phasing out of fossil fuels - programme

[peterboat]

1 minute ago, Alan de Enfield said:

 

I thought all the gyms were closed, or are they now diversifying into boat sales so as to remain open ?

Buddy spulchucker ?

[Dr Bob]

13 hours ago, Jackofalltrades said:

I do hear what you are saying but going down the (more expensive) lithium route seems risky from where I'm standing at the moment and the secondhand lithium battery route seems potentially fraught. Would it be possible for you to describe your setup in detail?  I appreciate you might not want to though.

It seems crazy to fit anything other than Lithiums if you are planning electric drive. Li's are just so much better at accepting all the power thrown at them and do not need to be taken to 100%. Lead carbon are too new to understand the real performance but if you have to take them back to 100% regularly then that means lots of engine running. If they are discharged to 50% then that last 10% of charge is going to take hours of engine running. It is chalk and cheese with Li and I am flabbergasted just how easy they are to charge and keep healthy. I know the claims for Lead carbon but having to take them 100% will mean long engine hours. Li's dont degrade significantly with big loads and partial charges. My Tesla has an 8 year warranty on its batteries and my boat batteries - now 2 years in havent changed performance at all. I am sure Lead Carbon will degrade more.

Now, I know the 'engine' is a purpose built genny, but how quiet will it actually be? If you have to run it for 8 hours to charge for the netxt day because it is raining, just how much noise polution is that going to cause? A gentle hum in the background to one person is a 'roar' to others. The majority of the time peeps run their engines now are when they are motoring. Will you be running it most of the time when you are moored up?

I sincerely hope that all these hybrids that appear dont set a pattern of noiseless motoring down the canal then when moored, turn on their humming gennies for 8 hours, spoiling the slient countryside.

Edited January 12, 2021 by Dr Bob

[IanD]

1 hour ago, peterboat said:

Go to finess job done if you want an electric boat 

Yeah I looked at that. Remind me again how big the motor is, and what kind of batteries they use?

 

Real continuous kW, not a peak headline figure at a different voltage...

 

Is it the same as this one?

 

https://www.canalboat.co.uk/canal-boats/boat-test-mothership-marine-s-solar-powered-semi-trad-1-6215195

 

Looks like an IPM200:

 

https://www.danatm4.com/products/electric-motors/ipm-200/

 

These are pretty feeble. The one in the article doesn't look like the biggest one, it looks like the IPM200-50 AHOI which is rated at 16kW peak (emergencies), but <10kW/30min and <8kW/60min (both around 4000rpm, hence the toothed belt) which are the ratings used for marine motors e.g. suitable for going upstream on the Trent.

 

Together with the Leoch lead-carbon batteries, this smells to me like a cheapskate solution...

14 minutes ago, Dr Bob said:

It seems crazy to fit anything other than Lithiums if you are planning electric drive. Li's are just so much better at accepting all the power thrown at them and do not need to be taken to 100%. Lead carbon are too new to understand the real performance but if you have to take them back to 100% regularly then that means lots of engine running. If they are discharged to 50% then that last 10% of charge is going to take hours of engine running. It is chalk and cheese with Li and I am flabbergasted just how easy they are to charge and keep healthy. I know the claims for Lead carbon but having to take them 100% will mean long engine hours. Li's dont degrade significantly with big loads and partial charges. My Tesla has an 8 year warranty on its batteries and my boat batteries - now 2 years in havent changed performance at all. I am sure Lead Carbon will degrade more.

Now, I know the 'engine' is a purpose built genny, but how quiet will it actually be? If you have to run it for 8 hours to charge for the netxt day because it is raining, just how much noise polution is that going to cause? A gentle hum in the background to one person is a 'roar' to others. The majority of the time peeps run their engines now are when they are motoring. Will you be running it most of the time when you are moored up?

I sincerely hope that all these hybrids that appear dont set a pattern of noiseless motoring down the canal then when moored, turn on their humming gennies for 8 hours, spoiling the slient countryside.

Shouldn't need to run the generator for more than about 2 hours per day...

Edited January 12, 2021 by IanD

[Mike Todd]

16 hours ago, IanD said:

OK, that's fine. But 0.3l/kWh is make-believe until he's got measurements to prove it, no matter how good an engineer he is ?

