1201
Net zero
I thought we were supposed to be keeping topics on topic?
Deciding to DIY my solar battery was one of my worst mistakes ever
- Thread starter kolek
- Start date
OP brought the topic into the conversation.
If the OP wants topic cleaning, a simple report gets it done.
ksmithaz1
Solar / EV Junkie
Circling back on topic then, DIY 16S harness has 16 sensor/charge wires each need to go to on battery. A ground, and the primary connection thru the relay. A couple of control pins maybe 24 or so pins with RS-422/CAN you have to pin out. Back in the day a CEN50, you soldered down onto the pins and clamped it in maybe 12 wires, 8+4 control if uni-directional. The BMS harnesses are kind of annoying if you need to extend the sensor/bleed wires, but you should be able to get away with some crimp connectors and heat-shrink tubing. The issue with DIY is where to put the BMS. For a 15KWH setup with ~300AH batteries, you may want a 300A BMS, this makes for bigger wires, but interconnect FTA you can probably get away with a pair of #1/0 or something. Now you have to mount this bad-boy on something strong and clamp all the high current bus wires to something strong as well. If you are like some of the guys above with small machine shops, and tools, and can source raw materials easily it's not a problem. If you don't, then you have a tendency to spend quite a bit more than you realize on do-overs and waste. 1/0 is around $4 to 5 per foot. Waste 4 feet, you are out $20. It just adds up when you build it out. Now if you already figured all this out so it would scale, adding additional capacity would get much cheaper, because you know exactly what you need, so if you have the space and can engineer it to scale out, you will benefit greatly if you DIY it. The last part is you are going to want to make sure you decide how you want to communicate with the BMS system(s). Most of them will now talk to the bulk of the larger scale systems, but you are not going to get the integration of say an EG4 AIO with EG4 batteries. Back to the computer analogies, your going to have a custom SCSI card that runs your drives, that might create boot problems if you don't get out in front of it.
Definitely not for everyone.
Definitely not for everyone.
1201
Net zero
Considering that buying prebuilt batteries would have cost me about $9k more, a couple of hundred Dollars of waste is not so bad, I think.
Also by using the savings on extra battery you can reduce the size of wire in most cases.
Example I have 4x 280ah batteries with 12kw inverter. The most one battery will ever see is around 60a. Wire size for that is reasonable
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Brett V
Solar Wizard
That was how I designed my battery rack. With 4 batteries each having a 100 amp BMS and breaker, I used #2 wires to the bus bar and 4/0 to the 12k inverter. Theoretically it’s still ok if 2 batteries are off line for any reason.
Sanwizard
Solar Wizard
- Joined
- Feb 2, 2021
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Or you could just buy the cells you want, and purchase a vertical wall mount or horizontal server rack kit ( like a Seplos Mason) which includes the BMS and everything you need for a few hundred bucks plus shipping.
SoggyShoes
Solar Enthusiast
I'm old enough to remember punch cards and being so excited to get an 80 column graphics card.
But all this talk of remembering back about building computers does remind me of the classic Monty Python skit about "back in our day" (which I am so guilty of).
Oh how times have changed. My kids equivalent to "when dinosaurs roamed..." is "the olden times like when phones were stuck to the wall."
Back on topic. For me, I really enjoy the discovery and tinkering of DIY.
But all this talk of remembering back about building computers does remind me of the classic Monty Python skit about "back in our day" (which I am so guilty of).
Back on topic. For me, I really enjoy the discovery and tinkering of DIY.
Sanwizard
Solar Wizard
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- 2,778
Love that skit. Is that from "Secret Policeman's Other Ball"?
SoggyShoes
Solar Enthusiast
I think it is from Live at the Hollywood Bowl.
A lot depends on time and circumstances as well. I DIY'd my batteries from individual cells, and at the time it was absolutely a mistake. Health issues were very severely limiting my physically functional time, and DIYing my own batteries probably added a year to the project. Should have just bought off the shelf batteries and been done.
