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Post by twerpv3 on Oct 10, 2022 5:52:34 GMT
Are you here, do you post?
I have some questions regarding lithium, and you seem to be the master on such matters, what with the big head and all that..
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Post by JohnV on Oct 10, 2022 7:10:29 GMT
Are you here, do you post? I have some questions regarding lithium, and you seem to be the master on such matters, what with the big head and all that.. He hasn't joined (or requested to) and at the moment there are no visitors allowed to view (that may change as it does seem somewhat draconian) but it needs putting before everybody to get a consensus first. (I did it originally to stop some of the crap that used to be posted about Thunderboat on CWDF after the original split .... because of the different circumstances probably not needed .... but I do still have L plates just a PS Peterboat probably has more lithium batteries than anyone else I know of, his boat is totally powered by them plus other things |
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Post by pattyann57 on Oct 10, 2022 7:50:56 GMT
Are you here, do you post? I have some questions regarding lithium, and you seem to be the master on such matters, what with the big head and all that.. He hasn't joined (or requested to) and at the moment there are no visitors allowed to view (that may change as it does seem somewhat draconian) but it needs putting before everybody to get a consensus first. (I did it originally to stop some of the crap that used to be posted about Thunderboat on CWDF after the original split .... because of the different circumstances probably not needed .... but I do still have L plates just a PS Peterboat probably has more lithium batteries than anyone else I know of, his boat is totally powered by them plus other things Maybe once visitors can view and its seen that we r not all here to bitch some of the the others may come This forum has a friendly atmosphere and I know we shall have our spats.. tis human nature to dissent and argue but hopefully we shall go from strength to strength and weather squalls. |
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Post by twerpv3 on Oct 10, 2022 11:54:42 GMT
Are you here, do you post? I have some questions regarding lithium, and you seem to be the master on such matters, what with the big head and all that.. He hasn't joined (or requested to) and at the moment there are no visitors allowed to view (that may change as it does seem somewhat draconian) but it needs putting before everybody to get a consensus first. (I did it originally to stop some of the crap that used to be posted about Thunderboat on CWDF after the original split .... because of the different circumstances probably not needed .... but I do still have L plates just a PS Peterboat probably has more lithium batteries than anyone else I know of, his boat is totally powered by them plus other things Is peterboat on here? |
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andyberg
Very gobby
They say nothing is impossible yet I manage to do nothing most days?
Posts: 212
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Post by andyberg on Oct 10, 2022 12:03:29 GMT
If he is, I doubt he will appreciate being ‘sloppy seconds’ after Nick! 😱 |
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Deleted
Deleted Member
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Post by Deleted on Oct 10, 2022 14:10:02 GMT
He hasn't joined (or requested to) and at the moment there are no visitors allowed to view (that may change as it does seem somewhat draconian) but it needs putting before everybody to get a consensus first. (I did it originally to stop some of the crap that used to be posted about Thunderboat on CWDF after the original split .... because of the different circumstances probably not needed .... but I do still have L plates just a PS Peterboat probably has more lithium batteries than anyone else I know of, his boat is totally powered by them plus other things Is peterboat on here? Yes. At least there is a member of that name that joined in Dec 2020 theunstablebar.freeforums.net/user/14 |
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Post by twerpv3 on Oct 10, 2022 14:14:24 GMT
Maybe he will come along then..
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Post by telemachus on Oct 10, 2022 14:57:11 GMT
Alright well stand by your beds, I am here now.
