All Electric?

[TheBiscuits]

Just now, MtB said:

[...] whether living on a narrowboat was more 'eco-friendly' than living in a house, or less. The answer seems blindingly obvious nowadays that it is so much less. 

 

Not convinced Mike.  Space heating and electricity usage are the big two, and on most boats are much lower than in most houses - if only because it's a smaller space to heat and there's less room for electrical appliances.

 

HVO instead of diesel would make quite a difference, and most liveaboard boats now have at least some solar if they aren't on permanent hookup.

[IanD]

On 13/11/2021 at 14:08, Up-Side-Down said:

....... and run their engines for leccy generation in the meantime??

Running the main diesel engine and using alternators to charge the batteries is horrendously inefficient, by the time you add up the low diesel efficiency when lightly loaded to alternator losses you'll be doing well to get even 10% efficiency -- and this is ignoring the need to run for hours to fully charge lead-acid cells, which wastes even more fuel. Bad enough even on a conventional boat, but much worse on an electric-heavy one with higher power needs. If you need a lot of power for this an onboard diesel generator is a far better idea, typically these are about 25% efficient.

 

Another point is that with lead-acid batteries you not only have high losses during charge/discharge -- typical round-trip efficiency is maybe 70% at best, which makes the above problem even worse -- but also the long run times to fully charge them and prevent sulphation. LiFePO4 avoid both these problems, round-trip efficiency is typically 95% and there's no need to fully charge them.

 

So using the main engine and alternator to charge lead-acid batteries results in maybe 3x-4x the fuel consumption (and emissions) compared to using a generator with LiFePO4 batteries, which is a real problem on an electric-heavy boat and can even mean higher fuel/emissions cost than domestic heating. However the heating use is still there even if you go down the generator/LiFePO4 route.

 

Of course a generator and LiFePO4 batteries cost *far* more (at least £10000) than an alternator and lead-acid cells, which just doesn't make financial sense because this completely swamps the fuel cost saving (and the removal of any gas installation costs)...

Edited November 14, 2021 by IanD

[Up-Side-Down]

We're undoubtedly on the same page here.

 

Any views on hybrid battery systems where a lithium battery is 'put in front' of LAs? The reverse is, of course possible, but with far fewer gains. There are couple of convincing YouTube videos that I might just be able to dig out and at least one proprietary system on the market which uses the first example.

[Tacet]

10 hours ago, IanD said:

Running the main diesel engine and using alternators to charge the batteries is horrendously inefficient, by the time you add up the low diesel efficiency when lightly loaded to alternator losses you'll be doing well to get even 10% efficiency -- and this is ignoring the need to run for hours to fully charge lead-acid cells, which wastes even more fuel. Bad enough even on a conventional boat, but much worse on an electric-heavy one with higher power needs. If you need a lot of power for this an onboard diesel generator is a far better idea, typically these are about 25% efficient.

 

So using the main engine and alternator to charge lead-acid batteries results in maybe 3x-4x the fuel consumption (and emissions) compared to using a generator with LiFePO4 batteries, which is a real problem on an electric-heavy boat and can even mean higher fuel/emissions cost than domestic heating. However the heating use is still there even if you go down the generator/LiFePO4 route.

All assuming the engine is not propelling the boat at the same time?  It's a novel idea, I know, and may not catch-on.

[ditchcrawler]

10 hours ago, Up-Side-Down said:

We're undoubtedly on the same page here.

 

Any views on hybrid battery systems where a lithium battery is 'put in front' of LAs? The reverse is, of course possible, but with far fewer gains. There are couple of convincing YouTube videos that I might just be able to dig out and at least one proprietary system on the market which uses the first example.

I know people that do that and if I am still boating when I need ne batteries I will be going that way

[IanD]

Just now, Tacet said:

All assuming the engine is not propelling the boat at the same time?  It's a novel idea, I know, and may not catch-on.

 

The issue under discussion was "running their engines for 'leccy generation", meaning while stationary (as many boats do, lots of the time), not while travelling along.