If anyone else is in the same situation, don't beat yourself up or worry about it, just buy the off the shelf solution and carry on. On the other hand, if you enjoy this kind of thing, then definitely build your own and enjoy it.
Going forward, now that I'm getting on top of my health and back on my feet again, and already having the experience and tools to build batteries out of individual cells, future batteries will absolutely be DIY for the cost savings. Trade a few hours work to save thousands, yes please. The only thing I'll do differently is buy cells from more reputable vendors.
If anyone else is in the same situation, don't beat yourself up or worry about it, just buy the off the shelf solution and carry on. On the other hand, if you enjoy this kind of thing, then definitely build your own and enjoy it.
Going forward, now that I'm getting on top of my health and back on my feet again, and already having the experience and tools to build batteries out of individual cells, future batteries will absolutely be DIY for the cost savings. Trade a few hours work to save thousands, yes please. The only thing I'll do differently is buy cells from more reputable vendors.
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Embarrassingly, yes. At school we learned FORTRAN; handed in punched cards which were sent away to a PDP11 somewhere and got a print out / result a week later - frustratingly slow, especially if you made a typo and it didn't run!LOL... lucky you... I had to use a soldering iron to build my first computer. Not just for connecting bits together, but soldering all the components to the PCB... Yes, I am that old
LOL - sounds similar era to my Z80 based computer, with lots of TTL chips and about 8k bytes of static RAM.
ksmithaz1
Solar / EV Junkie
MMM, "A few hundred" meaning ~ $600 + shipping from Alibaba or something. This of course includes no cables
https://www.amazon.com/LiFePO4-Bluetooth-Appliances-Off-Grid-Maintenance-Free/dp/B0C4LB48MV $700 thru amazon. + shipping
I did look. I've bought a few e-device batteries from aliexpress, < $100, but I'm hesitant to send > $500 to some place in china. Also this results in a extremely heavy 300-odd pound cabinet. If someone made a DIY "Shelf" or battery cabinet similar to some of the stuff these guys are making, with a bus bar, BMS mounts and wiring channels with fitment for the 280AH/305AH profile I'd re-consider. Something with 6-8 shelves engineered for it. Some of these folks have made some pretty impressive mounts/racks.
SilverbackMP
Solar Addict
- Joined
- Apr 4, 2022
- Messages
- 1,004
Unless you have slightly oddball cells like me (230AH) and your master BMS expects all of the same capacity batteries.
Sanwizard
Solar Wizard
- Joined
- Feb 2, 2021
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I use a seperate BMS for each battery, so every cell is monitored, I can remove an entire battery for maintenance if needed, and I can mix battery sizes (like 135AH in parallel with 280AH) on the same busbar.
Sanwizard
Solar Wizard
- Joined
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My Seplos Mason 280AH kits were around $400 shipped. I also lucked out and bought four of the complete 135AH kits (which included the cells) for $1000 each introductory offer rate.
Attachments
Hitechluddite
New Member
But did you have a Merlin modem?LOL... lucky you... I had to use a soldering iron to build my first computer. Not just for connecting bits together, but soldering all the components to the PCB... Yes, I am that old
wheisenburg
Owner Operator of Heisenberg Electric
Where do I start?
I bought a professionally installed grid tied system with Enphase IQ8+ micro inverters. I had the idea at the time that I would eventually add a battery backup system to it as a DIY project. The Enphase system, as a grid tied system has really met every expectation. It is reliable (not a single panel of inverter has failed). I actually oversized the micro inverters over what was recommended. I figured at the time they were designed to handle larger panels so smaller panels would not push the micros as hard and there should be less heat build up and longer life.
On paper these micros can deliver 10.3 KW. Because some of my panels are east facing and the others are west facing, at most I get around 9 KW at the peak of the season. So to AC couple I wanted inverters that could do at least 180 amps of charging and 9 KW of output. I looked at Sol Ark and thought they were good, but too expense. I also saw some videos about them not handling surge current very well. I heard the Schneider Low Frequency inverters had great surge capability. One would now provide enough charging or inverting power, so I got the "Two Inverter AC Coupled combo".
