[DRIVING] Project RX8 , Prius gen2, Lexus transaxle to rwd

[Ev8]

Ok so turns out range is more like 40miles the way I drive, unfortunately I ran out of charge and stupidly tried limping the few miles home, eventually had to stop and get a friend to give me a tow hopefully I’ve not done major damage to the battery but I did have some cells go under minimum voltage, and ended up with a large delta, it charged up ok without any sign of the modules getting over hot, I’m just scared I’ve wrecked if and now charging whenever I can, to this end I decided to install the type2 socket I had so I can use public charging points, albeit only with my tiny 3.3kw obc.
Tested with some free electricity from my local Tesco supermarket

[MattsAwesomeStuff]

550Wh/mile.

Not great efficiency, no. However, you were going 80mph, so, you're well up into the cubed power draw dominating your power reqs.

[arber333]

Ok so turns out range is more like 40miles the way I drive...

Unfortunately we too noticed DC motor has greater consumption regardless of higher voltage. That is the tradeoff to simplicity of control.

Maybe you can tune out your gearbox further to figure which gear is better to drive in?

Also you really need to fit a low SOC warning. You said you use teensy to read voltages from stock BMS?

[Ev8]

Yes the teensy for the bms is running simpbms code, unfortunately some wrong settings lead the calculated SOC to be reading 27percent when actually I needed to be charging if seems these phev modules get to 3.3v and fall off a cliff, all my mistake I’d set low cell voltage to 3.0v I’ve changed that now, and hopefully iv got away with it

[RetroZero]

Nice project. I think I'll be getting the spray can out for Jenny's (Gen2) cover..
Looks top notch for a 'budget build'

[Ev8]

Thanks, the budget part keeps becoming more distant!

[Ev8]

Well I guess my motor doesn’t like 1000 amps and 200 volts after all.

Tbh feeling pretty shit about the whole thing and considering pulling the whole thing apart and selling what’s left rather than throwing motor time and money at it to convert to AC

[arber333]

Well I guess my motor doesn’t like 1000 amps and 200 volts after all.

Tbh feeling pretty shit about the whole thing and considering pulling the whole thing apart and selling what’s left rather than throwing motor time and money at it to convert to AC

Thats the problem of all DC motors.
No need to give up as now you have HV in the car allready.
You can get Nissan Leaf motor and put it to your gearbox.
Even with 200Vdc it should give plenty of power at low speed. If you go to 400V you will burn out rubber.
Your Inverter works. You just need to make it 3phase again.

[Ev8]

Thanks, I am looking at motor options at the moment, battery pack is 80s so 300v nominal, can you believe I was limiting inverter output to 200v and still did this ( I’d did spin the wheels from standstill in 3rd gear though) if I was sensible I would have turned the current limit down! Oh well you live and learn

[arber333]

Thanks, I am looking at motor options at the moment, battery pack is 80s so 300v nominal, can you believe I was limiting inverter output to 200v and still did this ( I’d did spin the wheels from standstill in 3rd gear though) if I was sensible I would have turned the current limit down! Oh well you live and learn

Even beter! My friend runs RX8 and back when he had 200Vdc he could do a quick start, but later he had to shift because of backEMF and FW. He uses Leaf motor gen1 with Volt inverter and Lebowski brain. So i can say out of experience that motor will work.

EDIT: I think Leaf motor is your best bet for economical conversion. You could take Lexus GS450 rwd transmission, but that would be even more costly.

[Ev8]

I have temporary resurrected the dc motor, after cleaning the commutator with a couple of blocks I made that slot in in place of the brushes with 800grit paper on the ends, turns out it was mostly carbon and not much damage. Resurfaced the brushes and repaired the brush retainers with new springs, also found and replaced a crimp on one of the wires feeding the brushes that had burnt off!

I’ve re run in the brushes and added about 10 degrees of advance, also adjusted software to be much more conservative, read less fun, but it’ll keep the car on the road while I work on my next motor arrangement

[arber333]

I have temporary resurrected the dc motor, after cleaning the commutator with a couple of blocks I made that slot in in place of the brushes with 800grit paper on the ends, turns out it was mostly carbon and not much damage. Resurfaced the brushes and repaired the brush retainers with new springs, also found and replaced a crimp on one of the wires feeding the brushes that had burnt off!

I’ve re run in the brushes and added about 10 degrees of advance, also adjusted software to be much more conservative, read less fun, but it’ll keep the car on the road while I work on my next motor arrangement

There you go! Try that with siezed up petrol engine... did i mention i drove on 2 phases at one time?

[Ev8]

Thanks for the support, looking forward to going 3 phases!

[MattsAwesomeStuff]

You're disappointed at a 266hp acceleration burning things out?

It's a touch aggressive.

I'm surprised it was the motor that got grouchy and not the Prius Gen 2 inverter. 1000 amps? Jebus.

You're definitely pushing everything to the bleeding edge.

If you really need faster acceleration you could gear down a bit, you had voltage to spare.

