KiwiEVs next project fast EV

Thanks Blake great minds think alike just as you posted I had a pm from our ES spot welder manufacturer and have ordered one.
The winston batteries were going to cost me $14k anyway so 18650 are no brainner imo.

So regarding my motor choices as I will like to keep this car a while I would like to go AC I could up the anti and use either two hpev AC 75 which need two controllers at 96 volt and 650 amps giving a total 156hp and a whooping 366 ft/lb of torque or a
Hpev AC 76 which needs two controllers at 144 volt and 500 amps giving a total 180hp and 360 ft/lb of torque.

The Audi TT gearbox apparently is good for 550 ft/lb but I dont think thats at less than 1 rpm.

So the AC 76 is about $750 usd each more is it worth it do I just change gears more often :roll:

Cheers Kiwi
 
A quick glance at some formulas for calculating gear strength suggests (intuitively) that torque rating decreases with speed (due to impact forces between meshing teeth), so the motor producing gearbox-rated torque at lower speeds than an ICE should not be a problem. What might be is the more aggressive take up of drivetrain backlash during hard launches (impact forces again), but as with ICE drag racing would hopefully be solved by lightly preloading the drivetrain before giving it full welly. I guess that could be done manually with throttle control or with a software acceleration ramp in the controller.

IIRC people have been able to pick up whole used Leaf and Volt packs for around $3000 USD?
 
kiwiev said:
Thanks Blake great minds think alike just as you posted I had a pm from our ES spot welder manufacturer and have ordered one.
The winston batteries were going to cost me $14k anyway so 18650 are no brainner imo.

So regarding my motor choices as I will like to keep this car a while I would like to go AC I could up the anti and use either two hpev AC 75 which need two controllers at 96 volt and 650 amps giving a total 156hp and a whooping 366 ft/lb of torque or a
Hpev AC 76 which needs two controllers at 144 volt and 500 amps giving a total 180hp and 360 ft/lb of torque.

The Audi TT gearbox apparently is good for 550 ft/lb but I dont think thats at less than 1 rpm.

So the AC 76 is about $750 usd each more is it worth it do I just change gears more often :roll:

Cheers Kiwi
Click to expand...
I would be looking to drop the gearbox and clutch altogether if possible. I know you might not get as much torque to the wheels off the line, but nothing beats the simplicity of it IMO. You also have far less drivetrain efficiency losses.

I'm not too sure on the motor options, but if the AC 76 has a higher power density then that would be the motor I would go for...especially if it doesn't need as many amps.
That will be your limit with the 18650's...depending on how many you parallel you won't be able to suck quite as many amps from them compared to the A123's or similar, but they make up for it in weight and power density.
I reckon 30-36 series and 75-90 in parallel is the sweet spot for the 18650 route.

Cheers
 
I would be looking to drop the gearbox and clutch altogether if possible
Click to expand...

Without a transmission you need double the motor to get the same powerband, and the driveline efficiency is offset by losses from running at lower efficiency. A clutch is also a great safety feature for mitigating the risk of a runaway motor.

_JD
 
oatnet said:
. A clutch is also a great safety feature for mitigating the risk of a runaway motor...._JD
Click to expand...
:shock: I'm no expert, but I can think of several ways to disconnect the motor (power) which would be simpler, lighter, and cheaper, to implement .!
Or maybe someone should give Tesla a heads up about their oversight ? :wink:
 
Hillhater said:
oatnet said:
. A clutch is also a great safety feature for mitigating the risk of a runaway motor...._JD
Click to expand...
:shock: I'm no expert, but I can think of several ways to disconnect the motor (power) which would be simpler, lighter, and cheaper, to implement .!
Or maybe someone should give Tesla a heads up about their oversight ? :wink:
Click to expand...

The hazard of breaking a 400v/2000a load might be more of a challenge to overcome than you think, but maybe you have the skills to engineer a pyrotechnic disconnect system like Tesla uses, whereas I do not. Even though I have dual contactors I like having a mechanical disconnect, because my one-off Towdster didn't have the benefit of the rigorous engineering and extensive fail testing the model S went through.

