Please adjust my assumptions and advise on BMS.

[Monsterthews]

Good morning! I only found this site a day or two ago, so I haven't looked over previous posts.

I am finishing the first phase of my lifestyle batterification project.
I have three solar trackers that output 60V each. My first assumption was that I wanted maximum wattage to dump on the batteries, but listed charging wattage for the batteries themselves is low, like 16V or 20V. So the first thing I'd like your help with is understanding how much juice I want to generate for this sub-home scale battery setup. I've heard people say they have eight 300-watt panels for their house, and people have a few KiloAmpHour batteries. I want maximum wattage. I'd like to discuss this.
My diode is 60W, which is going to be my peak output. I figure a charge controller should be able to split that into three 16V charging lines.

Two of my trackers ( a photosensor tells a motor to follow the sun) have four little 213x92 panels. The other has two bigger panels with one little one. In series, it's 180V. It's cool, you can feel the electricity in your fingers.

The PCB-style BMS on AliExpress all distribute ~16V to four cells, but they all want you to daisy-chain your batteries. I don't want to do that. The batteries I've selected are the blue LiFePO4 that bolt together to make 12V. I don't want a daisy chain for that, I want balancing.
I want each of my trackers to charge one battery at a time, because I'm not going to be able to run them down quickly. So I really only need one of them for now, but I'll use the same unit. So price matters.

I have one battery with 200 Ah, and another coming with 800 Ah. There are two 100 Ah Lithium ion batteries with built-in BMS, but I don't want to use them. They are available.

Now it isn't too cold to play outside, I want to be outside watching the trackers work. The only piece missing is the BMS. I got some 12V kitchen equipment and a cheap-ass inverter to run the batteries down.

What can I do with 180V with no batteries to charge? I can't install an electric fence. Maybe a motorized mechanical sculpture.

 

[sunshine_eggo]

Good morning! I only found this site a day or two ago, so I haven't looked over previous posts.

I am finishing the first phase of my lifestyle batterification project.
I have three solar trackers that output 60V each. My first assumption was that I wanted maximum wattage to dump on the batteries, but listed charging wattage for the batteries themselves is low, like 16V or 20V.

You talk about charging wattage and then list voltages.

So the first thing I'd like your help with is understanding how much juice I want to generate for this sub-home scale battery setup. I've heard people say they have eight 300-watt panels for their house, and people have a few KiloAmpHour batteries. I want maximum wattage. I'd like to discuss this.
My diode is 60W, which is going to be my peak output. I figure a charge controller should be able to split that into three 16V charging lines.

Why do you have a diode, and where is it?

Why do you want "three 16V charging lines?"

Why not just simply wire the batteries parallel with each other?

Two of my trackers ( a photosensor tells a motor to follow the sun) have four little 213x92 panels. The other has two bigger panels with one little one. In series, it's 180V. It's cool, you can feel the electricity in your fingers.

180V is relatively high and will restrict your choice of charge controllers.

The PCB-style BMS on AliExpress all distribute ~16V to four cells, but they all want you to daisy-chain your batteries. I don't want to do that.

Not really sure what you're talking about here. I know if no BMS that insists you place separate batteries in series.

The batteries I've selected are the blue LiFePO4 that bolt together to make 12V.

The individual elements are not batteries. They are cells. Batteries are a group of cells. You use cells to build batteries.

I don't want a daisy chain for that, I want equalization.

Not sure what you mean here.

I want each of my trackers to charge one battery at a time, because I'm not going to be able to run them down quickly. So I really only need one of them for now, but I'll use the same unit. So price matters.

Not sure why this matters.

I have one battery with 200 Ah, and another coming with 800 Ah. There are two 100 Ah Lithium ion batteries with built-in BMS, but I don't want to use them. They are available.

800Ah is massive. Are you adding up the individual cell Ah? If so, that's not how it works. if they are in series, they do not add, voltage does. If they are in parallel, Ah adds, but voltage does not.

 

[Monsterthews]

You talk about charging wattage and then list voltages.

