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ivan&alice last won the day on June 22

ivan&alice had the most liked content!

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    Middlesex, UK

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  1. 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.
  2. 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. 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 personally find that the forum is more interesting and useful on those occassions that it stays on topic (some don't and fine, each to his own). The topic of this thread is whether the benefits of installing Li are mitigated by instead investing in a lot of relatively cheap solar to charge your LAs. And I think there have been a number of good counterpoints to that thread. 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. 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. 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'm not really understanding the question, it might be that I'm locking incorrectly. What I normally do is: Moor up on the lock landing and set the lock as needed. Board the boat and slowly drive it into the lock. Stop it with reverse and get the aft deck near the ladder if possible. If I'm going up, climb up the ladder which I find is usually conveniently located towards one end or the other of the boat, requiring at most a metre of shimmying along the gunwale or edge of the roof to reach it. Alternatively if the lock isn't too deep or I'm going down, I can just step off or climb straight up onto the wall from the very edge of the roof. Now that I'm off the boat, loosely tie the boat by the midline to the centre bollard. Close gates. Fill/empty the lock. Close the paddles. Open the other gates. Either climb back down the ladder or step onto the edge of the roof. Drive the boat out and tie the boat up on the lock landing. Close gates and make sure paddles are all closed. Drive off. Of course, if I'm not single handed, which I'm not most of the time, my boatmate can get off in Step 1 and I can just stay on the boat until they rejoin at step 9. So I can only really imagine needing to walk along the roof at Step 3, if I am singlehanded and the ladder happens to be in an unusually awkward position. Even so, I could probably shimmy along the gunwale if I don't think there is a chance of being squished between the lock wall and the boat. At what point are all of you pacing up and down the boat roof while locking?
  4. OK, I hear the advantage of not needing to get to 100% with Li. But how many people get their LAs up to 100% more than once a week (at most)? Still, I see that you can stop worrying about your battery capacity once you have Li's. Saying that the tail current will kill the input is a non-issue with solar in my view, because the energy is free, quiet and the generation equipment requires little to no maintenance, unlike generation with your alternator. I think there have been a number of good points made but none so far that (to me) justify the cost of Li's. I think I probably need to get some much more accurate figures of how much a LA vs a Li system would cost me and how long I'd expect it to last. One thing that I probably should also mention is that we only expect to keep our boat 4-5 years before we upgrade. So batteries that last a thousand years are a bit wasted on us. So when I'm calculating the cost of LAs vs Lis, I really need to amortise over 5 years - it doesn't help me much if Li's save me money over 20 years. Of course the next owners would appreciate them I'm sure, and that might add a bit of value to the sale price of the boat, but if I was buying a boat I wouldn't put much stock in the quality of the batteries they had on board because you'd have no idea if they had been abused. I guess what a lot of it comes down to is that I'm not sure it's wise to invest in something fragile - and if you are comparing the cost of LAs and Li's over many years then what you are doing is comparing an investment.
  5. Thanks @Tom and Bex and @MoominPapa for your insight - it's certainly very helpful to hear the testimony of the people who have them. Had you increased your solar to 1.5kW or 2kW on your 4 t105s or 5 sealed batteries, instead of going lithium, how would your life be different than it is with Li's?
  6. When you must say I must buy now, do you mean if I wanted them to arrive by April 2020? A quick look says they output are around the same price as the 100A Victron, are they of better quality? I did for a second consider the idea of having a larger than 12V system (to save money on the solar controller) but as all of my stuff is 12V it didn't make sense to me to have to step down everywhere. Of course, I don't have an electric drive and never will in this boat, it's a wonderful idea for a new build but it's unlikely I'll ever have that kind of money. So apart from (potentially) an immersion heater I only need 12V and 240V for washing. You answered my question though - your panels are switched before the controller to feed the immersion heater at whatever voltage they are naturally coming out at.
