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Discussion Starter · #1 ·
I am looking to convert a 1961 Willys Truck to an EV. I am trying to figure out the the correct motor (or motors) to use. I would like to keep the 4x4 and the original 3 speed transmission. I would like to use this truck to commute dailyt to work (40 miles round trip) and do some mild off-roading (rocks and trails) on the weekends. I am looking to have an all in cost of $10-15K.

I am really looking for suggestions on the motor or motors and pack size for such an endeavor, any help or opinions are appreciated.
 

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Great idea for a conversion. I have ridden and driven these and know them well. The are compact, relatively lightweight, and have an a really classic look. Those crazy pivoting pedals!

You can go a lot=t of ways, but with your budget, I would do a mix of new and used:

New:

AC-51 motor with Curtiss 144 Volt controller ($6K)
Some sort of Charger ($2K)

Used: Rejigger two Volt battery packs ($5K)

This leaves the DC-DC converter, battery monitor, throttle pedal, adaptor plate and other bits I'm not thinking of. I would build or at least partially build the adaptor plate myself.

At 88 HP you will be a little under stock, but it will have more HP through most of the RPM range.

Keeping the stock transmission and drivetrain I wouldn't go too high a torque motor.
 

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Discussion Starter · #3 · (Edited)
Great idea for a conversion. I have ridden and driven these and know them well. The are compact, relatively lightweight, and have an a really classic look. Those crazy pivoting pedals!

You can go a lot=t of ways, but with your budget, I would do a mix of new and used:

New:

AC-51 motor with Curtiss 144 Volt controller ($6K)
Some sort of Charger ($2K)

Used: Rejigger two Volt battery packs ($5K)

This leaves the DC-DC converter, battery monitor, throttle pedal, adaptor plate and other bits I'm not thinking of. I would build or at least partially build the adaptor plate myself.

At 88 HP you will be a little under stock, but it will have more HP through most of the RPM range.

Keeping the stock transmission and drivetrain I wouldn't go too high a torque motor.
Would it be advisable to use the "marine" AC51 for this application? I am worried about the occasional water crossing or mud hole that cannot be avoided.

On the batteries, what brand should I look out for? with a 2 volt battery I will be looking at 36 batteries for the total pack correct?
 

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Marine or not? 1961 Willys Truck Conversion

Would it be advisable to use the "marine" AC51 for this application? I am worried about the occasional water crossing or mud hole that cannot be avoided.

On the batteries, what brand should I look out for? with a 2 volt battery I will be looking at 36 batteries for the total pack correct?
I'm not sure whether the marine version would be necessary or not, that might be worth a conversation with HPEVS. Marine would be cool for sure.

I would lean towards building a water resistant enclosure setup for all or most of the electrical equipment under the hood. something lightweight riveted up out of .040 alclad perhaps.

That way if you get in a very wet situation your electronics are protected.

As far as the battery, I believe that the 144 volt Curtiss controllers can handle up to about 155 volts, so build a pack up to be between 144 and 155 volts fully charged.

You can see from this webpage that they come bunched in groups of 12 and 6 cells. I would string 36 together in series, you can make 5 of these which you will parallel together for about 32 KwH total 36S5P pack.

http://www.schultzengineering.us/delta-11-12.htm
 

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The only batteries that make economic sense for a conversion these days are batteries out of a crashed Volt, Leaf, Tesla etc. They vary in price, ease of re-use etc. but all are available in the US for a fraction of what the prismatic LiFePO4 batteries that people like myself used in their conversions. OEM batteries have a higher energy density per unit mass than the LFP cells we used too, so a pack of a given capacity will weight less too.

As to using an HPEVS set-up: be aware that the high voltage (144 V) controllers for the AC-50/51 put out 500 A, whereas the lower voltage (96V) units put out 650 A. Torque is proportional to current, so the lower voltage in this case gives you the higher torque...note also that 96V means 96V nominal- your pack can sit as high as 130 V when fully charged and that won't bother the 96V controller IIRC- best to confirm that with HPEVS.

Note that the Li-ion cells in OEM packs tend to be 3.8V nominal, 4.2 V peak (generally charged to less than that for longevity and safety reasons), whereas the LFP cells are 3.2V nominal, 3.6-3.8V peak. You'll need a different number of cells in series depending on your nominal voltage.

Note also that in my opinion you either NEED a BMS when using an OEM battery, or YOU will ultimately be the BMS. Realizing that screwing up just once can lead to a fire during charging might convince you that a BMS is mandatory, not just a nice idea. In my mind it's necessary safety equipment AND cheap insurance against unforseen problems. And I had one of those- one cell which mysteriously dropped in capacity relative to the others with no warning. Hasn't recurred, but my BMS prevented me from either over-charging or reversing that cell- not a huge problem either way (other than cost) for a LFP cell, but a potential disaster with an OEM cell. Others may differ in their risk tolerance, but on safety issues like this it's best to err on the side of caution in my opinion.
 

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Discussion Starter · #7 ·
With the suggestion of using readily available production packs, I see this most feasible as 3 - 48v packs out of a Chevy Volt (3 in series/2 packs in parallel). (what are the thoughts on this?)

I have a request in to HPEVS on the use of the marine AC51 and hope to hear back from them soon.

