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Discussion Starter #1 (Edited)
1. Am fairly well versed in electrical components and OK with most mechanical procedures including unfamiliar ones with decent instruction.
2. Not looking to retain any legacy related to gasoline motive drive with the exception of perhaps building a master black box which intercepts certain signals like gas tank level and motor sensors to fool the onboard computer in to allowing all peripherally attached systems to continue to operate without complaint (ignition/wireless keys, alarm, breaks, power steering, etc). Need to put the car permanently in EV-only mode? Not sure if that's necessary if I fool the computer about engine functions running A-OK.
3. The point in conversion right now is gutting the car. I have removed the hybrid battery which I deem inadequate and old and am selling it on eBay to help pay for the new EV conversion parts
4. DO not expect to retain the car's transmission as it is highly integrated with the hybrid driver and gas engine, so direct motor drive to the drive shaft is likely how I will proceed. Permanent magnet DC motor?
5. Am worried about how the breaks on the car will perform with the loss of regenerative breaking as that is integrated into the hybrid drive which is being sacked. (The hybrid drive and engine were critically damaged by front end impact but the car frame looks good... hence the impetus to convert the car rather than replace all that expensive gear. Better to go gas free. I don't need a lot fo range.
6. Range expectations.: 20-40 miles would be nice. I'll accept less but not much less.
6. Budget: $3000. (is it possible?? used parts?? scavenged batteries??)
7. Battery preference: #18650 Lithium Ion batteries in individual plastic holders tightly packed to make a super battery. This way bad individual cells can be easily changed out. I expect it will be series/parallel to meet the requirements of the motor and any motor controller gear.
8. 12 Volt system to be step-down transformed from the high voltage lithium ion battery pack. There will not be an alternator because there will not be a transmission or an "idle" to turn one with reliably to make an alternator practical.
9. Top speed.. 65 would be nice but I'll accept 45 if thats what budget allows.
10. Acceleration: Doesn't need to be a dragster. Don't want cars behind me honking at me either to hurry up. A nice conservative to moderate pickup is fine. I don't want to be merely seeking over hill tops if I hit any but there will be few in this general locale and they are small and gradual.
11. Nu nuclear fusion garbage digesters are available for a decent price, so I guess I'll have to go with standard plug-in recharge with 120VAC slow charge overnight which is fine. That will work nicely with my self-made solar array at the house which is grid-tied.
12. Not too concerned about the loss of heater functions. It rarely gets to freezing here. I'd like to retain the air conditioning system if its not too damaged from the accident (unknown at this point)
13. Want to keep my efficiencies maximized for range, not power. To that end the less conversion the better. I'd like to go straight DC voltage through a controller reusing the existing gas pedal which has a dual rheostat type function, to a DC motor. DC to DC converter for 12 volt system. And do I need a pump or something for vacuum lines which are needed to run the air conditioner and other systems like power steering or brakes? (unknown to me yet)

Anyone with any experience to share please shed light on the practicalities of all of this and reasonable cost expectations to validate if I'm completely nuts or if I have the right general ideas here.

Thanx,

Matt
 

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4. DO not expect to retain the car's transmission as it is highly integrated with the hybrid driver and gas engine, so direct motor drive to the drive shaft is likely how I will proceed.
Do you really expect to connect a motor directly to the axle shafts? For one thing, unless you use two motors (one per wheel) you will need a differential so that the car can go around corners. Next, if you don't have some reduction gearing, the motor will turn at wheel speed, which is much too slow... you would need an enormous motor or motors to produce enough power at a such a low speed.

Every practical electric car has a reduction drive of some sort.
 

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7. Battery preference: #18650 Lithium Ion batteries in individual plastic holders tightly packed to make a super battery. This way bad individual cells can be easily changed out. I expect it will be series/parallel to meet the requirements of the motor and any motor controller gear.
An 18650 cell is a single cell, not a battery; a battery is a group of cells connected together. The car needs one battery, composed of many cells. There's no reason to call the car's battery a "super battery" just because it has a lot of cells... they all do.

This way bad individual cells can be easily changed out.
It's not so easy. Each cell is normally connected by a small wire which is welded to the cell; the wire is so fine that it serves as a fuse. It's hard to tell which cell is doing what once they are connected together, and hard to pull out and replace individual cells. If you don't have a robot building up the battery out of those little cells, it's easier to use larger cells.

I expect it will be series/parallel to meet the requirements of the motor and any motor controller gear.
Well, yes... motors of a useful size don't run on the less than four volts of a single cell, so you need a lot of them in series. At any reasonable voltage a useful amount of power is far more current than a single 18650 cell can produce, so you need a lot of them in parallel. In any battery made of such small cells, you will have at least a thousand cells.
 

