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Suzuki Cappuccino Conversion

40210 Views 96 Replies 11 Participants Last post by  tylerwatts
Hi all.

I’ve been lurking on these forums for quite a while but I have finally begun a conversion.

The donor is a 1994 Suzuki Cappuccino. For those who don’t know it’s a tiny Japanese kei sports car weighing around 725kg stock. It comes with a 660cc 3 cylinder twin cam turbo engine as standard in front engine RWD layout. Great fun to drive even with its 64hp power output.

I have begun work on the car to get it ready for the conversion. They all have a problem with rusty floors and although mine is a good example it needs some welding before I can go any further.

I have one of the Enova 90kW AC induction motors which I have been able to get turning on the bench using Damien’s combi control PCB controlling the original Enova power electronics. The plan is to connect the motor directly to the prop-shaft for direct drive (diff ratio is 5.125:1). I believe this should give me pretty good performance considering the motor has around twice the power of the stock ICE.

Recently, I obtained some Boston Power Swing 4400 batteries. They have been used but seem to be in pretty good condition. I have around 20kWh in total but I’m unsure whether I will be able to fit them all in! I will be using the car for my commute which is 19 miles each way. I can charge at work but would like to be able to get there and back comfortably on one charge so I’m aiming for a 50 mile range.

The biggest unknowns at the moment are the charger and BMS options. I need to do some research on this as this is the area I know the least about and seems to be the biggest minefield!

I’ll try to keep you updated with progress and I’m sure I will have plenty of questions!

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Hi Tom. thanks for the link from the Enova 12v discussion we are having. You certainly have/had your hands full with the rust bug. Invest in a TIG welder, you can control the weld a bit better in my humble opinion for thin sheet.
Looks so much easier with front motor and rear wheel drive, my transverse rear drive set up in the Smart has been a challenge so yours should be done a lot quicker.
You could trim the Enova heatsink quite a lot if necessary. Attached pic of initial cut down plate. It did have one of the attached pipe fittings (I broke off later to use plate as a welding heatsink) the cut section of the cooling channel I was going to make a stub to fit a new connection. Makes the whole heatsink half the size :) Let me know if thats an option for you. Plenty of machining time spare and welder at the ready. Speak soon. Peter P.S. Dont forget the splines on the motor, I used a cheap clutch plate from Ebay which fit nicely. Alternatively if you strip the gearbox the primary gear will fit (obviously) but you will have to machine it down and its been hardened so that may prove a grinding job if not careful. I will ask my buddy to see if he can machine it on the lathe.


