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Discussion Starter · #1 ·
Howdy,

I purchased a 59 Sprite this weekend that was converted to EV in 2006 using lead acid batteries, back then it had a range of about 25 miles. Those batteries are now very dead and I'd like some advice on how to proceed. I've included pics of the electronics and motor. If I can get in to the rear storage area (there is no trunk) I'll take pics of the other equipment. Any input would be appreciated!

Thanks,
Mark
 

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Big things are your range goals and what voltage is required by the motor. Used OEM batteries (from a Leaf, Tesla, Bolt) etc, tend to be the best and the cheapest. You should be able to get to the ~140V range pretty easily.

You'll probably need to buy a battery management system, charger, and charge controller which can run a couple thousand bucks (lithium batteries are less forgiving than lead acid and catch fire). You'll also probably wind up with a couple thousand worth of batteries. The upside is that, for the same weight and space, the car will fly and go a lot farther.

Tesla modules are the best, but they're large, not cheap, and like liquid cooling. Bolt batteries might be the best $/kWh deal going, with 2017 cars selling for $10-15k...The trick there is that you have to buy the whole car! Leaf packs are good, air-cooled, easily reconfigured, and are pretty easy to find for cheap. Hybrid batteries might work for you, too. Electric GT also released their "OX" batteries that seem great, but are pricey, and not too many have been seen in the wild yet.

There are a lot of ways to go about this...Big thing is to figure out the space you have, and start putting the pieces together...I expect all the bits that make the car "go" can stay as-is, but the charging stuff will probably have to come out. You might want to pull out the batteries fully and see what you're working with.

The longer you wait to buy batteries, the more you'll probably get for your money...but there's a lot to be said for just getting some modules to see if the motor is spinning, controller is working, 12v battery is charging, etc, etc...
 

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Discussion Starter · #3 ·
Thanks Tremelune!

The batteries are out so the engine compartment is basically empty. Do you think the existing motor will suffice or should I look at replacing it too?
 

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Tough question. Since you have a few forward gears, it's probably fine if it doesn't spin very fast, and even if it's rated to a mere 21kW, you might be able to push way past that for longer than you think...I don't really know...but I might be inclined to just go for it. Worst case you can pull it out as planned anyhow! I've never messed with DC motors, but they seem to take a ton of abuse. I suspect you'll always be torque-limited by the gearbox in that car.
 

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Discussion Starter · #5 ·
They took out the gearbox and had a custom drive shaft connector made, so it's a straight shot from the motor to the wheels. Unfortunately I don't have the original motor/gearbox so would have to find one on salvage to go that route. This would also mean re-engineering the car. I'd rather just replace the current motor if that was the case. There is already some water cooling in place for the motor and inverter.
 

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Interesting. That's not a bad setup, but it does beg for a motor with a whole lot of torque. How is it mounted to the car? Is this motor any kind of "standard" size/shape?

I'd probably still do the same thing: Put in some lithium batteries and see how hard you can push the motor before it heats up too much or gives up the ghost entirely...Monster-torque DC forklift motors aren't too costly a component to come by.

Might as well hit us with some shots of the engine bay and battery boxes.
 

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Discussion Starter · #7 ·
Kinda hard to see but the engine bay pic is without batteries. The battery jig pic is what the engineer created to hold the 29 lead acid batteries. There is a pic of the batteries against the wall in my small garage. There is also a pic of the the batteries in the engine bay with wiring, and one from a few feet way. And the obligatory pic of the car as she is now. :)
 

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Hi,
besides from the batteries this is a pretty "modern" conversion. The induction motor (not DC) allows more power output temporarily, as you can read on the label the 21kW is rated in S1 mode (=continuous). Water cooling does help.
Lithium batteries will reduce the weight considerably (-75%), and if you install enough of them they will deliver the needed current. As Tremelune wrote, that motor might give you sufficient power, the inverter also seems capable to provide it.
(From what I have read about MES-DEA, they made the communication stuff rather complicated. Could be tricky to implement other components like charger/BMS, or to change parameters.)
I am looking forward to your modernization's progress!
Markus
 

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Wow, a great project! Great car, looks to be in good shape. Looks like a good controller and motor also.
My free advice for what it is worth is:
You will want to keep your voltage high to stretch out the torque curve to make up for no transmission.
All batteries have pros and cons so get the ones that can be configured to your itty bitty car.
I have Enerdel batteries and I love them. Bought them new old stock for cheap for 3500 They can easily be disassembled to the cell level and reassemble. I even have one battery block with the positive on top and negative and bottom and then laid the battery on its side.
For a battery monitor, I have the old Orion BMS. The new Orion 2 has the capability to talk to DC fast-charge stations.
I have a much larger car "a spitfire " and still do not have enough room and weight capacity for an onboard charger.
So I will just charge at home and if I do go for a drive of more than 60 miles, I will throw the Manazita charger in the trunk, where it would live any way.

Good luck
and keep us posted
 

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Discussion Starter · #11 ·
Great advice guys!

I finally got my hands on the software for the TIM so I'm a big step closer.
For some reason <cough, beer>, I forgot about this thread and started a new one which has some good advice as well. I'll probably post future updates to that thread if you're interested in following:

Scotty2u, no idea. That's the craigslist pic from the owner. The car was being stored at a hanger at the airport with a couple of planes, one of which was a Beechcraft Bonanza, which was cool to check out.
 
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