i was under the impression toyota did not give up the new modules to regular people and were fairly expensive.

 

around portland oregon a mid level refurb pack is around $ 1000 a high level $1500 and the new cells i got about $1950