 

Incidentally, even of you do it while cruising the electricity isn't "free" because it puts extra load on the engine which burns more fuel. If you plug the actual numbers in instead of guessing, it now turns out that diesel/alternator/lead-acid while cruising still uses a lot more fuel/emissions than generator/LiFePO4 (whether static or cruising) -- so just not *quite* as appalling as running the engine when stationary... 😉

 

(diesel efficiency while cruising typically 20%, alternator efficiency typically 70%, battery round-trip efficiency typically 70% ==> 10% overall compared to 25% for generator/LiFePO4)

[Up-Side-Down]

6 minutes ago, ditchcrawler said:

I know people that do that and if I am still boating when I need ne batteries I will be going that way

Anyone with this sort of practical experience that you can put me in touch with so that I can learn more? I'm not that far off speccing off-grid electrical systems for my liveaboard boat (replacement systems from the bottom up) and and a replica showman's living van that I'm building.

[IanD]

10 hours ago, Up-Side-Down said:

We're undoubtedly on the same page here.

 

Any views on hybrid battery systems where a lithium battery is 'put in front' of LAs? The reverse is, of course possible, but with far fewer gains. There are couple of convincing YouTube videos that I might just be able to dig out and at least one proprietary system on the market which uses the first example.

As you say the gains are much lower though so is the cost. You need to arrange things so that most of the current in/out goes to/from the lithium batteries, which tends to happen naturally anyway because they have lower internal resistance and a much flatter charge curve. The problem is that the lead-acids never see enough voltage to prevent sulphation because this would kill the lithium cells, so unless you arrange for the lithiums to be disconnected regularly while you run the lead-acids up to 100% charge the lead-acids will have a very short lifetime -- OK if you see them as cheap and disposable.

 

Also you still need to put in a BMS to stop overcharging or overdischarge of the lithium batteries which kills them very rapidly. And the lithiums need to have most of the capacity anyway. So sonce you've basically done all the hard work (and expense) of installing lithium batteries, what's the point of having the lead-acids?

Edited November 15, 2021 by IanD

[Up-Side-Down]

4 minutes ago, IanD said:

As you say the gains are much lower though so is the cost. You need to arrange things so that most of the current in/out goes to/from the lithium batteries, which tends to happen naturally anyway because they have lower internal resistance and a much flatter charge curve. The problem is that the lead-acids never see enough voltage to prevent sulphation because this would kill the lithium cells, so unless you arrange for the lithiums to be disconnected regularly while you run the lead-acids up to 100% charge the lead-acids will have a very short lifetime -- OK if you see them as cheap and disposable.

 

Also you still need to put in a BMS to stop overcharging or overdischarge of the lithium batteries which kills them very rapidly. And the lithiums need to have most of the capacity anyway. So sonce you've basically done all the hard work (and expense) of installing lithium batteries, what's the point of having the lead0-acids?

I'm with you some of the way here but see what you think of: 

 

 

Of less relevance to me, but interesting nonetheless: 

 

 

He also references (which I have yet to study) https://www.wildebus.com/hybrid-battery-bank-introduction/

 

[Tacet]

13 minutes ago, IanD said:

 

The issue under discussion was "running their engines for 'leccy generation", meaning while stationary (as many boats do, lots of the time), not while travelling along.

 

Incidentally, even of you do it while cruising the electricity isn't "free" because it puts extra load on the engine which burns more fuel. If you plug the actual numbers in instead of guessing, it now turns out that diesel/alternator/lead-acid while cruising still uses a lot more fuel/emissions than generator/LiFePO4 (whether static or cruising) -- so just not *quite* as appalling as running the engine when stationary... 😉

 

(diesel efficiency while cruising typically 20%, alternator efficiency typically 70%, battery round-trip efficiency typically 70% ==> 10% overall compared to 25% for generator/LiFePO4)

Whether there are lead acid or LiFePO4 batteries is a separate issue to how one produces the electricity.

 

You are well ahead of me regarding the numbers, but when the alternator is generating incidentally due to cruising, it is the marginal increase in fuel that is relevant.  And I'll hazard a guess that you would consume less fuel overall by combining propulsion/alternator than charging your batteries using the onboard generator before loosing the ropes and heading out for a cruise. 

 

 

 

[IanD]

Just be *very* careful about internet videos telling you how easy it is to either install lithium batteries or add them in parallel with lead-acid, because a lot of them frankly don't know what they're talking about and the end result is dead batteries -- there are *loads* of cases of this happening in the much bigger yachting and RV communities.