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Hi Tom. Sorry for the confusion, I am having two conversations at once and got mixed up thinking we were talking about the Enova 12v converter. Engage brain this time :) Peter
Hi Tom. A step closer with motor in temporary position, all fits nicely. Dont forget your cooling pipes, I had to buy some elbows to allow pipes to fit on my install, elbows in stainless of course :) You struggled a bit with TIG, so did I at first, especially as mine has HF start which is a wake up call if I forget to attach the earth/ground lead. Not managed to zap myself yet but give it time. Let me know how you get on with turning the gear, my colleague is a toolmaker by trade and has all the equipment and turning tips if you are struggling, fingers crossed. All the best. Peter
Hi Tom. Would you like me to try machining the primary gear ? If so send me a drawing of what the final splined unit is to be and I will let you know the progress. If all goes well we can swap gears so I have an original :) Thanks for the link to the BMS too, I am investigating and my credit card is twitching ! Peter
Hi Tom. I am also working on my inverter parameters at present. What I expect to happen doesnt seem to be however. One thing I will say is be careful with Boost, dont set that too high or the instant torque will be detrimental to whatever else the motor is driving. I have asked Damien Maguire if he will give me some insight into fslipmin, I asked that because the Enova motor states two frequencies on the name plate... 121Hz & 305Hz. If we use Johannes equation for the 121Hz we get a negative value for fslipmin... that cant be right, but I need a definitive answer to be sure. The equation works for the 305Hz and gives a positive value but I am not sure if thats the one we should use ? I do have the motor rotating with gearbox connected and one wheel jacked up but its definitely not right yet. Maybe we could collaborate on settings and see if we can get a good result. Peter
P.S. For those who know Damien in one way or another... he is in hospital at the moment, lets wish him luck and a speedy recovery.
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Hi Tom. Thanks for the parameter lists. Somehow I think my micro or pcb may have a bug ! No matter what I do with the parameters the motor jumps around like mad, some settings its not too bad others it tries to rip itself apart. Also it doesnt save the last set of parameters properly. Next power up it has saved some of them and reverted to ones from a session before ! I am using a wifi link which could be the issue as its a bit hit and miss somtimes and I have to keep refreshing the link as well as the page. Are you talking to your system direct via USB ? If its anything other than wifif please would you tell me how you are doing parameter changes please, thanks. Frustration has gripped me big time today !! All the best. Peter
P.S. Its thrown so many ERROR signals which shut down the main Kilovac style contactor each time that the contactor is now knackered, wave goodbye to £130.
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Hi Tom. Some news.... more by luck than judgement I increased fslipmin to 5 and fslipmax to 10 (default parameters say 1 and 3) hey presto the motor now responds in a much more controlled manner. I have had the wheels spinning (car jacked up) and so far its looking ok but max RPM is not being acheived as yet, need to play again tomorrow. However a new issue has appeared... if I plug in my encoder the inverter just sits there doing nothing !! Checked 5v, thats not being pulled down and the encoder channel is switching between 0.2v and 2.2v so that seems ok (ish). Need to check if encoder channel gives a higher voltage when not connected to inverter next. Contactor has definitely stopped working, its popped a control fuse so maybe the wiring/coil has had an issue, about half a days work to take battery box out and get to the contactor itself... another reason I shouldnt have done a Smart car as the box is under the car floor. Now why wasnt there a Suzuki Jimny or Pinin Junior when I was prowling around Ebay at the time :-(
As to your dilemma, thinking about that, will check schematic. What does the direction switch look like physically, is it new, check its resistance and try it with a couple of leds to see if it is working 100%. Separate the direction wires to fwd and rev, check the resistance to gnd on each wire with control power switched off. Are the wires pulled down to gnd with a resistor? If not try adding a 1K resistor to each wire so its definitely pulled down to gnd, that makes sure it is either high or low when its meant to be. Let me know what you find. Good luck. Peter
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Hi Tom. Forget Hayabusas, two Enovas would be better :) Been a while since I have been on the forum too. Update from me being my inverter/motor parameter issues were down to my encoder signal. I had extended the cabling from the inverter via an interface box to my encoder wiring. The penalty for doing that being I induced a lot of noise onto the 5v bus supply to the encoder. Add to that I also made a stupid mistake in linking the motor frame to the gnd of the 5v supply. The encoder signal instead of being a square wave was just a mass of noise and spikes. Disconnect the cable to the motor frame and the signal is almost perfect. So, as things are looking better I decided to take the plunge and send off my covering letter and pictures of the build (on local garage headed notepaper, with their permission and approval of work done) to the DVLA in hope they will accept the change from ICE to EV this time. Previously I just sent in the reg docs with a simple 'change of fuel' but got a letter back saying they need proof. Fingers crossed I get an 'ok' this time. Keep in touch. Peter
