Tony1

Thanks Tom and Bex- so you can get four 200Ah cells to make a full battery, for under £300? I'm seriously tempted, because on cruising days (and good solar days) I could store up hundreds of Ah worth of charge, for use on the following days. But my worry is whether I could use them seamlessly alongside my existing three Valence batteries....

On that first point, I would want to check that the BP will work via two 'routes' simultaneously, i.e. direct disconnection of 12v loads, plus remote switch off of the inverter. If I read the instructions correctly (which is admittedly far from certain), my BP will not perform any of its preset disconnects, if a remote switch is plugged into it, so I'm a bit wary of assuming these things will do all the things I might initially expect. Don't get me wrong- I'd be fairly confident the BP will work as you've planned it, but I would be inclined to test it out. This remote switch off function of the BP was no use to me. My inverter has a socket that looks like an RJ45 type, and that means it might be switch-offable by a remote, but I cant be sure, and anyway I dont know which of the wires in the RJ45 thing would connect to which wires on the BP unit, so I didnt even go there. So in my case, the BP was no use, and I ended up using it as a high-voltage disconnect instead- and to be fair, when controlled by a BMV712, it seems to do that job very well.

What I'm saying is that you're going cruising anyway, right? So the diesel is going to be used up anyway, for that purpose. So why not get the extra (and free) benefit of doing the battery charging whilst you're on the move? After all, your system is capable of delivering a very large charge even in an hour's cruise.

But if you're going out cruising, there's no point wasting charge beforehand getting the batteries up to 80% or 100%? Won't the cruising get them up to full charge? I never have shore power these days (although I remember it being a lot cheaper than diesel-generated electricity), so maybe my approach is different as a CCer. But if I know I'm going cruising the next day, I wont worry if the batteries go a bit low the day before, because I know they'll be getting a good long charge once I set off. I would never dare charge to 100% remotely in order to synchronise, if I was not there in person. Is it worth it? That said, I'm not an electrical wizard, so I would have an innate hesitance about pushing the batteries to extremes when I'm not around.

Hi Richard, apologies for pestering you with questions but I've just got my new victron battery protect, planning to install it tomorrow, and just noticed something that Jetzi also mentioned, which is a statement that the BP should not be connected to devices with capacitors on their inputs, e.g. an inverter. They suggest that in these cases you use the BPs relay function to switch off the inverter- but what about the 12v loads? Its hardly a complete solution. In my case, I have a fall back plan, which is to use the BP as my high voltage disconnect, placed between chargers and batteries, and control it with a BMV712. But before I start doing any work tomorrow I wanted to ask whether you had connected your BP to an inverter (as I would expect), and if so, whether you had tested it out, whether you had noticed any potential problems? If it genuinely canty be connected directly to an inverter, I'd rather make a call on which way to use it before I spend two hours configuring the cables, lugs etc.

