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Lithiums only beat LA if you don't have enough solar


jetzi

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2 hours ago, PeterF said:

I thought that 360 to 375W solar panels are about 1m x 2m so you will need 8m total length. Suggest you check this because if you are limited to 6.6m

The panels I'm considering are 315-400W and are 1675x995. If I was to fill the roof I would have space for 9 of these, or 2.8kW to 3.6kW. I have a 65' narrowboat and currently nothing on the roof. Perhaps technology has moved on since you last looked? Or perhaps we're comparing apples and pears - of course a max 400W solar panel is almost never going to produce anything like 400W. Are you talking about usable power or rated maximum?

 

There may be solutions to the walking on the roof problem, such as a removable gangplank over them, or perhaps a ladder kept on the boat, or perhaps my idea to hinge them on both sides would allow me to stand them up on one side when locking to allow walking "underneath" them. Either way I don't find myself walking on the roof that often, and I believe that in almost all cases I'd be able to avoid it. @Sea Dog is right though and whatever I end up with must be traversable in an emergency.

 

Alternatively I could plaster the whole roof on the (understandably less efficient) stick on type that can manage having someone walk on them.

 

I wonder what it is about people choosing to have such a small solar generation? PV panels are really, really cheap, and if you are primarily having many of them to handle the darker months, I think you might be able to get away with a smaller solar charger and simply disconnect some of the panels in the height of summer (or switch them over to an immersion heater).

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5 minutes ago, ivan&alice said:

PV panels are really, really cheap, and if you are primarily having many of them to handle the darker months, I think you might be able to get away with a smaller solar charger and simply disconnect some of the panels in the height of summer (or switch them over to an immersion heater).

Getting cheaper all the time. My 1000W of secondhand Panasonic/Sanyo panels cost me approx £600 five years ago. I bought some solar bits last week, the guy was selling new 280W panels for £99 each delivered. Things can only get better.

Edited by rusty69
280, now 380
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2 hours ago, PeterF said:

I thought that 360 to 375W solar panels are about 1m x 2m so you will need 8m total length. Suggest you check this because if you are limited to 6.6m then you may have an issue with one of your base assumptions. However, if you have found some panels with a much higher yield per square meter let me know.

 

The recently publicised Mothership Marine 57ft Narrowboat "Shine" was almost completely covered in solar panels and that was 1.8kW.

Shine has flexi panels I have 9 for the bathtub 100watts each same size very nearly as a 300 watt rigid, my flexis are quality ones from the USA so have a chance of a good long life

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8 minutes ago, ivan&alice said:

The panels I'm considering are 315-400W and are 1675x995. If I was to fill the roof I would have space for 9 of these, or 2.8kW to 3.6kW. I have a 65' narrowboat and currently nothing on the roof. Perhaps technology has moved on since you last looked? Or perhaps we're comparing apples and pears - of course a max 400W solar panel is almost never going to produce anything like 400W. Are you talking about usable power or rated maximum?

 

There may be solutions to the walking on the roof problem, such as a removable gangplank over them, or perhaps a ladder kept on the boat, or perhaps my idea to hinge them on both sides would allow me to stand them up on one side when locking to allow walking "underneath" them. Either way I don't find myself walking on the roof that often, and I believe that in almost all cases I'd be able to avoid it. @Sea Dog is right though and whatever I end up with must be traversable in an emergency.

 

Alternatively I could plaster the whole roof on the (understandably less efficient) stick on type that can manage having someone walk on them.

 

I wonder what it is about people choosing to have such a small solar generation? PV panels are really, really cheap, and if you are primarily having many of them to handle the darker months, I think you might be able to get away with a smaller solar charger and simply disconnect some of the panels in the height of summer (or switch them over to an immersion heater).

 

3 minutes ago, rusty69 said:

Getting cheaper all the time. My 1000W of secondhand Panasonic/Sanyo panels cost me approx £600 five years ago. I bought some solar bits last week, the guy was selling new 280W panels for £99 each delivered. Things can only get better.

