[DRIVING] Porsche Boxster 986 Tesla conversion [FINISHED]

[Boxster EV]

I see your DCDC mounting. Good use of space available. However if you read Volt manual this APM(DCDC) was considered IP51 protected, that is why they put it inside the cabin. I would advise you to make a screen in front of DCDC that would repel moisture.

Thank you for the advice.

Hopefully it wont be a problem as all the under-trays still need to go back on the car and it's hidden behind the frunk bulkhead, and reasonably high up comparatively speaking. I've also fused it.

In all honesty I probably wont use the car too much during the wet.

Here's how it presently looks:

[Isaac96]

Hi,
I've been following this conversion with interest as I have been working on a similar Boxster S for about 3 years now - had it running but then had battery issues and decided to rebuild the inverter with a Huebner system, as well as converting to liquid cooling. Almost back on the road.

I'm mounting all my batteries in the engine compartment along with a Siemens motor running with the transmission. I see that you have about half the Volt battery in the engine compartment. Are they just mounted straight to your motor support system?
Thanks!
-Isaac

[Boxster EV]

Hi,
I've been following this conversion with interest as I have been working on a similar Boxster S for about 3 years now - had it running but then had battery issues and decided to rebuild the inverter with a Huebner system, as well as converting to liquid cooling. Almost back on the road.

I'm mounting all my batteries in the engine compartment along with a Siemens motor running with the transmission. I see that you have about half the Volt battery in the engine compartment. Are they just mounted straight to your motor support system?
Thanks!
-Isaac

The larger of the three banks sits across the frame system inside the engine bay. It rests on the original volt battery tray which has been cut to size and reinforced with some steel box sections welded on. It's then bolted onto the frame.

The weight of the Tesla drive unit and battery bank that the frame system is supporting is connected to the bolt holes of the original front engine mount (and rear mounts). The whole system is still less than 100kg lighter than what the same bolt holes were supporting with the OEM ICE.

It will be very tight to stack another bank of volt cells on top. It's doable but not without more fabrication and grief.

Hope this helps.

[Isaac96]

The larger of the three banks sits across the frame system inside the engine bay. It rests on the original volt battery tray which has been cut to size and reinforced with some steel box sections welded on. It's then bolted onto the frame.

The weight of the Tesla drive unit and battery bank that the frame system is supporting is connected to the bolt holes of the original front engine mount (and rear mounts). The whole system is still less than 100kg lighter than what the same bolt holes were supporting with the OEM ICE.

It will be very tight to stack another bank of volt cells on top. It's doable but not without more fabrication and grief.

Hope this helps.

Yes that is very helpful. As I've retained the original transmission I chose not to mount the batteries to the engine mount, instead I have a frame member under that area connected to the diagonal braces. Incidentally I was looking at your previous pictures; I seem to have a similar power steering pump. However I placed the vacuum booster in the frunk just to have a shorter run.
How are you cooling the LDU? Will you use the original radiators?

-Isaac

[Boxster EV]

A couple of updates from the past month or so:

OEM automatic shifter installed (car was a manual):



Commisioned the charger and SIMPBMS:




Homemade EVSE control:

[Boxster EV]

Bit of MOT prep:



Shakedown testing:

[Boxster EV]

Additionally I've been testing drive unit parameters by using Jon and Damien's as starting point. Couple of questions for those that know:

1) Despite my best efforts I can't get my drive unit logic board to work on the latest firmware and have reverted back to 4.56 (which works fine). 4.79 uploads with no issue, but the inverter just hums at me and does nothing else. Anyone else have this issue?

2) I'm considering installing an HV contactor in-line with my Volt charger (it's already fused) which is connected directly to the battery. This is because the charger is at the front of the car behind the bumper and in the event of a fender bender there will be no danger of the HV shorting out. The idea is that it'll close upon activation of my charger and open when not in use. Can anyone see any reason why this isnt a good idea? Any concerns over current rush etc....?

[Kevin Sharpe]

Can anyone see any reason why this isnt a good idea? Any concerns over current rush etc....?

