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Genny vs engine vs solar?


Jak

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5 hours ago, rgreg said:

I had the same concern before having my panels fitted, but ended up with some slimline ones (150w each) which left a comfortable walkway on either side. 

 

Same here. I just don't understand Slim's objection. I have 560w of solar on my NB roof and when single handing locks, I just walk along the roof past them. 

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10 hours ago, Tony1 said:

The other mitigation I have is that I can charge the batteries at 90amps or more, so even in winter I can get a days charge in about an hour. Some days, if there is a bit of sun, its half an hour. 

 

Unless they are lithium batteries I think that you will find you are deluded in that statement. No way will LA batteries and typical usage take 90 amps for more than 15 minutes or so The other mitigation I have is that I can charge the batteries at 90amps or more, so even in winter I can get a days charge in about an hour. Some days, if there is a bit of sun, its half an hour.  and I don't know what you consider "a day's charge" but with LA batteries it is all but certain you are gradually destroying them.  How are you monitoring the state of charge that allows you to believe what you say?

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3 hours ago, MtB said:

 

Same here. I just don't understand Slim's objection. I have 560w of solar on my NB roof and when single handing locks, I just walk along the roof past them. 

 

I do get the reasoning for some boaters not feeling solar is that useful- for example those who are not able to spend as much time as they want on their boats, and are restricted by career or other commitments to a week or two at a time, a few times each year. 

In these situations I sense that they are keen cruisers once afloat, and want to cover a good distance, and see as much as possible in their limited boat time. 

This means typically their engine is being used for at least a couple of hours most days for cruising, and so they find they have enough charge in the batteries without needing solar. 

But I must agree with you in respect of liveaboards who cruise less often and tarry more in the attractive locations, and therefore are not running their engine every day. For these boaters, solar would surely be a fantastic upgrade. 

Solar is not a very expensive or even difficult upgrade (trust me, if I can DIY it, almost anyone can). 

Imagine rocking up at a nice mooring with decent solar potential, and then getting all your hot water and electricity from the solar for the next week, or until you next move- so your engine never runs, the whole time you are moored. 

With say 1500 watts of panels, I think that is a realistic prospect between say May and August (I'm going to find out soon).

But even without the hot water, you can at least supply your electrics between March and at least Mid-October, although around the limits of that time period, the solar supply gets a bit intermittent as you would expect, with some great days and some pretty poor days.  

 

Edited by Tony1
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21 minutes ago, Tony Brooks said:

 

Unless they are lithium batteries I think that you will find you are deluded in that statement. No way will LA batteries and typical usage take 90 amps for more than 15 minutes or so The other mitigation I have is that I can charge the batteries at 90amps or more, so even in winter I can get a days charge in about an hour. Some days, if there is a bit of sun, its half an hour.  and I don't know what you consider "a day's charge" but with LA batteries it is all but certain you are gradually destroying them.  How are you monitoring the state of charge that allows you to believe what you say?

 

Mine are lithium, I've had them for over a year now, and touch wood they've survived my ignorance and occasional mistreatment, and are still going strong.

I use BMV712s to monitor their charging and discharging activities, and to trigger the disconnects if the voltage/SoC get too high or too low. 

After starting the engine for a charge, I keep an eye on the charge current, and it rarely varies from 85-90 amps. 

I use between 100 and 120Ah each day, so with a bit of solar added in, one hour is usually more than enough to recharge the batteries.

I have 400Ah of batteries, so 90amps is not too strenuous for them. I could up it to 120amps by working the alternators harder, but then they tend to go over 100 degrees, and I dont think thats good for their longevity, or for the belts (they are V belts, not poly V, so not really designed for heavy charging loads)- so I stay below 90 amps as an all round compromise. 

 

Edited by Tony1
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10 minutes ago, Tony1 said:

 

Mine are lithium, I've had them for over a year now, and touch wood they've survived my ignorance and occasional mistreatment, and are still going strong.

I use BMV712s to monitor their charging and discharging activities, and to trigger the disconnects if the voltage/SoC get too high or too low. 

After starting the engine for a charge, I keep an eye on the charge current, and it rarely varies from 85-90 amps. 

I use between 100 and 120Ah each day, so with a bit of solar added in, one hour is usually more than enough to recharge the batteries.

