[DRIVING] Porsche Boxster 986 Tesla conversion [FINISHED]

[Boxster EV]

Hi, good find.
I wouldnt bother with connectors though. You can make your own flanges from plastic and new cables.
I am interested in what happened to DCDC that you had to open it.

Thanks - I'll replace the flanges/connectors as you suggest if I cant find another connector.

Regarding the DCDC, I just wanted to replace the HV wires to the correct length for my conversion and fit crimped eyelets. That's all.

What is your solution for BMS?

You can see my blog for control of DCDC and charger.
https://leafdriveblog.wordpress.com/201 ... a-charger/
https://leafdriveblog.wordpress.com/201 ... dc-or-apu/

Thanks. I'm going with SIMPBMS

[Boxster EV]

A few more updates:




Hacking out the fuel tank:







Batteries all wired in. I'm amazed that despite not receiving a charge in over a year and being used for EV testing, they still hold 350v.

[Boxster EV]

Jobs to do this week:

1) Finish off the LV wiring and test system at full HV.

2) Start wiring in BMS

[Boxster EV]

[Boxster EV]

A few pictures repairing and modifying charger and mounting it into the car:

[Boxster EV]

[bulletbug]

Looking Great! In your contactor box, would you mind sharing the part numbers of both your 2 large contactors and the 1 smaller one used in precharge?

Also, what size are the 2 resistors?

Thanks

[Boxster EV]

Looking Great! In your contactor box, would you mind sharing the part numbers of both your 2 large contactors and the 1 smaller one used in precharge?

Also, what size are the 2 resistors?

Thanks

All purchased through zero-ev.co.uk. They're available in their webshop. Not cheap but the quality seems excellent.

[Boxster EV]

Small update: The layout and position of the batteries and HV junction box has been bothering me. With the existing design, there’s a huge amount of unused space in the mid-engine bay, frunk and boot and in reality some consolidation was needed. Last Friday evening I put the thinking cap on and quickly starting ripping out many weeks’ worth of work to review the design. I’m so pleased I did as the revised solution works so much better in space efficiency and technical terms. Here’s a summary:

• The bulky HV junction box is now mounted inside the mid-engine bay. It hovers above the drive unit on two 25mm aluminium box sections and is secured to the car’s frame rails. This is a major improvement electrically too. It means I don’t need to modify the Chevy Volt BMS harness at all, the battery HV cables are a fraction of the length making them safer, and the drive unit can connect directly to the HV box without extending its cables.

• The small and medium battery modules are now be mounted in the boot – they just about fit with the use of some custom brackets and rubber bases. In time this may change again as there is space for them to hang under the boot.

Presently I don’t have the inclination to do the fabrication work. It’s something I can come back to if it bothers me, but I doubt it will. It means the boot can now be used for two batteries and most electrical services including LV junction box, BMS junction box and LV bulkhead connectors that run to the front of the car for the charger integration and DCDC communications.

• The frunk is now completely empty and free for luggage once again – back to OEM. The charger will remain behind the front bumper and the DCDC in the fuel tank area – perfect locations for these items on the Porsche 986.

[arber333]

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.

[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.