Building a lithium ion battery power wall.

[stefangous]

Will Prowse's video​

I have a question regarding Will Prowse's video.

I want to build my own lithium ion battery power wall. I'm planning a 12S 100P pack, using 3000mAh lithium ion cells. Producing a 300Ah pack, with about 14.4kWh storage capacity. So unlike the battleborn batteries Will Prowse uses mine will be different.



The questions are:

1) I assume I will need a 12s BMS to balance each of the 12s cell/banks containing 100 cells each? I guess the 100 cells connected in parallel will balance themselves? Does the BMS prevent the cell/bank to overcharge, therefore not above 4.2V nor drop below 3.2V?



2) I know how to connect the small balancing leads to the pack / battery wall, but have no idea where in the system to connect the BMS to? Is that perhaps in series between the PPM positive connection out to the battery wall and the positive terminal of the battery wall. Can anybody please help here?



3) I am planning to buy a 48V, 5kW MPP solar inverter, see below. BUT is says a max of 66V DC, is that for the battery power wall or the solar input? If required I can hook up additional inverters in parallel to increase output to 10kW and also increase power wall storage capacity.



4) To charge a 48V system, I need to connect 4 x 12V solar panels in series, is that correct? If I have 12 x 300W solar panels, connecting 4 in series with 3 sets in parallel, it produces 48V and only 900W, is that correct? It seems way too little solar generation to charge the battery power wall?

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5) Can anybody recommend a BMS for this project? I found this BMS on ebay, will this do the job?

12S 36V 3.2V LFP LiFePO4 Lithium Battery Protection Board BMS Balance Waterproof | eBay

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Any help / advice will be greatly appreciated.

 

[John Frum]

1) I assume I will need a 12s BMS to balance each of the 12s cell/banks containing 100 cells each?

I see 13s and 14s bms's made by Dali, I don't see 12s

Does the BMS prevent the cell/bank to overcharge, therefore not above 4.2V nor drop below 3.2V?

BMS's usually have low voltage and high voltage disconnect.
You need to check the specific bms to see at what voltages they cutoff.
In my experience they the low voltage is too low to be useful and you should not need to depend on the high.
Your charging solution should be looking after that.
Think of the BMS is a backup parachute.
The batteries you are planning on using are the dangerous kind so be careful.

2) I know how to connect the small balancing leads to the pack / battery wall, but have no idea where in the system to connect the BMS to?

The dali BMS comes with instructions.
The blue wire goes to the battery negative.
Your fuse block connects to bms black wire.

5) Can anybody recommend a BMS for this project?

Perhaps one of these.

Group - Shop Cheap Group from China Group Suppliers at DALY Official Store on Aliexpress.com

Shopping for Cheap Group at DALY Official Store and more from on Aliexpress.com ,the Leading Trading Marketplace from China

daly.aliexpress.com

You will have to do some research to see which one is a better fit for the mpp.
Most of this stuff is geared for lead acid and lifepo4 batteries, keep that in mind.

16 x 3.2 is 51.2 nominal volts
16 x 3.65 is 58.4 max volts
16 x 3 48 low voltage cutoff

13 x 3.7 is 48.1 nominal volts
13 x 4.2 is 54.6 max volts
13 x 3.0 is 39 low voltage cutoff

14 x 3.7 is 51.8 nominal volts
14 x 4.2 is 58.8 max volts
14 x 3.0 is 42 low voltage cutoff

 

[John Frum]

I just had a closer look at the bms you enquired about.
I think the cells you have are the explody kind which is not lifepo4.
Job one is determining for sure which type of cells you have.

Until you confirm it I will assume you have the explody ones.
Making one battery with 1300 or 1400 cells is not a good idea imho.

Tell us more about the individual cells.
What is the cell chemistry?
What is the nominal voltage?
What is the max voltage?
Do you have a discharge graph?
What is the ah rating?
What is the discharge rate?
What is the charging rate?

 

[Supervstech]

Will Prowse's video​

I have a question regarding Will Prowse's video.

I want to build my own lithium ion battery power wall. I'm planning a 12S 100P pack, using 3000mAh lithium ion cells. Producing a 300Ah pack, with about 14.4kWh storage capacity. So unlike the battleborn batteries Will Prowse uses mine will be different.



The questions are:

1) I assume I will need a 12s BMS to balance each of the 12s cell/banks containing 100 cells each? I guess the 100 cells connected in parallel will balance themselves? Does the BMS prevent the cell/bank to overcharge, therefore not above 4.2V nor drop below 3.2V?



2) I know how to connect the small balancing leads to the pack / battery wall, but have no idea where in the system to connect the BMS to? Is that perhaps in series between the PPM positive connection out to the battery wall and the positive terminal of the battery wall. Can anybody please help here?



3) I am planning to buy a 48V, 5kW MPP solar inverter, see below. BUT is says a max of 66V DC, is that for the battery power wall or the solar input? If required I can hook up additional inverters in parallel to increase output to 10kW and also increase power wall storage capacity.



4) To charge a 48V system, I need to connect 4 x 12V solar panels in series, is that correct? If I have 12 x 300W solar panels, connecting 4 in series with 3 sets in parallel, it produces 48V and only 900W, is that correct? It seems way too little solar generation to charge the battery power wall?

