Quick rundown on the E-Polo
 

Well, since it has come up in a few posts, and people have been asking, I thought it appropriate to make a separate thread for it...

Basically, it started with a 2001 Volkswagen Polo that i purchased on the cheap for a winter ride, when icy roads prevent two wheel riding... It was in good nick, but bargain basement purchase, since we already have a near new estate car for the family, and I just needed it for the winter...

Then, as temps was nearing riding weather, it decided to blow a head gasket and chew up the internals of the engine in a single moment of smoke... And not having the need for it at the moment, I just parked it and forgot about it, once it was towed home... So, with this winter looming, I decided it might be worth fixing it, and started looking... Turns out the parts needed was about the same as a donor engine, and that still cost more than twice what I paid for the car in the first place... So, back to square one...

Until a mate and me had imbibed a few bottles of thinking juice, and had a creative moment... Said and done, we ripped everything out, and still hungover the next morning we hooked up an old DC electric motor from a forklift and whatever 12V lead lumps we could scrounge from friends and family... So by the time the hangover and the weekend ended, we had actually built a very DIY electric car, in just two days... It had huge vibration issues, and a top speed of a fast snail, but it actually worked... (No, I'm not joking or exaggerating, we actually did that! Thinking juice is bad for you kids!)

But fully sober, and not hungover, we started to actually think it through, crunch a few numbers, and eventually decided that we actually could do this for real... And, that it would cost about the same as the donor engine, or perhaps even less than that... And would work just fine for what I needed the car to do...

So, we pulled the trigger and purchased a few parts brand new, and made the rest of it from scratch... It helps having a more or less full workshop at the house, so you can go spend an hour or two when you have the time, milling or welding whatever...

More posts later, now I have to go work... ;)

This is going to be good

Next step after throwing out the forklift motor, was to purchase a WarP 9" DC motor instead. It's direct drive, ie we threw out the clutch assembly on the Polo, and coupled the motors output shaft directly through a semisolid mount to the gearbox input shaft. The result is that you cannot switch gears unless at standstill, but with an electric drive, this isn't an issue at all (well, more on that later)...

For proof of concept, we went with 12V lead lumps, normally used for boats and motor homes, (tolerates deep cycling whereas normal starting batteries does not) 12 in a string gives 144V to run the motor and controller, (the motor supports up to 170V) and that gives a lot less losses than lower voltage, and a lot better oomph... We started with a purchased motor controller, low budget, but that mostly pissed the both of us off, so in the end, I just built one myself... (I'm an EE, so it's not something I recommend to the average Joe) I get better efficiency than most claimed specs, on all controller in the price range that's within my reach, and so far my very overbuilt PCB has performed flawlessly...

To keep weight within reason, and also distributed correctly, the car has a battery box under the rear seat and boot, where the spare wheel and fuel tank was before, and a rack in front/over the motor, where the radiator was originally... A standard 144V capable charger is installed in the boot, connected to the plug located in the fuel filler cap, for easy use... Total weight as the car sits, is about the same as with a full tank before, (actually as of now a bit less) with roughly the same weight distribution, so the car handles like expected from an early nineties city car with front wheel drive, ie decent enough unless you push it too far, trying to have fun...

As for little issues needed to be fixed, the vacuum system for the power steering and power brake was the first issue, as it runs of a pump on the main belt... That was solved with a simple 12V pump, a pressure switch and a reservoir tank... When it needs too, it re-pressurizes the system, using very little energy, so more efficient than the standard design really...

What great enginering Tweety. The coupler you built is to help mate the electric motor to the cars gear box. Was this a five speed originally ? In which gear did you end up gearing it in, since you can only change gears at a stand still ?

Jack, we'll get there... ;) Patience... ;)

Here is the new vacuum system...

Rear battery frame under the boot/rear seat... Front where the radiator used to be...

So at this point we have the basics in place... DC motor hooked directly to the five speed gearbox, a bunch of batteries with a charger in place, and since we started with a very basic motor controller in a sort of "kit" we got a decent enough throttle or potentiometer assembly really, to feed a signal into the controller...

