Suzuki Cappuccino Conversion

I've been slowly working on a box to contain all the electrical components over the last few weeks. This will be mounted on top of the battery enclosure where the passenger seat used to be. This means that I can have the majority of the wiring in one place and should keep things fairly simple. The box will contain two main contactors, the precharge circuit, the BMS, some charger circuitry, a JLD404 Ah meter (and shunt), an emergency stop button, a battery enclosure temperature display and a low voltage alarm/beacon (triggered by the BMS LV output). I've built the box and checked the positioning of all the components so I will be wiring this up over the next couple of weeks. Then I've got a bit of wiring to do in the 'engine' bay in order to be able to test the whole system with a power supply.

I've also mounted a forward reverse switch where the gearstick used to be. This is an illuminated switch which I've made a custom 3D printed housing for.

Hopefully I will have some exciting new developments over the next few weeks!

I've made some good progress over the last week. The majority of the low voltage wiring has been completed and I was able to power everything up today and spin the wheels!

It's still only on a 30V power supply as I've got the battery pack to sort out. I was able to turn on via the key and the forward/reverse switch and throttle worked perfectly. The precharge and contactor circuits seemed to work fine too.

The bad news is that I still have an intermittent problem with the inverter gate drivers/IGBTs. I had this before when testing on a bench but I decided to get it all wired in properly before investigating further in case it was a wiring problem with my test setup.

This is the process I went through today:

- I turned the ignition on, and then to the momentary start position after a couple of seconds. The power supply hit the current limit (20A). (no throttle input and neither forward or reverse selected)

- I knew the problem before had been related to the gate drivers/IGBTs so I unplugged the lead between the driver board and the first IGBT. The whole system then turns on fine and forward or reverse can be selected.

- I then plugged this lead back in. Everything turned on but the PSU hit the current limit as soon as I selected either forward or reverse. (no throttle input). If I then flick back to 'neutral' it stays at the current limit but if I turn it off and back on again it will be fine until I then select forward or reverse again.

- Unplugging the other driver-IGBT leads doesn't help at all so it seems related to the first IGBT lead that I unplugged.

- Eventually, after a few minutes of turning it on and off and fiddling with these leads I got it to the point where I could select forward or reverse without it hitting the current limit but upon applying some throttle the PSU would cut in and out and the motor would turn rather jerkily.

- It then started working perfectly, spun the wheel up fairly quickly without hitting the PSU current limit

- After taking some videos and enjoying seeing the wheels spinning for the first time it then stopped working again. This time there was no PSU current limit but the motor would only jerk back and forth however much throttle I applied (as if one phase was not working?).

- It then went back to hitting the current limit every time forward or reverse was selected

My feeling is that it is something to do with the gate driver or connections on the combi board. The intermittent nature makes me think it's not a parameter issue or a something broken in the power electronics. I had a few suggestions back when I was testing it on the bench that I still haven't tried but if anyone has any ideas let me know.

I have some videos of it working that I'll try to upload later.

Nice to hear from you. I'm keen to see it finished too! I've got some time off work over the next few days so I'm trying to make some progress. Currently working on BMS and charger wiring.

You could fit some batteries in the fuel tank space but I don't think you could fit a whole pack in, even if you only need a really low range. I've got a ~20kwh pack and could probably fit no more than a quarter of the pack in there. It's a really awkward shape (I'll try to get a photo of the shape of the fuel tank later) so it would also depend on what format your batteries are in. If they are small cells and you're willing to fabricate a crazy shaped box then you could pack quite a lot in but with any kind of larger format batteries you'll struggle to fit anything in. I've attached an image of the fuel tank space without the fuel tank in place (the subframe is not attached in this photo and has been lowered slightly on a jack so you'd actually have less space than this).

I think you could fit a full battery pack in a Cappuccino (without using the passenger space!) by spreading them around the car - some in the boot (trunk), some in the fuel tank space, and some under the bonnet (hood). I decided that I'd rather simplify the conversion and keep all the batteries in one place. It's a long and complicated project as it is!

My motor and inverter are quite large as well so if you had a more modern and sensibly sized motor/inverter package then you'd have lots more room in the engine bay for batteries. I literally have no space in the engine bay at all. Ideally, you'd want a motor that fitted in the transmission tunnel or within the rear subframe.

Do you have any components yet or are you still at the dreaming stage?!

Edit: for some reason it's rotated the photo but you should be able to make it out. The fuel tank sits right up against the top (the only bit that's not rusty!)