Edit. Keeping batteries a constant 100% SOC for 5 years and at an average of 15degC will likely cause a 21% drop in capacity. Clearly you are not doing this but it gives a measure of how charging to 100% impacts on battery life. Hope this helps
The 100% SOC doesn't assume the batteries are on float. It assumes they are charged up to maintain 100% periodically. The natural depletion of charge is about 3% per month for lithium. All the scholarly articles I have read make this clear. Floating at 100% is another whole new level of battery destructionFrom what I can see it's mostly pushing more juice in that kills capacity. Maintaining them at 99% isn't a lot different to maintaining them at 50%, they just internally balance to a given voltage. When you keep applying power then they'll gas which presumably is the point they chemically change irreversibly.
Either way, 21% in 5 years time I can live with if it is that high. That's still way more remaining than the old bank and by then I expect battery costs to drop anyway. I didn't factor in a 20 year life to the purchase decision so 5 years is acceptable I think, and at that point I'd probably be a year into a new lead bank had I gone lead
Not really any different chemically from having two charged cells in parallel I'd have thought? Once the voltage equalises everything just sits at that voltage and no amps flow. Not that I let mine hit 100%. In theory you could set the voltage even lower and they'd all sit at 80% with no amps flowing, I'd be interested in an explanation of why that's not the same situation since no electricity is actually flowing.
We use the boat all year around. It's not practical or desirable to leave them at 50% so this is the best compromise I could come up with. They're not being rammed with power so unlikely to puff up, and a bit of capacity loss is better than starting every trip with a lengthy recharge. Either way it's a million times better than the old lead system
I don't tend to charge them while on the boat so most of the time they will be lower than that as in winter it'll take days/weeks to get them up to 99%.
.Lifepo4 isn't like lead. Voltage tells you very little. You have the same voltage from 30 to 70% SOC. It's not an issue of voltage flowing but a chemical status. I would have to refer to my more knowledgeable chemical qualified friends, I am an engineer not a chemist. All I know is from the results of research published in scholarly article, the findings are that maximum longevity in Lifepo4 is obtained at 50% state of charge and 25degC. Higher temperatures increase calender aging rate and lower temperatures reduce life cycles. The cross over is at 25degC
Yes, I o like the idea, and even though I have a wheel, I have wondered if such a set up connected to he rim of the wheel might work? Definitely something to experiment with?
Hi Tranona, agree the existing 330Ah is enough really but I have had them for 7 years and have used them carefully but a bit concerned they might start to degrade quickly if I start taking them to lower percentage charge levels. I like being away from marine and can easily be away a week or so. So the fast charge rate of the lithium is very appealing. With the ketch rig I have very little space for solar and don't want panels on rails etc. Still umming and argghing . .......
Thanks, have a little appeciation of the differences or at least to use the right sort, more my dyslexia /laziness in typing! Must type liFePo, must type LiFePo............ thank you.
Ignoring the fact that you have bought the lithium, in your situation I would simply replace your existing batteries with similar capacity AGMs. While the lithium has a high acceptance rate you will still have to run your engine a lot if you don't have solar. The reason I suggested a consumption audit is that I suspect when you are sailing your consumption will be lower than you think and a bank of that size will recharge from the alternator adequately. You don't say what alternator you have, but the fact that you have an Adverc suggests it is an old style low output (60A?) and will not like running at the kind of outputs the lithium will accept. Might be OK with a 30A B2B, but not a 60A.
I always wonder what the point of fitting LFP batteries when you have a prefectly good enough system with LA. I had an Oceanlord with 400 amp/h on domestic, and 100 on engine. The alternator was a 110amp alternator on a sterling controller. This would, if the batteries were at 50% start up at some 80 amps input but quickly reduce as its hard to push a charge into LA batteries. However if I put in LFP batteries then they would just suck in the full 110 amps until nearly full. This with the heat of the engine room in the med would destroy the alternator very quickly. Lithium batteries are a bit like feeding a dog - it will eat everything you give it! This means that you have to pass everything through a lead acid and battery to battery charger. at say an effective 30 amps once the LA have got reasonable charge in and creating resistance.