You  might also find you need to consult a physicist as well as an engineer. Does seem to be a tendency for the latter to ignore former and vice versa.

 

In case that is too cryptic, you not only have to take into account practical factors which can make quite a bit of difference between theoretical and actual - there are good engineers and there are bad engineers - but also accept the limitations of known physics such as Newton, Maxwell and Thermodynamics. The latter do not bring fake news but they may bring bad news.

 

Way back in the mists of time, I spent a decade in ship research and, at that time anyway, we were often approached by an 'inventor' with a marvellous way of reducing ship resistance which he (almost always not a she!) claimed was independent of anything else. We used to say that we should get together half a dozen of these ideas, implement all of them (after all they are are independent aren't they?) and we should get a ship that no longer needs an engine . . . 

 

In other words, be very careful when adding together separate efficiency gains etc. They rarely add up to what you might think - too often 1 + 1 is closer to 1 than 2

[Dr Bob]

6 minutes ago, IanD said:

Shouldn't need to run the generator for more than about 2 hours per day...

I'm not sure I follow that.

If we are talking Li's ok, as they take everything you throw at them but Lead Carbons? Once up to 90%, surely they will only take what the batteries allow and the slowing down tail current will kill you when you need to be up at 100%. Ok, if you can go for weeks/months at partial charge (<80%) but I'm not sure I believe that to be the case - but I have no experience of Lead Carbons. Pete, how long do you run your 'genny' and how long would it be without Li's?

[IanD]

24 minutes ago, Dr Bob said:

I'm not sure I follow that.

If we are talking Li's ok, as they take everything you throw at them but Lead Carbons? Once up to 90%, surely they will only take what the batteries allow and the slowing down tail current will kill you when you need to be up at 100%. Ok, if you can go for weeks/months at partial charge (<80%) but I'm not sure I believe that to be the case - but I have no experience of Lead Carbons. Pete, how long do you run your 'genny' and how long would it be without Li's?

I was talking for lithiums. I don't think lead-carbons make sense for a series hybrid (or a parallel one) in spite of the claims, if you look in detail they still need fully charging/equalising regularly when used under PSoC conditions, and they're not even that much cheaper than lithiums -- and they're double the cost of 2V traction cells.

 

If you want to penny-pinch and put up with slow charging and equalising and low efficiency, use flooded 2V traction cells which are much cheaper. If you want to pay more for a solution without any of these disadvantages, go lithium.

 

For those who think the Leoch pure-lead-carbon means you can stop worrying about fully charging and equalising and get huge lifetime, here's the crucial page from the (similar technology) NorthstarBlue+ manual:

Edited January 12, 2021 by IanD

[peterboat]

43 minutes ago, IanD said:

Yeah I looked at that. Remind me again how big the motor is, and what kind of batteries they use?

 

Real continuous kW, not a peak headline figure at a different voltage...

 

Is it the same as this one?

 

https://www.canalboat.co.uk/canal-boats/boat-test-mothership-marine-s-solar-powered-semi-trad-1-6215195

 

Looks like an IPM200:

 

https://www.danatm4.com/products/electric-motors/ipm-200/

 

These are pretty feeble. The one in the article doesn't look like the biggest one, it looks like the IPM200-50 AHOI which is rated at 16kW peak (emergencies), but <10kW/30min and <8kW/60min (both around 4000rpm, hence the toothed belt) which are the ratings used for marine motors e.g. suitable for going upstream on the Trent.

 

Together with the Leoch lead-carbon batteries, this smells to me like a cheapskate solution...

Shouldn't need to run the generator for more than about 2 hours per day...

Nope ian 20kw motors he has made for the job and 30kwh battery bank. 

I have seen one being assembled stunning piece of kit, they are direct drive

Edited January 12, 2021 by peterboat

[IanD]

2 hours ago, peterboat said:

Nope ian 20kw motors he has made for the job and 30kwh battery bank. 

I have seen one being assembled stunning piece of kit, they are direct drive

Good, it'll be great if somebody finally does this properly instead of corner-cutting and bodging -- direct drive is a much better solution (but more expensive) than belts, longer life/no maintenance/belt breakage and lower noise levels, higher-speed motors with belts are cheaper but tend to whine like a milk float...

 

20kW peak or continuous (1 hour rating) at 48V? ?