But, being the asswards stubborn mule I am, I first re-bult the controller when it fried a second time, and it cost too much to ship it for an exchange, and then built my own... During that time, the car ran in a semi-legal state as it was taxed and MOT'd (or our equivalent) in gas configuration, and nobody really could tell the difference...

But, the main goal was always to register it as an electric... And once the motor controller actually worked like I wanted it too, it was time to plan for that... Since getting it through the bureaucratic jungle, meant that I had to either disable all the meters that didn't do anything useful, so no fault lights existed, and add the needed ones back again, but again... Me = Stubborn...

The second option was to hook up a micro-controller to the various signals into the existing ECU which partly still lives on, and instrumentation, and feed it the signals it wanted, but with values that makes sense... So, now the engine temp readout actually tells the engine temperature, but in the DC motor, not in a combustion engine... The fuel gauge actually gives a decent approximation of the state of charge on the battery bank, good enough for normal usage at the very least... And so on...

Basically, all existing instrumentation works, and the car has a 12V battery for powering that stuff, as well as the factory radio, which is in turn charged off a DC to DC converter taking power from the main battery bank... Even hooking up a diagnostics tool to the OBDII port gives you no fault codes, but not much useful info, unless you have my own software... Hehe.... Serves the inspectors right... :rolleyes:

Other than that, the interior of the car is bone stock, or was up until this point, with the exception of a normal emergency stop button for electric equipment on the dash to kill the battery in case needed... For the test period, I ran the car with the stick-shift in place, just like normal, only with the mental note not to touch it unless stationary... But having caught myself just in time more than once, I figured it was darned stupid, and that the first time someone else drove the car, they'd likely grenade the gearbox in the first intersection... So, the stick had to go... In it's place is now an electric switch knob for selecting the equivalent to "D" or reverse... In theory you can go full tilt in reverse, but the controller limits the speed to a normal reversing pace, and makes the throttle a bit more sluggish in software, so it works just fine...

After tweaking the motor controller and throttle to my liking, and a few revisions on the controller to get the efficiency up, I settled for third gear in city driving, the car is quick nipping in and out of traffic like nothing, out pacing most sports cars off the line, but tops out at about 100 kph or ~62 mph... 2'nd gear turns it into a dragster off the line, and it will without breaking a sweat turn the front tires into a ball of melting rubber, as it goes 0 to 70 kph/40 mph in nothing flat in a cloud of smoke... First gear is all but useless as the top speed is too low, and the tires will last about ten minutes, even if i turn the controller down as far as I can...

Fifth gear is about equally useless, since the car wont get off the line, being outpaced by grandma with a walker... But, fourth gear is very useful for driving outside the city, the car is decidedly sluggish from a standstill, but has a useful top speed of 145/90, with decent driving performance down to about 40/25... In the test phase I just shifted manually at the last stop sign going out of town, but with the stick-shift gone, I added a solenoid and a shift gate in the engine bay, hooked to a bit of electronics which makes it only activate if the motor is stationary with no throttle input... Makes it impossible to wreck anything, even for a unknowing driver...

So, you'll be running the pump to operate the tranny. Can't wait to see the end result of this project. Give Tesla a run for their money....


Nice work on the battery boxes.

No "tranny"... I'm in the EU remember... Stick-shift... ;)

So, the last little niggle that is till sort of in the process of being fixed or at least tested, is the heating...

With no engine, no heat is produced, or at least very little... The batteries have insulation and a small heating system in the boxes, allowing me to "pre-heat" or atleast keep them toasty for charging, running off 230V from the house or run it off the 12V system for very cold driving conditions, when too cold temps otherwise would make the battery performance on lead lumps take a huge nose-dive, part way through the drive...

But, that doesn't take care of demisting the windscreen, or remove the need for double pair of undies in the winter... So, an big ass electric heater core was sourced, and shoehorned into the motor compartment, to provide heating... It'a trade off of mileage vs freezing my nuts off, but so far it's working... As I can also run this on both 230 VAC and 144 VDC, if the car is plugged into the charger over night, I have a toasty car to work in the morning without trading off mileage... (And yeah, I'm just geeky enough to make a micro controller board for making that an automatic feature... :lol:)

So, once I had jumped the bureaucratic hoops for a while, and gotten the car legally plated and insured, it's now my normal driver...

