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Forum Index : Solar : Solar BMS 40A/80A for Lithium battery
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electrodacus Newbie  Joined: 30/03/2014 Location: CanadaPosts: 39 |
Hi this is my first post here. I live off grid since last years. And when I searched for the best battery for energy storage about two years ago I found that Lithium batteries are less expensive for energy storage but almost anyone was using them. One big problem was and still is that there was no solar charger for Lithium batteries. Since I'm an electrical engineer and done similar things before I decide I will build a solar charge for lithium batteries. Is more complicated since it needs to measure each individual cell and do cell balancing but the many advantages of lithium make up for that. I'm just working on a video it should be soon on my youtube channel explaining (demonstrating) how are Lithium batteries less expensive for energy storage. Here is a 3D render with my Solar BMS (Battery Management System) is not just a render I have a working beta sample already and the project is on Kickstarter. 
http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| davef Guru  Joined: 14/05/2006 Location: New ZealandPosts: 499 |
Understand that to mean "that no one is using them". Impressive video and project concept. Good luck! davef |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
:) Yes almost no one is using them. Is there a way to edit once you have posted? I do not see an edit button on this forum. Thanks. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499 |
I thought if you are the thread starter you can edit it. However, I looked at one of my own threads and I don't see an EDIT button. I know I have edited threads before. LiPO are about 4 times more expensive than lead-acid in NZ. They claim about 6 times the service life, so I guess that does make them more economical in the long run. I see a local supplier warranties them for 10 years, the same as 2V lead-acid. They also place many conditions on how they are charged, monitored etc and etc in order to claim on that warranty. I would expect the LiPo prices to drop over the next few years are manufacturing ramps up. |
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| davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499 |
I see you have the opportunity to edit your last posting even if you are not the thread starter. I know other forums you can edit the subject ie as [Solved] ... it is often a help to the community that there is really a solution here! |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Lead Acid manufactures hide or oven over inflate the battery life. A Lead Acid is way more prone to failure and short life especially in solar applications. If they are not charge completely they degrade fast and that is often the case in solar charging. The only things you need to care with Lithium battery is to stay under the max charge voltage / cell and over the minimum. Nothing more there is no float charge and the equalisation is done by the BMS. Lithium has no problem to stay at 50% charge or less it even likes that where Lead Acid likes to stay charge as much as possible but not the case in a solar installation where most of the time is not fully charged. Another is the charge discharge efficiency you need a larger solar array to compensate for that on Lead Acid at least 30% larger. Then they make the tests at 0.1C charge discharge rate where on LiFePO4 is about 1C and usually you will use the batteries at 0.3C charging and 0.5 to 1C discharging in a solar application at least for the most of the energy used from the battery. But I will post a link to my video about all this once is ready. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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| davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499 |
Thanks for the added information. The warranty conditions they talk about appear to come from Champion: CHAMPION Lithium Iron Phosphate Yttrium Battery Limited Warranty Conditions I'll not copy the content. You are probably already aware of these conditions. Cheers, Dave |
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| 4KBO Newbie Joined: 06/06/2014 Location: AustraliaPosts: 3 |
I Have one of the modules running in an experimental using a 60AH LiFePO4 bank. It is cycling quite happily on 1.6KwHr/day using a couple of 250 Watt panels. Besides looking after the battery very well it performs like a Rolls Royce compared to some of the simple Aliexpress BMS units I have tried. Efficient and extremely simple to implement. |
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| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Thanks for the feedback. The analogy with Rolls Royce is quite good :) since this where individually hand made. I'm now thinking about next version that should be easier to mass manufacture but also have quite a few improvements. Some of them are increased current capabilities 100A for both charging and discharging in similar footprint and TDP so even more efficient. It will have larger power connectors to accept #2 AWG wires or 35mm2 dual independent PV input for two different PV arrays facing in different directions Will have a larger 320x240 colour LCD to be able to display more data on a single screen. Dedicated 24bit ADC for much more accurate current measurement. Bluetooth 4.0 for remote data logging and probably some more smaller improvements. Dacian. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
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