 

(only asking because loads of motor specs -- and suppliers -- are being "economical with the truth" on power ratings for electric boats, the headline number isn't deliverable longer-term because of motor and/or controller power continuous current limits)

Edited January 12, 2021 by IanD

[jbzoom]

On 09/01/2021 at 23:17, Mike Todd said:

I really don't get the promotion of hybrids as a route to lower carbon unless the running costs are so much lower that they offset the extra capital cost and likely carbon tax (however hidden) that some promote as a means of accelerating the rate of change.

The series hybrid offers a path to the future - for now a diesel genset is needed, but much smaller than in a direct drive or parallel hybrid. Eventually it can be run on bio- or tvo-diesel of replaced with whatever greener technology comes along. Batteries, solar panels, controllers etc. account for most of the costs.

[jbzoom]

On 09/01/2021 at 20:20, IanD said:

I'm aware of all that. The "electric motors have full torque at low revs" is completely irrelevant for boats, at low revs a propellor needs very little torque -- for emergency manoeuvring or going upstream what matters is power, and here 15kW is the same as 20hp (at the propellor) whether it comes from an electric motor or a diesel.

 

If the 15kW power limit is the motor/controller then it doesn't matter whether the source is batteries or generator or both.

 

Alternators and gearbox do absorb a few bhp, but nothing like enough to make a 15kW motor equivalent to a 40bhp diesel, suggest you go and look at the numbers.

 

Series 12V LiFePO4 "off-the-shelf" batteries present huge challenges for charging/protection/BMS and are not suitable for boat propulsion, suggest you go and read up on the marinehowto site. Many people have made this assumption and come unstuck...

 

But I do agree that it's possible to build a good 48V series hybrid today, and that this is probably the solution for the future -- at least for those who can afford it or build their own, until there's a cheap second-hand market.

You're a bit dogmatic here - the torque is less important on a boat, but it still reduces the time a propeller takes to get up to full revs in an emergency. My comparison was a 40 hp diesel running a heavy alternator load - say 200 amps - versus a 20kw electric drive.  40 hp is pretty much 30kw. The alternators alone, with a charitable 60% efficiency, would absorb 4 Kw and the drive train maybe another Kw, resulting in around 25 Kw at the prop. The 20Kw electric motor should deliver 20Kw at the prop and take maybe 23 kw out of the electrical system - most are specified with peak ratings higher than nominal, so even higher kw bursts are feasible. A 5kw difference at the propeller will make no difference on the canal and a minor difference of perhaps 1 mph in top speed on the river, which no-one does with a diesel, because they're worried about overheating and noise. Several US electric boat vendors use serial LiFePO4 installations and Victron have all the necessary control equipment to do it available in the UK.  Not cheap but, in my opinion, worth it for mostly quiet cruising, with maximum use of shore power and solar for charging and the genset cocooned for those occasions when it is necessary to use it.

 

[Mike Todd]

59 minutes ago, jbzoom said:

The series hybrid offers a path to the future - for now a diesel genset is needed, but much smaller than in a direct drive or parallel hybrid. Eventually it can be run on bio- or tvo-diesel of replaced with whatever greener technology comes along. Batteries, solar panels, controllers etc. account for most of the costs.

Whilst you could be right for the immediate future, I thought that the objective was to eliminate fossil fuels such that they become increasingly difficult to source. Hence, a hybrid (of any type) seems to be fudging the issue. It may be justified on cost grounds but not on 'save the planet' basis. (If it is OK to use diesel for the genny why is it wrong to pour it straight into the engine? At the moment it seems that there might be a modest gain in efficiency and pollution but some of the developments being described might achieve much of that for a more conventional solution - but is it worth the capital cost?) Those doing the comparative calculations should also take into account the projection that wood, diesel and gas may all be unavailable for heating and have to devise a sufficiently large solar array for winter survival - or even a typical rainy August day!

