[etlaare]

My first ev-conversion

Skills: semi-professional car mechanics, welder, metalworker, system engineer, programmer, ICT-architect
Required range: 10 KM/charge
Perf: 40-50 KM/hr
Budget: 1000 Euro's
Hoping to get it street legal which is supposed to be easier for conversions of cars registered before 1998 as the official institute in my country (The Netherlands, Europe) assured me.

Donors:
-Renault Twingo 1994 obtained as a real bargain for 250 euro (tip-top shape apart from a defective crankshaft bearing). It's a small car but will only need to be used as a 2 seater with the batteries covered in the extended back having the seats removed).
-Hyster Forklift 48V motor with fuse, emergency switch, controller (but considering the gate driver part of Paul and Sabrina's Open Source controller with my own microcontroller, 68HC11 based (as I built most of my robots with them and it has programmable pwm pins as well)) although seriously considering an Altrax controller as well (laziness).
-Got me some second hand agm batteries already which for the initial requirements might still be sufficient (I heard the other day that the company that I work for seems to start a new development on Lithium air batteries but I doubt I will ever get my hands on any of those :-)
http://www.technologyreview.com/energy/22780/ ).
-Collecting transformers for a custom charging managent system (but maybe my laziness wins as well there causing some strain on the budget which my wife guards so thoroughly).

remaining challenges:
-an affordable vacuum system for the power brake assist (you knew that one was coming I guess)
- machining down the existing hubs from the clutch and the drumbreak from the Hyster and adapting them to the lovely joints (still keeping an eye open for those).

no power steering required with the old model I got.

Bought the car a week ago, fuel tank, exhaust and engine are gone by now, cleaning and small exterior repairs on the way, I got myself a service manual for the car today as well.

ok question:

If the motor indicates 48V is that for a parallel setup ? And if I serially connect the field and armature coils, does that mean I can run it on 96V ?

I read about the robustness of the forklift motors and tend to go for 6x12V and indeed serial anyway but just curious.

thank you all for creating such a wonderful and resourceful forum.







ok I need some cleaning on the motor too....

[etlaare]

Not sure if this is the right place to keep you all involved about the progress.
So please stop me if it's annoying I share my little victories with you all.

But what better thing to do on a bright Saturday than to remove a defective gasoline engine ?
The Twingo turns out to be such a nice and easy car to work on. As an example, all the engine electronics were totally separated from the other mechanical electrics and lights. They even had separated 12V leads coming to the battery. Meaning: Everything is still functional while all wires that had to do with the engine have been removed in one large bundle even without cutting anything. The only thing I have to reconnect now are the wires for the speedometer that plugs into the gearbox (it's digital so I do cross my fingers for a couple of weeks ). But everything else just works as it should. I even managed to repair the windshield blower on the go. The digital display shows an empty fuel tank now. And while admiring that I suddenly started tinkering a bit on how to turn that into a battery status indicator. I might need your help with that, but it's one of the lowest priorities on my list at the moment.

So fuel tank and exhaust are removed as well and there is just some deep space waiting for the combined motor, gearbox and transmission to be lowered into.

It seems I only need to adapt one engine mount as the other 2 are connected to the gearbox, unless some of you would recommend an extra mount somewhere. I read some posts about replacing or even removing the rubber mounts. But what would be the drawback to leave them where they are ?

Activity will be moved to my little workshop now as I have the gearbox available ready do be measured for the connection plate that has to be constructed.

Are there any hints on best/proven ways to lineup the motor and the gearbox ?

Please fire any comments or questions, In this phase I am still flexible enough I think/hope.

Regards,
Ed

[Woodsmith]

That's a cute little car you're converting there.

The motor looks plenty big enough. I don't know enough about them to say what you can put through it though. Have you thought about the adaptor to the gearbox yet? Clutch or clutchless?
The fuel gauge may not be much use as a battery monitor as you would want to have more information then it would show.

There are a few options on the vacuum pump for the brakes. You could buy one from an EV parts website or you can find an electric vacuum pump from another car. I got one from a Saab 9000 but I have decided to use the aircon compressor as a vacuum pump as it is there and I can use the electric clutch to control it. Another option is to use an alternator with a built in vacuum pump and that will give you the 12v to charge the accessories battery as well. It isn't as efficient as a dc/dc converter though.
There is one chap here, Simon Rafferty, who has made, his own vacuum pump using a reciprocating piston in a small cylinder driven by a windscreen wiper motor. Makes a sound like a steam engine apparently.

I would opt for keeping the engine mounts from the chassis to the rubber as conventional as possible so that they are able to absorb the torque movement of the transmission as much as possible. Just change the engine side of the mount to fit the motor.

