Prius III hybrid to PHEV convertion

Hi there, I have seen many tries to achieve a Phev conversion in gen2 , and as I understand most of them finally work almost properly! But there is not much info available fore gen3 yet...

In my case I would like to do something very simple , and I would like to ask Specific questions in some hypothetical problems that might come that I have not understand yet after all this research ...

My Intention is to take out the NIMH batteries on the final stage of the experiment. BUT before I reach this point I have some steps to achieve...

SO The project should go like this...

I am planing to use either 56s Li-ions like 18650 like 20 or 25 parallel (depend on the max Charge Current)

Or 70s Lifepo4 multi ah cells(Probably 70s 1p) ,

I believe most of you have already understand the concept (14 blocks of 4s lions or 5s lifepos)

Lets say for the moment that I have solve the balancing troubles (OR OVER and UNDER voltage related managing for each case) The question that remains is that ... If the car is In proper temp and there is enough juice in the batteries(more that 8 bars or 80%, and I go in EV mode with top speed of 49-50km(The limit in mine for ev) will it run on them without any modification?, after the calculated 60% of the 6Ah capacity?? Or does it somehow count the available juice and will cut of because it things that the nimh is to low(Because I intend to add in parallel the extra pack with some solid-state relays and some fuse so I will be able to cut out the extra pack if any emergency occurs...??? So will it operate in the available extra kwh that will be available or it will stop and start charging even if it used only 10kwh out of the 40 or 50kwh that will be available?(depended on the final setup) ...

If after the first try the car operates as normal,it will probably take some time to reach this point(wich will mean that the nimh will be almost dead....... then I intend to rewire the spagetti so the battery controller will manage the li-xxs and from time to time I will balance them according to what the needs will be...
And even if this step gets achieved then the only thing remains will be to charge it with some 220v charger from my garage... which will be great if it finally gets achieved!!!

Thanks ,
George

 

Hi there,

As I can see during to further research over internet, the batery controller probably can learn the batery capacity after some charge recharge cycles...!!! if this is true... does anyone have any idea what the max capacity (if there is such a limit) the orfiginal batery controller can read and handle in order to project the proper SOC to the rest of the systems???

 

Wow thanks alot for your replys!

Well as regards the type of cells that will be used... 56 liions have a nominal of3.6 per cell so 201.6v same as the 168 nimhs @4.2 per cell is 235.2 lower than the 168x1.5v 252 nimhs cells (that is something to work with...) and @2.8 x56 lions have a 156.8v value lower that the 185 that i have read in the torque app during all my tests until now... So @185 wich is the lowest value the liions will have 3.3v wich is extraordinary safe for lowest value... In this point I have to refer that 185v is under load so the cells will be more than happy... On the other hand 70 lifepo4 have a nominal of 3.2 so a total of 224v more than the 201.6 (which is nimh's nominal) , max value is 3.6 per cel x 70 =252 which is the hiest vallue I have read during hard regen... And last but not least is the lowest value of 185v during hard acceleration before engine kicks in wich translates as 2.64v per cell ... Which i hope that will not have to reach because of the high power that can offer the lifepo4s 40ah cells... Also this vallue is mommentary... But I believe that we will know for sure only after the tests... also there will be a big enough co2 extinguisher in the batery box which not only will serve as a fire extinguish in an emergency but because of the co2 ability to cool whille discharging it will lower the temp as well physically in a runout situation... So the only main trouble for the momment is that if it goes parallel to the nimh (with some rellays maybe solidstate so it can disengage also there will be alot of fuses to help if needed.... Will it allow the juice to be used? My intention is in next step the lifepos(probably beter than lthe 18650 iions choice) to replace the nimhs and the new cells to be managed by the original prius batery controller... Also at this point I would like to mention that the extra cells no matter if they replace or not the nimh are going to stay outside the batery box... With their own cooling system and and the original box will contain only the batery controller(if finaly replaced the nimhs) and the needed plugs for the 14 blocks that it will constantly manage... ... ...

On the other hand if it can not adapt to the extra ah ... Then I believe that I will have to spoof the controller and then I will have to manage the extra batery manually with external balancers etc like we do all these years in other kind of applications... Wich I would love to avoid because my point is to just replace the nimhs ... ... ... What do you think about the concept?

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Also as regards the total cells as far as I know... The gen3 have the same layout with Gen2 168 nimhs in 28 modules of 6 cells (7.2 nominal) that managed by the controller as 14 blocks of 2 modules ... So each block have a nominal of 14.4v. With full charge of 18v 1.5 per cell and lowest voltage of 9.6 that is .8v per nimh cell of each block... That is why it is possible to be replaced by 4s lions or 5s lifepo4s... The only main diference respectively to the original nimhs will be the available ahs that will be more than 10 times probably of the original... But needs extra research for safety reasons.........