[peterboat]

4 minutes ago, Mike Todd said:

Whilst you could be right for the immediate future, I thought that the objective was to eliminate fossil fuels such that they become increasingly difficult to source. Hence, a hybrid (of any type) seems to be fudging the issue. It may be justified on cost grounds but not on 'save the planet' basis. (If it is OK to use diesel for the genny why is it wrong to pour it straight into the engine? At the moment it seems that there might be a modest gain in efficiency and pollution but some of the developments being described might achieve much of that for a more conventional solution - but is it worth the capital cost?) Those doing the comparative calculations should also take into account the projection that wood, diesel and gas may all be unavailable for heating and have to devise a sufficiently large solar array for winter survival - or even a typical rainy August day!

My genny is a backup in reality if the weather is naff I won't move.  I will be running mine on full biodiesel and expect to use a few gallons a year not the hundreds I used before 

[IanD]

1 hour ago, jbzoom said:

You're a bit dogmatic here - the torque is less important on a boat, but it still reduces the time a propeller takes to get up to full revs in an emergency. My comparison was a 40 hp diesel running a heavy alternator load - say 200 amps - versus a 20kw electric drive.  40 hp is pretty much 30kw. The alternators alone, with a charitable 60% efficiency, would absorb 4 Kw and the drive train maybe another Kw, resulting in around 25 Kw at the prop. The 20Kw electric motor should deliver 20Kw at the prop and take maybe 23 kw out of the electrical system - most are specified with peak ratings higher than nominal, so even higher kw bursts are feasible. A 5kw difference at the propeller will make no difference on the canal and a minor difference of perhaps 1 mph in top speed on the river, which no-one does with a diesel, because they're worried about overheating and noise. Several US electric boat vendors use serial LiFePO4 installations and Victron have all the necessary control equipment to do it available in the UK.  Not cheap but, in my opinion, worth it for mostly quiet cruising, with maximum use of shore power and solar for charging and the genset cocooned for those occasions when it is necessary to use it.

 

I'm not being dogmatic, I'm being accurate -- plug in some torque and estimated moment of inertia numbers and you'll find the difference in prop acceleration delay is a tiny fraction of a second (electric motor+prop has much faster acceleration than a diesel with a heavy flywheel), far less than your reaction time to an emergency.

 

Obviously if you move the power numbers closer the difference between electric and diesel gets less. You can skew them against diesel by adding a 200A alternator load, while ignoring the fact that the chance of this happening while you need peak power is low. The extra-peak-power for electric argument (for emergencies only, not sustainable for river use) only works if you deliberately underprop, because PMAC torque falls off above the rated rpm -- yes you could get an extra 5kW out of the motor but only if you reduce the prop loading to push rpm up, either by deliberate underpropping or fitting a variable-pitch prop. And you also just happened to drop 3bhp off the diesel numbers -- if you move the numbers like this by adding 5kW to the electric and taking 3bhp + 200A charging (4kW) off the diesel then you're correct, the difference is smaller because you've shaved 16bhp off the difference.

 

What I said was that there's a big power difference between a 15kW/20bhp electric motor and a 43bhp diesel, even after allowing for gearbox losses and a reasonable alternator load, and this is still the case. If there wasn't a big difference boatbuilders could have been fitting Beta 25 instead of Beta 43 all these years and saved everyone a lot of money, but they didn't. When you take everything into account including losses, an electric motor of at least 25kW (continuous 1hr rating) is needed to have the same effective power in all cases as a Beta 43 (32kW), 15kW falls a long way short.

 

[how much you *need* and whether a Beta 43 is overpowered is a separate issue...]

 

Several boat vendors do use serial 12V LiFePO4 installations and -- as the marinehowto article says -- this can be OK so long as you use high-quality (read: expensive) 12V LiFePO4 batteries -- which is not most of the "12V drop-in" batteries on the market -- and deal with balancing between the series batteries. But also note that very few 12V LiFePO4 batteries are suited for marine propulsion applications especially high continuous current drains like in a series hybrid, I'm not even sure about the Victron ones.

 

A proper serial hybrid built using correctly-specified components and not corner-cutting and with a decent cocooned generator is indeed an excellent solution, but it's not cheap.

Edited January 12, 2021 by IanD

[jbzoom]

34 minutes ago, Mike Todd said:

Whilst you could be right for the immediate future, I thought that the objective was to eliminate fossil fuels such that they become increasingly difficult to source. Hence, a hybrid (of any type) seems to be fudging the issue. It may be justified on cost grounds but not on 'save the planet' basis. (If it is OK to use diesel for the genny why is it wrong to pour it straight into the engine? At the moment it seems that there might be a modest gain in efficiency and pollution but some of the developments being described might achieve much of that for a more conventional solution - but is it worth the capital cost?) Those doing the comparative calculations should also take into account the projection that wood, diesel and gas may all be unavailable for heating and have to devise a sufficiently large solar array for winter survival - or even a typical rainy August day!

