[ThomasJ]

I'm currently interested in converting a small speedboat to electric, using this 40kw peak brushless electric motor.
The plan is to run it on around 100v, using the 50kv variant of the motor to produce our 5000-6000 RPM desired. This motor is 40KW peak, and around 25KW constant so the battery calculations - in terms of duration - will be done from these lower numbers (in the table below).

For example, the most current drawn is 230 amps, multiplied by the voltage of 111v to get a power of 25,530W. To get a few hours running out of the boat, this means I would need a battery of around 50KWh (or 460Ah at 111 volts). That of course is if I was running the boat flat out (on constant power of 25kw) so less then that would probably be fine

This seems widely done using EV car batteries and from my quick-looking leaf batteries seem fairly plentiful and cheap in the UK.
This eBay listing is for the whole lot, which I assume I would disassemble and then connect to this orian controller. Unfortunately, the whole nissan leaf battery is only 24KWh so I would probably need two to last more than an hour or an hour and a half in the water.
Even if I just opted for a single set of Nissan leaf batteries, £1,890 for only 24kwh is quite a lot, and would be interested if there were cheaper ways of doing it. I have seen a number of people making their own power walls using cheap 18650 cells so could that be a potential option?

Thanks, Thomas.

 

[hallkbrdz]

"Even if I just opted for a single set of Nissan leaf batteries, £1,890 for only 24kwh is quite a lot "

How much do you value your boat? Compared to new cells, it's a steal in comparison if they are in good shape.

Remember that both the motor and controller have inefficiencies that need to be multiplied together, so a 24kWh pack (new) won't get you 24kW of power over an hour, probably more like 75% of that.

That motor says it's only rated for 18kW continuous. And it's made for aircraft with lots of air cooling from a prop in front of it, something you don't have in a boat (unless you are making an airboat). The dropdown shows watercooling, but I don't see any motors like that (confused). A water cooled motor would be ideal for a boat use, given that you have an ample heat sink available.

 

[ThomasJ]

The boat is currently just a concept, with a growing parts list of things I am planning to order. The hull is the most undecided, however, almost certainly a used GRP 13/14-foot v bottom.
The total for the boat should hopefully be under £4000 however that may be optimistic. I have many of the parts and fittings in hand so I only really need a few expensive electronics. The motor and speed controller totaling 1000, and battery + BMS around 2000.

And the motor has two, admittedly very well hidden, water cooling nozzles (attached image).

 

[John_G]

Sorry, I just HAVE to ask... why not use the Leaf motor and controller as well? If you bought a used Leaf you would have ALL the bits needed for the conversion at once, with a far more powerful motor too boot!

 

[ThomasJ]

That’s a very good point, which I did briefly think about however discounted because I have never worked with anything even close to similar in the past.
Even so, now you say that it is very tempting. I would have the battery, bms, motor and controller though I would need to learn a lot about how it all works and interfaces together. With ‘hobby’ parts like that ultralight aircraft motor, it is all very easy for me and I could debug quickly.

I might see how much written off leafs go for, providing I can find one of course.

Edit:
Unfortunately Nissan leafs and even more so wrecked Nissan leafs are impossible to find, so unless one pops up I think it might be more viable to still go with the old plan and use a leaf battery

 

[G00se]

Edit:
Unfortunately Nissan leafs and even more so wrecked Nissan leafs are impossible to find, so unless one pops up I think it might be more viable to still go with the old plan and use a leaf battery

Eh?

There are loads.

Check Copart and eBay.

The cheapest Leaf you can find will still be cheaper when you factor in all the parts you can use.

 

[G00se]

Here's one for £4k:

Nissan Leaf 2011 white pearl SAT NAV rear camera 12 MONTHS MOT till June 2022 | eBay

Find many great new & used options and get the best deals for Nissan Leaf 2011 white pearl SAT NAV rear camera 12 MONTHS MOT till June 2022 at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

 

[ThomasJ]

I was looking for one that had rolled or something and would be scrapped, instead of buying a working one.
That link you sent is promising though, and £4k doesn't seem that bad when sometimes the batteries seem to be almost that themselves.

 

[G00se]

Yeah, I saw one on Copart (although a 2017 model) that was already bid up to £3500.

If you're willing to put the work in it can be cheaper to buy the whole car and strip it, than the individual parts.