Now individually, both the micro system and the hybrid system have many great features. The problem is getting them to actually work together has proved more challenging then I anticipated. First, for 1.5 years I couldn't get the micro inverters to turn on and produce power at all. Then Enphase released an update to the firmware that fixed this issue. Thank you Enphase. Then I could get on string to come up and run fine. When I added a second string in ALL the PV would shut down. Presumably, this is due to some incorrectly configured setting that I have yet to figure out.
So, I built a PV shedding controller to manage the PV strings myself and turned off the "AC Coupling" function in the Hybrid inverter. On testing this worked perfectly. My system always would have worked fine as a battery backup system. I could have used a generator during those rare actual blacks outs we experience, if needed. The thing is I really wanted to be able to recharge my batteries with my solar when needed. I have that working now proving that the hardware is not the issue. More than likely it is a configuration problem. I am going to try and experiment more with the setting to see if I can figure out why the PV shuts down and won't come back on without rebooting the PV inverters.
So I think my biggest mistake was just not asking on this forum "Has anyone gotten this combination of hardware to work together, when connected in this manner"?
At least I hooked everything up the way it was designed to work. Maybe I would have decided to try and do this anyway. At least I would have gone into this with totally different expectations. I see many new forum members here thinking that AC coupling is going to be easy. You just buy a bunch of different stuff from different manufactures. Then you plug it all together in a novel way that it was never intended to be used, and everything will just work. Sorry but with AC coupling it is just not that easy.
I also see people thinking they can just add a generator, AC coupled PV, and their Hybrid Inverter. Then start them up all at the same time and some magical electron controller will make electrons go where they are supposed to. In reality these devices are connected to an AC bus just like the one in your main electric panel. Now some devices such as the Enphase "System Controller" do have CTs on each input / output and they do actually have proprietary communication channels to control the attached devices. They actually can balance PV production, battery charging, grid power and generator power. Most Hybrid inverter companies can't do this. Grid tied inverters are not designed to work with generators. They will attempt to back feed power into them. Sometimes the companies will give you this information, but it is not always prominent. Like Sol Ark on it's "AC coupled to Load" line diagram has a little "Do Not Use" blurb on the Gen Input. They don't explain why. It seems like AC coupled requires a whole different level of understanding to get it all working correctly.
So can AC coupling be made to work as a backup system when the grid is down? Yes, but don't expect that is will be easy or that any products will actually work together, unless you know of people that have gotten it to work.
diysolarforum.com
I bought a professionally installed grid tied system with Enphase IQ8+ micro inverters. I had the idea at the time that I would eventually add a battery backup system to it as a DIY project. The Enphase system, as a grid tied system has really met every expectation. It is reliable (not a single panel of inverter has failed). I actually oversized the micro inverters over what was recommended. I figured at the time they were designed to handle larger panels so smaller panels would not push the micros as hard and there should be less heat build up and longer life.
On paper these micros can deliver 10.3 KW. Because some of my panels are east facing and the others are west facing, at most I get around 9 KW at the peak of the season. So to AC couple I wanted inverters that could do at least 180 amps of charging and 9 KW of output. I looked at Sol Ark and thought they were good, but too expense. I also saw some videos about them not handling surge current very well. I heard the Schneider Low Frequency inverters had great surge capability. One would now provide enough charging or inverting power, so I got the "Two Inverter AC Coupled combo".
Now individually, both the micro system and the hybrid system have many great features. The problem is getting them to actually work together has proved more challenging then I anticipated. First, for 1.5 years I couldn't get the micro inverters to turn on and produce power at all. Then Enphase released an update to the firmware that fixed this issue. Thank you Enphase. Then I could get on string to come up and run fine. When I added a second string in ALL the PV would shut down. Presumably, this is due to some incorrectly configured setting that I have yet to figure out.