I'd connect the charger direct to the battery and use a collision sensor to cut 12V power to the contactors. If you follow what the OEM's do you can't go far wrong

[Boxster EV]

Can anyone see any reason why this isnt a good idea? Any concerns over current rush etc....?

I'd connect the charger direct to the battery and use a collision sensor to cut 12V power to the contactors. If you follow what the OEM's do you can't go far wrong

Do you have a link to one of these sensors, please? Ideally something that can be used in a EV conversion scenario / by a DIY'er.

[Kevin Sharpe]

Do you have a link to one of these sensors, please? Ideally something that can be used in a EV conversion scenario / by a DIY'er.

We've used the AC Delco D1876D Inertia Switch in the past, they are often used as fuel cut-off switches on OEM vehicles;

https://www.ebay.com/itm/Fuel-Pump-Cuto ... 3713650226

We usually wire them in series with the emergency cut-off switch which kills 12V to the contactors, inverter, etc.

[Boxster EV]

Thanks for the advice, Kevin.

Just wanted to provide an update to the cheap Chinese Dracarys brake vacuum sensor. It’s junk so I binned it. Worked perfectly for a month or so then started playing up.

I’ve upgraded it to the multicomp PSF109S-81-330 as recommended. It now works as expected with the pump kicking in every few presses of the brake pedal. Cost was £30.

Installed on my Porsche:

[arber333]

Well yes Dracarys switch can act up. But really it is just a mechanical switch with brass body, membrane, nut and spring. You torque the internal nut and increase pressure so equilibrium is reached sooner or later.
Whenever it acts up i remove it from my car and clean it up and reset the spring. This spring sometimes wedges against membrane and switch is allways on or wont work. After i cleaned it, it works as before.

[Boxster EV]

Well yes Dracarys switch can act up. But really it is just a mechanical switch with brass body, membrane, nut and spring. You torque the internal nut and increase pressure so equilibrium is reached sooner or later.
Whenever it acts up i remove it from my car and clean it up and reset the spring. This spring sometimes wedges against membrane and switch is allways on or wont work. After i cleaned it, it works as before.

I just don't want to have to worry about 'servicing' it every few months. Better to just buy the unit above and be done with it. Also, the multicomp version is adjustable. I've done 250 miles on the car since fitting and very pleased with the braking performance.

[arber333]

I agree. I need to warn you though, i used the PSF109S switch in my car. After couple of years of use i saw its contacts rusted out since they are exposed to elements. If you put the switch in a box then i think it will not rust.

[Boxster EV]

I agree. I need to warn you though, i used the PSF109S switch in my car. After couple of years of use i saw its contacts rusted out since they are exposed to elements. If you put the switch in a box then i think it will not rust.

Thanks. it's already inside the car (in the frunk) so it should be fine. I'd be happy to service or replace it every few years if necessary.

[Boxster EV]

A few more updates:

I placed all of the carpets back in the frunk (you can just about see the wires for the vacuum sensor):

A little tidying up of the HV junction box, but still more to do:

Fitted a battery brace to the middle battery:

The car is driving really well and I'm starting focus on some of the 'nice to haves', such as getting all of the gauges working, lock pin for charge socket etc.

[Boxster EV]

The larger of the three banks sits across the frame system inside the engine bay. It rests on the original volt battery tray which has been cut to size and reinforced with some steel box sections welded on. It's then bolted onto the frame.

The weight of the Tesla drive unit and battery bank that the frame system is supporting is connected to the bolt holes of the original front engine mount (and rear mounts). The whole system is still less than 100kg lighter than what the same bolt holes were supporting with the OEM ICE.

It will be very tight to stack another bank of volt cells on top. It's doable but not without more fabrication and grief.

Hope this helps.

How are you cooling the LDU? Will you use the original radiators?

-Isaac

I'm using a Davies Craig EWP and one radiator (2.7 Boxster has two). Pump is just after radiator then drive unit, then batteries, charger and return. Drive unit hasn't got above 30 degrees. I'll need to incorporate a valve and battery heating as we approach winter.