My Aixam mega truck has 3 mono rigids on the roof, they are 300 watts each I saw 895 watts input from them in full sun earlier this year, they cost 80 squids each from a chap that installs solar farms they are as cheap as chips to say the least.

Ivan put the most solar you can fit on the roof and like me you will have hot water in the summer and just enough electric in the winter

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7 hours ago, ivan&alice said:

I have no doubt that I am not ready for Li's (or LAs for that matter!) I am beginning to look into the options so it seems reasonable that I don't know what I'm talking about yet. As I say, I have an April install date so I have several months to think about it and ask other questions

I'm the first to admit lithiums are not for everyone, but it seems like you're keeping your options open and doing the right thing by researching and asking questions. There was very little experience with lithiums on here when I designed and installed mine, but there's several of us now with practical hands on experience and I don't think any of us would consider going back.

 

7 hours ago, ivan&alice said:

Thanks for the hint that I'll need to DIY a BMS to make Li's cost effective. I haven't forgotten and I'm bearing it in mind.

It's not so much the BMS that is the issue, as how you control your charge sources, particularly the alternator. I've used a dedicated Arduino based alternator regulator for day to day control, and (as a failsafe backup), a relay controlled by the BMS to cut all charge sources if a single cell voltage goes too high. Dr Bob (and I think MP) keep a lead acid bank in parallel and isolate the lithiums when they consider them charged enough. This can simplify things, and the lead acid acts as dump load for the alternator.

 

7 hours ago, ivan&alice said:

I'm not sure if I see this as a problem, rather a solution. My proposed solution to having enough electricity, to not having to charge my batteries as often, and to keeping costs low, is to have a larger than average bank of batteries and a larger than average solar array. Another possible solution is to have an average solar array and an average battery capacity, but to make them Li's. I haven't done the sums properly because I haven't really specced out the two options and costed them properly yet, but at first glance it seems that the big solar & LA solution will suit my needs better for less money. And it's quite possible I'm wrong which is why I proposed the hypothesis to hear some debate on this one particular point. Yes we could get into the virtues of building your own BMS and how long a life you can expect from your batteries and so on, but I prefer to clear up one question at a time - and the question is can you increase your solar generation to such a degree that the advantages of Li over LA lessen and no longer justify the cost? We've had four good arguments but not dealbreakers, and I still reckon yes, but I'm very open to being convinced otherwise.

You need to remember LA's start to sulphate and lose capacity very quickly if left in partial state of charge, and really need some daily charging, and at least weekly charging to 100%. Regardless of bank size, if off grid, you'll be running your engine/generator for many more hours a week than I will in winter. We're in the fortunate position to have experience of both your ideas to a greater or lesser degree. Our last boat had 1kw of solar, and 450ah T105's. Currently we've got 500w solar with 320ah 2nd hand lithiums. I certainly know what option I prefer and it's the one I don't really have to think about and never seems to leave us short of power ?

 

7 hours ago, ivan&alice said:

I envisage 4 solar panels which would be around 1m x 6.6m for 1500W. Mounted centrally this would give me 30 odd cm either side of the panel for a walkway (more if I hinged them up on one side, and more than 10 metres of roof still walkable. I'm not completely sure why 1500W seems like such a ludicrous amount.

I don't think 4 panels is necessarily a ludicrous amount. Our 1kw on our last boat was 4 panels, and I'm sure we paid more for them than you will for 1.5kw! Don't underestimate the difficulty of walking along a 30cm wide strip high on the roof with nothing to hold onto though. Not as easy as it might seem. Personally I wouldn't bother with hinging them though. The ones on our last boat were designed to be angled slightly, but in reality we never did so our current ones are fixed flat. Not convinced it really makes a lot of difference unless you accurately track the sun, and only then in winter when you get virtually no solar anyway. 

 

7 hours ago, ivan&alice said:

'm not really understanding the question, it might be that I'm locking incorrectly. What I normally do is:

.....