I dunno, I get that you're a bit disappointed in the car not doing everything, but from where most of the rest of us stand I think we're all really impressed with your build.

[Ev8]

Cheers guys, the motor actually only threw its toys out after I’d already turned things down to 800a.

Yes it’s a touch aggressive but that comes from my days of engine tuning, build, break, build better.

I’m probably more disappointed at my lack of self control, I could have run things at a lot lower levels and not melted things, but I didn’t, anyway it’s on the road again and in a more sensible state of tune, I shall try to keep it that way!

[esoneson]

Looking for schematics of your dc controller board so I can build my own. Got the code, looks good. Just need to build a board to control the Prius Gen 2 inverter. Schematic and BOM needed.
Thanks for your help.
Eric

[Ev8]

Hi Eric will try and finish the schematic some time, am very busy with work at the moment, but you could probably backwards engineer the schematic from the code as the inputs and outputs are pretty well noted you’d just need to know the resistor values for the various voltage dividers. Will at least look them up and put them up, also I recently switched the pwm frequency up to 6khz as it’s slightly easier on the ear,

[Ev8]

will need to double check but from memory:

all digital inputs are no inverted opto isolated using pc817 with 1k on the input 10k pulldown on the output,
voltage dividers for GIVA, GIWA, MIVA, MIWA current sensors have a diode inline on the input so we only see + voltage and with 20k inline and 10k to gnd
voltage divider for GFIV nd MFIV fail also 20kinline 10k to gnd,
voltage dividers for MIVT and HV 18k inline 33k to gnd
throttle input i used 2 diodes inline to adjust my throttle output of 1-4volts to suit a 0.3.3v input but you could also use a suitable voltage divider like 18k,33kgnd to scale a 5v throttle to 3.3v

[Ev8]

Eric I have put the latest code on my github (tuned down to not melt motors) also the HMI for the nextion display
https://github.com/EV8-Steve/Prius-GEN2 ... controller

[esoneson]

Thank you for the hardware info. I'm a software guy so it will take me a while to understand what you posted. Will dig in and see how far I can get. Much appreciate you posting this info. Do you have any pictures of your board?
Eric

[Ev8]

Next time I open things I’ll get pictures for you, hey I’m not a hardware or a software guy, just a mechanic/fabricator who knows enough to be dangerous, keep on at it Eric

[Alibro]

Looking great, well done.

[Ev8]

Thanks

[esoneson]

will need to double check but from memory:

all digital inputs are no inverted opto isolated using pc817 with 1k on the input 10k pulldown on the output,
voltage dividers for GIVA, GIWA, MIVA, MIWA current sensors have a diode inline on the input so we only see + voltage and with 20k inline and 10k to gnd
voltage divider for GFIV nd MFIV fail also 20kinline 10k to gnd,
voltage dividers for MIVT and HV 18k inline 33k to gnd
throttle input i used 2 diodes inline to adjust my throttle output of 1-4volts to suit a 0.3.3v input but you could also use a suitable voltage divider like 18k,33kgnd to scale a 5v throttle to 3.3v

I have removed the booster modules from my inverter.
I bolted the MG1 and MG2 output buses together.
I now have my Teensy3.2, plus 3 4-channel pc817 modules
I have a large assortment of resistors
I have an assortment of diodes
I have several small pcb's.

I would like to start building the circuits to control the Prius Gen2 inverter.
I need clarification on the input side circuits for the Teensy3.2 to make sure I am going in the right direction. Any EEs out there?


Instructions from Ev8 with questions from esoneson:

1. all digital inputs are no inverted opto isolated using pc817 with 1k on the input 10k pulldown on the output

There are 13 inputs defined in the code, do all of these follow this rule?
Also the 1k on input is in line, corect?

2. voltage dividers for GIVA, GIWA, MIVA, MIWA current sensors have a diode inline on the input so we only see + voltage and with 20k inline and 10k to gnd

Should the diode be just prior to the 1k input resistor or after or doesn't matter?
What value diode, I have 1 amp 50v, 100v, 200v plus schottky diodes 20v 30v 40v?

3. voltage divider for GFIV nd MFIV fail also 20k inline 10k to gnd,

Voltage divider should be after 1k input resistor?

4. voltage dividers for MIVT and HV 18k inline 33k to gnd

Same question here.

5. throttle input i used 2 diodes inline to adjust my throttle output of 1-4volts to suit a 0.3.3v input but you could also use a suitable voltage divider like 18k,33kgnd to scale a 5v throttle to 3.3v

I will use a voltage divider after the 1K input resister, right?


Thanks to anyone who can hold me hand with this assembly.

[Ev8]

The 1k is inline on the digital inputs only (those that see a +12v signal from brake etc) it is there to limit current to the input of the pc817

All other inputs are analog inputs and use the voltage divider values as listed before, in the case of the current sensors yes the diode goes ahead of the inline resistor, any diode it suitable really i had some 1n4001 so used them