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Hi all, I have been lurking and researching for quite some time and I think I have most of the mechanics worked out in my mind. I have my eye on a few Land Rover Disco's to use as a donor vehicle. All the US versions come with auto transmissions.

What I'm hoping to accomplish is at least a 100 mile range and a top speed of 75 or 80 would be nice. I would like to use a 3 phase ac motor and regen braking but I'm not sure if the regen is possible with an auto transmission. Is there no way to just bypass the transmission all together?

Or... as another option -- would it be feasible to use 4 hub motors? I have done an electric bike and love the freedom and simplicity of hub motors, but not really sure when it comes to powering a car.

Any recommendations on motor and battery combos to help us accomplish this would be fantastic. Excluding the car itself I would like to keep the budget to around 15k.

Thanks for any tips!
 

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Okay then let's say the budget is 35k. I really just want to hear from someone who can recommend configs for suv's and shed a little experience on it for me.
Hi Bee,

Hub motors are not an option. Maybe something from these guys: http://uqm.com/products/full-electric/production/commercial-vehicles/ For a battery, maybe 32 ME350-049 EnerDels: http://www.ev-wholesale.com/Lithium-ion-battery_c3.htm Of course you'll need to electrify the auxillary systems. And you can regenerate through an automatic tranny, if you know what you're doing.

There's a lot of choice in design approach. Not many here have done large SUVs which come close to your stated objectives. There are a few conversions like that out there, but those guys stick to themselves or have their own TV show :)

I'm surprised Ivan didn't tell about Kevin in Topeka with a big AC motor auto trans big Chevy pick-up. Maybe he'll chime in with a link. Hopefully some other members will throw in some ideas,,,,hint, hint.

Regards,

major
 

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I'm surprised Ivan didn't tell about Kevin in Topeka with a big AC motor auto trans big Chevy pick-up. Maybe he'll chime in with a link. Hopefully some other members will throw in some ideas,,,,hint, hint.
I think Ivan likes to be non predictable. Lol


You really need a transmission on a large/heavy vehicle, especially if it is going to be driving any kind of terrain that is not flat. You need gears in an EV for the same reason you need gears in an ICE vehicle, to get the best acceleration and speed over changing conditions.

As Major said, automatic transmissions can work just fine if set up correctly.

Ivan is building a Sonoma with a 4L60 transmission. He eliminated the torque converter and has it directly driven. It still has all of the gears, it still shifts up and down automatically.

(It would if he would work on it and possibly finish it sometime this century)

This forum is the best place for you to be to learn and plan your EV build, welcome to the community.

Miz
 

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I wonder why none of the OEM EVs use transmissions, Miz. But let's not hijack Bee's thread. Use a transmission if you want to.
Well, it helps to have more than 70-80hp peak if you want to skip the transmission... Even the runty Nissan Leaf has 110hp on tap.
 

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Hijack away! I also wonder why none of the OEM electrics use a transmission?

But at any rate can someone tell me what's involved in mounting the motor to an auto transmission properly?
There is a simple answer for that, Most of OEM electric car are city cars (exception is Tesla Model S). Meaning that they have limited power requirements. Bigger OEM electric vehicles (Fuel cell buses) use often two motors with a planetary gearbox (summation gearbox with different ratios).
If you really want to convert the Landrover Discovery and you are able to control their Transmission (you must do that) you should keep it if possible. Then you could get away with a 40 KW (100 KW max) electric motor. The process of mounting a transmission to an electric motor is basicly the same as a gearbox without clutch (making an adapter-plate and connecting the shafts of motor and transmission).
But the Discovery is not the best car for conversion. If you take out their ECU, you will have to deal with their BCU and believe me that is not fun.
 

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The thing is, my wife really loves the Land Rover discovery, and in my opinion the only way that car would ever be practical is if it's electric. It would really only be used for around town driving. But sometimes, our around town driving can be upwards of 75 miles since we will be driving all around the Charleston area.

Can you expound on how the ECU comes into play? that's another area where my knowledge is a little bit shaky.

Thanks again
 

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The thing is, my wife really loves the Land Rover discovery, and in my opinion the only way that car would ever be practical is if it's electric. It would really only be used for around town driving. But sometimes, our around town driving can be upwards of 75 miles since we will be driving all around the Charleston area.

Can you expound on how the ECU comes into play? that's another area where my knowledge is a little bit shaky.