Not wanting to sound a negative note or anything, but my relay was rated at 200 amps (continuous), and its contacts became very very hot when it was handling a charge of 100-120 amps. That was a £12 unit from amazon, but it did have hundreds of very good reviews- so I'm a bit sceptical of the stated ratings, certainly on the cheaper units. Maybe dont make too many permanent or complex changes until you've installed and tested it out properly... But there are many lithium users who dont bother with high or low voltage disconnects, since they take other precautions that make the over-voltage event extremely unlikely- and we havent heard of any wrecked batteries from users like Peter and others, after several years of daily use. But I had a scare- a situation back when I first got the lithiums, and tried to charge them using my A2B charger. Despite the set charge profile being about 14v, when the SoC got up to a high level the voltage suddenly started to shoot upwards to 15v and beyond. I was seconds away from ruining my new £1500 batteries, and it was only that I was checking the voltage every few minutes that saved the day- thankfully they didnt seem to suffer any long term damage from that event. That experience encouraged me to take a very cautious approach- and I think even over-cautious, if I'm being honest. The other thing is that, like you, I havent ruled out letting friends and family use the boat for a few days (particularly my brother who has a brand new burstner motorhome), and I know from hiring experience how easy it is for people to miss or ignore important instructions on electrical issues, whilst being given a full familiarisation tour of a boat. There's so much to take in, they are bound to miss or forget some important information. Plus they'll be using it it the summer probably, with lots of solar flooding in and potentially making it more difficult to understand whats happening. So I feel that automatic disconnects would be advisable. Although I got rid of the A2B charger, my current setup is still somewhat risky, in that I have six charging devices in play (two MPPTs and four B2Bs) when doing a full-on charge. And to keep them all charging at once, I seem to have to set the charge voltages a bit on the high side (e.g. 14.2v). If I set them all to 13.9v, some start going into float when the batteries are only 75% full. Plus with six of them, there is the increased risk of malfunction in one. Its a proper Frankensteinian monster of a setup (and not one I would recommend at all), but it does work. On a good day I'll be getting 60-70 amps from the solar, and maybe 90 amps from the alternators (via the B2Bs). I only switch on all four of B2Bs when I am static and doing an engine charge, running at 1400rpm so that the alternators stay cool. When cruising (and thus when the rpm is often at tickover for long periods), I only use two of the B2Bs, and that reduces the load and keeps the alternators cool. If anyone ever borrows my boat my instructions will be to pretend that the 'extra' two B2Bs dont exist. The standard two B2Bs come on automatically anyway- and they still deliver about 60 amps between them. Its a lot of messing about for only four months of the year, I must say, but its great on the really crappy solar days to see 100 amps going into the batteries, and getting charged up in less than an hour, when the boats around me are all too often running engines and gennies both morning and evening. ETA- I think I remember you saying that you are a CCer. Is it much of a hassle to transport petrol back to the boat? Would it be a pain without a car? I did try out a cheap genny to reduce the engine hours spent on charging, but after a couple of trips (on foot and bike) to nearby petrol station forecourts with my jerrycan, I went off the idea. But I can see that with a nice quiet genny, it makes sense to use that, and save loads of running hours on your expensive diesel engine.

I'll certainly test the low voltage disconnect with the BP thoroughly, and that will include the inverter running. The inverter is a load after all, and in my system its only the loads that will get disconnected by the BP due to a low voltage event. If victron are saying that the BP will not disconnect when the inverter is running, then it is not fit for purpose- not for most of the boaters and motorhomers who would use it. My charging current is handled by a separate high voltage disconnect device, so that bit is not a concern, at least in my case. Re the width of the charging/discharging range, I'm ok with it being 50-60% of the total capacity. I'm sure you can push them harder (e.g., 10-95% each day) and you wont immediately damage them, but there is some evidence to suggest they wont last as long. I want them to last a decade, so I'm being conservative and generally going between 40-85%. One of the reasons I dont go lower than 40% is that I dont quite trust the accuracy of the BMV712 after say a week or two since its last synchronisation. If the BMV does stray in its accuracy, then when the discharge goers into the knee phase, a fairly small error could be amplified in terms of consequences. Its still early days for me in terms of managing these batteries, so I'm being cautious. But for me, the big benefit of these batteries is not about getting a bigger % of the total capacity than you can get with lead acid. It's how readily and quickly they will absorb charge compared to my old lead acids, especially solar charge. The guy on the boat behind me has about half the solar I have, so I know he will have collected about 550 Wh today, but he had to run his engine for two and a half hours this afternoon, whereas I ran mine for 30 mins (and even that was mainly for a test). The lead acids, for whatever reason, just dont seem to soak up the solar as well as lithiums, and for 8 months of the year that is a huge benefit of having the lithiums.

