Converting a boat to electricity

[bluesatin]

IforB if you have a picture of the sealine s37 in Bourne End can I have a copy. Hi Steve!

[IforB]

bluesatin said:

IforB if you have a picture of the sealine s37 in Bourne End can I have a copy. Hi Steve!

I only have pics of Eva-May from the original sea-trials in Essex rather than elsewhere, but I'll happily stick them on a download site for you to grab if you want.

[Mr2Mike]

Simpo Two said:

(you know what I mean!)

27' GRP cabin cruiser, currently powered by 40hp inboard diesel. It's noisy and vulnerable to weed clogging.

Top speed required is 7mph (normal cruising speed 4-6mph), and enough power for a weekend trip - say 12 hours' cruising between charges.

How fast is the boat with the 40hp diesel engine?

[Simpo Two]

Mr2Mike said:

How fast is the boat with the 40hp diesel engine?

I've never used all 40hp. At 2200rpm (less than halfway round the dial) it does about 6mph which is all I need and makes quite enough noise and wash.

I'm not sure if it would be best to have a motor that's flat out at 6mph flat out, or one with extra power that's not used. Are these things most efficient at max rpm? Talking of rpm, a gearbox could be an issue as I have no plans to change the prop.

One gotcha may be cooling. Some of these motors seem to need water cooling - and if so, a big advantage of changing over is lost.

[Simpo Two]

anonymous said:

[redacted]

There's shore power.

Thanks to Ifor I'm making constructive progress. Currently trying to evaluate costs, as there are costs and savings both on one-off and ongoing bases. There's an amount I'm prepared to invest but not more. Also a few technical/practical issues to sort out such as heating and hot water.

I had hoped that electric boats would be tariff free, but no luck, only a 25% discount


I know there are some brokers here - would an electric inland cabin cruiser be worth more than an identical diesel-engined version?

[NeilB12]

Heating and hot water could be provided by a Webasto / Eberspacher / Mikuni unit. Just need a small diesel tank somewhere.

[Simpo Two]

NeilB12 said:

Heating and hot water could be provided by a Webasto / Eberspacher / Mikuni unit. Just need a small diesel tank somewhere.

Actually it has an Eberspacher D4 already, for hot air heating (but it's noisy and the control panel is too clever). Don't suppose it can do hot water too with some kind of conversion?

[dhutch]

The problem will always be range, a few hours is easy, maybe even 8hours, but every time you increase the range you increase the capacity required and hence the cost and weight.

I know a lot use lynch motors for this sort of application, which are air cooled, but I don't know much out them technically. High torque low speed, for a DC motor I believe.

Unless using secondhand kit I expect it will be a lot of money, but I understand about the noise and weed on the cooling inlet being annoying.

This is a company on the side of Windermere who do an electric launch, with LiFe batteries. Not idea of the cost of the batteries but you could enquire.
https://youtu.be/ybrVAI7AwwU


Daniel

Edited by dhutch on Tuesday 18th September 19:20

[Simpo Two]

Thanks Daniel; I'd need more than 8 hours but on the plus side I only need to do 6mph which should help.

Unless you're going to burn more electricity to run a cooling fan, air cooling doesn't really work on river cruisers so if it's not water-cooled it will just have to radiate. Hull cooling would be wonderful but no-one seems to have the courage to fit it to a cruiser.

[hidetheelephants]

Air cooling should not be a problem with such an undemanding installation; your existing engine already sucks in huge amounts of air so there must be some ventilation, addition of a suitable fan to extract heated air from the engine compartment should be adequate. Your speed requirements call for perhaps 8-10kW at most and as you cruise slower most of the time battery capacity to run 12 hours might be ~70kWh, allowing for contingency and battery protection perhaps you might specify a 90kWh battery. The problem is that even wholesale that capacity will be the thick end of £30k, which makes assembling a kit from salvaged EV batteries attractive; for example 3rd party electric conversions of Pug Partners/Experts/Boxers often sell for little more than the scrap value of the battery because there's no manufacturer support, so you could potentially pick up 3 partners or 2 boxers and/or experts for less than £10K and have enough cells to make a 80-90kWh battery.

Alternatively you could make do with a smaller battery and fill the range gap with a generator.

Simpo Two said:

NeilB12 said:

Heating and hot water could be provided by a Webasto / Eberspacher / Mikuni unit. Just need a small diesel tank somewhere.

Actually it has an Eberspacher D4 already, for hot air heating (but it's noisy and the control panel is too clever). Don't suppose it can do hot water too with some kind of conversion?

There are heat exchangers that claim to allow hot air heating to provide hot water but they get a bad press; it's a lot easier to go the other way, heat water then provide hot air using radiators. Considering the cost of converting to electric propulsion the added cost of a ebby DW4 or similar is negligible, especially as good used ones are available for not much.