I made my adaptor mesurements by setting an x and y axis through the end of the primary shaft and through a convenent bolt hole and then measure off the co-ordinates of each hole. I was then avised that it would be easier to place a large sheet of paper over the bell housing and then, with a greasy finger, rub over each bolt hole ad the casting to leave a dirty outline of the bell housing and the holes. That made it easier to measure the co-ordinates. Getting the centre of the primary shaft can be a litlte more difficult as some shafts have some play in them. I found with my belhousing that there was a circular outline of the bell housing inside edge was concentric about the shaft so I just spent some time with a centre finder on the paper to locate it.

[etlaare]

Thank you Woodsmith, those are already great hints.

And yes, I decided to go clutchless, mainly because of the size of the motor and it seems a little easier to implement.

I'll drop the fuel gauge battery monitor idea. Maybe I program the dots as a night rider like walking led's series instead.

I was collecting car brands at a multi-brands dealer this morning that have electric vacuum pumps. Some Japanese and Korean brands seem to have them as well, but your Saab 9000 sounds as a great tip. We might have some more Saabs on the scrap yards where I live.
I was experimenting a little with changing the little valves of an emergency electric tire pump. My wife drives a company car that runs on Liquid Petrol with the tank placed where the spare wheel used to be. Once she had a flat tire and used the emergency repair, She got a complete new set. But indeed, such piston solutions make a lot of noise..
The ev-parts versions I have found so far seems above budget for me though.. ah well, there's plenty of other things to do first while still looking around. Or would you maybe be willing to sell your Saab 9000 version ?

When you wrote clutch and vacuum pump in one sentence I had a flashing brainwave of operating a pump on muscle power by connecting it to the clutch pedal to keep the pressure down with your own foot while driving and using an audible alarm when the pressure drops too high (could not resist mentioning it .. but nah, lets not even try that)

I am very happy with your mounts answer as I had no real clue how to convert them into a more firm mount anyway.

And the adapter measurements surely looks as a way to go.
It will be one of the first things to look into from where I am now.

Many thanks

And wow... that MR2 looks so awesome

[Woodsmith]

The Saab pump I have is noisy, here is a video of it.


The AC compressor is a lot quieter.
You can see the develpment of it on my build thread from post 182.

I'm sure there are lots of cars now using an electric vacuum pump just as there are lots with electric power steering. However, some are only able to produce a low level of vacuum. The Americans seem to recommend around 20-25 inches of mercury as a suitable vacuum, I found that my brake pedal felt fine with 11"hg but that was static without the car moving. It would be worth checking how it feels.

One of the downsides of converting a pressure pump for a vacuum is that many are not able to pull sufficient vacuum. They are designed to push a fairly dense gas through a valve but they can't pull a decreasing density of gas through a valve and then push it out another. That is one reason why commercial and industrial vacuum pumps are so much more expensive then pressure pumps.

[etlaare]

took the clutch disc apart today and machined a ring that can connect the spline part of the disc brake that came with the motor to the flywheel (yes, connecting two splines here).

I also found a cheap IGBT on e-bay, seems I will make myself a controller with that now. Using some of the 68HC11 boards I still have available for the pwm and safety checks (hall effect sensor, temperature, pre-charge sequence, break/throttle pedal check at startup).

Does any of you have experience with IGBT blocks (got one for 1/10th of the regular price, I simply couldn't resist) ?

It seems capabable of handling a 16KHz wpm frequency easilly, 500A 1500V (eeeeeeps !!) I hope saturation will not be too much, there always seems a voltage loss with them.

hmm.. maybe I should have posted that in the controller section...

[jackbauer]

Take a read through my build thread when you have the time:
http://www.diyelectriccar.com/forums...rks-35098.html

I'm using a brake vacuum pump that i got cheaply from the US ebay. I'm also using the open source controller main pcb driving an igbt power stage. One of the best tips I got on here was to drop the pwm frequency to 8khz. this solves a lot of problems and was easy to accomplish by use of an 8mhz crystal on the micro.

[etlaare]

wow

many very interesting topics in your thread, thanks.
Can you hear the pwm at 8KHz ??
I would figure the frequency would depends on how fast the IGBT can switch, there seem to be many differences with different models there.

Maybe I browsed your thread too quickly, but is there a drawing on how you connected the IGBT or is that on one of the video's ?

I never knew there were pneumatic shrinkers, I want one :-) !!

thank you for the link

[jackbauer]

The 8khz is only barely audible at low currents and speeds. Inaudible as current increases. Remember switching speed is not switching frequency The hydraulic crimper cost about 50 euros on ebay and has worked great.

[etlaare]

Originally Posted by jackbauer

The 8khz is only barely audible at low currents and speeds. Inaudible as current increases. Remember switching speed is not switching frequency

Ahhh yes, true off course. That will help a lot. Also to reduce the skin effect since I just learned that at 16KHz that turned out to be a significant factor as well.

I still didn't went through all of your thread yet, but did you make a drawing of the power part ? I always thought the Insulation of the IGBT's meant the optocouplers where in the IGBT's so I did not need to use a gate driver, but somehow it seems I still do. Are you using one ?

sorry for all the questions suddenly ...