Hi! Thanks! There is no Amperage, because there is no load. Literature says 2.5W, which is absurd.
Thanks again, I learned about Ah. All the cells in the present battery are 50Ah, and the incoming are 200Ah, so I'll have 250Ah in parallel.
The goal of 1,000 Ah is not relevant to anything, so it's not a valid goal. 250Ah is plenty for a 12V rice cooker.


Why do you have a diode, and where is it?

The diode is to prevent voltage going backward, between the panel and the positive terminal.

Why do you want "three 16V charging lines?"

Why not just simply wire the batteries parallel with each other?

Again, thank you. Since I'm going to have one battery to charge at a time, there is one battery. There will be a BMS between the battery and the panels.

180V is relatively high and will restrict your choice of charge controllers.

I looked at some this morning that accept 75, 100, 150 Volts incoming and dispense 10, 20, 30 Volts to the battery. I've learned that you can match your Panel magnitude to the controller.

Not really sure what you're talking about here. I know if no BMS that insists you place separate batteries in series.

No kidding. Four batteries in series. I bought one, but the literature says it's not for LiFePO4.

The individual elements are not batteries. They are cells. Batteries are a group of cells. You use cells to build batteries.




Not sure what you mean here.



Not sure why this matters.



800Ah is massive. Are you adding up the individual cell Ah? If so, that's not how it works. if they are in series, they do not add, voltage does. If they are in parallel, Ah adds, but voltage does not.

 

[sunshine_eggo]

Hi! Thanks! There is no Amperage, because there is no load. Literature says 2.5W, which is absurd.
Thanks again, I learned about Ah. All the cells in the present battery are 50Ah, and the incoming are 200Ah, so I'll have 250Ah in parallel.
The goal of 1,000 Ah is not relevant to anything, so it's not a valid goal. 250Ah is plenty for a 12V rice cooker.


Why do you have a diode, and where is it?

The diode is to prevent voltage going backward, between the panel and the positive terminal.



Again, thank you. Since I'm going to have one battery to charge at a time, there is one battery. There will be a BMS between the battery and the panels.

I looked at some this morning that accept 75, 100, 150 Volts incoming and dispense 10, 20, 30 Volts to the battery. I've learned that you can match your Panel magnitude to the controller.

No kidding. Four batteries in series. I bought one, but the literature says it's not for LiFePO4.

It seems like you lack a basic understanding of how this stuff works and as a result have some atypical ideas.

Recommend you start with the FAQ:

Thread 'Frequently Asked Questions'

Sep 21, 2019

Links to commonly asked questions with long explanations:

• Beginner Video Playlist
• How much power does my device consume?
• Energy Audit
• How much Solar Energy should I expect where I live?
• What does it mean to have solar panels in parallel and series?
• How to figure out how much Solar and inverter wattage is needed to charge a battery
• Figuring out how many panels in series and parallel based on your MPPT
• What wire gauge should I use? (video, calculator)
• Comparing Solar...

• svetz
• Replies: 3
• Forum: Frequently Asked Questions

• 

 

[Monsterthews]

I am not expert. I have a finite goal here, to charge batteries. These batteries have a maximum charge voltage of 3.65. How the hell am I going to get to 3.65V???
I do need a simple, basic BMS to take my solar current and charge and balance a battery.
I don't see such a thing.
I guess I can just cover the panel until it's generating 3.5V, and just check on it every ten minutes.
Nowhere near as cool as I wanted to look.

 

[timselectric]

The BMS doesn't charge the battery. (That's the chargers job)
The BMS protects the battery, if it goes out of safe parameters, and balances the cells.

 

[timselectric]

I guess I can just cover the panel until it's generating 3.5V

This makes no sense.
Your not connecting the solar panels directly to individual cells, hopefully.

 

[Monsterthews]

This makes no sense.
Your not connecting the solar panels directly to individual cells, hopefully.

I have a few weeks, but yeah. It's one battery. I can sit out back next to it and give it the meter every few minutes.

 

[timselectric]

I have a few weeks, but yeah. It's one battery. I can sit out back next to it and give it the meter every few minutes.

Battery, or cell?
Either way, please don't connect a solar panel directly to it.
That's an unregulated power source. And you will more than likely damage the battery or cell, whichever it is.