# going to convert 1990 Nissan 300ZX...



## dbotos (Aug 18, 2010)

Originally, I was going to put her back together as a gas-guzzler, but the more I read about electric conversions, the more I'm set on going that route.

My intent for the car is to drive it back and forth to work and also for around-town errands. Work is ~8 miles away on local roads (<=45 mph) or ~10 mi on a mix of local and highway (~7 mi on highway, speed limit 65 mph)

The car is currently completely stripped down (I just went and picked it up from chemical stripping a week ago), so that should give me plenty of time to plan things out while I work on the unibody and powdercoat all the suspension components and start putting some of that back together. I uploaded a few pics here:

http://www.diyelectriccar.com/forums/album.php?albumid=112

I've started doing some calculations in Excel for horsepower eaten up by drag, gear ratios, etc.

Here's the drag hp numbers using a 0.31 C_d, rough frontal area of 2.24 m^2 (just multiplied the published width and height), and air denisty at 20*C (68*F):

25 mph - < 1 hp
35 mph - ~2 hp
45 mph - ~4.5 hp
55 mph - ~8 hp
65 mph - ~14 hp

As far as motors go, I'm considering the NetGain WarP 9 or 11 or maybe a forklift motor of comparable specs.

Given the tranny gear ratios of 3.214, 1.925, 1.302, 1, and 0.752; a diff ratio of 4.083; and tire size of 225/50-16, here's what 3000 and 3500 rpm motor speeds (continuous rated speeds for WarpP 11 and 9, respectively) translate to in vehicle speeds for the different gears:

1st:
3000 rpm = 16.9 mph
3500 rpm = 19.7 mph

2nd:
3000 rpm = 28.2 mph
3500 rpm = 32.9 mph

3rd:
3000 rpm = 41.7 mph
3500 rpm = 48.7 mph

4th:
3000 rpm = 54.3 mph
3500 rpm = 63.4 mph

5th:
3000 rpm = 72.3 mph
3500 rpm = 84.3 mph

For batteries, it looks like a bank of 12 (144 V nominal) is a pretty common. I've got a decent amount of trunk and engine bay space, so I could probably do a 6/6 or 4/8 front/rear split depending on how big of batteries I use and how things end up laying out.

I should be able to fab mounts, adapters, boxes, etc, but I'll probably be spending the bulk of the cost on a motor, batteries, a controller (or parts to build one), and other electrical supplies (cables, etc).

I need to work on my weight estimates some more - I'm hoping I can come in not over the original stock 3220-lb curb weight. I think not having an iron-block 3-L V6 with four cams, dual exhaust, gas and gas tank, etc will shed some weight. But, I'm sure the batteries and electric motor will quickly add a lot back. Interior is also gone and I'm planning to shed AC and PS (going to get a manual rack with different ratio to simplify things).

Anyone got any advice/comments? I'll try to post more as I do more planning / calculations / actual work.


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## echas (Jun 25, 2008)

Excellent, another Nissan EV conversion. 

I converted my 1993 Nissan 240sx a few years ago. I choose to use 18 8V flooded batteries which gave me a 30 mile range on the highway. Had a hard time fitting all these batteries without taking over the rear seat but did it with an even 9/9 front/rear distribution. You can't even see the motor unless you get down real low and look under. Other than squeezing all the batteries in, which I would not do the same again, the overall conversion process went very smooth. Shifts are smooth even without a clutch.

She is about to loose the lead and get a 16 kwhr Lithium pack once I complete refurbishing the Headway batteries (long story). 

Here are the links to my car:
http://www.evalbum.com/2059

http://vintage-voltage.com/240sx/

Great pictures of your 300zx. Keep up the good work. It's often the restoration that takes the longest time. 

Charlie


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## rillip3 (Jun 19, 2009)

When you say stripped down, you are not kidding!!

So you need to drive at least 20 miles. Let's say 30 so you can go do some errands after work. Let's assume 300 wh/mi (pretty average, ballpark number for a 4 seater). 300 wh/mi x 30 mi = 9000 wh. Now if you're doing lithium or AGM, we have to increase by 20% for Puerkert, or 50% for FLA. I'm not sure what Puekert's like on gel, but I've seen people suggest not using gel due to poor ability to put out amps instantaneously.

Assuming Li/AGM, that's 10,800. Now increase by 20% to keep from discharging the batteries to an unsafe level, that makes it 12,960 wh. Divide that by 144v and you get 90 Ah batteries are needed. Extremely reasonable. Quick Google search shows me a 12v 100 Ah battery weighing in ~75 lbs. That's 12 x 75 = 900 lbs. Warp 9 is 143 lbs, so 1043 lbs. Let's round up for the charger, cabling, vacuum pump, etc. and say maybe 1200 lbs. added. 