Smaller diesel, higher efficiency and less pollution for now. Running on TVO or similar in a few years, made redundant by faster charging, higher density and cheaper batteries by the time it's due for replacement. Can be cocooned and made much quieter than a larger engine.

[IanD]

22 minutes ago, jbzoom said:

Smaller diesel, higher efficiency and less pollution for now. Running on TVO or similar in a few years, made redundant by faster charging, higher density and cheaper batteries by the time it's due for replacement. Can be cocooned and made much quieter than a larger engine.

One of the biggest reasons to get a series hybrid today instead of a diesel is not just fuel/emissions saving (maybe 40% or so, which is green but in no way pays for the installation), it's silent/vibration-free cruising. Put a cocooned generator with a hospital silencer in the bows and it's literally inaudible with zero vibration at the steering position, even when the generator is running. And if/when charging points appear the emissions saving will only get bigger, even more so as the grid gets greener.

 

But if cost is more important, by all means stick with a noisy smelly diesel ?

Edited January 12, 2021 by IanD

[Mike Todd]

2 hours ago, IanD said:

I'm not being dogmatic, I'm being accurate -- plug in some torque and estimated moment of inertia numbers and you'll find the difference in prop acceleration delay is a tiny fraction of a second (electric motor+prop has much faster acceleration than a diesel with a heavy flywheel), far less than your reaction time to an emergency.

 

Obviously if you move the power numbers closer the difference between electric and diesel gets less. You can skew them against diesel by adding a 200A alternator load, while ignoring the fact that the chance of this happening while you need peak power is low. The extra-peak-power for electric argument (for emergencies only, not sustainable for river use) only works if you deliberately underprop, because PMAC torque falls off above the rated rpm -- yes you could get an extra 5kW out of the motor but only if you reduce the prop loading to push rpm up, either by deliberate underpropping or fitting a variable-pitch prop. And you also just happened to drop 3bhp off the diesel numbers -- if you move the numbers like this by adding 5kW to the electric and taking 3bhp + 200A charging (4kW) off the diesel then you're correct, the difference is smaller because you've shaved 16bhp off the difference.

 

What I said was that there's a big power difference between a 15kW/20bhp electric motor and a 43bhp diesel, even after allowing for gearbox losses and a reasonable alternator load, and this is still the case. If there wasn't a big difference boatbuilders could have been fitting Beta 25 instead of Beta 43 all these years and saved everyone a lot of money, but they didn't. When you take everything into account including losses, an electric motor of at least 25kW (continuous 1hr rating) is needed to have the same effective power in all cases as a Beta 43 (32kW), 15kW falls a long way short.

 

[how much you *need* and whether a Beta 43 is overpowered is a separate issue...]

 

Several boat vendors do use serial 12V LiFePO4 installations and -- as the marinehowto article says -- this can be OK so long as you use high-quality (read: expensive) 12V LiFePO4 batteries -- which is not most of the "12V drop-in" batteries on the market -- and deal with balancing between the series batteries. But also note that very few 12V LiFePO4 batteries are suited for marine propulsion applications especially high continuous current drains like in a series hybrid, I'm not even sure about the Victron ones.

 

A proper serial hybrid built using correctly-specified components and not corner-cutting and with a decent cocooned generator is indeed an excellent solution, but it's not cheap.

My worry about accepting a much lower power for a narrowboat, based on normal cruising requirements, concerns emergency situations. Not infrequently I find it necessary to use as much powere as my Beta 43 can produce, including:

 

1. Suddenly faced with a boat coming through a blind bridge hole with too much speed (or insufficient inclination) to stop in time.

