Converting Fuel to EV

[bobski1]

Getting bored so thinking about a project and one which has come up is to convert an existing fuel car to EV. Plan is to have something functional around town, nothing too long distance. Just to make sure of an old car and to engineer something because what else is there to do.

Question in old top gear form, how hard can it be?

Parts required so far are:
-Battery
-Inverter to convert AC to DC
-Motors x2
-HV to LV convertor
-Charging system
-Control system

Is it easier to just rip it all out of an existing salvaged car or is it possible to piece together from different areas.

[Brian_996TT]

there was a tv show called vintage voltage and the majority of the work is fabrication. They used Tesla motors in most i think.

[Knoxville2410]

Wheeler Dealers did this a few years ago on an old Maserati too... https://wheelerdealers.discoveryuk.com/episode/sea...

[uknick]

You could convert a TVR to electric like these three wise men did;

https://www.youtube.com/watch?v=PCSNCs7bwCw

[Spunagain]

bobski1 said:

Getting bored so thinking about a project and one which has come up is to convert an existing fuel car to EV. Plan is to have something functional around town, nothing too long distance. Just to make sure of an old car and to engineer something because what else is there to do.

Question in old top gear form, how hard can it be?

Parts required so far are:
-Battery
-Inverter to convert AC to DC
-Motors x2
-HV to LV convertor
-Charging system
-Control system

Is it easier to just rip it all out of an existing salvaged car or is it possible to piece together from different areas.

To that list a few more bits spring to mind:
Battery management system (protects from fire and also detects and protects HV shorts to chassis)
Pumps, rads and hoses to cool (and warm) the battery and cool the motor controller (and sometimes the motor) Along with relays and temp sensors to turn them on when needed.
Charging connector and interface box so you can plug it in!
Cooling plate to get cool water onto the motor controller
Vacuum pump and vacuum reservoir for brake servo if you have it.
Electric steering pump for power steering if you have it.
HV High current cables and connectors (and hydraulic tool to apply connectors to cables)
2 main Contactors (big relays) to isolate HV+ and - Lines
Big fuses.
Shunt (basically low value hi current resistor to allow controller to know what current is going in and out of the battery)
Electric heater to replace heater matrix + Contactor and switch gear to control it.
Robust metal boxes for the batteries to protect slow down fire spread and secure way to fix them down so they do not fly off and kill you in a crash
Way to interface the motor control system to the any existing traction control or ABS system (it is not legal to just disconnect it)
Interface plate to bolt the motor onto your existing gearbox (not cheap to buy - better to make if you have skills!)
Mounting bracket to mount motor to chassis which can handle extra torque.
Way of interfacing to your existing gauges or but extra guages for motor controller and BMS. (You can get a widget to bolt onto the motor that outputs the coil signal which can attach to a typical tacho but EV motors can rev to 10K so you might need a new one)

There are good motor and controller kits out there for about £4k with manuals and lots of on line experience (look at EVWest in USA) They also have schematics showing what you need.
There are homebrew boards which can drive OEM motors but these need more knowledge and need lots more research

The ECC guys make it look easy but there is a lot to it if you want a safe conversion!
A simple set up with Hyper 9 and 5 Tesla modules will cost in parts I reckon about £17k to 20k
Plus you may need to beef up the gearbox, drive shafts and brakes if the motor is more powerful than your old ICE motor!


I recently costed up the EV parts to take a solid Sprite or Midget and convert it - so no power steering or brake servo. It looked like this (including VAT):

Item	Amount
Rear brakes	£1,277.04
Front brakes	£849.48
Rear suspension	£295.75
Front suspension	£692.18
Wheels	£402.34
Tyres	£200.00
Hyper 9 Motor Kit	£4,580.60
5 Tesla Batteries	£5,000.00
2 Battery boxes	£1,000.00
Charger kit	£2,183.66
BMS	£1,459.91
Anti Roll Bar	£77.99
Springs	£46.18
Uprated Type 9 Gearbox	£2,860.73
Uprated diff and pinion set	£237.84
Rear traction link	£566.17
Motor adapter plate	£1,200.00
Cables	£200.00
heater core	£149.93
DC DC connverter	£300.00
water pumps	£156.00
TOTAL	£23,735.80

This would be a straight forward way to do it using well documented kits and parts that we know work well together.
This is the higher end approach!

You can do it much cheaper using a DC motor from an old fork lift and batteries from an old Nissan leaf, but they are much bigger and heavier for the same kWh or range. Or even go Lead acid but have a crap range and performance.
You can make a 13.7V DC to DC converter out of an old PC power supply.
You can get pumps from scrap yards
You can either dial down the torque and power or buy a lower power motor so no drive train upgrades.
You can make a heater matrix out of an old hairdryer.
You could skip the BMS and risk a fire - please don't do this!
But each of these may reduce your reliability performance and range and increase the complexity and likelihood of things not working and letting all the smoke out of the wires!
It all depends on your patience expertise and wallet!

I would love to have the skills of Mr McGuire and his 1k euro project: https://www.youtube.com/watch?v=qR1y9947j-c&li... amongst many others.

Well worth a watch!