If a high current really does prevent the Victron BP from actually doing what its been purchased to do, that will be very disappointing and annoying... But my level of concern on this depends upon what you consider to be a high current- or rather, what the BP considers to be a high current. My new kettle draws a horrific 80amps, but only for 3 minutes, whereas almost everything else draws 5 amps or less. But if the kettle is on, then I'm there and able to react to the situation. Almost any current draw on the boat is well below what even the most feeble and cowardly BP unit would consider to be high, so I'm guardedly optimistic that the BP will not be challenged by a genuinely high current situation, and certainly not when I'm away from the boat. I will also connect the remote switch on the BP to a BMV712, so that will act as a secondary instruction to disconnect the loads. The low voltage protection is a thing that I need either when I'm away from the boat for a couple of weeks and the solar is very poor, or when I am aboard but for some reason I haven't noticed the falling voltage. I do take your point about 12v being a bit close to the edge, which is why I'm looking more at 12.5v myself (although in terms of SoC, those correspond to 9% and 14%, so not a huge difference. In practice, I cant even remember the last time my voltage dropped below 12.9, other than a test I was doing a few months ago, so its a very uncommon scenario. That said, the voltage sag when I plug in the new kettle is huge, so I do need to consider that when setting a cut off. I dont want the loads to be disconnected because of the voltage sag if I use the kettle when the batteries are below 50% SoC, and the voltage is already around 13v. I did originally set the low voltage alarm on the BMV at 12.8v, but in the early days I was woken a couple of times by the low voltage alarm in the early hours, so I backed off a bit, and set it to a more 'emergency' level. The valence batteries dont have any self-disconnection function. If you do feel it is necessary - and to be fair, there are long term users who have no disconnect and have had no problems), then you must set it up yourself. After a few early near-misses during charging, I decided that I did need both high and low voltage disconnects, and initially I did both using a single BEP switch. But recently I've separated out the high and low voltage disconnects, so that if there is a high voltage event, only the chargers are disconnected. And if there is a low voltage event only the loads are disconnected. Fingers crossed, the BP will do that disconnection job better than the cheap relay I tried out. I only have 400Ah so I dont have a lot of room for manoeuvre, but I cant monitor individual cells (at the moment), and I think the best thing is to avoid the 'knee' phase at both high and low SoC, so I tend to stay between 40-85% (unless synchronising).

Brill, thanks Richard. Btw, if you dont mind yet another question, what f anything do you have in place as a warning or emergency disconnect in case of high voltage events?

Dont go digging for ages, I'm being lazy, it should be possible to find one using my old friend google

Thanks Richard, thats really interesting. I think your more pragmatic approach will suit me- which is to say, avoid going into the 'knee' phase, so that even if one of the cells goes out of balance, it wont be harmed. Its a challenge for me because my system has turned into a Frankensteins monster, with two MPPTs and four B2Bs. And with so many devices charging at once, there is a tendency for a couple to pack in early and go into float mode, when there is more charging to do. So the temptation is to use a higher charge voltage to make sure they all carry on charging and dont go into float too early. My hope is that setting a disconnect at 85% SoC will stop the charging before any individual cell is damaged, but its been ages since I even looked at how each individual cell was doing. In fact I've changed laptops since, and I've no idea where the PC cable is. Do you have a link for the one you have? Cheers

If the BMS cable can read data from individual cells, maybe you could get one of those victron battery balancers, which might help to actively keep the cells in balance? If its do-able, it would be 60 quid well spent. I'm gutted I didnt get a fourth valence battery when I had the chance, as Peter advised- it would give me more flexibility. I have three 135Ah units, but a fourth would have been great. https://www.amazon.co.uk/Victron-Energy-BBA000100100-Battery-Balancer/dp/B01DH6B2D2/ref=asc_df_B01DH6B2D2/?tag=googshopuk-21&linkCode=df0&hvadid=310746095651&hvpos=&hvnetw=g&hvrand=2569593360304888800&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006940&hvtargid=pla-351132180708&psc=1&th=1&psc=1

Mine have a BMS cable connecting the batteries together, so although it doesnt act as a full BMS (which is an external module that nobody can get hold of), I believe it does help to keep the cells in balance.

