# Planning Nissan 240sx conversion



## brian_ (Feb 7, 2017)

It looks like you're well into planning. If you go ahead with the Smart battery modules, where were you planning to put them? They might all fit in one layer under the hood over the motor, but that would be a lot of weight up front (8 x 42 lb of battery + 233 lb of motor + adapter etc), and the battery mass would be high above the ground. Perhaps half of them could go in the back (but as close to the axle as possible) with the fuel tank (and probably spare tire) out of the way?


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## brian_ (Feb 7, 2017)

mishkuh said:


> Want to have a fun drive and be able to go to the track every now and then.


Which kind of track? I would want to lap a road race track, but some prefer drag racing.


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## mishkuh (Oct 24, 2018)

brian_ said:


> It looks like you're well into planning. If you go ahead with the Smart battery modules, where were you planning to put them? They might all fit in one layer under the hood over the motor, but that would be a lot of weight up front (8 x 42 lb of battery + 233 lb of motor + adapter etc), and the battery mass would be high above the ground. Perhaps half of them could go in the back (but as close to the axle as possible) with the fuel tank (and probably spare tire) out of the way?


The placement is one thing I've been trying to look into. Ideally I'd like to keep it close to 50:50 weight distribution. I like the idea of putting some battery up front and some in the back, but was unsure if there were complications with a setup like that. 
Also from my understanding the max voltage with these packs would be 114 V since the setup would be 2 modules in series times 4 in parallel. Is that correct?



brian_ said:


> Which kind of track? I would want to lap a road race track, but some prefer drag racing.


I'd prefer lap race more than drag. I'd love to try a little bit of everything so it doesn't have to be specially built for a certain application at this point.


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## mishkuh (Oct 24, 2018)

brian_ said:


> It looks like you're well into planning. If you go ahead with the Smart battery modules, where were you planning to put them? They might all fit in one layer under the hood over the motor, but that would be a lot of weight up front (8 x 42 lb of battery + 233 lb of motor + adapter etc), and the battery mass would be high above the ground. Perhaps half of them could go in the back (but as close to the axle as possible) with the fuel tank (and probably spare tire) out of the way?


I'd love to keep a 50:50 (or as close as possible) weight distribution if I can. I like the idea of splitting up the weight of the battery modules to help with that, but I wasn't sure if that would cause complications or was feasible. The trunk is completely empty. I thought it would be great to remove the fuel tank and install the battery modules to replace it. I'd have to look into that more.

Also, am I right in thinking that the voltage with these modules would be 114 V since there would be two 57 V in series?



brian_ said:


> Which kind of track? I would want to lap a road race track, but some prefer drag racing.


I prefer lap track over drag, but I'm hoping to do a little of everything with it so it doesn't have to be built for any specific application at this point. All around fun and solid performance.


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## brian_ (Feb 7, 2017)

mishkuh said:


> I'd love to keep a 50:50 (or as close as possible) weight distribution if I can. I like the idea of splitting up the weight of the battery modules to help with that, but I wasn't sure if that would cause complications or was feasible. The trunk is completely empty. I thought it would be great to remove the fuel tank and install the battery modules to replace it. I'd have to look into that more.


Those Smart battery modules are very long, so packaging is a challenge. One planning technique is to make cardboard or foam mockups of the modules, and physically see how they fit in the available space. mfor1000 did this for the 911 RSR with Tesla Motor and found a way to pack in an impressive amount of battery.

_(I edited a section out here, because I had projects mixed up had posted something relevant only to a different car model)_



mishkuh said:


> Also, am I right in thinking that the voltage with these modules would be 114 V since there would be two 57 V in series?


A source of the those Smart battery modules is EV West; they suggest a 2S4P configuration, so that's four in parallel (so 57 Ah x 4 = 228 Ah total), then two groups of four in series. Yes, that's a 114 volt nominal voltage for the pack, which they're suggesting for typical conversion motors.



mishkuh said:


> I prefer lap track over drag, but I'm hoping to do a little of everything with it so it doesn't have to be built for any specific application at this point. All around fun and solid performance.


Sounds good - just keep performance expectations moderate... you're not going to lap a road race track for very long at full power before running out of energy, and cooling will likely be an issue, too. Check out autoslalom - the car would probably work well for that.


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## Duncan (Dec 8, 2008)

114v for a Warp 11 will severely limit your rpm's

Using an 11 inch Hitachi motor at 130v flatlined my car at 100 kph - you need at LEAST 144v 
And I'm using 340v 

Incidentally you can save a LOT of money if you use different parts

I paid $200 for my motor, $1000 for my controller and $1800 for my batteries


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## MattsAwesomeStuff (Aug 10, 2017)

Duncan said:


> And I'm using 340v


You're using 340v for 660 feet at a time.  That doesn't count for good driving practices.



> Incidentally you can save a LOT of money if you use different parts. I paid $200 for my motor, $1000 for my controller and $1800 for my batteries


Shhh. If he's got money to burn, let him. Else he's going to price out the rest of us vultures.

Actually, controller I can see why you might want new with warranty. And batteries, ehn, okay, choose your flavor and form factor.

But I'm with you on motors. I do not understand anyone who pays thousands of dollars for a DC motor. With minimal servicing they last 100 years.