Edited by Spunagain on Thursday 11th February 16:32

[gangzoom]

Don't forget to check up on your house/garage insurance for electrical fires

https://youtu.be/WdDi1haA71Q

[Spunagain]

I would add a smoke detection system to my charge controller to my build! (one day)

I would also add a smoke detection and fire suppression system to the garage.
Actually I should do that anyway with my TVR sitting in there on the 12 V trickle charger!

[No ideas for a name]

Brian_996TT said:

there was a tv show called vintage voltage and the majority of the work is fabrication. They used Tesla motors in most i think.

They always seem to leave the old gearbox in ... surely it would be much better if this was to come out.
As far as I can see, the clutch, flyweel and box are all redundant.

[Chris-S]

If you make any chassis/monocoque modifications that involve cutting or welding, then in the UK it'll need an IVA as well. If you can do it with purely bolt-in bits then it's a bit less onerous.

It's been done often enough, but to do a decent job it isn't cheap.

This is a decent summary of what's needed to do a good job:

https://www.youtube.com/watch?v=PX5XE5mMF38


And if you just want a dangerous POS to hoon about in, then try this one:

https://www.youtube.com/watch?v=eRnFzklXi4o

[gmaz]

No ideas for a name said:

They always seem to leave the old gearbox in ... surely it would be much better if this was to come out.
As far as I can see, the clutch, flyweel and box are all redundant.

They are, but it I guess it is a very convenient way to get the power to the wheels and mount the motor to the clutch bell housing. Surely there would be some way to connect the motor directly to the prop shaft and avoid the losses and extra weight of the gearbox?

[so called]

I knew a guy in the US who converted a TVR Tasmin.
It was a very tidy job.
Unfortunately I don't know any details. I dont know what the electric motor. etc were from.

[aestetix1]

You can get a lot of what you need in kit form. People make circuit boards designed to control Nissan or Tesla gear that can be salvaged from wrecked cars.

[Evanivitch]

Spunagain said:

I would add a smoke detection system to my charge controller to my build! (one day)

I would also add a smoke detection and fire suppression system to the garage.
Actually I should do that anyway with my TVR sitting in there on the 12 V trickle charger!

You don't want smoke detection, that's too late. A good thermal detector would alert you if your batteries are going into thermal runaway.

And then lithium can only be extinguished by completely quenching it I.e. drop it in a big bath. Handheld extinguishers will achieve absolutely nothing.

[gangzoom]

Evanivitch said:

Handheld extinguishers will achieve absolutely nothing.

Am pretty sure this guy knew that, but when the S*** hits the fan, our brains go into auto mode and starts doing crazy things like trying to blow out a lthium ion battery fire as though its a candle on a birthday cake

Theres also a post on the Tesla forums about a chap who wired in his own Tesla charger, and ended up burning down half of his garage......The lessons appears to be unless you know what you are doing, don't mess with these things, but that would make a very boring world if everyone followed sensible advice!!

[Evanivitch]

gangzoom said:

Am pretty sure this guy knew that, but when the S*** hits the fan, our brains go into auto mode and starts doing crazy things like trying to blow out a lthium ion battery fire as though its a candle on a birthday cake

Theres also a post on the Tesla forums about a chap who wired in his own Tesla charger, and ended up burning down half of his garage......The lessons appears to be unless you know what you are doing, don't mess with these things, but that would make a very boring world if everyone followed sensible advice!!

I watched the video and did chuckle, but completely gave them benefit of the doubt given how experienced they all are. I certainly wouldn't have been touching the fried remains bare handed, there's a lot of heavy metal going on there. But again, I respect the guys for what they've achieved in the past.

ETA - Did you see the video of the RS6 with Tesla pack? It looked reasonably good until he mentioned he'd put two battery modules where the radiator used to be and had zero cooling.

[Spunagain]

The one thing that worries me about some of the "professional" conversions is that they have used Tesla Model S packs and have not fitted water cooling. One of the key parts of the design (stated in the Tesla patents) is that compromised cells are protected from thermal runaway by the circulating coolant. With out that, a week or damaged cell could (in my opinion) easily go into thermal ran away and catch fire. If you are either charging or discharging a Tesla pack I would always run a coolant pump and also have a timer to run on for a while afterwards (like the old Renault 5 GT turbo cooling fans)

[Evanivitch]

Spunagain said:

The one thing that worries me about some of the "professional" conversions is that they have used Tesla Model S packs and have not fitted water cooling. One of the key parts of the design (stated in the Tesla patents) is that compromised cells are protected from thermal runaway by the circulating coolant. With out that, a week or damaged cell could (in my opinion) easily go into thermal ran away and catch fire. If you are either charging or discharging a Tesla pack I would always run a coolant pump and also have a timer to run on for a while afterwards (like the old Renault 5 GT turbo cooling fans)

That's not quite true. A good BMS/thermal monitoring system is what monitors cell temperatures and keeps the cells from approaching thermal runaway.

A coolant system only increases the ability to dissipate the energy from working the batteries hard and reduce the temperature rises, thus allowing the BMS to work the battery harder and for longer.

If the BMS fails to manage the temperatures, active cooling or not, you won't have the ability to quench a system in thermal runaway.

[Spunagain]

The Tesla bricks only have 2 temperature sensors in each brick and over 400 cells in each brick. If the water is not circulating I would be concerned that a cell a long way from either the temperature sensor could get pretty hot before it is detected by the BMS.