-JD
 
Punx0r said:
A quick glance at some formulas for calculating gear strength suggests (intuitively) that torque rating decreases with speed (due to impact forces between meshing teeth), so the motor producing gearbox-rated torque at lower speeds than an ICE should not be a problem. What might be is the more aggressive take up of drivetrain backlash during hard launches (impact forces again), but as with ICE drag racing would hopefully be solved by lightly preloading the drivetrain before giving it full welly. I guess that could be done manually with throttle control or with a software acceleration ramp in the controller.

IIRC people have been able to pick up whole used Leaf and Volt packs for around $3000 USD?
Click to expand...


Thanks mate they don't make the AC 75 so back to the AC 51 twin which should be great as electric motors are rated about 1.5 times equivalent to an ICE motor so should be able to get 225hp equivalent but with more torque.

Cheers Kiwi
 
Hillhater said:
oatnet said:
. A clutch is also a great safety feature for mitigating the risk of a runaway motor...._JD
Click to expand...
:shock: I'm no expert, but I can think of several ways to disconnect the motor (power) which would be simpler, lighter, and cheaper, to implement .!
Or maybe someone should give Tesla a heads up about their oversight ? :wink:
Click to expand...


I agree I will use the clutch and gearbox.

As far as safety goes I'm still a big fan of the big red button mechanical disconnect. The HPEV run two contactors which also run thru a crash sensor.

Cheers Kiwi
 
Cowardlyduck said:
kiwiev said:
Thanks Blake great minds think alike just as you posted I had a pm from our ES spot welder manufacturer and have ordered one.
The winston batteries were going to cost me $14k anyway so 18650 are no brainner imo.

So regarding my motor choices as I will like to keep this car a while I would like to go AC I could up the anti and use either two hpev AC 75 which need two controllers at 96 volt and 650 amps giving a total 156hp and a whooping 366 ft/lb of torque or a
Hpev AC 76 which needs two controllers at 144 volt and 500 amps giving a total 180hp and 360 ft/lb of torque.

The Audi TT gearbox apparently is good for 550 ft/lb but I dont think thats at less than 1 rpm.

So the AC 76 is about $750 usd each more is it worth it do I just change gears more often :roll:

Cheers Kiwi
Click to expand...
I would be looking to drop the gearbox and clutch altogether if possible. I know you might not get as much torque to the wheels off the line, but nothing beats the simplicity of it IMO. You also have far less drivetrain efficiency losses.

I'm not too sure on the motor options, but if the AC 76 has a higher power density then that would be the motor I would go for...especially if it doesn't need as many amps.
That will be your limit with the 18650's...depending on how many you parallel you won't be able to suck quite as many amps from them compared to the A123's or similar, but they make up for it in weight and power density.
I reckon 30-36 series and 75-90 in parallel is the sweet spot for the 18650 route.

Cheers
Click to expand...

Hey CD

I don't know if the 18650 are going to give the amps I need 1300 amps for the AC 50 at 120v or 1000amps for the AC 51 at 144 volts that's a lot of cells mate.
Waiting on a reply from a mate who has A123 cells.

Another thought is buy 100ah CAB cells one set for start that I can mount in the front and under the rear seat where the fuel tank is. This would be for around town and the odd hill climb I could hook up 2 x 2.5kw chargers which would charge at 22-25amps the reason for 2 is I can only run one at home off the stand alone solar but 2 in town.
Then run a second set when funds arrive and set up in the boot for a lift in lift out box in parallel with the permanent set I know this isn't ideal charging but gives me the option to lighten the car but 150kg easily.

Cheers Kiwi
 
Hillhater said:
Cowardlyduck said:
You could go with fewer cells and add some super capacitors for the high amps.
...
Click to expand...

Has anyone ever actually tried that ?
Click to expand...
No idea....but it's an idea that could work in theory.

Another option could be to mix batteries. I know for a fact that it has been done before to achieve high capacity and high amps output. How wise it is, I don't know though. If both batteries had there own BMS, I could see it working well.

I'm just keen to save the idea of 18650's for this build since I think benefits far outweigh the extra effort involved.

Cheers
 
CD I can also get those Tesla packs for about $1300. Per 3kw module complete in housing heating cooling bms and fuse only problem is I need 14 modules :evil: to get enough amps I need to win Loto :idea:

Cheers Kiwi
 
kiwiev said:
CD I can also get those Tesla packs for about $1300. Per 3kw module complete in housing heating cooling bms and fuse only problem is I need 14 modules :evil: to get enough amps I need to win Loto :idea:

Cheers Kiwi
Click to expand...
Yeah, that's still 18k.