 

2. Mis judging the approach into a lock and needing to avoid crashing into the far gates

 

3. On a river. approaching a lock at right angles off the river and finding the fresh stronger than the previous lock keeper had advised

 

4. Coming round a bend to find a boat across the channel having lost its mooring pin.

 

5. Approaching or exiting a lock with an especially strong bywash

 

and many others. It is easy to forget just how much momentum a narrowboat carries at cruising speed and how quickly it needs to be reduced to avoid collision. Normal cruising revs around 1250 but there can be few days when at times well over 2000, even max, is called for. Even 'normal' manoeuvring, including winding, needs a surprising amount of power at times.

 

One of the reasons why we went up from the Beta 34 in our previous boat (which could cruise quite happily on most waterways) was the lack of safety margin it offered in emergency situations. For me, I'd rather design on the basis of such needs rather than efficient 'normal' cruising. 

[TheBiscuits]

7 hours ago, IanD said:

The one in the article doesn't look like the biggest one, it looks like the IPM200-50 AHOI which is rated at 16kW peak (emergencies), but <10kW/30min and <8kW/60min

 

I was looking at the spec sheet for the BYD Battery-Box Premium LVL you mentioned yesterday.

 

It says:

Nominal Voltage: 51.2V
Max Output Current: 250 A
Peak Output Current: 375 A for 5 seconds

 

So:

51.2 V x 250 A = 12.8 kW

51.2 V x 375 A = 19.2 kW (but only for 5 seconds ...)

 

So unless I'm missing something you can't run anything bigger than a 12kW motor off one of these LVL battery systems.  You might be able to parallel 2 of them to run a 24kW motor, but that's another six grand and some pretty serious cabling!

[ditchcrawler]

24 minutes ago, Mike Todd said:

My worry about accepting a much lower power for a narrowboat, based on normal cruising requirements, concerns emergency situations. Not infrequently I find it necessary to use as much powere as my Beta 43 can produce, including:

 

1. Suddenly faced with a boat coming through a blind bridge hole with too much speed (or insufficient inclination) to stop in time.

 

2. Mis judging the approach into a lock and needing to avoid crashing into the far gates

 

3. On a river. approaching a lock at right angles off the river and finding the fresh stronger than the previous lock keeper had advised

 

4. Coming round a bend to find a boat across the channel having lost its mooring pin.

 

5. Approaching or exiting a lock with an especially strong bywash

 

and many others. It is easy to forget just how much momentum a narrowboat carries at cruising speed and how quickly it needs to be reduced to avoid collision. Normal cruising revs around 1250 but there can be few days when at times well over 2000, even max, is called for. Even 'normal' manoeuvring, including winding, needs a surprising amount of power at times.

 

One of the reasons why we went up from the Beta 34 in our previous boat (which could cruise quite happily on most waterways) was the lack of safety margin it offered in emergency situations. For me, I'd rather design on the basis of such needs rather than efficient 'normal' cruising. 

You are going to maximum revs but are you going to maximum power, is your prop/gearbox spect to absorb the maximum power your engine can put out.

[TheBiscuits]

32 minutes ago, Mike Todd said:

My worry about accepting a much lower power for a narrowboat, based on normal cruising requirements, concerns emergency situations. Not infrequently I find it necessary to use as much powere as my Beta 43 can produce, including:

 

1. Suddenly faced with a boat coming through a blind bridge hole with too much speed (or insufficient inclination) to stop in time.

 

2. Mis judging the approach into a lock and needing to avoid crashing into the far gates

 

3. On a river. approaching a lock at right angles off the river and finding the fresh stronger than the previous lock keeper had advised

 

4. Coming round a bend to find a boat across the channel having lost its mooring pin.

 

5. Approaching or exiting a lock with an especially strong bywash

 

and many others. It is easy to forget just how much momentum a narrowboat carries at cruising speed and how quickly it needs to be reduced to avoid collision. 

 

I'm not having a dig, but I can't help noticing that most of that list can be countered with better boathandling ...

 

Use of horn on blind approaches to bridges or tight corners. (1)

 

Slower approach into restricted channels like locks or tight corners (2, 4)

 

I'll admit points 3 & 5 are a bit trickier, but speed and approach angle can mitigate these more than raw power in many cases. 

 

 

 

 

 

 

 

 

[IanD]

49 minutes ago, TheBiscuits said:

 

I was looking at the spec sheet for the BYD Battery-Box Premium LVL you mentioned yesterday.