So, I built a PV shedding controller to manage the PV strings myself and turned off the "AC Coupling" function in the Hybrid inverter. On testing this worked perfectly. My system always would have worked fine as a battery backup system. I could have used a generator during those rare actual blacks outs we experience, if needed. The thing is I really wanted to be able to recharge my batteries with my solar when needed. I have that working now proving that the hardware is not the issue. More than likely it is a configuration problem. I am going to try and experiment more with the setting to see if I can figure out why the PV shuts down and won't come back on without rebooting the PV inverters.
So I think my biggest mistake was just not asking on this forum "Has anyone gotten this combination of hardware to work together, when connected in this manner"?
At least I hooked everything up the way it was designed to work. Maybe I would have decided to try and do this anyway. At least I would have gone into this with totally different expectations. I see many new forum members here thinking that AC coupling is going to be easy. You just buy a bunch of different stuff from different manufactures. Then you plug it all together in a novel way that it was never intended to be used, and everything will just work. Sorry but with AC coupling it is just not that easy.
I also see people thinking they can just add a generator, AC coupled PV, and their Hybrid Inverter. Then start them up all at the same time and some magical electron controller will make electrons go where they are supposed to. In reality these devices are connected to an AC bus just like the one in your main electric panel. Now some devices such as the Enphase "System Controller" do have CTs on each input / output and they do actually have proprietary communication channels to control the attached devices. They actually can balance PV production, battery charging, grid power and generator power. Most Hybrid inverter companies can't do this. Grid tied inverters are not designed to work with generators. They will attempt to back feed power into them. Sometimes the companies will give you this information, but it is not always prominent. Like Sol Ark on it's "AC coupled to Load" line diagram has a little "Do Not Use" blurb on the Gen Input. They don't explain why. It seems like AC coupled requires a whole different level of understanding to get it all working correctly.
So can AC coupling be made to work as a backup system when the grid is down? Yes, but don't expect that is will be easy or that any products will actually work together, unless you know of people that have gotten it to work.
Building a PV Shedding Controller for AC Coupled Solar
Back Ground I have an Enphase system with 35*350 watt panels. It uses the IQ8+ micro inverters at 295 watts each. So the total possible output is 10,325 watts. The actual maximum output is about 9000 watts. I have 7 panels that face east and 28 that face west. The slope of my roof is about...
diysolarforum.com
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I trust that is a sarcastic "thank-you"... 1.5 years with no power !
OMG
wheisenburg
Owner Operator of Heisenberg Electric
Just to clarify, this has to do ONLY with their off grid operation. When these inverters were grid tied they produced power as they should. They operated with basically perfect reliability. It was only when "cutting my cord" to the grid that I had problems.I trust that is a sarcastic "thank-you"... 1.5 years with no power !
Lily Aldridge
New Member
There are things that we think we can manage to do. I've done some DIY myself, and it surely wasted my time.
squowse
Solar Enthusiast
- Joined
- Jan 4, 2021
- Messages
- 605
Possibly you’ve over complicated it? Can be as simple as lining the cells up, crimping rings on the balance leads, placing the busbars and screwing them all down.
Daddy Tanuki
Emperor Of Solar
No I get that, building a computer is easy, I didn't mean to compare the complexities, but the broad strokes of it all. But with the amount of time you've spent, I bet you've learned some stuff along the way, so maybe not a complete waste of time
Shiiii--it! 20 years ago building a computer was easy... these days i just buy them as too many ocnfsing choices to track and research. So while I find the battery builds easy and fun, you find the computer builds easy and fun. To each his own, but like above you are learning something even if you decided to never do it again.
Daddy Tanuki
Emperor Of Solar
i have mine compressed to raise cycle count, to keep the pack neat, and to bring my aluminum plates in firm contact to transfer heat in the winter from the heating pads. I used spring loaded rods to put a variable load that starts out at 10PSI at 30% charge and climbs up to 16 at full charge.
Daddy Tanuki
Emperor Of Solar
Brucey
Velcro Man
Are those the 180Ah from batteryhookup?I recently completed my first battery build using nylon case CALB cells. I used a MRBF terminal fuse and corrugated plastic separators.
Do I qualify for "CHAD" status? Please note it is only a 12 volt system.
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