ADAM SMITH COLLEGE >>>EV

[TOPGUN]

Thanks for all the links Night train. We will be getting back in touch regarding manual.

[Night Train]

A bundle of thanks for Night Train. I guess we will be needing your expertise in the near future. Thanks for all the useful information you put forward. There is a lot of food for thought. Our college is very helpful in supporting us. In fact this project is being completely funded by college. Our marketing department is also doing its bit. So in terms of support, we are not short of that.

That is great to have the college support the project. Need to be careful with the £8k budget and try to offset it against in house labour and expertise. You will want to save as much of that as possible for batteries.

I would suggest getting a good fork truck motor and then servicing and adapting it in the college to save money.
Fork Truck Service near Chesterfield has a huge stock of assorted motors all at £300. Maybe you can find a similar place nearer your college.

Also have a look at the Paul and Sabrina Open Revolt Controller. It is open source and well documented here on EcoModder. It would be a good controller at a lot less money, especially if you just bought the boards and then get the discrete components locally (or at least in the UK) and then manufacture the bus bars, heat sinks and case in house. It would be a good addition to the project to build and test the controller and maybe make some modifications (open source) to it as some users have done.

The decision is tilting for DC motor. The only problem I have heard with them is inability to climb and do long distance runs. Warp9 seems to be a popular DC choice. I am sure it will be able to climb as it seems powerful enough. Dont know if you can run the motor at very high rpm for 2 hours continuous.

The constraints on the motor are really down to designing the project right for your needs.
The Warp9 is popular. You could also consider the Kostov11. It is a more torquey motor then the Warp9 but also a little smaller in diameter then the Warp11 and so might fit.
The chaps in the States seem happy with a 9" motor run fast at higher voltage to cope with hills. Larger motors can't spin as fast. A Warp9 may run at 6-7000rpm or sometimes more. My 12" won't be risked at above 3600rpm.

The motor will be run over voltage to give it sufficient speed for the car, that makes it run hotter. To solve the heat issue you could:
Add forced ventillation in addition to the existing fan.
Raise the voltage to reduce current and so reduce I2R losses that cause the heat. This is one reason for looking for a fork truck motor at 72v or 80v rather then 48v.
Reduce the load by making the car as light as possible, fibre-glass wings, frunk lid, door skins, etc. and removing the spoiler and other unnecessary parts.

Also it is unlikely that the motor will be running at maximum power for two hours continuously. You batteries will be probably be dead long before that, maybe after half an hour at full motorway speed.

Even then, changing the driving style makes a big difference.

Pulse and glide:- driving by pulsing the pedal, when the car is moving at a good speed let it glide a while and then nudge the pedal again to bump the speed up a bit. It is very energy efficient and practiced by sparrows and EV drivers alike.
Sparrows and other small birds fly by flapping frantically very briefly and then folding their wings for a while before flapping frantically again.

Changing gears to keep to maximum rpm:- Series DC motors are different to an ICE. With an ICE you would want to keep the rpm low to run a cool and efficient engine. With series DC motors they run at their most efficient when they are at maximum rpm. This is because the back emf in the field coils prevent any more torque being developed and so very few amps are drawn. You maybe driving using only 2nd gear in urban runs and 3rd or 4th gear on the motorway. On hills you would select the gear that just provides enough torque to keep moving at the desired speed. You will then rest the motor on the down hills. Just don't over speed it on the over run or it will explode.

Useful links:
Agni motors: Efficient Axial flux motors.
NetGain motors: Suppliers of Warp motors.
Albright International: High voltage DC contactors.
Jim Husted: DC motor Guru.
Gav's EV videos: A series of YouTube videos documenting Gav converting his car to an EV.
MR2 mk1 conversion: A good read.
DIY Electric Car Forum: A very active and helpful international EV forum. Again, I am on there as Woodsmith.

[Peter Eggleston]

I have to express some concern at advice to use either milk float or fork lift motors for electric car conversions. I know a few people have built small cars with fork lift motors which just about get bye, but these motors are in no way the best option for an electric car. The main reason they tend to be used is because they are easily available and there is little else available that would be suitable in the UK.
The main reasons they are not suitable are that they tend to be rated at a maximum of 72 volts. Most people would want at least 120 volts. They can be overvolted to as much as 96 volts without any trouble but probably not any more.
The other reason is that they tend to be rated at much lower revs i.e. about 2000 compared to about 6000 for somthing like a Warp 9.
If you overvolt and over rev then they will blow apart.
They are ideal for slow vehicles like the fork lifts and milk floats for which they were disigned but are not an ideal compromise for a car.
When I built my truck 9 years ago I started off with a 72 volt milk float motor, mainly because the base for my truck was a milk float. I soon found that it was not ideal for the job. I searched the country for suitable alternatives but hit the same brick wall of nothing suitable in the UK, so I imported a 9" Warp motor from the USA. It was the first one in this country and the best thing I did.
I do not like to see people wasting their time on a poor compromise and ending up spending more money in the long run.
Peter

[Night Train]

I appreciate your concerns, Peter, 'real' EV motors would be ideal hence I suggested the Warp or Kostov and have linked to Agni for the axial flux motors.

But, depending on budget and available skills and access to machining processes, it might sometimes be simpler to have a vehicle that goes fairly well and can get to a reasonable road speed rather then a car that could have done great things if there was money left for the batteries.

My conversion overall, less batteries, needs to come in at less then the cost of a Warp9 motor or a good 'off the shelf' controller.
It is just another option though, aknowledged, a compromised one.