I have 400Ah of batteries, so 90amps is not too strenuous for them. I could up it to 120amps by working the alternators harder, but then they tend to go over 100 degrees, and I dont think thats good for their longevity, or for the belts (they are V belts, not poly V, so not really designed for heavy charging loads)- so I stay below 90 amps as an all round compromise. 

 

That all sounds ideal except I would be wary about any state of charge reading the monitor gives but then I have no experience of how its "fudge factor" matches lithium batteries.

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50 minutes ago, Tony Brooks said:

 

Unless they are lithium batteries I think that you will find you are deluded in that statement. No way will LA batteries and typical usage take 90 amps for more than 15 minutes or so The other mitigation I have is that I can charge the batteries at 90amps or more, so even in winter I can get a days charge in about an hour. Some days, if there is a bit of sun, its half an hour.  and I don't know what you consider "a day's charge" but with LA batteries it is all but certain you are gradually destroying them.  How are you monitoring the state of charge that allows you to believe what you say?

He has Valence LifePo4s Tony 

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27 minutes ago, Tony Brooks said:

That all sounds ideal except I would be wary about any state of charge reading the monitor gives but then I have no experience of how its "fudge factor" matches lithium batteries.

 

Thanks Tony, and on that point, I am actually slightly unclear about the exact state of charge. I think I have a reasonable idea of it, but I dont trust the BMV712s in terms of being 100% accurate.

I have three BMV712s placed in direct sequence (each does a different job), with all three positive wires going to the same post (on the first battery), and each BMV712 gives different values. They are fairly similar values, but I'm not sure which one is the most accurate in terms of showing the battery state. 

About once every 2 or 3 weeks I try to charge the batteries up to 100% to synchronise them, but they soon begin to diverge again, so I tend to take the most conservative reading in each situation.   

E.g. if I'm looking at how low my voltage or SoC is, I'll look at the unit with the lowest values, and if I want to look at how high my voltage and SoC might be (e.g. during a synchronising charge up to 100% SoC), I look first at the unit which gives the highest readings. 

It all feels a bit heath robinson, but I did come close to ruining the batteries when I first got them through ignorance, so now I tend to be very cautious, and I avoid stressing them as much as possible, and I generally stay well within the safe ranges of their performance. 

 

I would guess I've probably lost a few Ah of capacity from them as a result of my early experimenting and charging (in particular I once briefly let the voltage get up to 15v), but they survived my stupidity, and I still have 90-95% of the capacity I started with, which is more than enough for liveaboard use, and touch wood they will be in good shape and perform as they do now for the next ten years. 

 

 

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25 minutes ago, Tony Brooks said:

That all sounds ideal except I would be wary about any state of charge reading the monitor gives but then I have no experience of how its "fudge factor" matches lithium batteries.

Tony as strange as it seems its just plain volts, valence batteries can be charged safely at 14.6 volts and floated at that voltage! However for maximum cycles it's better to aim lower, I bulk charge at 13.9 absorb at 13.6 and float at 13.4. I consider 12.8 to be running nearly on empty and 12 volts empty! Now unlike LAs they will sit at a voltage for many many many months although 60% SOC is best for storage. i am now in my fourth or fifth year with them and haven't noticed any change in the batteries at all, they were my best purchase for my lifestyle ever!

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1 hour ago, Tony1 said:

They are fairly similar values, but I'm not sure which one is the most accurate in terms of showing the battery state. 

 

The differences might be related to top or bottom balancing that, I think, should be automatic if the batteries have a built in BMS but again I don't know enough about how lithiums and their associated electronics behave. I suspect you method is an effective and practical one.

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18 minutes ago, Tony Brooks said:

 

The differences might be related to top or bottom balancing that, I think, should be automatic if the batteries have a built in BMS but again I don't know enough about how lithiums and their associated electronics behave. I suspect you method is an effective and practical one.

 

Thanks Tony- unfortunately my batteries dont have a built in BMS as such, that will disconnect them if they in danger.

But they do have some circuitry that helps them to balance, and it does seem to work. 

A couple of times I've separated the batteries after a 100% charge and checked their voltages individually, and they are the same (to 2 decimal places anyway).

So I think the Valence electronics are keeping them in reasonable balance. 

But because I dont have monitoring at the level of individual cells, I have to play it safe and not push them too hard, in case there are individual cells that might be out of balance, and would be ruined by too much stress. 

I must say that without the advice and information given by people here, I would never have been able to wire in all the components, BMVs etc, and I would have ruined the batteries long ago.  