The exhaust system is, for the most part, empty space. From what I've taken off, I'd guess only fifteen pounds or so. The gas tank, assuming it has something like a 16 gal tank, is about 150 lbs (130 or so is the weight of the gas). So if the engine, alternator, et al., weight in around 1000 lbs, you should be right around the same curb weight. I think that is likely pretty optimistic. If you can get the current, stripped down weight of the car, you can get a good feel for how much it will weigh with the numbers above. Of course you can go lighter with lithium.


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## TomA (Mar 26, 2009)

rillip3 said:


> Assuming Li/AGM, that's 10,800. Now increase by 20% to keep from discharging the batteries to an unsafe level, that makes it 12,960 wh. Divide that by 144v and you get 90 Ah batteries are needed.


Maybe, but 90Ah LiFePO4 prismatic cells are going to be quite current-limited in that configuration- ThunderSkys will be limited to 270 Amps (3C) at full power. In a 3200lb car performance is going to be very leisurely, and a programmable battery current-limiting controller would be a must.

130Ah CALB cells would be more usable, up to 520 Amps, (4C) with 180Ah or 200Ah cells making the most sense for this car. Its probably worth trading voltage (fewer cells) for current capacity (bigger cells) here, it all depends on what the purpose of the vehicle is intended to be, but in any case I doubt that 45 90Ah cells will be a satisfactory pack.

When pulling weight out of a car like this, look at the interior. The front seats (power, heated?) probably weigh a lot, and if they aren't perfect, maybe swap them for something really light, like the seats from a Toyota Yaris. Remember, you aren't going to drive this car more than an hour or so at a time. There's also insulation everywhere that can often be removed. Look under the carpets and panels, and if they're also shabby, consider replacing them with much lighter weight materials. The new powertrain is so quiet that you won't miss the insulation, either. Fancy factory radios in these cars are also heavy, especially the component-type units with lots of speakers. That all adds up fast...

TomA


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## dbotos (Aug 18, 2010)

Charlie - the 240 looks good! Reassuring to see somone with a somewhat similar vehicle.

Phil / Tom - thanks for the battery calculations and reccommendations. Based on my initial reasearch, I'm leaning towards true deep-cycle FLA batteries for cost reasons.

I've read up on and understand DoD and Peukert effect, but I think I'm a little hazy on the effects of voltage per cell and trading voltage and current.

With voltage per cell, assuming your total amp hours are equal, what's the difference in using 24 6V cells vs. 12 12V cells vs. 6 24V cells, etc?

With voltage and current, I've always thought (and maybe this is just my knowledge of industrial AC motors) that generally the more powerful the motor, you want to use higher voltage in order to keep current (and thus wire size/cost).

On the topic of weight, the exhaust totals about 71 pounds (8 per manifold, 12 per cat pipe, and 31 for the cat-back (weighed with el-cheapo 50-lb-capacity fishing scale)). Complete engine is said to weigh about 550 (the block alone is ~130). I haven't had an interior for a while. Everything behind the seats (2 seater) is gone. Up front, I had carpet, seats (all manual), a center console, no dashboard (just gauge cluster and single-DIN radio on the dash bar), and no interior on the doors. I did still have A-pillar covers and a headliner. I need to dig out the alternator and AC compressor and see how much those little piggies weigh...

What's the current state of homebrew controllers? Does anyone sell any solder-it-yourself kits or are there plans out there where you source your own components and assemble?


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## Crash (Oct 20, 2009)

I had a 90 300zx as well. They certainly guzzle gas a lot.

The VG30DE weighs 660Lbs. The exhaust weighs over 110Lbs (crazy, huh?). I assume you'll be removing the radiator and don't forget you'll be losing the weight of the coolant and cooling components (like the reservoir and the hoses). The cooling system weighs just over 60Lbs. You'll be removing the gas lines and tank. I don't recall how much the tank weighed, but it was hefty. 

I remember doing the math on how much is actually removed from the car and it left the car at around 2000 Lbs. But there is still stuff you can do to lighten up the car. The 2-piece drive shaft weighs 40Lbs. You can get a 20Lbs 1-piece driveshaft from Z1 motorsports that will handle MORE power and drain your batteries less. Also, you'll probably want to do that anyway if you're experiencing the mid-RPM vibrations that you get with the stock driveshaft. You can also lose lots of weight by getting rid of the stock wheels and getting some lighter wheels or even get some 350z touring wheels (like I did) which are nicer looking and still lighter.

