openinverter forum

I've been a petrol head ever since I was a young teen some 30 years ago and been lucky enough to own many great sports cars including building bike engined kit cars and a few track toys.


I was the proud owner of a Tesla P85+ 5 years ago and kept it for 4 years (I usually change cars every few months) and I'm now in a BMW i8. 


Anyway, its not a car that I'm now looking at converting to EV. It's a BMW powered boat.


It's 36ft, weighs around 9 tons and is usually powered by twin 200bhp BMW/Mercruiser diesel lumps until I managed to blow and engine a few weeks ago.


I now plan to pull out the dead engine and replace it with a motor so I can run as a kind of highbred setup with the motor used for low speed cruising 4-10mph and the engine for when I need more speed/range. 


Hopefully I will be able to charge the batteries from the engine somehow or possibly an old 3.5kw Farymann diesel 240v generator which I have on board.


So I'm after some help and advice which route to go down. Ideally I'd love to keep something BMW about the boat and would absolutely love to use an i8 or i3 motor but I do like the sound of the Lexus GS450h gearbox/inverter so maybe I could use this but with BMW batteries?

DannyBuoy wrote: ↑Tue Nov 10, 2020 7:04 pm So I'm after some help and advice which route to go down. Ideally I'd love to keep something BMW about the boat and would absolutely love to use an i8 or i3 motor but I do like the sound of the Lexus GS450h gearbox/inverter so maybe I could use this but with BMW batteries?

You would have to put in a lot of batteries to offset the weight difference. That 200Hp diesel must be heavy.

Very interesting and compact choice. You could have the MG1 coupled directly to engine in front and MG2 disengaged from the two and driving the prop shaft only. I can see application with Volt/Ampera or Prius gen3 inverter with 12V DCDC regulator immediately. You can also use something small and compact like the Smart car diesel engine...

Awesome project. Please keep us posted.

As an aside, what are your thoughts on the i8? What range do you typically get in max e drive?

arber333 wrote: ↑Wed Nov 11, 2020 7:28 am

DannyBuoy wrote: ↑Tue Nov 10, 2020 7:04 pm So I'm after some help and advice which route to go down. Ideally I'd love to keep something BMW about the boat and would absolutely love to use an i8 or i3 motor but I do like the sound of the Lexus GS450h gearbox/inverter so maybe I could use this but with BMW batteries?

You would have to put in a lot of batteries to offset the weight difference. That 200Hp diesel must be heavy.

Very interesting and compact choice. You could have the MG1 coupled directly to engine in front and MG2 disengaged from the two and driving the prop shaft only. I can see application with Volt/Ampera or Prius gen3 inverter with 12V DCDC regulator immediately. You can also use something small and compact like the Smart car diesel engine...

Each engine weights around a ton but so do each of the fuel tanks (which are either side). So my intention is to remove the tank that is the same side as the working engine to balance things up.

I am probably going to need a ton of batteries anyway because propellers are no where near as efficient as wheels/tyres. Does anyone have any recommendations for batteries? What types are best for quantity vs price, I'm not short of space.

I want to keep the working engine completely separate to the EV side of things so don't want to link them up.

Boxster EV wrote: ↑Wed Nov 11, 2020 12:15 pm Awesome project. Please keep us posted.

As an aside, what are your thoughts on the i8? What range do you typically get in max e drive?

They're an awsome car, massive grin factor when driving and just looking at it but unpractical and pretty useless as an EV. They're only good for about 10-15 miles on pure electric. As good as the Tesla was in terms of ticking boxes I still prefer the i8.