Thanks Richard- and hopefully Mr Victron wont sue me for defamation- I had another look at the instructional video and on the drop-down list of presets there is one for user defined values. Just on that issue of what is the best emergency cut off, I do think I was being a bit conservative. According to the rough guide I've been using, 10v is effectively zero SoC, so it wont be easy to recover from that sort of event. But 12v is about 10%, which is the point I'd want to disconnect, so maybe somewhere between 12 and 12.4v. I do recall that the voltage will read lower if the battery is under load than if it was resting, and in these situations it will be under some sort of load, so it will reach the cutoff voltage at a higher SoC than you would think, if you were using the resting voltage vs SoC graphs. All of which I think means you have a margin of error sort of built in.

Hi Nick- since you've been so kind with advice and info about all these BMS/charging issues, I just wanted to let know how the cheap relay turned out- which was not very well. It certainly works, in that it disconnects the chargers in response to the BMV signal, but the terminals, and the lugs attached to it, are getting very hot to the touch. The other cables and connectors before and after the relay are all fine, but the relay is not. Part of its problem is it has small M6 terminal studs, so I did try using large flat washers to get a lot of contact area, but its not resolved the heat problem. My next cunning plan is to use my BEP switch (currently being used as my low voltage disconnect) instead of the relay- that is rated at 275 amps, and it has giant M12 studs so its bound to stay cool. That plan leaves me short of a low voltage disconnect, so the other part of my cunning plan is to get a victron battery protect to do that job, as Richard suggested. They do a model rated at 220 amps, and even in high summer the highest charging that could ever happen will be about 160 amps, so it should be fine. It doesnt need a BMV either. Rather disappointingly, its not truly programmable, but allows you to select from a range of presets for your low voltage disconnect, and the highest voltage preset available is 12.0v, which as I understand it is too low, and by the time the battery gets to 12.0v I'm assuming its already at risk of being damaged. So its not ideal, but it is a good quality reliable unit. What I would like is a low voltage cutoff at about about 12.6v, but I'm hopeful I can link the BP unit to a BMV712, and control it remotely. So sadly the cheap relay didnt do the job (safely), and I'll have to use the BEP instead for my high voltage disconnect. But the end of the BMS saga is definitely very close.

Sadly I'd left my time machine in the house, and had no idea that CRT were going to stop the use of separating toilets a year later. The ones I feel sorry for are those who've paid £1000 and more for the natures head and similar models- thats going to be a very unwelcome loss. Tbh I dont want a fancy unit, just a cheap and simple model to see if I can get on with them. It may be I'll still go for a pumpout in the end.

There are loads for sale on ebay, and lots that you can get via click and collect, eg this little beauty: https://www.ebay.co.uk/itm/224089926616?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20201210111314%26meid%3Df9a5f8441bc84e628882adb0142928da%26pid%3D101195%26rk%3D2%26rkt%3D12%26sd%3D173581554884%26itm%3D224089926616%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv9PairwiseWithPLXWeb&_trksid=p2047675.c101195.m1851&amdata=cksum%3A224089926616f9a5f8441bc84e628882adb0142928da|enc%3AAQAGAAACEEVkMa5zf4NURfO%2FO%2Byq2mbhy6%2FidHDW%2BHgoxM8nu%2Blpxp5VnJ9bWXsAIkqgAuKl1ZO41WI0F%2BC5UBKvcaoUmLlapBOKfYFYPfAj%2BbPS%2BeSSfLhQFLWXSh%2FWN%2Fxzprjvkl1T%2FSgwPtXLEknT7iqwm4ovr1k8yeNpWLN1874PTxqOAZsKmxLAgD5AiTRTpXf8Ml9RQZdBLQRd1w7MxETTgn6%2Fd3LNZ%2BfLiU8vcapKusP8mSa0NI1qame4xyw9GOydYbVZy8yQHHIzsJhJ9JuDURSoNHKd1AsbGYxVsxWHTut79vn4REntBCNPZshQbLAB%2Frv0uu48nKs%2BUdxb0REm89aKgvVIJQZHqN5Ac5AnNCkT2ebFqYrTbnN7L6nzletmUD1TdGenVUJpCAHMPL2gY1fEAhWf04gOfypxJvoftDYsR9Xd2MZTuRWj4ydKrmse3xpiVAIuVSnzL6%2BghQNiYllz%2B5bAM1RlzpGJa1%2Fjfjn2SezidMPU%2FOHPX8Mz3mTkg0OCR80mQeQyeA51ZZi8PkUhdI%2BGlQ%2B6lqQPFqfx53PVmUgh3lfeuv3XYHfnWSBSNSHEwb%2FUwnzB1tix6c88OloxkoKCimIfrTF%2BRpwPNO8x0a8gwMvYtTu8x8rwuQgHJBAHdUr8TgYoQfAiQi6myJYJuPBpiv39X7JuHHP0bXo5%2BIPcCDu6z8ej3hWl%2FY7NaA%3D%3D|ampid%3APL_CLK|clp%3A2047675 I just dont know if I can give up the space needed for a pump out tank, and not sure if I want the extra expense and hassle of the install- some of the kits are well over a grand. A mere £65 for this marvellous example of a luxurious modern dunny, with a princely 21 litre waste volume, and I'm sorted in two days. What more could the discerning toilet user want? Bish bosh, I'm almost tempted to say ETA- I'd be grateful for any recommendations from the "cassetteers" amongst us, regarding good/reputable models