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Post by dogless on Oct 10, 2022 15:11:40 GMT
I hope that after this big build up he's not simply going to ask you how to spell lithium ... it is twerpv3 we're dealing with 😁 Rog |
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Post by twerpv3 on Oct 10, 2022 15:23:22 GMT
Alright well stand by your beds, I am here now. good stuff! I guess really it's how i should treat my big new shiny lithium bank, how fast is safe to discharge, what should i take down to %. Cheers |
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Post by telemachus on Oct 10, 2022 15:45:41 GMT
Alright well stand by your beds, I am here now. good stuff! I guess really it's how i should treat my big new shiny lithium bank, how fast is safe to discharge, what should i take down to %. Cheers Edit: the below relates to LiFePO4 batteries. Is that what you have, or is it some different Li chemistry? Big differences in voltages between the chemistries. Lithiums like to be kept in a state of mid-charge, not full, not empty. Well the last 2 not for long periods of time, anyway. So when left for a period, arrange for them to be around 50% SoC. Don’t leave them on trickle charge at more than about 13.2v max continuous discharge rates are usually 1C ie for 400Ah bank, 400A. Unlikely to be an issue. But if the batteries have built in BMS, the internal switching MOSFETS may only be able to pass less current. Read the instructions! I think you can take them down to quite a low SoC. Low SoC is no worse than high SoC - you have to delete all that lead acid mindset! The issue is that at high SoC, all those tiny lithium ions are crammed into one electrode and it suffers physical strain as a result. And at low SoC, all those tiny lithium ions are crammed into the other electrode. Same same. My view is simply to avoid taking them up or down the voltage “knee” more than necessary. So discharge until the voltage starts to fall, maybe not below 12v (no load) which is likely to be below 10% SoC. Avoid routinely charging to 100%, but 95% is fine (ie don't go above about 13.7v at moderate charge rate). You might need to charge to 100% from time to time to allow the BMS top balancing to happen, and to reset any Ah-counting SoC meters. If you look at cycle life, it is more to do with total Ah put in / taken out, rather than the SoC range. So for example it might be 2000 cycles between 10% and 90% (80% range) or 4000 cycles between 30% and 70% (40% range). But the total Ah taken in/out is the same in both cases. charging rates are best kept at 0.5C (ie 200A for a 400Ah battery) and less at lower temperatures. It’s pretty hard to damage Li by discharging too fast, unless the cells get very hot. Much easier and more insidious to damage by charging too fast for the temperature - irreversible lithium metal plating on the electrode. |
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Post by dyertribe on Oct 10, 2022 15:46:12 GMT
Alright well stand by your beds, I am here now. Croeso! |
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Post by twerpv3 on Oct 10, 2022 18:27:33 GMT
good stuff! I guess really it's how i should treat my big new shiny lithium bank, how fast is safe to discharge, what should i take down to %. Cheers Edit: the below relates to LiFePO4 batteries. Is that what you have, or is it some different Li chemistry? Big differences in voltages between the chemistries. Lithiums like to be kept in a state of mid-charge, not full, not empty. Well the last 2 not for long periods of time, anyway. So when left for a period, arrange for them to be around 50% SoC. Don’t leave them on trickle charge at more than about 13.2v max continuous discharge rates are usually 1C ie for 400Ah bank, 400A. Unlikely to be an issue. But if the batteries have built in BMS, the internal switching MOSFETS may only be able to pass less current. Read the instructions! I think you can take them down to quite a low SoC. Low SoC is no worse than high SoC - you have to delete all that lead acid mindset! The issue is that at high SoC, all those tiny lithium ions are crammed into one electrode and it suffers physical strain as a result. And at low SoC, all those tiny lithium ions are crammed into the other electrode. Same same. My view is simply to avoid taking them up or down the voltage “knee” more than necessary. So discharge until the voltage starts to fall, maybe not below 12v (no load) which is likely to be below 10% SoC. Avoid routinely charging to 100%, but 95% is fine (ie don't go above about 13.7v at moderate charge rate). You might need to charge to 100% from time to time to allow the BMS top balancing to happen, and to reset any Ah-counting SoC meters. If you look at cycle life, it is more to do with total Ah put in / taken out, rather than the SoC range. So for example it might be 2000 cycles between 10% and 90% (80% range) or 4000 cycles between 30% and 70% (40% range). But the total Ah taken in/out is the same in both cases. charging rates are best kept at 0.5C (ie 200A for a 400Ah battery) and less at lower temperatures. It’s pretty hard to damage Li by discharging too fast, unless the cells get very hot. Much easier and more insidious to damage by charging too fast for the temperature - irreversible lithium metal plating on the electrode. Should have added, this is the battery i have on the solar system. batteryfactory.co.uk/collections/newest-products/products/sunsynk-catl-battery-lfp-5-12kwh |
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Post by GUMPY on Oct 10, 2022 18:43:01 GMT
Mine is 10% and 90% and says 6000 cycles
Although its set at that I sometimes see discharged to 8% and often see charged to 97%.
The charge and discharge limits should have been set by default in the inverter.
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Post by telemachus on Oct 10, 2022 18:50:38 GMT
Ah well, 51.2v = 14 cells in series. Anyway you can see that the BMS FETs are the limiting issue. It is 100Ah, so the actual cells could emit 100A ie 5kw or so, continuously (until flat!). Whereas the continuous output power is 2400w or about 48A. The short term higher ratings are ok at the expense of the electronics getting hotter and hotter.
So I would try to stick to the 2400w, which is enough for most thing used singly. Since you can’t see the cell voltages I would stick to a max discharge down to about 10%, 5% at a pinch. And try to avoid holding at 100% for long periods and or repeatedly going back to 100% without significant discharge in between.
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