Thanks again
Ok I do not want to discourage you but In my opinion ( and I certainly will disagree with a lot of british folk at least) a Landrover Discovery is a car which in my opinion will NEVER be practical. I could write an essay about why but lets leave that and agree on the point that it is a comfortable car to sit in until things get rough.
I have never converted such a car to electric but we have serviced them after the owner was not able to repair them any more due to costs and limited knowledge of the (in some cases trained) service persons.
The problems where usually disfunction of one of the many units regarding the BCU (Body control unit) resulting not getting into the car without alarm, car not starting, battery level dropping certainly, disfunction of ATM (transmission), and disfunction of the (automatic) suspension system which is partly springs and partly air (compressors) supported by a liquid stability system. Most of this problems where related to a voltage drop of the 12V battery system and could be removed by just putting in a 1000Ah battery used for bulldozers but it still left some systems in undesirable condition.
Most normal cars we have used for conversion have their ECU (Engine control unit) connected directly with other parts of the vehicle (ABS/ESP, Airbag and ATM which are autark (selfcontained) systems connected by CAN-BUS.
Some cars and the Discovery is one of those, have an additional control unit (BCU, body control unit for example) which maps some of the existing units together in a special logic group. For example in the Discovery, there is an extra lock in the fuel supply which only unlocks if security system is disabled with the appropriate key AND Transmission is set to P AND Key is in potion II of the starting switch. This logic is mapped in the BCU and results one relay to be put on "ON" which opens the fuel lock.
There are a lot of more things connected this way and problem with this logic is that some is in the ECU-software and some in the hardware.
To steal the Discovery it is enough to fool the hardware (no problem) but to convert it, which involves removing the engine and usually the ECU you would have to map the BCU logic to your new control unit if you want to retain the original logic.
And this includes going through all the BCU/ECU logic in addition to only have to adapt the ATM (which is controlled by an extra computer).
But I will stop here and if you like I can list the point what to do to convert a "normal" car with ATM...
 

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I wonder why none of the OEM EVs use transmissions, Miz. But let's not hijack Bee's thread. Use a transmission if you want to.
I thought some of the OEMS just used a 1 speed fixed gearbox?
With an Electric Motors wide torque curve, they are able to dispense with multiple gears, although I do believe the early Telsa Roadsters did use a 2 speed gearbox, but dispensed with it shortly after initial production.
 

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Discussion Starter · #18 ·
And this includes going through all the BCU/ECU logic in addition to only have to adapt the ATM (which is controlled by an extra computer).
But I will stop here and if you like I can list the point what to do to convert a "normal" car with ATM...

What exactly does the BCU control? Security system? Ignition? Could all of those things be bypassed by just disconnecting? I'm perfectly happy putting aftermarket amenities into the car to make things simpler if needed.

On the ATM I have been told that you have to keep a minimum rpm in order for it to maintain hydraulic pressure. Does that require tweaking on the controller? What other ATM considerations are there?

Thanks for all your help! :)
 

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What exactly does the BCU control? Security system? Ignition? Could all of those things be bypassed by just disconnecting? I'm perfectly happy putting aftermarket amenities into the car to make things simpler if needed.

On the ATM I have been told that you have to keep a minimum rpm in order for it to maintain hydraulic pressure. Does that require tweaking on the controller? What other ATM considerations are there?

Thanks for all your help! :)
It depends on the vehicle, but in general, the Body Control Unit (BCU) or Body Control Module (BCM) can control things like door locks, windows, heaters, air cond, seats, lights etc etc

Some vehicles have an electric park brake. I've heard that what sometimes happens is after the car has been parked for an hour, one of the computer modules (not sure which one), will get the park brake to apply more brake force to compensate for the brakes cooling down and contracting. I'm not an expert on this, but this is something to think about as well.

With maintaining hydraulic pressure on the automatic transmission, it depends on the transmission, but in general, you could make the electric motor idle. I'm not sure which off the shelf motor controllers have this feature. However, making the electric motor idle will consume energy and reduce your range.

Other things to think about are cruise control and any steep decent technology, EBD, Stability Control etc used in the vehicle.

At the end of the day, it depends how tightly integrated these modules are with the car. You also have to know which wires to disconnect if you want to bypass things. Some wires could serve several purposes.
 

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What exactly does the BCU control? Security system? Ignition? Could all of those things be bypassed by just disconnecting? I'm perfectly happy putting aftermarket amenities into the car to make things simpler if needed.
Sorry for the late reply, for some reason I did not get the usual post when you answered (or I have missed it).
In the attachment here I have a two manuals for the BCU of the Landrover Discovery.
You can bypass a lot of functions by putting the relays (yellow ones in the front) on "ON" by applying a 12V voltage but you have to be careful when doing that. My advice is to use a simpler version of a Landrover instead (Defender for example). I also can send you a complete landrover workshop manual if you are interested (it does not explain the BCU-part very well though).
For typical problems I recommend www.landroverhell.com - website :)
 

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