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Forum Index : Electronics : 12/24v DIY battery setup
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| druist Newbie  Joined: 18/09/2017 Location: United KingdomPosts: 17 |
I noticed quite a few sites where ppl are making powerbanks from the 18650 3.7V from laptop batteries etc. For an off grid system solar/wind i am using the old lead acid 100ah which probably dont have long for this world. What batteries would be best eg Lithium to make a comparable system, eg lots of 18650s or larger li-ion batteries? Am thinking of the cheapest but also reliability and lifespan |
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| Alastair Senior Member  Joined: 03/04/2017 Location: AustraliaPosts: 161 |
If you are after serious batteries to give long life, high charge/discharge capability and ability to go to low SOC then use LiFePO4 batteries NOT Li-ion. LFP batteries do not have the explosion/fire risk of Li-ion. They are also available in large capacities just like lead acid. Cheers, Alastair |
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Madness Guru  Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
But how do LiFePO4 batteries compare when you consider initial purchase price, life span and cost over the life of the batteries compared to FLA? There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 513 |
Honestly. .. im with oz on this one... lifep04 are awesome, but the old FLA are almost bulletproof when it comes to charging, cycle life vs cost etc. Until the other technologies mature more and the cost comes down the FLA are the hardiest. .. But it all comes down to your circumstances. . I think it works !! |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Well, I remember you mentioning you have 3000Ah of FLA batteries. Me thinks you could get the same performance easy from 1000Ah LYP batteries. The life span would be better than FLA and the performance streets ahead. I only have 200Ah LYP (48V system) but that runs my daily consumption (3-4KWh) fine. There is about 2 days reserve capacity and in the two years plus since I switched over to lithium they never run far below 50% capacity. 90% of the days overnight to perhaps 75%. Maintenance on my batteries is nil. I have a home made BMS that keeps the cells balanced very well. This item *is* important with lithium batteries. Klaus |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
My batteries are 1600AH however they were secondhand when I got them. They have suffered from the heat last summer also. My daily consumption is around 18KWH about 6 to 8 of that is overnight. So I am in the market for new batteries soon, maintenance free is attractive but what about keeping them balanced etc? I would be keen to hear of sources of batteries and prices too. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| druist Newbie Joined: 18/09/2017 Location: United KingdomPosts: 17 |
being new to solar and wind power what would be the ideal batteries for a) longevity b) price? |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
I got my batteries from forum member link If I were you I'd start with 800Ah LYP batteries. His prices quoted are $174/100Ah cell. Or $348/200Ah cell So you need 8x174=$1392.- for 3.2 Volts. Since you have a 48 volt system multiply that by 16 = $22,272.- Not cheap, compare that with twice the AH in FLA cells price. I would think that in 10 years (if I'm still around) my LYP batteries are still working fine since I'm not pushing them hard at all. I can help you with the BMS, its a great project and you can use a micro processor too  . Klaus |
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| druist Newbie Joined: 18/09/2017 Location: United KingdomPosts: 17 |
Thanks that's a bit too much for an allotment. That's about £10k? |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
You could start looking for second hand forklift or golf cart batteries and start from there. Its all a big learning curve. Klaus |
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| noneyabussiness Guru Joined: 31/07/2017 Location: AustraliaPosts: 513 |
Druist, I managed to source a traction battery for cheap (667 ah) for overnight loads and cloudy days, for about 2000 aussie dollars, so maybe start with one or two of them and go from there. If u get the ones with watering system built in they are very easy to maintain. Being forklift batteries they are designed to be used in a pretty harsh environment so very tough. I think it works !! |
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| Alastair Senior Member Joined: 03/04/2017 Location: AustraliaPosts: 161 |
LFP batteries are coming down in price but are still expensive. If it is an important installation for which you can take a long term view, then the extended life of LFP will mean that over 10-15 years you will come out better than for FLA on new prices. Plus the great performance and reduced size and weight. If it is something less important, then s/h FLA like forklift batteries would fill the bill. Just watch your back!! There seems to be a ready supply of s/h batteries coming out of golf carts. I think often they are changed as a part of a service when perhaps they don't need to be. Cheap = s/h FLA. High performance+long life=LFP for me. Each to their own. Cheers, Alastair |
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