Something that actually, no joke, involved a 5$ chromed exhaust tube tip and a self tapping screw to the rear bumper since the darned inspector needed a space to put the CO2/NOX and noise meter for the test... The fact that I mentioned that he could just as well put it up his own tailpipe didn't go down well, as I got a bit frustrated with his by the numbers, square box thinking...

As for performance, well, in city driving, it's just as nippy or more than it ever was bone stock, and on a half dozen used, and mostly discarded but identical utility batteries (I got two dozens from a motor home dealer that was discarded, for next to nothing and took the best of the bunch and have a few spares), which on paper has 180 Ah each, but in reality might get me half that on a good day, I need to charge the car two times a week, with a 40 mile round trip to work every day... I can get by on once a week, but then I run the batteries down more than my own comfort zone for margins, so for now I'm being prudent...

The biggest reason for that is that my controller includes regenerative braking... It's sort of an experiment as of yet, but works decent, and I get back about half the energy needed to accelerate the car the same amount, a bit more in really slow speeds, so in the city, I'm either sitting still, or making a half decent bid on perpetual motion... ;)

Taking the car on the freeway, or highway, I pretty much get awful mileage, but still good enough for a second car... I get to my parents and back on a fresh charge, just barely, and that's about a 130 miles round trip... That's doing the legal 110/68, or just above, following the normal flow of traffic... And with the car not being a long distance hauler in the first place but an econobox, that's pretty decent...

Charging from where I cut the controller off, which is about 20% SOC, to full takes a bit over 5 hours on 230, so like I said, for normal usage charging twice a week overnight works just fine... And If I'm in a pinch somewhere, having a decent roll of extension cord in the boot, and giving people a tour of the car as it charges a few percents of their outlet, has worked brilliantly so far... :lol: And, all malls and such around here has at least one parking spot with a charging outlet, so I can always pay the parking, buy a cup of coffee, and just kill the time... :)

Amazing Tweety. Great enginering work. Now, go to your Gov office, and have it patent.


Have you thought of heated seats ? Perhaps this can save you a little energy consumption when the weather outside is dry, but cool. Allows you to keep warm, without running the heater core.


Great work once again.

man i love this thread just enough geek for me

Heated seats is standard equipment on the Polo, and they are used when needed... Unfortunately they need about as much power as the heater, since they run of the 12v battery being stock equipment, so I'm wasting energy going from 144 to 12, and then again in a rather inefficient design altogether... But it's nice for the butt and back, so most mornings it's worth it... And, again... They don't defrost or remove the mist on my windscreen...

So the best option is if I can work out a heater core that is more efficient for my particular need... Big enough, but not too big, and capable of working on 230 VAC and 144 VDC... So, still looking, but eventually I'll work something out...

can't you just run the seats of a single cell???

Splitting out a single cell from the chain like that makes the whole string of batteries be discharged unevenly, which reduces mileage in itself, since I then cant run the car until all batteries are close to flat, without running one down to the point where it becomes damaged by it...

Even worse, with large cells like this, is that when sitting, the string of cells start to self balance, ie the discharged cell "feeds" of the others until the string is in balance again, at worst even drawing current backwards through the other cells if needed...

And that process wastes even more than the converter does, so the net result is that the least inefficient way to do this, is to just find a more efficient converter, and leave the rest as it is... Or, just build one from scratch, which I might do when I get the time...

The downside right now, is that I'm just weeks from being a father, (early January) so time seems to be something I haven't got at the moment...

Congratulations on the upcoming bit of your child mate its going to be a great time in your life enjoy every moment of it

Ahhhh Tweey congrats on becoming a father!! Haha, my boy is now 9 months so believe when I tell you that you have zillions of hours MORE time NOW than after the tike comes into the outside world!

Not sure if you have built in babysitters (family) but I dont and man you barely have time to put gas in the bike between feedings, diapers and all night crying sessions.

Many prayers for a healthy child and for you in this endeavor. It is a real journey. (and I know I aint seen nothin yet)