Indeed, and I hope all the separating toilet users will make their decision and get sorted asap. I expect there will be quite a rush on new cassette and pump out toilets in the next 2 months.

I'm really glad I got an insight into the hotbox whilst I still have time to rethink! The stern is tricky because my weed hatch access board is across the stern, so I cant block that off. I guess I could bend over and get in there via the engine bay... I think in the short term I'll probably get a cheap/basic cassette loo, and see if some sort of inspiration strikes... I dread the idea of being totally in thrall to a pump out tank, and having those occasions where you turn up somewhere with a totally full tank, and find the pump out machine is broken. But that said, there are lots and lots of users, and they clearly dont let these unusual scenarios play on their minds! I would bet there are lots of users of separating toilets who will be postponing the decision and carrying on using the bins for a while after the new rule is in place. After all, without physically checking every black bag that goes in, how would CRT enforce the rule? But I'd rather not break it anyway.

A cassette would certainly be less "invasive", in terms of installation, but what I really want is a solution that doesnt mean a trip to the elsan every 4 days, however that works out. A system that required emptying every 10-14 days would be great, as that would coincide with water refill and rubbish disposal. I did wonder about using a cassette only for No 2 activities (making elsan trips less frequent), and continuing to use a separate receptacle for No1 activities. But I can anticipate having real difficulty emptying a cassette that is mostly semi solid waste. And I certainly dont want to be the villain who causes a blockage in the elsan. So at the moment, a pump out looks like the least unpleasant option.

Well thanks very much for that insight into the hotbox usage. Its a bit of a blow tbh- I foolishly hadn't realised that they would be very messy to empty, and I dont like the sound of the smell during sunny weather. My plan was to stick it in the cratch, which has a pram style cover with windows, and so its like a greenhouse. And the idea of it smelling the whole time does not appeal at all. Looks like I'll have to get a pump out installed. Its not even the cost of it really, so much as the vital storage space under the bed that I'll have to lose.