 

This one isn't too bad, and most of what he says about lithium is correct -- which begs the question, why make things more difficult by keeping the lead-acids, why not just switch to 100% lithium?

 

Some suggested reading, if you haven't already...

 

https://marinehowto.com/lifepo4-batteries-on-boats/

https://nordkyndesign.com/category/marine-engineering/electrical/lithium-battery-systems/

21 minutes ago, Tacet said:

Whether there are lead acid or LiFePO4 batteries is a separate issue to how one produces the electricity.

 

You are well ahead of me regarding the numbers, but when the alternator is generating incidentally due to cruising, it is the marginal increase in fuel that is relevant.  And I'll hazard a guess that you would consume less fuel overall by combining propulsion/alternator than charging your batteries using the onboard generator before loosing the ropes and heading out for a cruise.

Nope, the numbers say exactly the opposite -- which is why I provided some... 😉

 

And they were optimistic -- typical alternator efficiency is 60% maximum, and more typically 50% (or lower!) at cruising rpm, and diesel efficiency is about 20% under the same conditions:

 

https://electronics.stackexchange.com/questions/96051/what-makes-automotive-alternators-so-inneficient-relative-to-other-applications

https://www.hybrid-marine.co.uk/index.php/hybrid-info/hybrid-efficiency

 

So fuel-to-amps efficiency while cruising is about 10% for main diesel engine compared to 25% for a generator:

 

https://www.victronenergy.com/upload/documents/VE_Marine_generator_test_RVA_07-jan-2008.pdf

Edited November 15, 2021 by IanD

[LadyG]

I'm late to the party, apologise if this has been covered. 

Summary

OP wants to design his boat electrics radically but has limited technical expertise, however he does know he is going to get older 🤔

I can remove my gas bottle fairly easily because they are empty. I am female, over 75.

Full bottles are delivered at any marina, and you will probably be able to lift them about ten inches, on to the bow, else wait till someone does it for you. 

Always fit the controller yourself and use gas test fluid. I now have a wheel type controller which is far superior to Calor mangled brass nut style. 

Do not use gas on board unless you have a good sense of smell, there are gas detectors but I don't think they are any use on a barge due to flat bilges. 

I have an extremely sensitive sense of smell, and could detect a slight smell of gas inside a sealed locker inside the boat with my last bottle, even though the gas locker should be sealed, appears to be sealed! 

Having just changed the gas bottle and controller, there is absolutely no smell, absolutely no bubbling of the gas leak detector fluid. Don't use Fairy except in emergency, then wash it off.

I am very careful with gas, keep it simple, have it installed properly. 

Ventilate the boat frequently by opening doors and windows. 

I never turn the gas off. Do not allow visitors to mess about in the gas locker compartment, ignorance can lead to error. DAMHIK. 

PS pay someone to change these big batteries and save yourself a hernia op. 😜

 

Edited November 15, 2021 by LadyG

[MtB]

3 minutes ago, IanD said:

This one isn't too bad, and most of what he says about lithium is correct -- which begs the question, why make things more difficult by keeping the lead-acids, why not just switch to 100% lithium?

 

For me, it was a simple way to use the existing engine alternator for charging without fear of it getting *ucked (technical term) should the lithium BMS decide to emergency disconnect. 

[IanD]

7 minutes ago, MtB said:

 

For me, it was a simple way to use the existing engine alternator for charging without fear of it getting *ucked (technical term) should the lithium BMS decide to emergency disconnect. 

All you need is to add an alternator load dump clamp circuit, relatively cheap and simple and off-the-shelf...

 

Using a standard alternator to charge lithium cells is a recipe for disaster, either by cooking the alternator or killing the batteries -- the emergency disconnect prevents extreme overcharging, but doesn't stop the lithiums being charged to close or even a bit over 100% SoC which drastically shortens their life.

Edited November 15, 2021 by IanD

[Alan de Enfield]

16 minutes ago, LadyG said:

Do not use gas on board unless you have a good sense of smell, there are gas detectors but I don't think they are any use on a barge due to flat bilges. 

 

??