 

.....
At what point are all of you pacing up and down the boat roof while locking?

Everyone develops their own locking technique as their experience grows. 

 

We virtually never use lock landings though, preferring to position our boat in the lock mouth. Going up I'll usually jump on the roof to  climb onto lock side and help my wife with the lock, before she goes on to set the next leaving me to finish closing up behind me. Going down much the same, she'll go and set the next lock and I'll use the roof to jump down at the front after opening gates and walk along the roof to the back. Also with a full length boat, the ladder never seems to be near front or back deck. I disagree with some of the other comments though, it's nearly always possible to shuffle along the gunwale to reach the ladder as long as you don't mind getting covered in slime from the lock walls! We've used this technique locking in heavy snow, I'd never consider using the roof when it's covered in 12ins snow!

 

As said, everyone's different, although the inefficiencies I see with some boaters locking technique, it's a wonder they make any progress at all! There's been a few times I've single handed up a flight with all locks set against me, setting the locks behind for a following boat and still got to the top a long time ahead of them, only to then realise they had a fairly fit and active crew of 4 or more!

 

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As to price of solar, couldn't agree more. Our last boat had 1kw solar, the first 2 panels I bought were around £200ea for 250w, the second set were around £100ea. 

 

I'm still not convinced more solar makes much difference in winter. We found virtually no discernable difference between our initial 500w and the upgrade to 1kw in winter. It did make a difference on cloudy summer days, and proved more reliable at meeting our needs early spring and late autumn. Still experienced very sudden drop off beginning November until mid February though, with virtually no useable output from our 500w or 1kw array. 

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9 hours ago, Tom and Bex said:

I'm still not convinced more solar makes much difference in winter. We found virtually no discernable difference between our initial 500w and the upgrade to 1kw in winter. It did make a difference on cloudy summer days, and proved more reliable at meeting our needs early spring and late autumn. Still experienced very sudden drop off beginning November until mid February though, with virtually no useable output from our 500w or 1kw array. 

I agree. We have 4kW on our house with a pitched roof pointing almost due south. We get bugger all from it during the winter apart from the odd cool and sunny day when we might see a few hundred watts for a short while. 

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5 minutes ago, WotEver said:

I agree. We have 4kW on our house with a pitched roof pointing almost due south. We get bugger all from it during the winter apart from the odd cool and sunny day when we might see a few hundred watts for a short while. 

And today Tony they like mine will be producing nowt!

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5 minutes ago, Mike the Boilerman said:

 

Its 0.4 ants per hours, silly. And my enjun room dunt have curtains, silly. Does yours?

 

 

 

Those ants are moving pretty slowly.

Less than half an ant per hour. Does the head an thorax count as 0.4 ant or is that not half an ant? I dont think my meter would be good at measuring ants.

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3 minutes ago, Dr Bob said:

Those ants are moving pretty slowly.

Less than half an ant per hour. Does the head an thorax count as 0.4 ant or is that not half an ant? I dont think my meter would be good at measuring ants.

 

Thems going so slow because there is not much room lefts in them batt trees. They are having to queue up and shuffle about to get in.

 

 

18376435-2CB7-41AD-BCF8-B293788500E2.jpeg

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25 minutes ago, Mike the Boilerman said:

 

Thems going so slow because there is not much room lefts in them batt trees. They are having to queue up and shuffle about to get in.

 

 

18376435-2CB7-41AD-BCF8-B293788500E2.jpeg

Oh, don’t believe that...

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28 minutes ago, Mike the Boilerman said:

 

Thems going so slow because there is not much room lefts in them batt trees. They are having to queue up and shuffle about to get in.

 

 

18376435-2CB7-41AD-BCF8-B293788500E2.jpeg

That looks like an interesting bit of kit Mike, don't think I've ever seen any discussion about them on the forum.

Are they any good then?

.

.

.

.

.

;)

 

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13 hours ago, Tom and Bex said:

As to price of solar, couldn't agree more. Our last boat had 1kw solar, the first 2 panels I bought were around £200ea for 250w, the second set were around £100ea. 