On the toilet thing- my understanding is that from December, user s of separating (aka composting) toilets are no longer permitted to use the standard CRT refuse bins to dispose of their 'solid' waste. I'm either getting a pumpout fitted, or else putting a mini 'Hotbox' composter in the cratch to fully compost the solid waste. Hundreds and hundreds of boaters with separating toilets will have to make a decision in the next couple of months. If you have a storage facility on land to allow full composting of the waste from your separating toilet, then its not a major problem for you. Lithium batteries will charge more easily than lead acid batteries under any conditions, whether from solar or from your engine. That is actually their problem- they suck out current from an alternator at a higher rate than lead acid batteries do, and they pose the risk of actually overheating and damaging alternators which were designed to work with lead acid batteries- which only take the high current draw for a short time, then it reduces- which spares the alternator, but means your batteries take longer (and use more fuel) to recharge. Lithium batteries work fantastically well with solar panels - for example, I haven't needed to run my engine (to generate electricity) in the last couple of months. But lithium batteries is a whole little world unto itself, tbh, with all sorts of info you need to take on board to look after them. Luckily the info needed is all here, and there are a few super-helpful people who unlike me have a real knowledge of the detail of installing and managing these brilliant devices. For a new build I would always suggest 500 or 600Ah of lithium batteries, provided you add the budget and the equipment needed to manage control them. If you look after them they could last a decade. Just another thing- if you are speccing from new, I would suggest a water tank level monitor. Its a pain in the posterior when you want to stay off grid in a nice spot for a few days longer, but you arent quite sure when your water is going to run out. ETA- dont worry about stagnant water as a result of a big tank. No tank will last you more than 20 days anyway, and most less than 15, so there isnt time for stagnation to be an issue. I put in some chlorine-based tablets every few months just in case.

You'll probably hear this a lot, but as a relatively new boater I certainly found it to be true: at the time you are thinking about buying boats, there are a few things that you think will be important to your lifestyle, which later turn out to be not important. Underfloor heating, I feel, may turn out to be one of those requirements which don't work out in practice to be as critical (or even as useful) as you envisaged. For one thing, it takes a good while for the heat to spread up and permeate the boat- and when you want to cool the boat down a bit, it may be slow to respond. I find that a solid fuel stove keeps everything warm, including the floor- and I doubt that underfloor heating can replace a solid fuel (or diesel) stove on the really cold nights. So maybe just go with the stove? If your objective is to be off grid as much as possible, then a large solar panel array is a good idea. I would get as much as the roof will allow, leaving some space for the centre line, and maybe some space at the sides to walk along the roof to reach a ladder, if singlehanding in a lock. If you are speccing the boat from scratch I would also ensure you get a decent alternator and a capable charging system, and maybe consider lithium batteries as well if the budget allows. You'll probably use at least 100-120 Ah of electricity each day off grid. In the summer your solar panels will replace all of that, and will also give you some free hot water, but you need to think about the winter when you have very little solar, and the engine (or genny) is your only source of electricity. A good charging system could have your batteries refilled in less than an hour, which is good as it saves on diesel - and who wants to be running the engine for 2 or 3 hours when 1 hour will do it? Also good for a more off grid lifestyle is a big water tank, and either a pump out toilet or a dry/separating toilet (but bear in mind that come December there will be drastic restrictions on the use of separating toilets.

I'm wondering if it might be worth taking a step back and re-evaluating the two criteria you've given which mandate a widebeam. The reason its worth doing this is that opening your radar to include normal narrowboats instantly gives you a much wider range of boats, which would be an issue if mooring constraints urge you to buy within a given time window. Have you tried visiting some boats, and walking the length of a normal narrowboat? The bit you walk in- the 'central corridor' area, is on my boat slightly over 6 foot 6 inches. I've no idea of that is typical, but I expect it probably is. Is it physically challenging, e.g. to avoid bumping your head? If you haven't tried it, it might be worth a visit to a big broker so that you can walk the length of a few different boats, and see if it really is the issue that you think it might be. The other issue- the length of the bed- could also be sorted out, by getting a boat with some extra length in the bedroom, and just making the existing bed a foot or so longer. It would cost a few quid, for sure- the mattress wouldn't be cheap for starters- but overall the cost of adjusting a bed in narrowboat would be a big saving on the price of widebeam. If you prefer a widebeam for further reasons (e.g. the interior space) then fair enough- a narrowboat cant give you that. But you can definitely get around the bed length issue if you pick the right boat, so its possible the interior height might be the only issue, and if you haven't yet been inside a boat, it might turn out to be less of an issue than you are expecting it to be.

My dear Mr Todd, you may rest assured that your post is entirely visible, at least when I view the page, as shown below: In terms of the (visible) reactions, it appears that three people have found it to be hilarious. I think congratulations may be in order.