Wow!I always wonder what the point of fitting LFP batteries when you have a prefectly good enough system with LA. I had an Oceanlord with 400 amp/h on domestic, and 100 on engine. The alternator was a 110amp alternator on a sterling controller. This would, if the batteries were at 50% start up at some 80 amps input but quickly reduce as its hard to push a charge into LA batteries. However if I put in LFP batteries then they would just suck in the full 110 amps until nearly full. This with the heat of the engine room in the med would destroy the alternator very quickly. Lithium batteries are a bit like feeding a dog - it will eat everything you give it! This means that you have to pass everything through a lead acid and battery to battery charger. at say an effective 30 amps once the LA have got reasonable charge in and creating resistance.
I cannot see the point of adding a huge additional battery capacity with no means of putting in the charge at a rate significanly higher than you could ever do with LA. You could add a huge array of sun pannels but to make use of the extra capacity, you will have difficulty finding un shaded space to mount them - especially on a ketch.
Add to that the issue of balancing batteries, I would require rather not be moored anywhere near your yacht!
I have stopped sailing, and having seen battery and charger fires on ordinary systems out in Greece (and having to use my own extinguishers to put them out as they were too close for comfort, I would rather not have amateur installations anywhere near my boat! Unfortunately you have no way of checking with your neighbour as he arrives, if he has lithium on board - and if is a professional install. You see EVs and electric bikes (cheap lithium) go up in massive jets of flame. Thank the lord that the design of these EVs is so good now that its a rarer event now than it used to be, but still happens.
As has been described here, your usage and charging of these batteries is also a major factor in safety - an area I can safely say I dont understand at all! But high charging and high discharge rates were mentioned above as a major life reducer - I hope that it does not at the same time mean that thermal runaway becomes more likely!
I note that Irish Ferries and P and O are proudly saying that there is high speed EV charging on board their ships..... that scares the pants off me. The Norwegian ferry operator on the west coast has banned EVs as to dangerous - original reason given was that the ramps might damage them .... but now they are more explicit. I am just booking some tickets on Irish ferries and I might instead go to France on Brittany Ferries which does not allow EV charging on board. One article - probably labeled as conspiracy - says that salt water cannot be used to put them out, requiring a huge amount of Fresh water to be carried on board - well beyond the capacity of the ferries.... Am I worrying unnecessarily?
hey ho - progress
Chris, your opinion is valid and I agree a LifePO4 (LFP) installation may not be for everyone, at least for a while yet. The reason we chose to go down this route was to have a mix of gas and electric cooking. During 2021 we halved our gas usage using an electric kettle, toaster and induction hob. Last winter we upped the solar to 590w and have recently added another 110w. This is our primary charging source and provides sufficient power during the summer to run the whole yacht including cooking. Last Spring we moved to an all electric galley. In the early Spring and late Autumn, we need an occasional top up from the alternator, stats from Sep 23 show 10%. Clearly in the depths of a UK winter we would need more or use shore power, but we have sufficient for several days. The last remaining small 904 camping gaz cylinder swopped for a Calor after the great gas debacle, sits in the gas locker disconnected. It can be connected back as a last resort, but we have no plans to do so. I think the point here is we couldn't have gone down this route with lead acid batteries without killing them in short order and struggle to charge them back up frequently. With LFP we don't worry. The 75Ah LFP battery is destined to run an electric trolling motor this summer. If it's successful in meeting our needs, then we will sell the little Honda 2.3hp and that removes petrol from the yacht as well.I always wonder what the point of fitting LFP batteries when you have a prefectly good enough system with LA. I had an Oceanlord with 400 amp/h on domestic, and 100 on engine. The alternator was a 110amp alternator on a sterling controller. This would, if the batteries were at 50% start up at some 80 amps input but quickly reduce as its hard to push a charge into LA batteries. However if I put in LFP batteries then they would just suck in the full 110 amps until nearly full. This with the heat of the engine room in the med would destroy the alternator very quickly. Lithium batteries are a bit like feeding a dog - it will eat everything you give it! This means that you have to pass everything through a lead acid and battery to battery charger. at say an effective 30 amps once the LA have got reasonable charge in and creating resistance.
I cannot see the point of adding a huge additional battery capacity with no means of putting in the charge at a rate significanly higher than you could ever do with LA. You could add a huge array of sun pannels but to make use of the extra capacity, you will have difficulty finding un shaded space to mount them - especially on a ketch.