 

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14 hours ago, Tony1 said:

 

You make some very good points here, and whilst I agree with most, it might be worth adding in a slightly different perspective to some of them. 

My initial mistake was to buy a £200 suitcase genny from Amazon, which was advertised as silent.

I knew that for £200 it wasn't really going to be silent, but I was dismayed at how 'not silent' it was. I think it was about 90db at 5 metres away, which is a lot.

I did consider making a box to house it, and lining it with some noise-reducing panels, but in the end I gave it away to someone who could put it to good use. 

I'm concerned that I have no contingency plan for the engine failing in winter, but on the other hand I dont really want to have a genny sat in the cratch for the next few years unused, until the dreaded day of engine failure comes. 

My boat is now about 6 years old, so fingers crossed I'm not expecting any major failures in the next couple of years (and I have RCR to fix minor things)- so at the moment I'm rather uneasily gambling that I wont need a genny. 

The solar panels mean that my period of being 'at risk' is reduced a lot. 

I have almost 1400 watts of6 solar, which generates the electricity I need for about 75% of the year. Even today, in early Feb, because there was a bit of sun this afternoon I got 1800 watt hours of charge into the batteries, and I havent had to run the engine for the last 2 days. 

The other mitigation I have is that I can charge the batteries at 90amps or more, so even in winter I can get a days charge in about an hour. Some days, if there is a bit of sun, its half an hour. 

I have a sort of fall-back plan that if I do have a major engine failure, I can order a new genny from a local supplier, and hire a small van to get it to the boat. 

But being honest, I'm not convinced that plan would go as smoothly as I've made it sound, and it is a bit of a nagging doubt.

 

 

You are worrying unnecessarily. It may be a problem with an ancient engine but unlikely with a new boat. 6 years is still new.

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1 minute ago, sueb said:

 

 

In fairness, I did say in my final conclusion about it that it was a 'bit of a nagging doubt', so its not a serious worry. 

 

My conclusion about the risks is similar to yours- I feel its quite unlikely to have a major failure, so its not worth me getting a genny as a backup, at least not for a few years yet. 

 

But there is always a small chance of any engine failing, even with low miles/hours. And as a liveaboard, the prospect of being without electricity in the depths of winter (even for a day or two) is a bit of a nightmare, hence the slight nagging doubt.

 

Perhaps I'm just a bit of a worrier 😄

 

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2 minutes ago, Tony1 said:

 

In fairness, I did say in my final conclusion about it that it was a 'bit of a nagging doubt', so its not a serious worry. 

 

My conclusion about the risks is similar to yours- I feel its quite unlikely to have a major failure, so its not worth me getting a genny as a backup, at least not for a few years yet. 

 

But there is always a small chance of any engine failing, even with low miles/hours. And as a liveaboard, the prospect of being without electricity in the depths of winter (even for a day or two) is a bit of a nightmare, hence the slight nagging doubt.

 

Perhaps I'm just a bit of a worrier 😄

 

 

Perhaps Sue has never encountered what tends to be called diesel bug. A bad case could bring a brand new engine  to a stop and it would take some getting rid of - as some on here can testify. I think planning to allow some redundancy in vital services is entirely sensible. Thinking about it, simply slipping into the engine hole could damage something that might take a day or two to resolve.

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Always have backups for power and heating…even something like running out of diesel is possible with a new engine. A 5 litre can which you can easily walk/cycle to the nearest petrol station with will not be enough diesel to reach the pickup tube in your tank, but in a genny it’ll be a good few days of charging. Enough time to sort out a diesel delivery. 

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7 minutes ago, cheesegas said:

Always have backups for power and heating…even something like running out of diesel is possible with a new engine. A 5 litre can which you can easily walk/cycle to the nearest petrol station with will not be enough diesel to reach the pickup tube in your tank, but in a genny it’ll be a good few days of charging. Enough time to sort out a diesel delivery. 

 

Point of technical order. If you run out of fuel the engine will stop almost a soon as the dip tube sucks air. That means the tank level will be to the bottom of the dip tube so 5 liters should get you going again but probably not for long.

 

Now, it the tank drain leaked then it would be as you say.

Edited by Tony Brooks
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On 04/02/2022 at 21:59, Tony1 said:

 

You make some very good points here, and whilst I agree with most, it might be worth adding in a slightly different perspective to some of them. 

