Open Source Solar BMS dev board for any Lithium cells and Supercapacitors - Page 1
Forum section: electronics / projects

author: electrodacus
author_rank: Super Contributor
timestamp: March 15, 2014, 07:28:06 pm
content: Hi EEVBlog forum members.This is my first post on the EEVBlog. I watch Dave's videos on youtube almost all since he started. He has an interesting personalityI can not compete with that I'm quite boring.The reason I made an account here is to advertise my new project maybe some of you will be interested.I do have a youtube channel with the same username as here but is not even close to be as popular as EEVBlog.I recently moved offgrid and since I use solar PV for electricity and decided that LiFePO4 are the best option for storing that energy (reason to use LiFePO4 are cost and safety but there are many other small advantages compared to traditional Lead Acid) the problem was there is no solar charger or even a good BMS to fit my needs so I made the decision to build one.Here is a 3D renderIs not just a render there is already a working beta sample and I have two videos a short 2 minute one made for Kickstarter if they will accept (as I just found out after I made the video and submitted they do not like 3D renders since people may confuse them with the real product) I hope they make an exception else I will probably move to Indiegogo there should not be any difference. What do you think?Anyway this is the video.If the first video made you interested you can watch this more detailed video explaining HW and user interface of the beta sampleI think the videos explain what it is and what is good for but if you prefer a text description I will be happy to do so.Also I will answerer any question you may have.I just hope I'm not to intrusive not sure how else I can advertise my product there is no budget for advertising and there is probably not much interest in this type of product so not that many will be interested. My minimum target for Kickstarter will be just 50 units.Your opinion is extremely important to me and I will really love to know what you think even if you are not interested in this product.PS (Is an open source dev board)

author: electrodacus
author_rank: Super Contributor
timestamp: March 23, 2014, 07:33:29 pm
content: A lot has changed since I posted this.Most important is that now is an open source dev board.I wanted to delete this entire thread since I posted about this on the Open Source.So if you are an moderator you can delete this if you want is up to you.

author: electrodacus
author_rank: Super Contributor
timestamp: April 23, 2014, 12:45:06 am
content: I needed to dig 20 pages to get to my post.Anyway only 15h left for the Solar BMS on Kickstarter.http://electrodacus.com/k/

author: madires
author_rank: Super Contributor
timestamp: April 23, 2014, 09:28:40 am
content: Have you thought about adding MPPT?

author: electrodacus
author_rank: Super Contributor
timestamp: April 23, 2014, 02:53:08 pm
content: Quote from: madires on April 23, 2014, 09:28:40 amYes I have thought but decided MPPT is obsolete at this moment do to PV price 1$/Watt. MPPT only made sense at over 10$/Watt or where cost of energy was not an issue.

author: madires
author_rank: Super Contributor
timestamp: April 23, 2014, 04:36:24 pm
content: Quote from: electrodacus on April 23, 2014, 02:53:08 pmThat's reasonable if you don't got space constraints for the PV panels.

author: electrodacus
author_rank: Super Contributor
timestamp: April 23, 2014, 04:50:10 pm
content: Quote from: madires on April 23, 2014, 04:36:24 pmActually even if you have space constrains getting a solar panel that is 2% more efficient will still be a better option like 18% efficient PV panel instead of 16% one and will provide about 12% more energy. The cost difference to get 18% efficient panels vs 16% is probably better than an MPPT charge controller.As an example my Solar BMS has a wight of around 200g and the thickness of just 15mm if I where to include an MPPT in the design (40A 24V = 1000W DC-DC converter) weight will have been at least 10x higher over 2kg because of the large inductor, big electrolytic caps and a large heatsink even just the additional international shipping from Canada will be over 80 to 100$ extra.

author: madires
author_rank: Super Contributor
timestamp: April 23, 2014, 05:06:08 pm
content: Quote from: electrodacus on April 23, 2014, 04:50:10 pmSo I have to built one myself ;-) Another nice feature of MPPT is that I can run a 12V battery bank with 24V PV panels. Most 250Wp panels are 24V which also helps with the wiring.

author: electrodacus
author_rank: Super Contributor
timestamp: April 23, 2014, 05:27:01 pm
content: Quote from: madires on April 23, 2014, 05:06:08 pmRunning 12V battery with 24V PV panels will make the MPPT (the DC-DC part) less efficient because of the high difference in input voltage around 29 - 30V max power point voltage for 60 cells 250W panels vs the 13 - 14V battery voltage.I will suggest getting 36 cell PV panels if you want to charge a 12V battery.You probably have an RV or something like that if you want to use 12V and have limited space for solar PV in that case wiring is not a problem since they are extremely short. There are no savings to be had there.

author: electrodacus
author_rank: Super Contributor
timestamp: April 23, 2014, 05:33:53 pm
content: Quote from: mojo-chan on April 23, 2014, 09:03:54 amHi sorry if it was annoying to see this in multiple threads in this forum.I had no idea were it was best to place this since is an Open Source and a Kickstarter project so I tried there and then here since is a Project and I wanted a technical conversion.It seems there is not much interest here for this type of project but I had to try. I was really surprised so little interest in a Solar BMS especially since is the only one I'm aware of available.Luckily I found enough interest in other places so the the Kickstarter project ended successfully about an hour or two ago.

author: Harvs
author_rank: Super Contributor
timestamp: April 23, 2014, 11:56:28 pm
content: Quote from: electrodacus on April 23, 2014, 05:33:53 pmThis forum rarely gets many replies for posts that don't ask questions, it doesn't mean there hasn't been any interest. Over the years I'll often link to open source projects I've built on this forum, received not a single reply, yet the page will receive hundreds of hits because of it.It's just not like some forums where everyone loves patting each other on the back for their latest Arduino creation.

author: electrodacus
author_rank: Super Contributor
timestamp: April 24, 2014, 12:26:11 am
content: Quote from: Harvs on April 23, 2014, 11:56:28 pmI was thinking there will be at least some questions about the LiFePO4 charging they are not that popular.Or Lithium charging for energy storage there very little information and a lot of misinformation on that.I was also thinking some will need something like that and where better to show this that here. About two years ago I will have been ultra exited to find someone working on thisI was really hoping will not be me putting in the effort. I'm a bit selfish that way