  7. I do most of the locking single handed and the only time I find the roof useful as a passageway is when I'm in a deep lock and the ladder is in an awkward position. Why can't Mrs Bob leave the boat at the bow? I'm envisaging a mechanism where I can tilt all the panels together. My thinking would be that I could hinge up the panels as needed when arriving at a lock or other place I needed to use the roof. The other option is to get a gangplank that you can place over the panels to protect them or the stick-on type that you can walk on. Of course these are less efficient, but the solar panels themselves are the cheapest component of the generation system, so it seems to me to make sense (if you have the space) to double or triple up on what you need so that you don't have to be as careful about squeezing every last drop out of them. In winter you can be more fastidious about angling them perfectly so you can maximise the energy. No, this is true. Around 700 GBP for a 100A Victron MPPT. 100A is loads though; perhaps to save money it might make sense to get only one smaller one for now and simply turn off solar panels when it gets too sunny. So in winter use 6 or even 8x 400W panels and then in summer just the 4 going through the 100A MPPT. That's why I was so interested in the immersion heater idea, and why I was curious to understand @peterboat's wiring. If he needs an inverter/controller for the excess panels then this is going to raise the price substantially. If I can somehow switch the PV away from my precious MPPT and straight to the immersion heater, that would mean I'd need less MPPT. I certainly will, thanks! My install date is only 2020-04-01, I don't see there being any point in installing before spring and this will give me time to save and study. I'm definitely keen to hear more about the battery monitor but I'm going to get the basics down first before I ask a lot of questions about that.
  8. Sure, that's the other way you can do it - cut your consumption to near zero. As we need to be able to work from the boat this isn't really an option for us. Point 4 for Li's then - less time mucking about with batteries is a fair pro. And I'm just trying to work out why, to see if they would be fantastic for me in my situation. I have 4 reasons so far, and none of them are enough to make Li's a go for me. I know, and this isn't about me trying to convince anyone that Li's are worse than LAs. I just can't see why anyone with a big solar array and minimal usage in winter would need Li's, and if I'm wrong I want to know because I need to know what batteries to buy!! I haven't settled, but I planned to get four of these which are 1675x998. My boat would take up to 9 of these on the roof lengthwise (up to 3.6kW max), which would leave a strip either side a little wider than a gunwale. I haven't decided, but I'm thinking of hinging them on either side so I could lift them up almost vertical in one direction to make it easier to move on the roof. I have never needed to walk on the roof at locks even though it is sometimes helpful. I have a centre lines each which run in that little strip so I don't see them getting snagged. In fact having a continuous strip of solar panels would in my estimation make for less spots to snag.
  9. Ah thanks, that was the question I was asking - so your PV comes in at 160V?! I'm still struggling to picture your system, you have a flip switch before your charge controller and you can send the power to either your solar charge controller or your immersion heater once the batteries are full? Can an immersion heater run at any voltage you like - it's just a coil of high resistance wire after all? Please understand, I know that I don't have experience here which is why I'm asking the question. I'm not trying to convince anyone of my opinion, I'm trying to understand the facts myself. People who have Li batteries love them, and I am trying to understand why because the facts as I understand them so far don't support it. I'm sorry but the arguments presented so far are not enough to justify Li's, from my point of view. If they are better for me needs I really would love to be convinced - but I can't see it right now. Maybe this is a 3rd point? These batteries don't wear out so they give consistent and predictable performance? Ah, so you must see that this is a bit of an unfair advantage you have here. I don't "know a guy" that could organise me 250 GBP 138Ah LiFePO4s. So it's not really fair to compare these with 90 GBP 110Ah budget LAs. Any Li's I buy would be from a shop.