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Hi Tom. Well here I am again, sadly no further on with my inverter !! Cant get it to spin up my motor without it shutting down. It spins up to about 500rpm then becomes as rough as anything finally tripping the inverter. I have been checking all sorts and trying various things to reduce the encoder/5v bus noise but the spikes are still there, frustration has kicked in big time now and have asked Damien Maguire to check my Combi board when he gets back in a few days from his Tesla venture. DVLA have not replied yet either, they do like me to keep worrying and my fingers have turned blue as I dare not un-cross them for fear of getting another 'NOT until' .... So, need to find out whats going on and why my inverter system/setup isnt working, so annoying as I am ready to test drive ! Keep in touch. Peter
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Hi Tom. I asked Damien for the new board but he is up to his neck in Tesla at the moment so waiting for his return, hopefully next week. In the meantime I am going to feed my encoder supply totally separate from the car 12v and run the signals back through an optocoupler into the Combi board to see if that helps, if I have any fingers left that are not crossed then they will be used ! As to DVLA.... Take as many pics as you can, engine out, fuel tank out... whatever to show empty engine bay firstly. Then show motor and associated control gear in various states of installation and finally what the installed engine bay looks like. I sent all the pics and a write up on my local garage headed notepaper (a good friend of mine who looks after my car) he supervised somewhat and participated in the work to a small degree, I returned the favour with elec help. He gave a lot of help with certain parts of it but left the grunting and sweating to me, typical :) The actual requirement options (if thats what they meant as to give all of them would be ridiculous) where...
1. Notification from vehicle manufacturer of modification (ask Mercedes to check it.. no chance).
2. Written report from RAC or AA, rang AA and didnt really get a final answer... "dunno if we can do that ?". To be fair I should have pursued that option harder which if I get another 'we need more proof' then thats my next option to try.
3. Written confirmation of change from a garage on their headed notepaper detailing the change, that was my best choice.
4. Hmm.. cant remember that one, will check and update you tomorrow but it was another long shot.
My garage friend told me however that a recently built ICE kit car had to be taken to a DVLA inspection garage for registration to prove its been done, not sure if for tax reasons or just to prove it exists, maybe I will have to do that too ?
As to your tripping problem, do you mean the main contactor drops out on an error? Mine did that so much initially trying to get the motor to run I ruined a Kilovac contactor, somehwat my fault as I had not fitted a bemf diode and had stupidly removed the economiser to site it in the control box instead but not connected it... doh!
Anyway fingers crossed for the postman tomorrow, I am now panicking when the letter box rattles in case its a NO from DVLA, not the end of the world but still a pain. I did a caclualtion the other day too.. How much have I spent so far £6000 ish, thats £500 more than a low mileage Renault Zoe and absolutely zero hassle, makes you wonder why I guess. Never mind, its been fun :) All the best. Peter
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Hi Tom. Been looking at Eric Tischers website where he uses an industry standard control board from a branded inverter drive coupled to his own power stage, sounds VERY interesting indeed. As an option to see if that would work with the car as a test unit for control I can see the benefits of having something already tried. I am only looking at this idea to gain back some incentive with my build, if I can just drive around the car park once it will lift my spirits :) The first pitfall however is my pack voltage 230v! The 1ph to 3ph inverters use 220vAC rectified up to 310vDC ish. Need to see if lower input voltage units are available or can be fooled to see my pack volts and work ok. I do have another 50v DC pack if I need to increase that but still only 280v DC. Thats tonights challenge, what minimum inverter input voltages are available ? Speak soon. Peter
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Hi Tom. Check my new post subject... DVLA registration :)
Hi Tom. Good to see you are progressing, a good feeling when each part is completed. Keep your head down with the work and you should be ready for Spring. Did you read my write up 'DVLA change to electrickery' :) What a relief to get that sorted, the rest is engineering thankfully before MOT. Inverter is still on the bench sadly, it developed a new fault which after investigation turned out to be a duff LEM HTFS400-P current sensor, output 2.5v was ok out of circuit but as soon as it saw 10K resistance to gnd the output fell to 0.2v ish ! New one purchased £16 so not the end of the world. So reassemble and see what happens, if still no joy then all will be shipped back to Damien Maguire for him to test. Have also been looking at Damiens videos on branded inverters, Leaf, Prius, etc. If Damien can hack one of those and if it can handle 90Kw then that could be my choice to run my next car challenge. All the best and keep in touch. Peter
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Hi Tom. Have asked Damien to supply a new STM microprocessor board with latest software, its the only thing I cannot check, the rest of the board checks out ok. Not sure if it will make a difference but I wont to be able to eliminate any unknowns... if that makes sense ! Encoder is the next thing to test as that didnt want to play, but again I cannot be 100% that the encoder is my problem. Will be bench testing that this weekend. Dont frorget to find your friendly neighborhood garage before Xmas and ply him/her with many alcoholic beverages over the next few months for the write up needed in Spring :) All the best. Peter
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