I do have to declare, I guess, that most of the help, advice and support I get comes from Americans (and a few Europeans) who have used fork truck motors sucessfully. Unfortunately I can't afford to follow the UK advice of using two, three or four Agni motors and controllers to be able to give any useful opinions in that direction other to suggest as a viable option to look into.

I suppose the other option that may be viable is to change the whole drive train. I believe there may be some Berlingo EV's being broken in the south east? Maybe a motor, gearbox and controller (the front half of a Berlingo, less body work) could be dropped straight in to the MR2 and then only the mounts and the drive shafts need to be made up.

I would love to see the students work on an affordable AC drive, developing the controller, writing software, testing motor performance, and then marketing their work if/when it proves sucessful.

Really, it would also depend on what the students want to get out of the project both in terms of performance and learning.
If it is to learn about how to make and EV then maybe low budget, low performance with lots of skilled learning input would be good. (This is where I am at, good old industrial revolution development stage, part blacksmith, part engineer. )
If it is to prove an EV can drive the length of the country then lease a mainstream EV and record the journey.

It could be open to anything in between so the balancing views are always good.

[GregsGarage]

The Warp9 motor will have no problems with the hilly terrain. I converted a Volvo 440 using a NetGain Impule 9 (a shorter version of the Warp 9, easier to fit into a transverse mounted engine bay), and the performance was very good. Acceleration like the original car, 60mph up hills, top speed over 80 mph. The car weighted 1400kg with 12x 100ah lead acid gel cells at 144 volts. You will probably find that for greatest range you will need to keep speeds around 30-40mph instead of 50-60mph. So either of these motors would suit your needs very well.

I used a curtis controller, but these are getting hard to find now. Have a look at this open source controller project; http://paulandsabrinasevstuff.com/
And the threads on the ecomodder forums; http://ecomodder.com/forum/open-revolt-open-source-dc-motor-controller.html
I have built one of these, the only testing I have done so far has been at 12 volts with the wheels off of the ground, but several are actually on the road and reports are good. The controller can output a data stream to let you see motor amps, battery amps, heatsink temp, etc. It also has many programmable features dealing with throttle response, battery amp current limit, motor amp hardware and software current limit, etc. RTD explorer is a program written to monitor and configure the controller.

Your project sounds very interesting. I would also recommend you do initial testing with some lead acid batteries and I might be able to help here. I have 17x 100ah cells from my Volvo project. They have been abused and I know that some have had it, but there should be enough good ones to do some testing on your vehicle. If you would like them for your college's project they are in Galashiels. I would be happy to donate them to the college, you just need to arrange collection. PM me if you are interested. I can also help you out with a new NetGain motor, not free but can arrange some discount for the college.

Greg

[TOPGUN]

Thank you Peter, Night Train and Greg. We got more information than we were expecting. I guess we will have to digest all these pearls before we get back to you.

Greg thank you for offering the batteries. I think we will get back to you in due course as many people including ones on this forum have advised us to test before we actually buy the battery pack.

Night Train your advise has been invaluable. We would like you to visit our college in the near future. I am trying to think the ways in which we can collaborate at college level. Perhaps when we are doing the tour we can arrange something there. We can also arrange for your car to be tested at the Knockhill race ciruit.

Peter we have certainly discounted Milk float and forklift motors. Initially we were extremely tempted to go for a forklift motor as we have a forklift repair garage just a 100 yards from our college. We are trying to keep the performance up by making lesser compromises (under limits off course).

Thank you all, I'll keep you posted

[Night Train]

It would be good to visit your college and see your project, at that point I may well be learning from you as your project will be moving ahead faster then mine.

I will be looking at getting the boards for the Paul and Sabrina controller to learn about how controllers work and how to test them. Up until now I had simply looked at them as 'magic black boxes'.

jackbauer on the DIY Electric Car site is in Ireland and he has been using and modifying the same controller with good effect.

[geekygrilli]

Hi Topgun

My only advice would be to trawl through nearluy every entry on evalbum.com. It was the most useful single source of information for me. Note the ranges of the people who have completed their cars, not their estimates, there seems to be a big difference!

OK, maybe that wasn't my only piece of advice; I have a few more...

I used a Forklift truck motor. Maybe you could contact a Forklift sale/repair centre. It appears that they just scrap whole machines including motors. Ask if you can remove a couple to experiment with. Maybe your marketing department will be able to help you out get the company some free advertising.

You have quite a nice budget. My total build came to about £2500, roughly broken down:

Car £150
Motor £50
Controller £700
Contactors £150
Charger £350
Batteries £450
Big Wiring £200
Little Wiring £100
Vac Pump £30
Other Stuff, erm, can't remeber, but you get the picture

I would look at using your 'extra' budget to invest in LiPos, if you can. But only get them when the rest of the car is ready; they just get in the way and will get damaged.

DC is a lot simpler than AC, in my opinion, unless you buy a complete system off-the-shelf, but thats very expensive.

Like Night Train says - DO NOT remove any of the loom until the car is running and you know what is no longer required.

Good luck, and if you have any questions, do not hesitate to ask

Christopher

[JonSpence]

Have a look at this open source controller project; http://paulandsabrinasevstuff.com/

Thanks Greg and NightTrain. I'm enjoying reading the development thread and am about 1/10 through. I should say that although I have not reached the end of the thread that the current design is clearly a work in progress.

Please don't think that "faint praise". It's brilliant stuff. However the current design is best suited to PM motors and not seperatly excited motors (such at yours NT and many others). It will work with them, but needs continued development. Then again that's the point of open source isn't it?

I have not reached the end, but I think that regen would only be possible (from the diagrams I have seen) with PM motors.

[Night Train]

Just to clarify, I am using a series motor not a sepex.