 

I'm still not convinced more solar makes much difference in winter. We found virtually no discernable difference between our initial 500w and the upgrade to 1kw in winter. It did make a difference on cloudy summer days, and proved more reliable at meeting our needs early spring and late autumn. Still experienced very sudden drop off beginning November until mid February though, with virtually no useable output from our 500w or 1kw array. 

 

As it gets later in the year you need more and more solar capacity. I agree there is a certain point of the year where you need so much capacity that solar becomes prohibitive. This can be extended out by using power increasingly conservatively. At the point that solar is worthless, yes Li's will mean much less generation from diesel.

I believe that November to February inclusive would require a prohibitive amount of solar so there is no point in aiming for that. But 1500W in October should meet my needs, and given how cheap solar is I may well over engineer it even higher than that.

Angling the panels perpendicular to the Sun I believe makes a very big difference. In summer though I'd be unlikely to need to bother with a large solar array, but I'd like the capability to do so if I wanted or needed to squeeze out a few more mA. My ideal would be to have them connected together on a winch like system, with a handle which, rotated one way, raises the left edge and the other way raises the right. When locking I can open it all the way to right or left providing a much wider walk way, and even - if the panel frame is rigid enough - a handhold. Furthermore it might provide a little storage space underneath the panels for (low value) items like coal, but I really want to keep the air draught as low as possible.

One thing that I feel so confused about is that people seem to think Li's are an advanced technology requiring a much deeper understanding than LA, but at the same time one of their primary advantages is apparently less maintenance and monitoring.

Is this a case of Li being tricky to set up but easy to use, versus vice versa?

@Tom and Bex @Dr Bob @MoominPapa do you use a conventional solar MPPT charger that you hook up to your BMS, or does your DIY BMS system include a charge controller? Does the alternator regulator feed straight into the BMS?

I know I need to learn more about how all that works, but it would be helpful if you could in very broad strokes tell me about the different components I'd need to consider with Li which I could then go and research.

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7 minutes ago, ivan&alice said:

 


@Tom and Bex @Dr Bob @MoominPapa do you use a conventional solar MPPT charger that you hook up to your BMS, or does your DIY BMS system include a charge controller? Does the alternator regulator feed straight into the BMS?

I know I need to learn more about how all that works, but it would be helpful if you could in very broad strokes tell me about the different components I'd need to consider with Li which I could then go and research.

 I use a conventional MPPT charger, and a conventional (though voltage-adjustable) alternator regulator. The engine-start LA battery is always in circuit, so terminating charge on the lithiums is achieved simply by opening the contactor that parallels the Lithiums and the LA start battery. The presence of the LA battery avoids a load-dump surge, and it's voltage rises very shortly after to the shutdown voltage of the regulators, unless there's some load on the system.

 

Once in this state, the BMS monitors the voltage on the LA battery to determine when the alternator and/or solar is no longer handling the load, and then closes the contactor again to begin discharging the LIthium bank.

 

MP.

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47 minutes ago, ivan&alice said:

One thing that I feel so confused about is that people seem to think Li's are an advanced technology requiring a much deeper understanding than LA, but at the same time one of their primary advantages is apparently less maintenance and monitoring.

The trouble I have with Lithium batteries, is not necessarily that they require a deeper understanding than conventional lead acid batteries, just a different understanding. I think if you knew nothing about LA's to start with, understanding the requirements not to knacker an expensive set of Lithium batteries would be so much easier. Of course, boats are not set up this way, so most people have some understanding of how to increase the lifespan of their LA's. Also, integrating lithiums in a system that already has conventional charging systems and LA batteries adds a level of complexity.

 

I suspect they require apparently 'less monitoring' because the people who have installed them have a great understanding of what is going on, and they have now lived with them long enough to have built up confidence in their systems. They will only loose confidence should some of their fail safes erm ....fail. 