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I have removed the hybrid battery which I deem inadequate and old and am selling it on eBay to help pay for the new EV conversion parts
Everybody else will consider it old, too, and inadequate for anything but direct replacement of a failed Prius battery... and Prius batteries are quite reliable. New Prius batteries are readily available, so there's not much reason to someone to put in your old one. Be realistic about the small amount that you might get for this battery.
 

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Discussion Starter #5
The Prius hybrid battery is not *that* old as it only has 5 years on it with a 10 year warrantee. It's not the original battery that came with the car, the original battery was damaged when I was rear ended on the freeway one morning by 3 pickup trucks behind me all hitting each other in a train line starting with me in the front. It cracked connections inside the battery and the damage went unnoticed by the collision people and Toyota for 2 years while I started seeing problems with acceleration dropping out on the freeway at random times and so it took so long the insurance wouldn't' back replacement by the time Toyota figured out what was going on after countless repair visits for reasons that weren't the reason and didn't fix the problem so Toyota was kind enough at that point to replace the battery under warrantee to make up for all the bogus repair bills of non-causes. Thus the battery is nowhere near the age of the car. No I wouldn't try to be selling an out of warranty battery. You think me crazy or something? It's been sitting 6 months without a charge and is still holding 212 Volts, so I don't think its so old nobody will want it... It seems sound still for a Prius but its not energetic enough for a full EV. The space is better spent on Lithium ION batteries than NiMH.
 

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Discussion Starter #6
An 18650 cell is a single cell, not a battery; a battery is a group of cells connected together. The car needs one battery, composed of many cells. There's no reason to call the car's battery a "super battery" just because it has a lot of cells... they all do.


It's not so easy. Each cell is normally connected by a small wire which is welded to the cell; the wire is so fine that it serves as a fuse. It's hard to tell which cell is doing what once they are connected together, and hard to pull out and replace individual cells. If you don't have a robot building up the battery out of those little cells, it's easier to use larger cells.

OK, let me correct my terms so we can have a more useful discussion here... Although its funny you don't find #18650 marketed online as "cells" they are sold as batteries by themselves. Argue that with the vendors. The #18650 cells were not going to be soldered or welded to anything they were going to be inserted into spring-loaded carriers just like sticking AAs into a common toy. Easy changeability. The carriers wiring would be soldered together in series parallel to achieve the correct voltage/amperage combinations needed.

If you wouldn't recommend using #18650s, what commonly available cheaper per kilowatt larger capacity lithium ions would you suggest and what kind of charging system?

Also, trying to pin down the exact energy toll, a Tesla is said to use 300 Wh per mile. I don't want a car that uses anywhere near that much and don't think it necessary to do so because I don't need Tesla style killer acceleration or top end. What could I more reasonably expect for a conservative build in terms of Wh/mile so I can figure out how many of what kind of batteries to get and how much the cost will be in the end.. ?
 

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The #18650 cells were not going to be soldered or welded to anything they were going to be inserted into spring-loaded carriers just like sticking AAs into a common toy. Easy changeability. The carriers wiring would be soldered together in series parallel to achieve the correct voltage/amperage combinations needed.
I'm not sure if you appreciate the currents involved here. Spring terminals are great for a flashlight or toy, but at the high peak currents of EV use, I don't think that's practical.

You could connect a set of cells in parallel to a bus bar with a soldered wire for each cell (so that each soldered connection carries the current of only one cell), but I doubt that you would want a soldered connection to carry the full current of the entire set. These connections are normally bolted together.
 

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If you wouldn't recommend using #18650s, what commonly available cheaper per kilowatt larger capacity lithium ions would you suggest and what kind of charging system?
The current trend, for a few good reasons, is to use modules salvaged from used production EVs. It usually doesn't make sense to break the modules down to the individual cells, but it is common to open the pack to take out the modules, and then re-arrange the modules both to package them in the vehicle, and to create the desired combination of series and parallel connections.

The most popular sources of used batteries are the most common EVs (the Tesla Model S/X and the Nissan Leaf) and the only common and high-capacity plug-in hybrid (the Chevrolet Volt).

You could buy individual 18650 cells, but it would probably be more expensive than buying used Tesla modules, and the modules come already assembled. Also, individually purchased cells are unlikely to be well-matched, and may not even be suitable for EV use; "18650" is just a physical format, and there is lots of variation of internal construction and cell chemistry between them.
 
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