 

[ThomasJ]

Yeah I am willing to put the work in, though I would be a bit concerned about getting rid of the car (- battery, BMS, motor and speed controller) because I feel that could have some cost attached as well.

The old method would be (approx for all of these) £600 for the motor, £400 for esc, £1900 for battery and £400 for BMS, bringing the total to around £3300.

I might see if I can find a Nissan Leaf for under that, and if I could get maybe a crashed or written off one for even less that would be ideal.

 

[G00se]

Have a word with some scrap merchants, they might even pay you to take the hulk away.

There are lots of plastic parts (wing mirrors, interior trim) that have some value. Just takes time to put it all on eBay.

I bought my Leaf motor including inverter and battery charging module with Chademo for £1750. I note that someone is selling just the final drive gearbox for £1,250.

 

[ThomasJ]

I have thought about it for a while and realised I don't really want to have to deal with a car and getting it/getting rid of it.
I don't mind the work of removing the parts that I want, however, I think it would be too much to have to take lots of other stuff out and sell them.
If possible, I might see if I can remove the battery/motor at the scrapyard.

I like the idea of using all Nissan leaf components, but really don't want the work of stripping a car completely, selling parts I don't need then getting the shell taken away.

 

[G00se]

That was my logic as well.

Currently my parts cost is going to be at least £4,500.

 

[ThomasJ]

Automotive parts that come from leafs seem to be a bit more expensive than stuff bought for hobbyist so I might try and do a mix of leaf batteries and BMS, with hobby controller and motor.

 

[brian_]

If possible, I might see if I can remove the battery/motor at the scrapyard.

You can't do that at normal auto wreckers (salvage yards) here, but there are some "do it yourself" (often with a name such as "U-Pull") which work that way - the customers are expected to remove everything they want. Perhaps you have that type of business there... but here they tend to have only older and less valuable vehicles (so I wouldn't expect to find a Leaf in one). The other issue would be high-voltage components: a business is unlikely to let customers near a vehicle with a live high voltage battery, so they would need to remove the battery first, and that would make the vehicle unattractive to them.

 

[ThomasJ]

Oh, interesting.
I guess ill be stuck with buying components off eBay, maybe I'll find a steal.

 

[ThomasJ]

Out of interest, how hard is using a leaf battery with the leaf controller and battery?
Does it require lots of in-depth/complex wiring or is it relatively simple?
Also, what do you need to make the motor work? Is it just the inverter or do you need a controller as well?

Sorry for the number of questions there, I don't know much about this end of electrical power systems.
Thomas

 

[John_G]

Out of interest, how hard is using a leaf battery with the leaf controller and battery?
Does it require lots of in-depth/complex wiring or is it relatively simple?
Also, what do you need to make the motor work? Is it just the inverter or do you need a controller as well?

Sorry for the number of questions there, I don't know much about this end of electrical power systems.
Thomas

If you use the whole 48 module pack, elementary. Keeping the voltage sense wires in order is critical, but if you take care to number them and the modules PRIOR to disconnecting or removing them, you should have no problems.... presuming you follow all appropriate safety protocols in so doing, or it won't much matter 'cuz you'll be fried.

 

[Swogm]

If you use the whole 48 module pack, elementary. Keeping the voltage sense wires in order is critical, but if you take care to number them and the modules PRIOR to disconnecting or removing them, you should have no problems.... presuming you follow all appropriate safety protocols in so doing, or it won't much matter 'cuz you'll be fried.

i have seen someone add more batteries to a leaf and the controller would only allow 24kw for some reason
There is a work around but I can’t remember it

 

[John_G]

i have seen someone add more batteries to a leaf and the controller would only allow 24kw for some reason
There is a work around but I can’t remember it

Dala has a work-around for increasing the battery capacity above 24kWh, but not for adding to the total number of cells, that stays the same at 96 (2 cells/module x 48 modules). Wolftronix devised a way to use a smaller number of cells, but it requires an advanced level of knowledge and understanding to make that work. As such, his solution is anything but DIY friendly.

To my knowledge, one cannot increase the number of cells and use the factory Battery Control Module, although it is theoretically possible to parallel modules to achieve a 96 module (192 cell) pack made of two strings, there is utterly no point as it would be much safer and easier just to utilize two separate BCMs.