 

I will jump on board the Lithium band wagon at some stage, as I did the solar one. I think I will wait for a while until more of the pioneers iron out the problems, prove their homebrew setups, prices come down and more kit becomes available, which it inevitably will.

 

My only hope is that those pioneers who post on here,for our benefit, continue to do so,and are brave enough to report any failures as well as the successes.

 

Edited by rusty69
add a bit
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8 minutes ago, rusty69 said:

The trouble I have with Lithium batteries, is not necessarily that they require a deeper understanding than conventional lead acid batteries, just a different understanding. I think if you knew nothing about LA's to start with, understanding the requirements not to knacker an expensive set of Lithium batteries would be so much easier.Of course, boats are not set up this way, so most people have some understanding of how to increase the lifespan of their LA's.

 

I suspect they require apparently 'less monitoring' because the people who have installed them have a great understanding of what is going on, and they have now lived with them long enough to have built up confidence in their systems. They will only loose confidence should some of their fail safes not work. 

 

I will jump on board the Lithium band wagon at some stage, as I did the solar one. I think I will wait for a while until more of the pioneers iron out the problems, prove their homebrew setups, prices come down and more kit becomes available, which it inevitably will.

 

Rusty is right in what he says. It is a different understanding rather than a 'deeper' one. Once you understand the basics of how not to overcharge (and to a lesser extent undercharge) then they are easier to manage.

 

25 minutes ago, ivan&alice said:

do you use a conventional solar MPPT charger that you hook up to your BMS, or does your DIY BMS system include a charge controller? Does the alternator regulator feed straight into the BMS?

 

 

That is a more complicated question. Firstly watch the word BMS. What does it stand for? Battery management system? Battery monitoring system? What is the difference?

MP has a battery management system that auto disconnects power from charge sources when voltage termination is needed (measured from a voltage and current). It also balances his cells.

Mine is more of a monitoring system. I have an auto disconnect switch which isolates the Li's so only the LA's are in circuit (mines a hybrid) when the voltage gets too high....at the bank level via a BMV battery monitor relay function...and at the cell level via a high/low voltage disconnect box. That box measures the individual cell voltages and sends a signal to the auto disconnect switch if the cell voltages are too high or too low. I do not use a voltage/current input for the disconnect.....too complicated for me. MPs system uses a small computer to do the thinking. Mine is just a voltage activated relay. I think MP's isolates the Li bank on termination. Mine never gets there! Mine is set up so the alternator and solar chargers stop charging when we get to 85% ish charge. In the 5 months we have been using it, the auto disconnect has never triggered...except when I have tested it.

The solar charger is a typical MPPT which I set to a high bulk and float voltage so it always trys to put in 14.something Volts. As I am usually 30-60% charged at the start of the day and only with 500W of solar, even a good sunny day will not take me to 100%. If it was going to, I would reset the float voltage to 13.3v on the mppt and it would back off well before 100%.

The alternator is a more difficult thing to sort out. There is loads of info on alternator control in the earlier Li threads. It really worried me as I was installing mine as there didnt seem to be an commercially available alternator controller on the market at a sensible price. When I put my Li's in, I anticipated that I would mainlyuse just solar to charge them and maybe wire it so I could isolate them from the alternator. The problem is that if you alternator is putting out 12.4V, it wont stop when the Li's get to 13.9V and so wreck them. MP solves this by his auto disconnect activating when the voltage/current tells him the Li's are near 100%. Mine however has turned out even easier. My alternator is pretty cr*p. It only puts out 13.9V max, so a few years back I bought a Sterling A to B charger which sits between the alternator and the batteries. It effectively boosts the voltage to 14.3V (for LA's) but has a habit of going into float too soon. On Li's however, I put it on a US gel setting and it goes into float as my system reaches 13.7 Volts which is around 85-90% SoC so it basically cannot overcharge. The charge rate is a litlle low, ie typically 40A which is fine for summer/autumn crusing - in the winter I will boost the charge by using the LA charge setting and get 60-70A in for a hour or two. Shock Horror.....a Sterling A to B useful for something!

