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Dr Bob

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Dr Bob last won the day on February 18 2021

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    Stuc A' Chroin

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  1. I actually entered the evening before the start.....but that was not within the rules. However we actually received bonus points for doing that .....I think it was for initiative...... but the real reason for the points was only to inflate our very poor score so we didnt come last allowing someone else to do so. I'm not bitter but the bitter was good at Ma Pardoes where we ended up that night. There is definitley a precedent for entering late and being awarded extra points m'lud.
  2. It is an interesting question. To answer it you need to understand where the LPG comes from. Energy companies get their fossil fuels from underground in the form of Gas ie Methane (C1- one carbon atom) with a bit of ethane in it (C2 – two carbon atoms) or Oil ie Propane (C3), Butane C4) and heavier molecular weights (C5 and above). Methane is the stuff that is piped from gas fields or chilled to form LNG and shipped in tankers. The C2 content has to be small for calorific value reasons. The Oil is sent to refineries where the C3/C4 is extracted and bottled for LPG with the higher carbon species then pushed through the refinery to generate as much cash as possible from fuels etc. The C2 stream is pretty useless and can only be used as a feedstock for Petrochems - so its pricing is handled differently. Demand for methane is going up and up so you can see why the price is doubling and with Russian supply to go down, even more market pull. The world is theoretically awash with oil but pricing based on OPEC restrictions to production, so not allowing it go into the market – and now Russian oil not wanted by the west will increase prices of road fuel etc. Is the C3/C4 fraction in short supply? It's production will be linked to the processing of crude oil rather than production of C1's (methane) – and I guess a lot of the C3/C4 was coming from Russia along with the oil, so yes, likely the market will be short so prices going up. I doubt if a lot of methane usage can be replaced by C3/C4 but that could tip the balance in a 'short' market. Pricing is all a big con! The people in need have to pay a lot more so drive the price up for everyone as the people with the fossil fuels make a huge killing. I'm nearly as right wing as Smelly but in this case an energy tax is essential.
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  7. Tesla now use LiFePO4s in some models ie the M3 SR+. They introduced them almost a year ago. Please attempt to be more accurate in what you say.
  8. What on earth is a 'car' lithium? The first adopters on here (Tom, MP and I) are all using LiFePO4s (thunderskys) ex vehicles. Peter is using LiFePO4s ex vehicle from Valance. These are the safest of the Li battery types around (but not fully safe). It is crazy to assume 'car' lithiums cannot be used on a boat - its not where it came from, its the battery type that is important. Too many peeps on here do not have a clue and certainly do not read what the people in the know are posting. I have mentioned likely a dozen times that mine are LiFePO4 yet a few posts ago someone questioned what type of batteries I have. For Christ's sake guys. Get a grip.
  9. Oh dear. Oh dear. How the understanding of safety has fallen on this forum over the last 2 years. Of course your system will work fine while the BMS works. Of course you are satisfied it is great after a few months. A few months of operation is not Proof. The issue is what happens if the BMS fails. Wake up and smell the coffee. It wont be long before someone has a bad fire (likely not caused by the Li bank) but the insurance assessors will hold the owner responsible as he has been negligent in homebrewing his Li bank (even if the Li's had nothing to do with it). Then we will all come under the insurance industries spotlight. We, as a group, have to get this right and clearly you have not. I will keep calling people out when they are negligent as it will certainly come back to bite us in the future. It's not just you though Mark. The other 'enquiry' from an LiFePO4 user - enquiring if taking his Li's to 16V was ok if an individual cell could be taken to nearly 4V - shows that the understanding of these systems is far from what is required. Your peer group also has a lot to answer for in not curbing the urges of the clearly uninformed. As they say on the telly, I'm out. Bye all.
  10. Dendrite formation is one of the routes but dendrites dont form suddenly. They grow slowly over time, possibly each time a cell get to a high voltage. In the link I posted earlier in the thread, I think there are some links to more detail on this. I am aware of one paper where it looked at dendrite growth over successive overcharges - ie dendrites were found after 10 excursions to 3.8V. It also can happen when charging below zero. If I was installing a system, I would be more woried about poor construction or contaminants in a new battery (again see links in the thread I referred to earlier), ie a 5mm length of wire nearly bridging across the anode/cathode. Is a cheap chinese battery going to be safe? Mine were in service in a van before I got them so I am fairly sure there are no 'manufacturing issues'. We are currently also involved in Li battery recycling and working with some of the new emerging gigafactories. One frightening statistic is that the biggest market for Li battery recycling is the waste from the manufacturing process itself. Typically you find 30-40% waste - and that is not just from floor sweepings! Their QC proceedures must be good. I hope they are spotting all the duff ones! Most LiFePO4s sold as cells (ie my Thunderskys) have plugs in the top casing that blow when the temp reaches a certain point and the liquid between the anode and cathode is expelled thus isolating the plates so no route for the energy to short out and heat up. Just the venting of the liquid makes it safer. The problem is that the thermal runaway could be well on its way when the plugs blow. None of the 'extinguishing' chemicals ie Brominated or phosphated species would stop a themal runaway but may help surpress flames around the burning battery.
  11. It was a long time ago! I may be wrong but after I put together my hybrid system of old LA's plus Li's, I posted a thread wondering if you could just have a simple Li battery on top of your LA's and have a very simple and cheap system. I think that is what Biscuits is referring to. Having now had the experience of running the hybrid system, the more simple system could work as in my summary to Rusty above, if it is big enough and you have some redundancy. It may be to expensive though if you have to buy B2Bs etc.
  12. ...ah but he has got a duck!
  13. BTW....... Wot are you doin' here? I've only been let out as @TheBiscuits was casting nasturtiums at my theories and there's rumours of a noodle conspiracy being reported.
  14. If an individual cell goes wonky, then one effect will be the capacity of that cell is likely to be different to the other 6 you have in parallel which will bring down the capacity of the 'large 7 cell' unit. When you charge, then the 4 large cells will likely go well out of balance. Here's where I am at my pay grade limit - but would anticipate that 7 cell unit will hit the voltage knee first and likely overcharge if you charge to your normal voltage. I'm sure Nick will have the right answer.
  15. I have never ever recommended 14.0V. That to me is too high at my 90A charging rate. I disconnect at 13.8V with the emergency cut off at 13.9V to give me lee-way if my cells ever drift out of balance (which I do look at monthly). I have Winston cells so also have yttrium in. What is the point of going over 80% SoC? If its about capacity then put bigger cells in. If newbies cant afford the investment then stick to LA's.
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