[Up-Side-Down]

21 minutes ago, IanD said:

Just be *very* careful about internet videos telling you how easy it is to either install lithium batteries or add them in parallel with lead-acid, because a lot of them frankly don't know what they're talking about and the end result is dead batteries -- there are *loads* of cases of this happening in the much bigger yachting and RV communities.

 

This one isn't too bad, and most of what he says about lithium is correct -- which begs the question, why make things more difficult by keeping the lead-acids, why not just switch to 100% lithium?

 

Some suggested reading, if you haven't already...

 

https://marinehowto.com/lifepo4-batteries-on-boats/

https://nordkyndesign.com/category/marine-engineering/electrical/lithium-battery-systems/

Nope, the numbers say exactly the opposite -- which is why I provided some... 😉

 

And they were optimistic -- typical alternator efficiency is 60% maximum, and more typically 50% at cruising rpm, and diesel efficiency is about 20% under the same conditions:

 

https://electronics.stackexchange.com/questions/96051/what-makes-automotive-alternators-so-inneficient-relative-to-other-applications

https://www.hybrid-marine.co.uk/index.php/hybrid-info/hybrid-efficiency

 

So fuel-to-amps efficiency while cruising is about 10% for main diesel engine compared to 25% for a generator:

 

https://www.victronenergy.com/upload/documents/VE_Marine_generator_test_RVA_07-jan-2008.pdf

Thanks for this IanD. I'm only too happy to do the reading and much appreciate you sharing the links.

[MtB]

15 minutes ago, IanD said:

All you need is to add an alternator load dump clamp circuit, relatively cheap and simple and off-the-shelf...

 

Never heard of one of these. Do you have a link to such a thing please? Thanks.

 

Regarding your other points, I am aware of all these potential shortcomings but it never hurts to spell them out for people new to the subject of lithium batteries, and who have swallowed the line peddled by some that they are easy. 

 

 

Edited November 15, 2021 by MtB
Missing word

[Up-Side-Down]

10 minutes ago, IanD said:

All you need is to add an alternator load dump clamp circuit, relatively cheap and simple and off-the-shelf...

 

Using a standard alternator to charge lithium cells is a recipe for disaster, either by cooking the alternator or killing the batteries -- the emergency disconnect prevents extreme overcharging, but doesn't stop the lithiums being charged to close or even a bit over 100% SoC which drastically shortens their life.

i) Pls could you reference a source of an alternator load dump clamp circuit. ii) Is it possible to simply dump surplus load into a calorifier? iii) How about simply using a Battery to Battery charger from the start LA battery to the lithium's with a lithium setting?

[MtB]

3 minutes ago, Up-Side-Down said:

i) Pls could you reference a source of an alternator load dump clamp circuit. ii) Is it possible to simply dump surplus load into a calorifier? iii) How about simply using a Battery to Battery charger from the start LA battery to the lithium's with a lithium setting?

 

i) I just asked the same question!

 

ii) The problem isn't 'surplus load' i.e. spare energy looking for a home, it is the sudden and instant disconnection of the load from the alternator that damages the alt if/when the BMS disconnects, causing a momentary spike in something. 

 

iii) Yes a B2B would work but introduces a massive 30% or more loss in charging efficiency, in heat chucked out by the electronics, AIUI.

Edited November 15, 2021 by MtB

[IanD]

14 minutes ago, MtB said:

 

Never heard of one of these. Do you have a link to such a thing please? Thanks.

 

Regarding your other points, I am aware of all these potential shortcomings but it never hurts to spell them out for people new to the subject of lithium batteries, and who have swallowed the line peddled by some that they are easy. 

 

 

https://sterling-power.com/products/alternator-open-circuit-protection-device

 

Also recommended by the marine-how-to-page in the alternator/charging section (a long way down a very long webpage!), along with a photo of an alternator fried by charging lithium batteries...

 

Some relevant quotes:

 

WARNING / DIY BUILDS:

I do not believe LiFePO4 is ready for mass DIY prime time builds. Read with caution, and especially focus on the things that you don’t want to hear rather than only what you want to hear.