I was doing my math as if to use a 160V (100AH) pack of LiFePo4 batteries and a Netgain 11". I think when everything was said and done the car weighed in at around 2700Lbs. Even if you use lead acid batteries, you're not likely going to match or exceed the stock weight of the car. That VG30DE motor was ridiculously heavy.


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## Bowser330 (Jun 15, 2008)

Crash said:


> I had a 90 300zx as well. They certainly guzzle gas a lot.
> 
> The VG30DE weighs 660Lbs. The exhaust weighs over 110Lbs (crazy, huh?). I assume you'll be removing the radiator and don't forget you'll be losing the weight of the coolant and cooling components (like the reservoir and the hoses). The cooling system weighs just over 60Lbs. You'll be removing the gas lines and tank. I don't recall how much the tank weighed, but it was hefty.
> 
> ...


ive always loved the shape of that 300zx


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## dbotos (Aug 18, 2010)

I actually passed enhanced CA emissions with mine when I lived out in Aliso Viejo. But it was still never a gas sipper...

I've got my gas tank, but it's kind of buried right now. I'll have to weigh it when I get the other junk cleared from around / on top of it. I did pull the alternator out of the box that it was in and that was 14 pounds (the alternator, not the box).

I've actually got a Z1 1-piece driveshaft - it is definitely a lot lighter than the stock 2-piece. Lighter wheels are a good idea - hadn't really thought about that as a factor, but I have always wanted different wheels, so we'll have to see how that fits into the budget (probably low on the list).

Did you have a specific brand/model of battery in mind? My options are still pretty wide open since I've got lots of time to consider while I work on body/frame/suspension.

On a semi-related note, I bought an electric lawn mower today and love it. It's corded (cause I'm cheap and didn't want the extra weight of a battery since _I'm_ the propulsion system), but the whole lack of noise, fumes, heat, and having to mess with oil changes, air filters, and keeping it gassed up is further reinforcing the desire to make the Z electric. Plus, it does a good job mowing too.


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## rillip3 (Jun 19, 2009)

dbotos said:


> I actually passed enhanced CA emissions with mine when I lived out in Aliso Viejo. But it was still never a gas sipper...
> 
> I've got my gas tank, but it's kind of buried right now. I'll have to weigh it when I get the other junk cleared from around / on top of it. I did pull the alternator out of the box that it was in and that was 14 pounds (the alternator, not the box).
> 
> ...


Yeah I did the same thing. The cord is a little annoying every now and then but it's so much easier to push around than that infernal gas engine. I can easily lift my electric with one hand. The gasoline mower probably weighs close to 200 lbs. I kind of feel like I'm vacuuming my lawn instead of mowing it from the noise.


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## dbotos (Aug 18, 2010)

rillip3 said:


> Yeah I did the same thing. The cord is a little annoying every now and then but it's so much easier to push around than that infernal gas engine. I can easily lift my electric with one hand. The gasoline mower probably weighs close to 200 lbs. I kind of feel like I'm vacuuming my lawn instead of mowing it from the noise.


Funny you should mention that - my wife did some mowing with it for the first time today and said she felt like she was vacuuming.


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## Crash (Oct 20, 2009)

dbotos said:


> I actually passed enhanced CA emissions with mine when I lived out in Aliso Viejo. But it was still never a gas sipper...
> 
> I've got my gas tank, but it's kind of buried right now. I'll have to weigh it when I get the other junk cleared from around / on top of it. I did pull the alternator out of the box that it was in and that was 14 pounds (the alternator, not the box).
> 
> ...


Yeah, I had to replace the alternator after the motor leaked oil on it and messed it up good. That thing definitely wasn't light and installing it was a pain in the butt since it's practically under the damn motor and there's no spring-loaded tensioner. 

I was going to use the Kokam 70AH or 100AH batteries but I never actually decided since I didn't find a motor/controller combo I liked. Kokam are the lightest of all the batteries that I've seen and my goal was to keep the car below 3000Lbs including my own weight (150Lbs). Eventually I decided I wanted to go high voltage and low current and started toying with the idea of 40Ah Kokam batteries since they can peak 400A and they're really light weight. Distance didn't really matter to me (and still doesn't) as long as I can get at least 40 miles out of them.

And BTW, I have an electric lawn mower too.  Still makes a bit of noise, but nothing compared to our old gas mower.


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## Nomad (May 8, 2009)

I am very interested in this build, so please keep us updated. I've found a 1990 and will be stripping it down as well.


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