My initial mistake was to buy a £200 suitcase genny from Amazon, which was advertised as silent.

I knew that for £200 it wasn't really going to be silent, but I was dismayed at how 'not silent' it was. I think it was about 90db at 5 metres away, which is a lot.

I did consider making a box to house it, and lining it with some noise-reducing panels, but in the end I gave it away to someone who could put it to good use. 

I'm concerned that I have no contingency plan for the engine failing in winter, but on the other hand I dont really want to have a genny sat in the cratch for the next few years unused, until the dreaded day of engine failure comes. 

My boat is now about 6 years old, so fingers crossed I'm not expecting any major failures in the next couple of years (and I have RCR to fix minor things)- so at the moment I'm rather uneasily gambling that I wont need a genny. 

The solar panels mean that my period of being 'at risk' is reduced a lot. 

I have almost 1400 watts of solar, which generates the electricity I need for about 75% of the year. Even today, in early Feb, because there was a bit of sun this afternoon I got 1800 watt hours of charge into the batteries, and I havent had to run the engine for the last 2 days. 

The other mitigation I have is that I can charge the batteries at 90amps or more, so even in winter I can get a days charge in about an hour. Some days, if there is a bit of sun, its half an hour. 

I have a sort of fall-back plan that if I do have a major engine failure, I can order a new genny from a local supplier, and hire a small van to get it to the boat. 

But being honest, I'm not convinced that plan would go as smoothly as I've made it sound, and it is a bit of a nagging doubt.

 

 

Your £200 new genny would have been in the same ball park as my suggestion of a £100 used genny.  This sort of thing should only be used as an emergency back up for the reason you've given - they're LOUD, and very likely to annoy people.  Better bet would have been to have forked out a bit more for a properly quiet genny with a smart throttle.  When mine is only charging batteries it's really quiet.  It's claimed to be 58db at 5m.  Which seems about right and barely registers above background noise when there's a road or town anywhere nearby.  Then you have something which, in many ways, is superior to running your engine, for the reasons I gave previously.

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On 04/02/2022 at 23:31, rgreg said:

I had the same concern before having my panels fitted, but ended up with some slimline ones (150w each) which left a comfortable walkway on either side. 

But are you 75? The older you get the more 'wobble room' you need. 😁

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1 hour ago, doratheexplorer said:

Your £200 new genny would have been in the same ball park as my suggestion of a £100 used genny.  This sort of thing should only be used as an emergency back up for the reason you've given - they're LOUD, and very likely to annoy people.  Better bet would have been to have forked out a bit more for a properly quiet genny with a smart throttle.  When mine is only charging batteries it's really quiet.  It's claimed to be 58db at 5m.  Which seems about right and barely registers above background noise when there's a road or town anywhere nearby.  Then you have something which, in many ways, is superior to running your engine, for the reasons I gave previously.

 

I'm wondering if you could use a sound-deadening lined box to reduce a lot of the noise from a cheap genny- but the bigger issue for me at the moment is storage space. I have at least 6 bags of coal in the cratch at the moment, plus my (lidded) ashbox, spare paint, mooring hardware, mallets, trolley, spare toilet cassettes- its getting increasingly difficult to find storage for anything, anywhere on the boat, so until I have a thorough reorganisation of the whole lot, I dont really have room for a genny.

It would be different if a genny was my routine electricity source (although I wouldnt fancy the routine task of fetching petrol from local petrol stations).

As it is, my engine can charge at 90-100 amps, so I don't have to run it for long in order to get the charge I need for a day. So I'm not getting into those issues of increasing engine hours, frequent services, wear and tear etc- especially because its only a winter issue anyway.

Between late Feb and the end of Oct, the solar will give me all the charge I need on most days. 

I would guess that between Nov and end of Jan, I probably ran the engine (just for charging) for a total of about 80 hours, so its not getting flogged to death just for electricity generation.

 

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30 minutes ago, Tony1 said:

I'm wondering if you could use a sound-deadening lined box to reduce a lot of the noise from a cheap genny-

Not without the risk of it overheating or ingesting its own exhaust fumes. And if you provide enough ventilation to avoid that, then the noise reduction will be negligible.

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3 minutes ago, David Mack said:

Not without the risk of it overheating or ingesting its own exhaust fumes. And if you provide enough ventilation to avoid that, then the noise reduction will be negligible.