I'm not giving up hope for an 18650 based pack for you though. Keep in mind that the 10 amps per cell of the above posted 3500mah 18650's is continuous...they can and will peak above that without issue.

If amps is the issue then you could easily get away with 50P of these:
http://ru.nkon.nl/lg-18650-hg2-3000mah-20a.html
With 50 of these in parallel you could pull 1000A continuous all day, easily hit 1500A peak. It would weigh less than 75KG, but only have 17.7KWh, and cost 11.4K before shipping.

If cost is the issue, then you could go with 100P of these:
http://ru.nkon.nl/rechargeable/18650-size/panasonic-ncr18650pf-3-7v-2900mah.html
At 32S X 100P so 3200 cells, that would still only be 12.5K AUD before shipping, still manage 1000A continuous, and still weigh less than 150KG and be 34.3KWh. Only catch would be the extra welding to do 3200 cells.

Given the above, I would go for the Panasonic's IMO. 12.5K for nearly 35KWh is pretty good TBH.

Cheers
 
kiwiev said:
I may have to give you a contract CD spot welder is on its way

Cheers Kiwi
Click to expand...
Well having never spot welded before, I'm sure I'd do a great job :p

I should get a move on and order some cells so I can borrow your welder to make my commuter pack.

When will you know which route your going to take?

If you end up getting any of the 3500Mah cells be sure to let me know as they are what I will be ordering for my Recumbent pack.

Cheers
 
Cowardlyduck said:
kiwiev said:
CD I can also get those Tesla packs for about $1300. Per 3kw module complete in housing heating cooling bms and fuse only problem is I need 14 modules :evil: to get enough amps I need to win Loto :idea:

Cheers Kiwi
Click to expand...
Yeah, that's still 18k.

I'm not giving up hope for an 18650 based pack for you though. Keep in mind that the 10 amps per cell of the above posted 3500mah 18650's is continuous...they can and will peak above that without issue.

If amps is the issue then you could easily get away with 50P of these:
http://ru.nkon.nl/lg-18650-hg2-3000mah-20a.html
With 50 of these in parallel you could pull 1000A continuous all day, easily hit 1500A peak. It would weigh less than 75KG, but only have 17.7KWh, and cost 11.4K before shipping.

If cost is the issue, then you could go with 100P of these:
http://ru.nkon.nl/rechargeable/18650-size/panasonic-ncr18650pf-3-7v-2900mah.html
At 32S X 100P so 3200 cells, that would still only be 12.5K AUD before shipping, still manage 1000A continuous, and still weigh less than 150KG and be 34.3KWh. Only catch would be the extra welding to do 3200 cells.

Given the above, I would go for the Panasonic's IMO. 12.5K for nearly 35KWh is pretty good TBH.

Cheers
Click to expand...

I Agree mate the director of finance would be happy with 12-13k maybe lol.

I just have to figure out how to cool and heat these packs and packing into mount boxes. I won't order u till the new year btw.

Still a crap load of spot welding.

If I do it I may do a bulk buy if other ES members are interested.

Cheers Kiwi
 
Just foudn this thread. Sub'd.

Kwi - I recently joined OZ-DIY Electric Vehicles on facebook. There's a great guy there called Graeme Manietta who does car conversions for a living and has offered to split up his next import of Nissan Leaf cells. Might be worth getting in touch...
 
Samd said:
Just foudn this thread. Sub'd.

Kwi - I recently joined OZ-DIY Electric Vehicles on facebook. There's a great guy there called Graeme Manietta who does car conversions for a living and has offered to split up his next import of Nissan Leaf cells. Might be worth getting in touch...
Click to expand...

Cool Sam can you post a link please


Cheers Kiwi
 
kiwiev said:
Here is an interesting video CD
Click to expand...
SO cool mate...just subscribed and watched all the episodes!

I guess that goes to show it is possible to draw way more peak amps from these cells. So the question is, how far would you be willing to push them?
I think 10A cells could handle 15A peaks and 20A could handle 25A or 30A peaks, but if your doing that it means you have less cells in parallel which also means you have less capacity/range anyway....but cost less.

Cheers
 
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