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Post by kris on Sept 25, 2020 11:08:42 GMT
You can have fun making the management system for that bank. I actually just received some LiFePo4 as well this week but much more modest. I found some mastervolt 20ah 12v batteries discounted to £100 each so had 4 of them. Built in BMS on each one can be paralleled up to 3 units. 60ah is enough for my purposes and the other one will be a general portable utility battery. Sticking with lead acid for the engines for now as lithium looks a bit complex for that purpose. The 60ah will be charged by my new 365w solar panel via Victron MPPT and be used as a secondary domestic power circuit separate to the existing arrangements. I use about 15-20ah a day, if that. If there is surplus it can be used to charge the electric outboard battery via inverter. All good fun. I thought your being a Luddite and not bothering with lithium? Anyway should be good for your electric vessel.
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Post by Deleted on Sept 25, 2020 11:15:55 GMT
I decided to dip a toe in. Well respected branded product with built in BMS. Careful now ! . Actually just charged one of the little 20ah blocks using a 15amp 230v ctek charger (SLA setting) and it sat exactly at the recommended 14.25v with 15.02a going in for most of the charge cycle. Very efficient ! Yes I can also use these little blocks for either of my electric canoes which is handy.
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Post by kris on Sept 25, 2020 11:23:13 GMT
I decided to dip a toe in. Well respected branded product with built in BMS. Careful now ! . Actually just charged one of the little 20ah blocks using a 15amp 230v ctek charger (SLA setting) and it sat exactly at the recommended 14.25v with 15.02a going in for most of the charge cycle. Very efficient ! Yes I can also use these little blocks for either of my electric canoes which is handy. They will probably be the same cells inside the boxes as the calbs. But yes I understand the reasoning, which is why I went for the s/h valence, even though for not that much more really,I could have bought new. These ones only have between 50-60 cycles on them so as long as I don’t knacker them, they should last a good while. Especially as I’m going to try to not take them down any lower than 12.5-12.6v.
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Post by Mr Stabby on Sept 25, 2020 11:23:18 GMT
If they last longer than six months they will be the only thing to have ever come out of China apart from the Coronavirus which did.
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Post by Telemachus on Sept 25, 2020 11:25:37 GMT
If they last longer than six months they will be the only thing to have ever come out of China apart from the Coronavirus which did. I think you will find that most lithium batteries come out of China.
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Post by Deleted on Sept 25, 2020 11:27:33 GMT
The mastervolt ones I bought were made in the PROC as well.
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Post by kris on Sept 25, 2020 11:28:03 GMT
If they last longer than six months they will be the only thing to have ever come out of China apart from the Coronavirus which did. I think you will find that most lithium batteries come out of China. exactly there aren’t that many factories producing them. Although I believe Germany is getting into them in a big way, and they have been made in America for a while.
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Post by Telemachus on Sept 25, 2020 11:28:40 GMT
I decided to dip a toe in. Well respected branded product with built in BMS. Careful now ! . Actually just charged one of the little 20ah blocks using a 15amp 230v ctek charger (SLA setting) and it sat exactly at the recommended 14.25v with 15.02a going in for most of the charge cycle. Very efficient ! Yes I can also use these little blocks for either of my electric canoes which is handy. They will probably be the same cells inside the boxes as the calbs. But yes I understand the reasoning, which is why I went for the s/h valence, even though for not that much more really,I could have bought new. These ones only have between 50-60 cycles on them so as long as I don’t knacker them, they should last a good while. Especially as I’m going to try to not take them down any lower than 12.5-12.6v. Be careful, 12.5v is about 12% SoC and approaching the “knee” where the voltage suddenly crashes. Does the Valance built in BMS have a low voltage disconnect built in? Not sure. Most people top balance the batteries, that means you can get to 100% SoC without an overvoltage on one cell. But typically the cells have slightly different capacities and thus a battery that is top balanced is not bottom balanced. It just takes one cell to run flat, with the others still at a reasonable voltage, to trash the thing.