How have people handled the BMS systems (either oem or home brew)
 

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Re: 1961 Willys Truck Conversion BMS HPEVS AC-50 vs. AC-51

Myself I would skip an active BMS, just bottom balance and monitor. Too many are Battery Murdering Systems. Exception would be if I used LiPO or Tesla packs.

This is a controversial subject, I don't want to start a flame war, that is my opinion; you make up your own mind.

The AC-51 makes more HP, and gets the HP level closer to the original Hurricane motor. AC-50 is 67 HP, AC-51 is 88 HP.

If you have the time, watch EVTV from the beginning.
 

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Discussion Starter · #11 ·
With the suggestion of using readily available production packs, I see this most feasible as 3 - 48v packs out of a Chevy Volt (3 in series/2 packs in parallel). (what are the thoughts on this?)

I have a request in to HPEVS on the use of the marine AC51 and hope to hear back from them soon.

How have people handled the BMS systems (either oem or home brew)
After doing some research, I believe that the volt pack may be a little too much for a first time conversion. What more "bolt together" packs will still help give me a 40-60 mile range and be easier to configure for a first time converter?
 

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Discussion Starter · #14 ·
Re: Simpler Battery Packs

75 100Ah Calb CA cells would give you 24 KWh. Only $135 each.
So with those batteries it would be a 9s5p configuration to maintain the 144v nominal for the Curtiss 144 Volt controller. Just asking for confirmation.

This packaging configuration should be easy enough to build into the frame I have chosen. I understand there is more cost here but this should make the first conversion more successful.
 

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Discussion Starter · #15 ·
I am looking to convert a 1961 Willys Truck to an EV. I am trying to figure out the the correct motor (or motors) to use. I would like to keep the 4x4 and the original 3 speed transmission. I would like to use this truck to commute dailyt to work (40 miles round trip) and do some mild off-roading (rocks and trails) on the weekends. I am looking to have an all in cost of $10-15K.

I am really looking for suggestions on the motor or motors and pack size for such an endeavor, any help or opinions are appreciated.
I have had to make some changes to the design due to the constrains of components I have chosen. So here is the current plan for the conversion:

JKUish frame (Jeep Wrangler 2 Door Frame stretched to the Willys wheel base of 118", this is 2" longer than the Jeep JKU)
Dana 44 Front and Rear Axles for a Jeep JK
Jeep JK 6 speed manual transmission and transfer case (I had planned on using the original Willys Transmission and Transfer case but it has passenger side front and rear drop and the JK axles are Front Driver Drop and Rear Mid).

Basically I will be making a JK EV conversion with a Willys Truck Shell to give it a cool vintage look.
 

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75 100Ah Calb CA cells would give you 24 KWh. Only $135 each.
So with those batteries it would be a 9s5p configuration to maintain the 144v nominal for the Curtiss 144 Volt controller. Just asking for confirmation.
Why 9s? At 3.2V nominal, a 144-volt (nominal) battery would require 45 CALB CA 100 AH cells in series; 9s would only be 29 volts.

At 3.2V nominal and 100 Ah capacity, the energy stored per cell is nominally 320 Wh per cell, or 24 kWh for 75 cells. With 45 cells in series, you can't use 75 cells (75 cells would be 240 volts), but you could have:
  • 45 cells all in series (none in parallel) for 14.4 kWh @ $6,075 and 153 kg (338 lb) occupying 90 litres (3.2 cubic ft), or
  • 90 cells (two in parallel) for 28.8 kWh @ $12,150 and 306 kg (675 lb) occupying 180 litres (6.4 cubic ft)

Of course those costs, weights, and volumes are just the cells... without a battery box, wiring, or battery management system.
 

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Discussion Starter · #17 ·
Why 9s? At 3.2V nominal, a 144-volt (nominal) battery would require 45 CALB CA 100 AH cells in series; 9s would only be 29 volts.

At 3.2V nominal and 100 Ah capacity, the energy stored per cell is nominally 320 Wh per cell, or 24 kWh for 75 cells. With 45 cells in series, you can't use 75 cells (75 cells would be 240 volts), but you could have:
  • 45 cells all in series (none in parallel) for 14.4 kWh @ $6,075 and 153 kg (338 lb) occupying 90 litres (3.2 cubic ft), or
  • 90 cells (two in parallel) for 28.8 kWh @ $12,150 and 306 kg (675 lb) occupying 180 litres (6.4 cubic ft)


Of course those costs, weights, and volumes are just the cells... without a battery box, wiring, or battery management system.
thank you for the reply! I see the error in my calculations, I fixated on the 144v final voltage instead of using 75 or more cells. With this cost so high for 90 cells, is there another solution that would be a good balance of performance to price with having to purchase 2 wrecked Volt packs (or similar production vehicle) to put the traction pack together for my conversion? At this time I can not commit to a lower total range (60-miles) as my current work does not have a charger so I need to plan on charging at home.
 

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I have run the numbers a lot.

The Volt batteries are, as far as I can tell the best price performance ratio available today.
 

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Discussion Starter · #20 ·
Well I guess I will have to tackle this into my conversion.

What are the thoughts about commercial chargers like the GE WattStation? One have come available for $400? Should I snatch it up?


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