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And the truth is that i will monitor the total batery behavior... I have seen some reference that the batery controler adapts to current available amperhours of the traction batery... (which seems logic) if we consider the fact that when the bat is almost ready to leave us for "other places" that the total time it takes to 8 bars turn to only 2 is much shorter than with a new bat... Also when a new bat is being replaced I believe it takes some time (some charge -discharge, cycles) for the car to determine the available ah... And adapt to it... ... ... The truth is that I donot believe that toyota have left unlocked and unlimited the ah capacity they will have probably locked it in the code... Which apparently i see nowone try to decode and play with except 1 maybe 2 exceptions that did it for gen 2...


But as regards the parallel conection... It will be able to connect and disconect at anytime ... Maybe one arduino will be monitoring the extra set of bateries and if they heat to much or they over or undervoltage it might disconect them and let the nimh continue... Until problem is solved... Also there is an other case... (That is why i itend to use solid state relays) maybe the relays will not stay on or off... I've been thinking to use pwm to modulate the voltage of the external batery ... Especially durning regen... of course if i Finally replace the nimh with the lifepos (at last stage of the expirament) i will not be able to take out the lithiums if they over heat or whatever... But will not replace them until I am 99%sure that it is safe to do so...

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Hi Guys,

I have been researching about the concept....... I have seen more solutions now... I believe I will stick to the original plan of using a bog battery ... And probably it is unavoidable to stay out of the can-bus communication... so does anyone now how is the ecu's architecture on Gen3??? I mean i have seen by now that the gen2 had a electric motor controller an ice controller and a battery controller ans the spoofing was somehow possible!!! but on gen 3 i read so far that the engine ecu is embedded in the inverted-electric motors' ecu!!! so probably needs deeper skills than what I Have... so any info would be appreciated...!!!

Is it possible for someone to explain to me what the BMS+ does? As far as I can understand it balances the battery cells like a BMS would normally do and also spoofing the can bus messages as regards the adapted SOC% ??? so it is like an handmade battery ecu??? Does it fit for prius III? Also I read about the battery tap emulator that operates on the previous car versions!!! It is a very simple and sophisticated way at the same time to avoid dtc's regarding the battery!!! and after that you connect your own BMS so you can monitor the battery "Manually" nice thought...

George

 

As far as I understand calcars and engineer are very similar approaches, as i do understand both charge the main nimh pack... calcars with alot of bats and engineer with less bats and dc to dc converter but practically they do the same they inject juice directly to the nimh or in the engineer case it refers something after the hall sensor or i get it wrong?

Also i bellieve both play with the comunications of the canbus to spoof the coulobs and make the inverter-electric motor ecu bellieve theat the soc is high enough so it is forced to take the extra amps.... at least until the extra bat gets depleted right??? does someone else understand what these gentlemen did in their succesfull setups???

And if i get it right it still a concept that doesnot fit my needs because i own a gen3 have anyone worked with the gen 3 architect? yet???

 

Well , it seems right, since it is in the relative "young" side of it's age ans still have warranty for the battery is normal that very few have been working with it yet... I have a couple of interfaces like galeto v54 and kwp-2000 with which i managed to read and remap the binary in my 2009 smart cdi last year but none of them seems to be able to read the prius ecu which is the same year 2009! ( it seems that came to Europe 1 year earlier than the american market)...... Has anyone any pointer about which device and/or software should be used in order to extract the binary???? until now I have only managed to communicate with the ecu through the Toyota techstream and read only a few very basic information about the car and some simple choices like the safety strap beeps or the reverse beep sound etc... I still don't know what the ecu is at all so I can not find a proper way to read it properly yet...... although in my opinion will be more difficult to remap it ... than just spoof the battery ecu as it happens on previews gen model... but i did not get the last about the 20 (maybe) amps ,the extra battery is connected through the hall sensor (on the nimh battery side) or after the hall sensor(towards the inverter side) in order to let it operate without dtcs?? thanks!

 

Well after all it seems viable... actually the best solution I bellieve that is a batery tap emulator and spoofing the soc% through the can-bus!
And external BMS to monitor and balance the real pack... Which must be able to accept peak charge current of 125A (I have seen many times these vallues under a bit stresfull situations...) and be able to feed 135A (since there must be alot parallels or strong cells in order to accept the charge without problem and increased temps they will probably be able to feed more than 300 or 400A peak currents......
So there must be a simple map that relates the SoC% according to user's needs (within some safety limits ofcourse) to the actual pack voltage, (Also this makes the ni-mh pack unescessary , So someone would be able to make the ecu spoofing and then buy some cells with enought aH so at the cost of a simple replacment of the normal nimh, would gain extra pure ev kms or miles (Ofcourse should plug it in during night but you get the point)
So as regards the project,
I have been trying to figure out what is going on with the canbus, I can not understand yet if there is a single canbus (the one that goes to the obd alsoat pin6 and 14 ) or if there is a secondary one (probably faster) which will have the batery ecu comunicating with inverter and engine ecu.... I will keep researching but...Is there someone that willing to help with this?
Thanks ,
George