[Boxster EV]

I decided to make a small panel out of ABS plastic to house the Nextion SIMPBMS display and also install a voltmeter gauge for the 12v battery. This little section replaces the redundant OEM CD storage slots. The finish is more than acceptable (the pictures don’t do it justice).

Any excuse to use Deutsch connectors too.

The attachment IMG_3985.JPG is no longer available

[tom91]

Looking good, its always great to get on to finishing touches like this on big builds.

[Isaac96]

Very nice! I hope you don't mind if I take inspiration from this

Have you thought about A/C compressors? In my Boxster I managed to find a couple of signals which tracked AC demand nicely; the AC control unit directly controlled the OEM compressor clutch but it also took advice from the instrument panel (so that wire had to be disconnected). I'll see if I can find the wires again and let you know.
-Isaac

[Boxster EV]

Very nice! I hope you don't mind if I take inspiration from this

Have you thought about A/C compressors? In my Boxster I managed to find a couple of signals which tracked AC demand nicely; the AC control unit directly controlled the OEM compressor clutch but it also took advice from the instrument panel (so that wire had to be disconnected). I'll see if I can find the wires again and let you know.
-Isaac

Cheers!

Thanks for the offer but I removed all of the AC lines and related hardware. It's a convertible and there really is no need for A/C in the UK 90% of the time. The added space after removing the hardware was also welcome (in front of the scuttle panel). I placed the control box for my EVSE and and 240vac relay coil there.

[Boxster EV]

Today I passed 800 electrical miles in the Porsche. The original petrol engine died on 95,801 and I’m now on 96,640. Car is fantastic. I haven’t visited a petrol station (for one of our ICE cars) since March.

During these electron powered miles I’ve had very little issue with the car. There was one mishap with a miscalculation of range and I had to nurse the car home, then another when my 12v battery decided not to charge whilst 10 miles away from civilization (old 12v battery not holding charge), however other than that it’s been trouble free.

I’m still getting an over current fault when pulling away from a standing start too quickly. This morning I stopped to wave a truck through on a tight bit of road, instead he returned the gesture, I went to pull away a little too hard and hit over current. The time waiting for the negative contactor to close before you can start pre-charge / ignition on felt like 5 minutes when it reality it was just 5 seconds and that feeling when you visualize the need to get out and push. in the end, no harm done and I went on my way.

I think the issue is boost related but despite lowering that parameter the flash doesn’t seem to always save it. I need to dig into this when time permits. Obviously it's not high on my priorities but it would be good to pull away at a green light without initially nurturing the throttle pedal.

Not that I’m into racing but a Porsche 911 decided to try his luck a few days ago. That didn’t end well for him.

[Boxster EV]

Latest update: my to do list on the car hasn't really been reduced. I've been too busy driving and enjoying the thing. I also pushed it to 58 miles on one charge last week which was pleasing.

Speaking of charge, I recently bought a Gen 2 Tesla charger for about 50% of the price they were going for a year ago. This'll be replacing my volt charger and hack job of an EVSE control (which does the job but was always temporary). Undecided where the new charger will be mounted, however as the Tesla unit isn't IP rated, it'll either be going in the frunk or the boot (along with the batteries).

I also need to install a charge locking pin, charge indication lights and get the stock dash gauges working (thanks to Tom Debree for providing the CAN DBC file).

I'd really like to resolve the OC issue mentioned in my previous post, as it's really the only thing holding the car back from a performance perspective.


Also threw a GoPro under the boot floor.

[Isaac96]

Hi,

It's possible your boost is too low or too high. I'm getting OC events (with Siemens drivetrain) when starting in 3rd gear or higher, due to the jitter of the motor (although I can burnout in 1st...)

-Isaac

[Boxster EV]

Hi,

It's possible your boost is too low or too high. I'm getting OC events (with Siemens drivetrain) when starting in 3rd gear or higher, due to the jitter of the motor (although I can burnout in 1st...)

-Isaac

This sounds like a similar issue. Doesn’t make much difference if I adjust the boost.