I also have a Victron IP22 battery charger which I use when on shore power to get up to 100% when I need to. This has an Li setting but it will overcharge if left on and thus activate the auto disconnect. I am careful when I use it and it has only every been used to do the 100% thing.....to reset the amp hour counter and to do a manual rebalance of the cells.

So to summarise, my BMS is a monitoring system that just disconnects the Li's if something goes wrong. For 5 months, it has never been called upon.

 

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Have been following the Lithiums v LA argument for a while; unfortunately most if not all folks overlook the paperwork.

 

Not the technical specs per se, which are interesting enough, but it is the warranty folks should read. The warranty is pretty specific about the range of temperatures it covers.

 

Lithium batteries are claimed to be the answer (for now ... I am intrigued about the application of hydrogen fuel cells in that French boat visiting the Thames ... narrowboat next?) for storage batteries and in specific circumstances they are truly excellent, but not necessarily in a temperate climate as we have in the UK.

 

And for those folks not in UK my observations may not necessarily apply to their locale.

 

The warranty virtually warns against their usage in in some climates (my interpretation of course) because you should avoid charging them at high rates at subzero temperatures.

 

Doing so can allow lithium to permanently plate one of the electrodes (Google for tech aspects, it is fairly involved. You will find details also on such arcana as Battery Management Systems ... extremely important in lithium battery chemistry).

 

The warranty will not cover you for this type of damage. Plus the upper limit for usage is described as 43C. Exceed this and you're on your own if seems.

 

Nobody will forget that a year of so ago we experienced winter temperatures of neg 14C in rural areas. 

 

So if your lithiums got below freezing then unless the BMS took this into consideration you risked over charging the batteries and their consequent destruction. Subzero charging rates are measured in milliamps, which rather defeats the claim of rapid charging.

 

There are some lithium batteries that incorporate an inbuilt battery heater, which is one solution, but it takes time to heat up the battery to a "safe" temperature for charging at a higher current. You will note this again defeats the claims of rapid charging.

 

And you may think that a lithium battery is getting more packed with BMS electronics and now heating equipment.

 

Does this complexity imply less reliable operation? I don't know and certainly don't want to find out when I have flat batteries on an iced up canal and not enough current to run my Webasto and circulating pump.

 

Of course I can fire up my Morso but I don't have a backboiler.

 

Please note too that discharging a lithium battery at subzero temperatures is not a problem ... until it goes flat.

 

These issues would put me off lithium batteries completely.

 

In light of this I have slightly altered the direct of this topic, so apologies up front.

 

I would suggest therefore researching the lead carbon technology.

 

Lead carbon technology is not new by any means but one plus is that by using carbon in the "electrode chemistry" sulphation is very much reduced. By reducing the action of sulphation, so to speak, this results in an extended life.

 

I gather too that lead carbon batteries can be charged at higher rates in less time cf ordinary lead acid batteries. Not quite a match for lithiums but not far off.

 

As above Google is your friend.

 

What might be of interest too is there are a lot of papers published by, for example, Ford  Motors and American universities, on the topic of lithium batteries regarding their application in the "real world". By "lithium" I refer specifically to the LiFePo types.

 

Lithium has been combined with many other elements to produce many variations of batteries for specific applications.

 

IE the lithium battery in your cellphone is an entirely different type of lithium battery we would use to replace a lead acid battery.

 

So, to summarise, quoting the technical aspects of a lithium battery is largely academic, it's the ambient temperature in which they are used is what you want to worry about.

 

In my opinion.

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9 minutes ago, Constant Cruise said:

The warranty virtually warns against their usage in in some climates (my interpretation of course) because you should avoid charging them at high rates at subzero temperatures.

 

This is fully understood by everyone on here and often discussed, so your post comes as  bit of a surprise.

 

The problem is easily circumnavigated on liveaboards by fitting the batteries inside the living quarters, e.g. under the bed. 

 

 

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