Say you're lazy and don't want to shop around, okay then, maybe $500 if you had to nag a guy to do it, at most, for a forklift motor. Add new brushes whatever those cost and you're still thousands and thousands of dollars less than any Netgain motor which probably comes out of the exact same factor. Honestly the only person I've ever heard blowing a motor is you (Duncan), and you were doing your damnedest to make it happen.


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## brian_ (Feb 7, 2017)

Duncan said:


> 114v for a Warp 11 will severely limit your rpm's
> 
> Using an 11 inch Hitachi motor at 130v flatlined my car at 100 kph - you need at LEAST 144v...


Sure... the 2s4p recommendation was for a different motor. Nine of the same modules in a 3s3p configuration would have a nominal voltage of 3 x 57 = 171 volts (and 3 x 57 = 171 Ah). Seven Tesla Model S/X modules (all in series) would provide 7 x 22.8 = 160 volts @ 232 Ah (37 kWh and 385 pounds). There are lots of possible combinations.

As for speed... gearing will affect top speed. The plan appears to be to use the car's original transmission, providing a choice of reduction ratio. The final drive ratio can also be changed - there must be a bunch of choices for the classic R200 final drive.



Duncan said:


> Incidentally you can save a LOT of money if you use different parts
> 
> I paid $200 for my motor, $1000 for my controller and $1800 for my batteries


For planning purposes it might make sense to stay with the WarP 11 from NetGain as an example of an 11" diameter series-wound DC motor, and when it comes time to buy something then shop around for some equivalent from a salvage source.

The dimensions of battery modules make the choice very specific - changing to modules salvaged from a different EV, or (unlikely) an aftermarket source, has significant implications to packaging and BMS choice. It might be worth examining what is really wanted from the battery, rather than jumping directly to a specific choice of hardware.


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## mishkuh (Oct 24, 2018)

brian_ said:


> ...One planning technique is to make cardboard or foam mockups of the modules, and physically see how they fit in the available space...


The cardboard is a good idea to get a sense of fitment, I'll try that out.



brian_ said:


> Sounds good - just keep performance expectations moderate... you're not going to lap a road race track for very long at full power before running out of energy, and cooling will likely be an issue, too.


Thanks, I'll keep performance expectations moderate... for now . I'm sure I'll get a better sense for what it would be capable of after having the build then I can adjust from there. I definitely want to start with a good foundation though.


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## mishkuh (Oct 24, 2018)

Duncan said:


> 114v for a Warp 11 will severely limit your rpm's
> 
> Using an 11 inch Hitachi motor at 130v flatlined my car at 100 kph - you need at LEAST 144v
> And I'm using 340v
> ...


oof I don't want that. I'll be sure to plan it at the bare minimum 144v.

Wow, that would be great to save that amount. I saw there were some listings for used parts, but I wasn't too sure about the reliability. I'll have to do some more looking around.


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## mishkuh (Oct 24, 2018)

MattsAwesomeStuff said:


> Shhh. If he's got money to burn, let him. Else he's going to price out the rest of us vultures.
> 
> Actually, controller I can see why you might want new with warranty. And batteries, ehn, okay, choose your flavor and form factor.
> 
> But I'm with you on motors. I do not understand anyone who pays thousands of dollars for a DC motor. With minimal servicing they last 100 years.


Haha, well I was ready to burn some money after researching cost for these projects, but I'd much rather not spend too much where I don't need to.

Time to start looking for a used motor! 

I'm going to look into how well battery packs age. I may start with a used one for my first build.


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## mishkuh (Oct 24, 2018)

brian_ said:


> The plan appears to be to use the car's original transmission


Yep, that is the plan.




brian_ said:


> For planning purposes it might make sense to stay with the WarP 11 as an example of an 11" diameter series-wound DC motor, and when it comes time to buy something then shop around for some equivalent from a salvage source.


That's a good plan. It will give a good reference and I do have time to shop shop around/wait for the right motor to come up.



brian_ said:


> The dimensions of battery modules make the choice very specific - changing to modules salvaged from a different EV, or (unlikely) an aftermarket source, has significant implications to packaging and BMS choice. It might be worth examining what is really wanted from the battery, rather than jumping directly to a specific choice of hardware.


What are the considerations typically made in choosing battery? I would imagine weight, size, ah, voltage. I can imagine I'm missing some things, what would those be?


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## brian_ (Feb 7, 2017)

mishkuh said:


> What are the considerations typically made in choosing battery? I would imagine weight, size, ah, voltage. I can imagine I'm missing some things, what would those be?


Amp-hour capacity and voltage by themselves don't matter; it's energy capacity that matters, although of course that is just amp-hours multiplied by voltage. You can re-arrange (series and parallel) to get the desired operating voltage level, although modules come in fixed numbers of cells which limit the possible combinations.

Power capacity also matters - how much power can you get out (briefly) without problems? As a requirement: how much power do you need?

Another factor might be the need for, or design of, thermal management. Do you need to be able to heat for cold-weather operation? Do you need to cool for hot-weather or high-power operation? Different types of cell have different temperature tolerance, and different module designs have different provisions for heating and cooling. Most modern production EV batteries are liquid-cooled (and heated).


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