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Tony1

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Tony1 last won the day on October 8

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    CCer, currently in Cheshire

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    All That Jazz

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  1. Cheers Peter, thats good news. My problem is how to get hold of one, now that I've given back the car. I guess I could get an off-peak day return train to his top secret location, and the battery would fit into a haversack- can you transport them in the vertical position? I'll have a look at the tickets and prices, and if it looks worthwhile I'll give you a shout. I lost his number when I dropped my phone in the marina last November
  2. I hear Batrium make some very good BMS kits, but I dont know if they have all those features- very probably not. I'm not actively researching them, since I'll struggle to find a battery that I can add to my existing bank seamlessly- perhaps it more of an aspiration. But if I were to find a compatible battery (or set of cells), and then I got seriously into BMS shopping, I would probably accept some compromises on that full set of features you've listed, if it meant I could save significant money and not run significant risks whilst doing so. The protection/disconnect features I already have- albeit only an overall level for the whole battery bank, which is why I try to be more conservative, and allow for individual cell variations but still give a decent level of protection. I've accepted the risk of basing the disconnects on an overall voltage level for the whole bank, rather than at cell level, so I'd probably be ok with continuing that approach with any new batteries, as long as the new batteries were very similar to the ones I have (which is not likely to be the case unfortunately). If I were starting again from scratch though, your list would be a great starting point.
  3. As much as I'd love to add more capacity cheaply, my three current units are I think valence U27-12XP (rated at 138Ah), and the new bargain cells are 200Ah. I dont think you can just add a new 200Ah battery into that existing bank can you? For one thing, two different types of cell will probably charge at different rates, and the valences might reach 100% SoC long before the 200Ah unit does, etc. It just seems fraught with issues. I did see a used Valence recently identical to mine, but it was £500 and collection in person in North London, which effectively adds £100 transport cost to the price. If I do find a compatible battery that I can build and add in, ideally I'd like one of the high-end BMS kits, this is one of the suppliers: https://www.batrium.com/collections/kits/products/watchmoncore The essential protection is there already with my disconnect systems, but it would nice to have some balancing functions as well. This one is 4 years old but it seems to have a good set of features:
  4. Even adding the price of s BMS and a battery case, its still a fantastic price. Nowadays I'm ok with the idea of building the battery myself, and adding an off the shelf BMS unit- there are some very good and configurable ones available these days. Thats a 200Ah lithium battery built for about £400. Wow
  5. 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....
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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).
  13. 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?
  14. Dont go digging for ages, I'm being lazy, it should be possible to find one using my old friend google
  15. 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
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