 

It says:

Nominal Voltage: 51.2V
Max Output Current: 250 A
Peak Output Current: 375 A for 5 seconds

 

So:

51.2 V x 250 A = 12.8 kW

51.2 V x 375 A = 19.2 kW (but only for 5 seconds ...)

 

So unless I'm missing something you can't run anything bigger than a 12kW motor off one of these LVL battery systems.  You might be able to parallel 2 of them to run a 24kW motor, but that's another six grand and some pretty serious cabling!

Absolutely correct. Which is one reason I was planning to use two of them -- and a six-phase 25kW motor with two controllers, that way the cables to each battery and each controller carry 250A.

 

(BTW, many other lithium batteries are even lower current)

20 minutes ago, TheBiscuits said:

 

I'm not having a dig, but I can't help noticing that most of that list can be countered with better boathandling ...

 

Use of horn on blind approaches to bridges or tight corners. (1)

 

Slower approach into restricted channels like locks or tight corners (2, 4)

 

I'll admit points 3 & 5 are a bit trickier, but speed and approach angle can mitigate these more than raw power in many cases. 

 

 

 

 

 

 

 

 

What none of these can fix is the need for high power sustained for some time on places like the Ribble Link and the Trent -- see videos and blogs, many people have found they need all the power they can summon up, and waiting for the tide or current to drop is not always an option. It's also why a battery bank of around 30kWh usable is a good idea...

[Ronaldo47]

Likewise for strong cross-winds: my post #1047 refers. 

Edited January 12, 2021 by Ronaldo47

[LadyG]

On 28/12/2020 at 19:14, Mike Todd said:

What was the date of the first approved ICE driven car in the UK?

 

What date was the last horse driven commercial vehicle taken out of service?

 

Does that help assess how long it might take?

There are plenty of horse driven hearse in the UK, and many more horse and carts in both Africa, and India. 

[Mike Todd]

15 hours ago, ditchcrawler said:

You are going to maximum revs but are you going to maximum power, is your prop/gearbox spect to absorb the maximum power your engine can put out.

Surprisingly I never thought about that in the moment . . . 

[peterboat]

16 hours ago, TheBiscuits said:

 

I was looking at the spec sheet for the BYD Battery-Box Premium LVL you mentioned yesterday.

 

It says:

Nominal Voltage: 51.2V
Max Output Current: 250 A
Peak Output Current: 375 A for 5 seconds

 

So:

51.2 V x 250 A = 12.8 kW

51.2 V x 375 A = 19.2 kW (but only for 5 seconds ...)

 

So unless I'm missing something you can't run anything bigger than a 12kW motor off one of these LVL battery systems.  You might be able to parallel 2 of them to run a 24kW motor, but that's another six grand and some pretty serious cabling!

Its strange but true my 2.5k secondhand valence bank can give out 400 amps at 72 volts, off the mark it can leave most boats for dead stopping is quick as well, my controller is the limiting factor as it only handles 400 amps. I am having a revamp after I have installed the genny to improve cooling to the motor and controller.

12 hours ago, Ronaldo47 said:

Likewise for strong cross-winds: my post #1047 refers. 

Do what most sensible people do and tie up until the bad weather/wind passes, its what I have always done, instead of damaging my boat and others.

40 minutes ago, Mike Todd said:

Surprisingly I never thought about that in the moment . . . 

Most boats are over propped and never come near max power all three of my boats have been like that and two were ex hire

[peterboat]

10 hours ago, LadyG said:

There are plenty of horse driven hearse in the UK, and many more horse and carts in both Africa, and India. 

As a percentage in the UK they wouldnt register the numbers are so small

15 hours ago, IanD said:

Absolutely correct. Which is one reason I was planning to use two of them -- and a six-phase 25kW motor with two controllers, that way the cables to each battery and each controller carry 250A.

 

(BTW, many other lithium batteries are even lower current)

What none of these can fix is the need for high power sustained for some time on places like the Ribble Link and the Trent -- see videos and blogs, many people have found they need all the power they can summon up, and waiting for the tide or current to drop is not always an option. It's also why a battery bank of around 30kWh usable is a good idea...

Ian proper boaters dont push the tide or current on the Trent, It uses huge amounts of fuel for nothing. I have been on the Trent more times than I can remember on many different boats, it was only on a massive Gin Palace did we push the tide all other times we went with it.