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Posted: Sun, 17 Nov 2013, 20:02
My lightweight EV platform developed in Margaret River WA has just been featured here on Instructableshttp://www.instructables.com/id/Electri ... platform-/
14kWh LfP battery pack, 45 100Ah CALB cells (150kg)
Twin Greatland AC motors, belt drive to rear wheels
Rated 30kW (two motors combined)
Peak 600A, 148V
MX5 wheels, brakes and hubs
Total weight 500kg
Posted: Sun, 17 Nov 2013, 22:49
Looks great Wayne! I wonder how hard it would be to get your platform road approved?
Posted: Mon, 18 Nov 2013, 00:11
Thanks. I don't think it would be hard, just time consuming, infuriating and slow. Have dealt with licensing before on a previous project and they specialise in being as difficult and unhelpful as possible so am in no hurry to get tied up by the worst bureaucratic red tape I have ever experienced in WA.
Posted: Mon, 18 Nov 2013, 01:42
I am absolutely in love with this idea. The box-tube centre spine for the battery is brilliant. I wonder if extruded sections exist in a similar size. It would likely be more rigid than the pressed box and bolt-on top. The batteries would have to be slid in on a sort of sled from one end or the other, but that could be dealt with in an elegant way. Ideally, you shouldn't need frequent access to the batteries anyway.
What was the total cost of the assembly as shown?
I can see myself doing this, but instead of the greatland motors using two of the custom-wound 132 frame motors I got from Catavolt and my own controller. It wouldn't be too difficult to build two controllers in to a single box for an application like this, and the performance would be brutal, especially with a reduction in the range of 5-8:1.
I would love to do this someday.
Posted: Mon, 18 Nov 2013, 02:45
Really big aluminium extrusions are possible, but not readily available and they will typically have a much heavier wall thickness, so pressed ali is the way to go. I have used 6mm socket screws into rivnuts at 50mm spacings to hold the lid down (should have put that in the instructable) and it is working perfectly so far. Not having built an EV before, I wanted to keep easy access to the battery. For higher performance fasteners with a slide in battery there are a whole range of structural rivets made for the transport industry that are used to fix truck bodies together so they would be ideal for the job.
You probably have a better idea of the cost of motors, controllers and batteries than I do. The remaining parts were $300 for the pressed ali box, $500 for all the wheels, brakes, hubs, steering ($1500 wreck minus $1000 for on selling the motor and gearbox) about $200 for misc metal and ply and about another $150 for fasteners. If you want to save money, you could pick up chains and sprockets from a motorbike wrecker, but I paid about $500 for the belts and pulleys for a belt drive setup using high performance industrial timing belts.
Posted: Mon, 18 Nov 2013, 04:32
Awesome stuff, and dirt cheap by the sounds of it. I have a background in aviation (LAME) so I'd be pretty comfortable putting something like this together myself. Be sure to share your progress with it as you continue. I'm keen to see what it becomes.
Posted: Mon, 18 Nov 2013, 08:21
Its also quite quick to build. Most of my time went into design and sourcing parts, the build component is actually quite fast. Unfortunately producing custom bodywork is laborious and slow, so am still trying to find someone with a body mould I can use to short cut the process.
Also would love to see how a lighter weight version goes as well with a smaller lower voltage pack, high performance BLDC motors, a short chassis from a 2400x1200 sheet and motorbike wheels. Could easily get the weight down to half and then I think you would have a great entry level electric clubman race formula.
Posted: Mon, 18 Nov 2013, 16:26
Hit up Damien (Canberra32) on this forum. He should be able to help you out with CNC plugs and moulds.
Posted: Wed, 20 Nov 2013, 03:47
Posted: Wed, 20 Nov 2013, 14:29
Thanks for hackaday headsup. Would have been nice if they let me know.
Posted: Wed, 20 Nov 2013, 14:33
Electronic throttle splitter.
Just wondering if anyone knows where I may find a circuit diagram. I am currently running two throttle pots mechanically connected to output to the twin controllers. An electronic splitter would be more elegant solution and wouldn't drift out of balance like the twin pots do.
Posted: Wed, 20 Nov 2013, 14:41
What is the throttle input requirement for the controller? Resistance or voltage?
Posted: Thu, 21 Nov 2013, 06:23
It's a resistive throttle pot (supplier link)http://www.evworks.com.au/index.php?pro ... EVW-TBX-5K
My understanding is that it takes 5V input from the controller and returns a 0-5V signal back to the controller.
From my limited understanding of the way things work, I thought it would be ok just to use the same throttle output wired back to both controllers, but I have been advised that this may not work and I don't want the project to end up in smoke and tears.
Posted: Thu, 21 Nov 2013, 14:18
Crash wrote: It's a resistive throttle pot...
I'm assuming that you have two of these and you are not happy with the tracking. It also sounds like you want the output of the throttle "splitter" to be isolated.
The first solution that comes to mind is Zeva's hall affect to throttle pot simulator.
In the blurb he says that the input and output are isolated so two of these would be perfect to feed the controllers. With the third wire modification mentioned on the EV Works site you can still use one of the throttle pots to feed it (hall effect would be more reliable but you already have the pot).
If it sounds like this might work for you, I'd get in touch with Ian at Zeva and see what he thinks about this application.
Posted: Thu, 21 Nov 2013, 15:44
My motorbike uses a single pot throttle to control 2 controllers. If you are worried you can also use a cycle analyst v3 to produce a stronger output. Either way if everything is connected to the same battery pack you can do it. Just only connect the source and negative from one controller and then connect the signal output to both controllers.