Add to that the issue of balancing batteries, I would require rather not be moored anywhere near your yacht!
I have stopped sailing, and having seen battery and charger fires on ordinary systems out in Greece (and having to use my own extinguishers to put them out as they were too close for comfort, I would rather not have amateur installations anywhere near my boat! Unfortunately you have no way of checking with your neighbour as he arrives, if he has lithium on board - and if is a professional install. You see EVs and electric bikes (cheap lithium) go up in massive jets of flame. Thank the lord that the design of these EVs is so good now that its a rarer event now than it used to be, but still happens.
As has been described here, your usage and charging of these batteries is also a major factor in safety - an area I can safely say I dont understand at all! But high charging and high discharge rates were mentioned above as a major life reducer - I hope that it does not at the same time mean that thermal runaway becomes more likely!
I note that Irish Ferries and P and O are proudly saying that there is high speed EV charging on board their ships..... that scares the pants off me. The Norwegian ferry operator on the west coast has banned EVs as to dangerous - original reason given was that the ramps might damage them .... but now they are more explicit. I am just booking some tickets on Irish ferries and I might instead go to France on Brittany Ferries which does not allow EV charging on board. One article - probably labeled as conspiracy - says that salt water cannot be used to put them out, requiring a huge amount of Fresh water to be carried on board - well beyond the capacity of the ferries.... Am I worrying unnecessarily?
hey ho - progress
Pete and Geem. Now that's much more reassuring that properly done, it is safe, and especially gets rid of gas, which in the hands of yacht owners who don't understand the meaning of maintenance is positively dangerous.Rob, your opinion is valid and I agree a LifePO4 (LFP) installation may not be for everyone, at least for a while yet. The reason we chose to go down this route was to have a mix of gas and electric cooking. During 2021 we halved our gas usage using an electric kettle, toaster and induction hob. Last winter we upped the solar to 590w and have recently added another 110w. This is our primary charging source and provides sufficient power during the summer to run the whole yacht including cooking. Last Spring we moved to an all electric galley. In the early Spring and late Autumn, we need an occasional top up from the alternator, stats from Sep 23 show 10%. Clearly in the depths of a UK winter we would need more or use shore power, but we have sufficient for several days. The last remaining small 904 camping gaz cylinder swopped for a Calor after the great gas debacle, sits in the gas locker disconnected. It can be connected back as a last resort, but we have no plans to do so. I think the point here is we couldn't have gone down this route with lead acid batteries without killing them in short order and struggle to charge them back up frequently. With LFP we don't worry. The 75Ah LFP battery is destined to run an electric trolling motor this summer. If it's successful in meeting our needs, then we will sell the little Honda 2.3hp and that removes petrol from the yacht as well.
This is me doing roast duck and later melting the ganache for the chocolate cake. Yes we could have done this on gas, at a price and if it was available, but the 34 year old cooker was giving me cause for concern and therefore decided it had to go. You wouldn't want to moor near a yacht with a decades old cooker, risky gas installation or someone decanting from large to small cylinders now would you
Finally we are very happy with our life style choices and enjoy cooking on sunshine. As I said earlier going full electric with LFP may not be for everyone, but certainly a mix of gas and electric makes significant reductions in gas usage. There are also real advantage for those in hot climates. The heat is created in the pan and twice as efficient as gas so the cabin doesn't heat up as much.
Pete
High performance EVs don't use the same batteries as yachts. EVs need a higher energy density. Weight is the killer for EV performance. Tesla have now introduced lifePO4 batteries in to their entry level cars where performance and range are not so important. The safer lifePO4 chemistry should eliminate battery fires. I guess it won't rule out electrical fires though. You still have several kW of energy in a small space. A good reason to follow ABYC and ISO standards when you install lifePO4 batteries on your yacht
Yes, I have a general principle that seems to work - if somebody refers to “Lithium batteries” without being specific about the precise type then can generally ignore the rest. Often not well informed hype.
C
Do you have a link for a run away LifePO4 battery? Please do make sure make sure its a LifePO4 variety of lithium which is what we are discussing here.
I have learnt a lot following this exchange. Thanks.
