General > General Technical Chat

Electric car for £9500?

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tom66:

--- Quote from: nctnico on October 05, 2023, 10:21:37 am ---
--- Quote from: tom66 on October 05, 2023, 09:05:22 am ---
--- Quote from: Simon on October 04, 2023, 05:25:03 pm ---Note that the OP gave no boundaries to what this car would be other than price and performance. So, lets think outside the box. In my odd trips to the scrap yard I see cars with early noughties registration plates on them, so 20 years old. Why are they scrapped I ask? Fag tray is full, or more usually they can't be bothered to replace the cam belt, stuffed engine. So here we have a complete car, just missing a working engine. Why not replace with an electric motor and some batteries?

--- End quote ---

An old car is unique; it might have rust, worn suspension, it might have one type of rear axle or another,  different braking systems, different final drive, etc.  Where is the engineering resource to design hundreds of custom systems for these vehicles and find places to fit electric motors and batteries?  And all this work on a car that might last 5 more years before having to have substantial overhaul?

--- End quote ---
I don't think Simon is writing about rare classic cars but common models build to reasonable quality standards like a Toyota Corolla, Ford Focus / Volvo V50, etc. The models that got sold in the hundreds of thousands with very little variation between them. There are two things that really wear on a car: the engine + gearbox and the suspension. If you do a complete suspension overhaul (which sets you back around 2.5k euro), you have a car that drives like new from the factory and has lots of life left. Still, for a battery conversion you'd need to have a place to put the batteries in an existing car which isn't very easy as it has not been designed to accomodate a battery pack. That is where the conversion gets labour intensive and thus expensive.

--- End quote ---

A car is more than just driving though.  You need DC-DC converter for 12V stuff, you need climate control, possibly air con, you need a radiator for the electric system and A/C (even if the electric rad is smaller),  you need to fit a charge port, you need to make sure all of the safety systems like airbags, ESP, ABS etc work ok.  All EVs need A/C because the battery pack needs cooling when charging (this is why even the 15kEUR Dacia Spring has A/C).  You need to replace the vacuum brake system with an electronic brake pump.  The dashboard needs to read speed and fault codes correctly.  The gearbox and clutch need replacement or adjustment to work right, it would probably want locking in 3rd/4th gear which could create unusual wear due to high motor torque.  All of this needs to be safe and reliable for 100k+ miles.

You might be able to build a package for something like a Mk4 Golf and save those from the recycler, but you'd have to have thousands of customers willing to pay 20kEUR+ for what is essentially an old slightly knackered Golf that's electric.  Meanwhile you can buy for not much more something like a brand-new e-208 or a second-hand e-Golf.  It would be a tough sell I think.

Simon:
Car conversions are a waste of time. it is bad enough that you can buy an "electric" car that is not more than a rushed conversion by the manufacturer from chitty chitty bang bangs to electric in the "design", they are generally awful. there is an MG car that only uses the hydraulic brakes in cruise control, because they did not want to re integrate. My cupra born does not seem willing to use the hydraulics when it has run out of regen braking, at least that is the impression I got when someone pulled out ahead of me and the car went bannanas and apparently could not slow down enough unless I slamed my foot on the brakes.

It's a shame that basically you can't buy a decent car these days, they are all crap unless you are minted.

coppice:

--- Quote from: Simon on October 05, 2023, 05:32:25 pm ---My cupra born does not seem willing to use the hydraulics when it has run out of regen braking, at least that is the impression I got when someone pulled out ahead of me and the car went bannanas and apparently could not slow down enough unless I slamed my foot on the brakes.

--- End quote ---
If that was in adaptive cruise mode its normal, and has nothing to do with the regen vs hydraulic braking split. If you look at the manual for most ICE powered cars with adaptive cruise they say the automated braking will not apply more than 40% or 50% of total available braking. I haven't seen one that explains why. Around town, when the collision avoidance braking kicks in, that can be quite aggressive. A pigeon crossing quite close in front of my car one day produced very heavy braking, so the automated system is capable of an emergency stop, even though that one was spurious. Its a good thing nobody was close behind me.

tom66:

--- Quote from: coppice on October 05, 2023, 05:46:30 pm ---
--- Quote from: Simon on October 05, 2023, 05:32:25 pm ---My cupra born does not seem willing to use the hydraulics when it has run out of regen braking, at least that is the impression I got when someone pulled out ahead of me and the car went bannanas and apparently could not slow down enough unless I slamed my foot on the brakes.

--- End quote ---
If that was in adaptive cruise mode its normal, and has nothing to do with the regen vs hydraulic braking split. If you look at the manual for most ICE powered cars with adaptive cruise they say the automated braking will not apply more than 40% or 50% of total available braking. I haven't seen one that explains why. Around town, when the collision avoidance braking kicks in, that can be quite aggressive. A pigeon crossing quite close in front of my car one day produced very heavy braking, so the automated system is capable of an emergency stop, even though that one was spurious. Its a good thing nobody was close behind me.

--- End quote ---

Yeah, this is definitely the case. My ID.3, which is essentially the German-badged version of the Born, is limited to somewhere around 50%.  I've had it light the collision warning up when approaching stopping traffic, it's essentially saying "I've reached maximum braking authority, you need to do more!"

As for hydraulic vs regen, not true at all. Braking performance is identical in ACC, it will modulate as required to reach equivalent deceleration. Regen is only about 10% of the total braking capacity of the car. Enough for normal usage, but certainly nothing like pressing the brake pedal even moderately hard.  So full battery with no regen doesn't make much difference and the control loop compensates by applying brakes more when battery is full if it's not slowing fast enough.

In 'B' mode this doesn't apply, since 'B' is just "max regen when not pressing the pedal", you need to press the brake pedal if you need more deceleration -- at a guess this is not done because you might not realise the brakes are being pressed while going down hill and therefore could overheat the brakes unknowingly.

Simon:
well I've not read enough of the manual to know the details but it is like, I can be in D mode and it will slow down by itself for a junction - only the junctions in it's database which makes it only semi functional - so you think cool, a bit like partial cruise control, will slow down for speed changes too. Oh but if there is a car in front of you it will do nothing and scream blue murder, I mean what the fuck is all that about. If it is strict adherence to law then they should not put such half cocked features in that turn out worse than nothing, or is it simply poor integration. The car has the ability to detect something ahead and slow down but in this driver assist mode it won't. It makes the thing so complicated to drive in a mode that is supposed to make life easier that you may as well turn the lot off.

Oh and don't beleive what cupra say about fitting a better media controller or whatever you call the screen, it's awful!

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