Agree about the danger of overheating with enclosure.The exhaust could be led overboard with a suitable length of flexible exhaust pipe.With a bit of "farmyard engineering",it may be possible to duct cooling air to your genny like a Lister engine.

Noise,well,earplugs for you,and don't run your genny between 8pm and 8am for everyone else.

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6 minutes ago, Mad Harold said:

The exhaust could be led overboard with a suitable length of flexible exhaust pipe.

 

Best not to. Extending genny exhaust pipes has lead to deaths on boats from CO poisoning.

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5 minutes ago, MtB said:

 

Best not to. Extending genny exhaust pipes has lead to deaths on boats from CO poisoning.

 

Summary

On 1 April 2013 a mother and daughter on board the motor cruiser Arniston suffered fatal carbon monoxide poisoning on Lake Windermere, Cumbria. They were overcome by fumes from a portable generator which had been installed in the engine bay and modified by the addition of an exhaust which subsequently failed allowing the small sleeping area to fill with lethal carbon monoxide.

Safety lessons

  • the installation of the portable air-cooled petrol generator in the enclosed engine bay was against the advice provided by the manufacturer
  • the improvised exhaust system fitted to the generator was not fit for purpose
  • ...

https://www.gov.uk/maib-reports/carbon-monoxide-poisoning-on-motor-cruiser-arniston-with-loss-of-2-lives

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22 minutes ago, David Mack said:

 

Summary

On 1 April 2013 a mother and daughter on board the motor cruiser Arniston suffered fatal carbon monoxide poisoning on Lake Windermere, Cumbria. They were overcome by fumes from a portable generator which had been installed in the engine bay and modified by the addition of an exhaust which subsequently failed allowing the small sleeping area to fill with lethal carbon monoxide.

Safety lessons

  • the installation of the portable air-cooled petrol generator in the enclosed engine bay was against the advice provided by the manufacturer
  • the improvised exhaust system fitted to the generator was not fit for purpose
  • ...

https://www.gov.uk/maib-reports/carbon-monoxide-poisoning-on-motor-cruiser-arniston-with-loss-of-2-lives

 

 

And to make it worse he was a 'time served' Gas-Safe' registered installer who should have known better.

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1 hour ago, MtB said:

 

Best not to. Extending genny exhaust pipes has lead to deaths on boats from CO poisoning.

When I was in the Army we had deaths from gennys a couple a year maybe? Small petrol gennys can kill to easily, wind changing direction was the norm, we had a minimum distance that a genny was allowed on boats that's not feasible as your genny would be either nicked or kill someone else 

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2 hours ago, Tony1 said:

 

I'm wondering if you could use a sound-deadening lined box to reduce a lot of the noise from a cheap genny- but the bigger issue for me at the moment is storage space. I have at least 6 bags of coal in the cratch at the moment, plus my (lidded) ashbox, spare paint, mooring hardware, mallets, trolley, spare toilet cassettes- its getting increasingly difficult to find storage for anything, anywhere on the boat, so until I have a thorough reorganisation of the whole lot, I dont really have room for a genny.

It would be different if a genny was my routine electricity source (although I wouldnt fancy the routine task of fetching petrol from local petrol stations).

As it is, my engine can charge at 90-100 amps, so I don't have to run it for long in order to get the charge I need for a day. So I'm not getting into those issues of increasing engine hours, frequent services, wear and tear etc- especially because its only a winter issue anyway.

Between late Feb and the end of Oct, the solar will give me all the charge I need on most days. 

I would guess that between Nov and end of Jan, I probably ran the engine (just for charging) for a total of about 80 hours, so its not getting flogged to death just for electricity generation.

 

 

I used to project manage the installation of standby generators, amongst other things.There are 3 sources of noise from a generator, all of which need addressing to make them quiet.

 

1. Mechanical noise from the engine. Relatively easy to reduce by boxing in with sound deadening materials and using double rubber seals on opening panels to minimise noise breakout. You may also need antivibration mounts to prevent vibration from being transmitted to the hull.

 

2. Noise from aspiration and cooling air. Relatively easy to reduce by louvres and baffles, but care must be taken to ensure sufficient volume of air whilst slowing down the airflow to make it quieter.

 

3. Exhaust noise. This is much more difficult to attenuate, because you cannot simply add a bigger silencer and more pipe to the existing exhaust. You need the engine manufacturers backpressure figures, then to come up with a design that meets this and is approved by the generator manufacturer.

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