Edited by hidetheelephants on Saturday 22 September 21:44

[Simpo Two]

Thanks HTE, you're obviously well up on this subject. The first quote has come in and you're right, e32K fro Oceanvolt (24% VAT doesn't help). That makes the whole project a non-starter by a country mile, and assuming other companies are similar, I'd have to look at 'salvaged' parts... but is a random collection of second-hand batteries wired up with no warranty a wise way to spend even £10K? I can't think so.

I think the electric dream - not just for me but for the world in general, is a long way off yet. It can't cut the mustard and it's too expensive.

[hidetheelephants]

The batteries are certainly worth it, as their capacity declines at a predictable and slow rate and cell failure is very rare they are a saleable commodity. A possible source of a suitable used motor would be a later Gwiz as they're AC, if you're particularly stingy you could reuse the Gwiz inverter. The toughest bit of DIYing it is getting the charging side right with what is by automotive standards a big battery.

Rob the battery out of one of these; the only down side is dealing with remelting the battery after it's been allowed to solidify, assuming you are cruising continuously for several days followed by a long period of no use then that would be manageable, the bms manages battery temp while charging.

Edited by hidetheelephants on Sunday 23 September 12:17

[Simpo Two]

hidetheelephants said:

Rob the battery out of one of these; the only down side is dealing with remelting the battery after it's been allowed to solidify, assuming you are cruising continuously for several days followed by a long period of no use then that would be manageable, the bms manages battery temp while charging.

Wow. Not sure if I'm up to remelting sodium nickel chloride though!

[hidetheelephants]

Simpo Two said:

hidetheelephants said:

Rob the battery out of one of these; the only down side is dealing with remelting the battery after it's been allowed to solidify, assuming you are cruising continuously for several days followed by a long period of no use then that would be manageable, the bms manages battery temp while charging.

Wow. Not sure if I'm up to remelting sodium nickel chloride though!

It sounds very alarming, as does the operating temp range of 250-250C, but the charger controls all that and the alarmingly hot molten stuff is safely locked up in the battery and insulated from you by what is effectively a vacuum flask, so the outside is just warm to the touch.

[Simpo Two]

hidetheelephants said:

It sounds very alarming, as does the operating temp range of 250-250C, but the charger controls all that and the alarmingly hot molten stuff is safely locked up in the battery and insulated from you by what is effectively a vacuum flask, so the outside is just warm to the touch.

YHM sir.

I wonder what the EA and BSS would make of it? They love electricity of course but are terrified of petrol so what would they make of a boat full of molten sodium?! Hopefully they'd be satisfied with just 'Batteries'!

[anonymous-user]

Second hand 3 phase 30kW AC motors are cheap and easily available eg:

30kW_ABB_motor_ebay





then you need a 30kW inverter:

30kW_AC_inverter_ebay





If you remove the Active Front End Rectifier from the drive, the bit that usually takes in the 3 phase AC input and rectifies it to DC, you are left with an 565 Vdc input (ie feed DC directly to the back end inverter stage)

So that's drive sorted for about £1k


If you bought a couple of used EV battery's from a crashed leaf or similar (budget around £2.5k each) , then a simple rewire of the 7.5v modules will give you the voltage you require and 50 KWh of energy, enough for 2 hours flat out, or 4 hours at quarter power (~half speed)

nissanleaf_battery_info




All done and dusted for £10k ;-)

[Simpo Two]

Max_Torque said:

Second hand 3 phase 30kW AC motors are cheap and easily available

What's the reason for having an AC motor and then having to buy an inverter to make it work? Is it just that AC motor + inverter = much less wonga than a DC motor?

Max_Torque said:

If you bought a couple of used EV battery's from a crashed leaf or similar (budget around £2.5k each) , then a simple rewire of the 7.5v modules will give you the voltage you require and 50 KWh of energy, enough for 2 hours flat out, or 4 hours at quarter power (~half speed)

2-4 hours is way short of requirement (12+ hours). But what speed is 'flat out'? If flat out to you is 20kts then as I only need 5kts the range/running time might work...

[Chainsaw Rebuild]

I'm no expert so forgive me if this isn't a workable idea; could you put solar panels on the boats roof to charge the batteries a bit while you are going along? perhaps you could alter your habits a bit and stop for once or twice for snacks/tea/lunch as well to give the solar panels time to top you up a bit more.

[Simpo Two]

Chainsaw Rebuild said:

I'm no expert so forgive me if this isn't a workable idea; could you put solar panels on the boats roof to charge the batteries a bit while you are going along? perhaps you could alter your habits a bit and stop for once or twice for snacks/tea/lunch as well to give the solar panels time to top you up a bit more.

Stopping for snacks, tea and lunch are built into the boating experience

Unfortunately solar panels wouldn't come close to providing/replacing the power needed.

[DJFish]

Electric boats are very much in vogue at the moment, my mate’s building this at the moment.
https://megayachtnews.com/2017/10/spirit-111-cocoo...
It’s rather large & very curvy & also uses car power cells.