  10. They are easy to do? I feel like I have read a number of people on this forum saying the exact opposite. I'd be willing to consider it but I am not sure it is a good idea given Li's volatility. Why are off the shelf systems so expensive? And what about these cheap Li's that @peterboat has with built in BMS? Ok so you just manually flip on the immersion heater (through the inverter) when you have tons of sun. Yeah, I really like that idea. This is an oversimplification. I think you are misunderstanding my argument. According to @WotEver the "throttling back" happens when the remaining Ah to be charged is less than the A coming in. My whole point is that the current from solar is going to be relatively low (maximum 50A). So, the batteries are going to be charging at full speed, i.e. almost as fast as Li; the only difference being any efficiency gain from Li technology over LA technology. I'm not expecting max (or even high) current for 14 hours a day. I'm expecting a low current for 14 hours a day. My point is exactly that with a charging current as low and extended as what you get from solar, the benefits of Li's diminish. Also, a digression, but 500W is less than a third of what I'm talking about. This is a valid point: when you are closing in on fully charged, you're going to "waste" some of the solar you get because LAs won't be able to take it all. However this will be a small proportion of the time, precisely because solar has such a low charging current, not in spite of it. In the 1000Ah battery / 1500W PV system I'm talking about, the batteries will not charge bulk in full sun only for the last 50Ah. That is 50Ah out of 500Ah usable capacity. So only a maximum of 10% of the charge I'm going to be wasting some proportion of the energy that falls on the PV panels. That said, it will be hard to get the batteries to 100% daily, and therefore you are likely to still need to run your engine for an extended period once a week to clear sulfation. So I am happy to add this above argument as a "pro" for solar with Li's. So far we have: 1. Li's charge more efficiently, so you get somewhat more effective power generated for any given PV system. 2. Li's can charge at full speed right up to full, so you will not waste solar energy when nearing 100% (about 10% of the time you will waste some solar energy with LAs). This might necessitate running your engine for extended periods once a week. For me, this simply isn't worth the extra hassle and cost of Li's. I need a better pro argument than this. Which implies 150Ah from the system I'm proposing on what you admit is a bad day. I calculated 300Ah odd from the system on an average day in October, and I'm basing this on data from @Col_T not making it up. Furthermore if this is not enough, just add more panels. For the price of 138Ah of lithium (even at a frankly unbelievable 250 GBP) you can get at least a half a kW worth of panels. PV is so cheap compared to Li batteries that it doesn't make sense to create an expensive, fragile battery bank that can suck up more solar power, instead of just adding more solar power.
  11. It is also worth noting that the description is completely ignored by amazon. So this goes to the exact same place: amazon.co.uk/pink-fluffy-handcuffs/dp/B07H1ZFVFM
  12. Fair enough on the description, but you should also remove the ref part after the product number - I believe that bit tracks who/what site referred you.
  13. May I ask how much solar you have and roughly how much power you use? The immersion heater for excess solar energy is a really good idea - I think I might copy you on that. Do you manually switch it on or do you have a clever system that automatically switches it to the immersion heater?
  14. But thank you for the offer. I would still be interested in what your washing machine uses on a cold wash if you are able to measure it easily.
  15. Amended to align with Ivan's question. FWIW I actually do live on the boat year round, this was a hypothetical to get the facts on whether or not Li is actually a good idea on a boat for most of the year because it seems plain to me that it, in fact, isn't. If you are someone who doesn't use their boat (much) in winter, you don't need Lis, you need LAs and lots of solar. That's a really important point I've not seen articulated before. For me, I am OK to rough it a bit in winter and not use the inverter - rather washing my clothes at the laundry. I'm also happier to spend out on lots of relatively cheap and hardy solar panels rather than relatively expensive and fragile batteries, so that I can live entirely on solar for as much of the year as possible. I'm speccing my system to be 100% solar for 8 months of the year, but secretly I'm hoping that all my pessimistic calculations and overengineering will add up to a significant solar input in 2 more months (making 10). In real life I can be flexible, and combine high-power activities with crusing or save them for an unusually sunny November day. I'll also use that time to holiday in warmer climes. And don't tell anyone, but for the deepest darkest bit of winter, I'm going to drink a bottle of sherry and hibernate under my sofa and I won't need power at all!
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