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Post by kris on Sept 25, 2020 11:33:38 GMT
They will probably be the same cells inside the boxes as the calbs. But yes I understand the reasoning, which is why I went for the s/h valence, even though for not that much more really,I could have bought new. These ones only have between 50-60 cycles on them so as long as I don’t knacker them, they should last a good while. Especially as I’m going to try to not take them down any lower than 12.5-12.6v. Be careful, 12.5v is about 12% SoC and approaching the “knee” where the voltage suddenly crashes. Does the Valance built in BMS have a low voltage disconnect built in? Not sure. No they don’t have the disconnect built in. I’m going from what James the guy I bought them from has said. Basically he told that if you can refrain from dropping them to 12.2 then the life will be much prolonged. Which makes sense,he’s the person I know with the most practical experience of these things as he’s been using them for quite a few years. He’s a very nice man and is always at the end of a phone line if i need help. Which is one of the reasons I bought from him.
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Post by Telemachus on Sept 25, 2020 11:41:28 GMT
Be careful, 12.5v is about 12% SoC and approaching the “knee” where the voltage suddenly crashes. Does the Valance built in BMS have a low voltage disconnect built in? Not sure. No they don’t have the disconnect built in. I’m going from what James the guy I bought them from has said. Basically he told that if you can refrain from dropping them to 12.2 then the life will be much prolonged. Which makes sense,he’s the person I know with the most practical experience of these things as he’s been using them for quite a few years. He’s a very nice man and is always at the end of a phone line if i need help. Which is one of the reasons I bought from him. 12.2v seems excruciatingly low. You do understand that if the cells have different capacities, your 12.2v could be 3 cells at 3.3v and 1 cell at 2.3v? The 4the cell having fallen down the “knee” in a short period of time.
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Post by kris on Sept 25, 2020 11:46:36 GMT
No they don’t have the disconnect built in. I’m going from what James the guy I bought them from has said. Basically he told that if you can refrain from dropping them to 12.2 then the life will be much prolonged. Which makes sense,he’s the person I know with the most practical experience of these things as he’s been using them for quite a few years. He’s a very nice man and is always at the end of a phone line if i need help. Which is one of the reasons I bought from him. 12.2v seems excruciatingly low. You do understand that if the cells have different capacities, your 12.2v could be 3 cells at 3.3v and 1 cell at 2.3v? The 4the cell having fallen down the “knee” in a short period of time. sorry I have got my voltages mixed up. What I meant was try not use more than 40% of battery capacity so down to say 60% soc. But yes I understand the balencing of cells. One of the reasons I’m putting in bussbars and same length cables rather than connecting diagonally like I’ve done with La’s
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Post by naughtyfox on Sept 25, 2020 15:07:25 GMT
CALB cells? That must have also been lots of money !! £2k ish at a guess. Yes well spotted, about £1800. But hopefully will last 20 years or so, which makes it £90 a year for batteries. Probably cheaper than crappy leisure batteries that only last 2 years, plus all the advantages of lithium, if you can stand the up-front cost. Made in China? I reckon two years. Did you get a receipt with phone number? Anyway, no point in phoning to complain as it will be the Wong number, and also they don't have telephones in China.
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Post by naughtyfox on Sept 25, 2020 15:13:14 GMT
In Kaustinen, where Pirkko hails from, 80km from here: "Keliber holds several advanced lithium deposits in a Central Ostrobothnian area that spans over 500 km². Observations of lithium have been made in the region as early as late 1950s. The known lithium reserves of Central Ostrobothnia have been estimated to be among the most significant in Europe. The area has excellent potential for increasing ore reserves and discovering new deposits." www.keliber.fi/en/about-us/our-story/
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Post by Deleted on Sept 25, 2020 15:14:30 GMT
This is quite an interesting article about LFP batteries which tends to reinforce the theory that LFP batteries which get well used are better than ones which only have partial cycles. Some slightly technical parts to the article but it's interesting. iopscience.iop.org/article/10.1149/1945-7111/ab7900
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Post by naughtyfox on Sept 25, 2020 15:14:57 GMT
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