Wallet Burns:

Since opening this article to the public we have now had what I consider a rather high number of LiFePO4 owners contact us who’ve ruined LiFePo4 batteries (not all marine based). In almost all of these cases of destroyed LiFePO4 batteries the resounding tone I hear come through is;

“But Rod, People on the internet made it sound so easy?“

Hey, lets face it, everyone gets excited with their new toys, and likes to talk about them, but we urge you to please do more research. In other-words, don’t jump to conclusions based on scant information, where large sums of money are involved.

YOUR RESEARCH DOES NOT END WITH THIS ARTICLE

Frustratingly only a few of the cases of destroyed LFP batteries we’ve been contacted about are getting reported in on-line in forums, on blogs, groups etc.. The folks who’ve ruined these LFP batteries are not all boaters. Some are electric vehicle guys, many are RV owners, a few of them were off-grid and the rest are boaters. The horror’s we’ve had from the RV crowd alone are frustratingly sad.

 

Even if your alternator were to survive a load dump, other items on-board your vessel, connected to the DC load bus, may not survive. This is why we recommend a Sterling Alternator Protection Device for every vessel or RV etc. that has drop-in LFP batteries. The Alternator Protection Device clamps the transient to a safe level. We have tested these in our shop, on our alternator test bench, to 130A and not been able to kill one.

 

 

Edited November 15, 2021 by IanD

[MtB]

2 minutes ago, IanD said:

https://sterling-power.com/products/alternator-open-circuit-protection-device

 

Also recommended by the marine-how-to-page in the alternator/charging section (a long way down a very long webpage!)

 

 

Excellent, thanks!

 

Another reason for keeping an LA is for that intensely annoying occasion when your lithiums are low, it's 10pm and you're all comfy watching the telly and your BMS or whatever you use to protect them as extremes of SoC decides to protect your batts, leaving you sitting unexpectedly in the dark and quiet with the fridge warming up. 

[IanD]

7 minutes ago, MtB said:

 

 

Excellent, thanks!

 

Another reason for keeping an LA is for that intensely annoying occasion when your lithiums are low, it's 10pm and you're all comfy watching the telly and your BMS or whatever you use to protect them as extremes of SoC decides to protect your batts, leaving you sitting unexpectedly in the dark and quiet with the fridge warming up. 

 

Of course that assumes the LA isn't completely sulphated by then because it's never been fully charged since the lithiums were installed... 😉

[MtB]

7 minutes ago, IanD said:

 

Of course that assumes the LA isn't completely sulphated by then because it's never been fully charged since the lithiums were installed... 😉

 

I'm not entirely convinced on that point. A 12v lithium bank spend most of time in the range of 12.8v to 13.6v AIUI, and that broadly equates to float charge for LA batts. So if the new LA is fully charged in the first place before connecting it up, it is unlikely to deviate much from 100% SoC for an awfully long while.

[Bee]

I have a somewhat mischevious desire to promote an all gas boat and bin the ferociously expensive electrics. When you add up the industrial processes, mining, ecological and political disasters, the raw materials, copper, lead, lithium, valium and all the other rare and expensive stuff in a modern electric boat it all seems to be the worst of every world. Gas heating, lighting, cooking, fridge, and diesel engine running on gas seems to me to be a whole lot simpler and cheaper and a simple dynamo off the engine charging a lorry battery (just the one) that runs a telly and radio looks like something I could live with and  understand and reduce the chances of electrical fires to zero. The last plus point is that you could keep a canary or two and if one fell off the perch you would know you had a gas leak. I am only half joking.

[MtB]

10 minutes ago, Bee said:

I have a somewhat mischevious desire to promote an all gas boat and bin the ferociously expensive electrics. When you add up the industrial processes, mining, ecological and political disasters, the raw materials, copper, lead, lithium, valium and all the other rare and expensive stuff in a modern electric boat it all seems to be the worst of every world. Gas heating, lighting, cooking, fridge, and diesel engine running on gas seems to me to be a whole lot simpler and cheaper and a simple dynamo off the engine charging a lorry battery (just the one) that runs a telly and radio looks like something I could live with and  understand and reduce the chances of electrical fires to zero. The last plus point is that you could keep a canary or two and if one fell off the perch you would know you had a gas leak. I am only half joking.

 

You'd need one of these on your foredeck!