(MGX) 5000w 48v 230vac Solar inverter 80a mppt solar charger Lithium BMS support | eBay

Find many great new & used options and get the best deals for (MGX) 5000w 48v 230vac Solar inverter 80a mppt solar charger Lithium BMS support at the best online prices at eBay!

www.ebay.com.au

5) Can anybody recommend a BMS for this project? I found this BMS on ebay, will this do the job?

12S 36V 3.2V LFP LiFePO4 Lithium Battery Protection Board BMS Balance Waterproof | eBay

Find many great new & used options and get the best deals for 12S 36V 3.2V LFP LiFePO4 Lithium Battery Protection Board BMS Balance Waterproof at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Any help / advice will be greatly appreciated.

I recommend following jehugarcia or Adam welch on YouTube if you are building a power wall with lithium ion cells. They cover the hookup and charging dangers and methods... jehu’s sells cell boards, etc... is kind of crazy at times... Adam is more methodical...
whatever you do, you need to have a plan first, you have to be careful, and have well researched plans. Watch a few videos of those cells burning down house,car,garage, etc...

 

[Craig]

Use a Chargery it will work perfect for your system you can adjust the high and low cell voltage levels. It can handle up to 16s in series or as little as 2. Also it can be configured for any discharge load you wish. It does require the use of relays but that is a feature for some of that we like.

 

[stefangous]

I see 13s and 14s bms's made by Dali, I don't see 12s



BMS's usually have low voltage and high voltage disconnect.
You need to check the specific bms to see at what voltages they cutoff.
In my experience they the low voltage is too low to be useful and you should not need to depend on the high.
Your charging solution should be looking after that.
Think of the BMS is a backup parachute.
The batteries you are planning on using are the dangerous kind so be careful.



The dali BMS comes with instructions.
The blue wire goes to the battery negative.
Your fuse block connects to bms black wire.



Perhaps one of these.

Group - Shop Cheap Group from China Group Suppliers at DALY Official Store on Aliexpress.com

Shopping for Cheap Group at DALY Official Store and more from on Aliexpress.com ,the Leading Trading Marketplace from China

daly.aliexpress.com

You will have to do some research to see which one is a better fit for the mpp.
Most of this stuff is geared for lead acid and lifepo4 batteries, keep that in mind.

16 x 3.2 is 51.2 nominal volts
16 x 3.65 is 58.4 max volts
16 x 3 48 low voltage cutoff

13 x 3.7 is 48.1 nominal volts
13 x 4.2 is 54.6 max volts
13 x 3.0 is 39 low voltage cutoff

14 x 3.7 is 51.8 nominal volts
14 x 4.2 is 58.8 max volts
14 x 3.0 is 42 low voltage cutoff

Would you rather recommend I build a 13s system rather than 12S? It seems the 48V MPP inverter can take up to 450V from the PV solar input. Unsure what the 66V charging volts then imply? Any suggestions?

 

[John Frum]

Would you rather recommend I build a 13s system rather than 12S? It seems the 48V MPP inverter can take up to 450V from the PV solar input. Unsure what the 66V charging volts then imply? Any suggestions?

When we talk about 48 volts we are referring to the system side of the device not the panel side.
They are separate domains.
We will determine which of 13s or 14s based on the charge and discharge parameters of the device.

 

[stefangous]

I just had a closer look at the bms you enquired about.
I think the cells you have are the explody kind which is not lifepo4.
Job one is determining for sure which type of cells you have.

Until you confirm it I will assume you have the explody ones.
Making one battery with 1300 or 1400 cells is not a good idea imho.

Tell us more about the individual cells.
What is the cell chemistry?
What is the nominal voltage?
What is the max voltage?
Do you have a discharge graph?
What is the ah rating?
What is the discharge rate?
What is the charging rate?

Thanks, your response is greatly appreciated.

I'm using 18650 litium ion cells, with a 3200mAh rating, but I know very little more about them. Reasonably sure they have a nominal voltage of 3.7V and a max voltage of 4.3V. According to some information I've read, they should NOT be discharged below 3.2V and definitely not over 4.2V.

I bought these ones I'm using for a 12V test system 2nd hand, they came out of Lime Scooters/ebikes. I have a large capacity AC smart charger which can charge a range of battery chemistry types. I usually charge very large (up to 30000mAh) LIPO batteries with it, but from AC. I built a 3s4p battery yesterday with balance cables and it seemed to charge them without a problem. However, I want to now charge them from solar. This is the bit I don't have much knowledge of.

I have 8 x 14W solar panels, which I want to charge them from. The plan is to connect 2 panels in series, producing between 24V and about 36V. Then connect 4 of these sets in parallel. Thereby I can "harvest" more sunlight, because the output can drop to about 7V for each PV cell, but still stay above the 12.6V required to charge the Battery. Does this all make sense?

I have a little 12V 600W inverter which I will use to test the concept. I have a small lead acid solar charge controller, but I believe I need to have some balancing system, if not a whole new solar charge controller including a balance system.

Ultimately I want to build a large 48V DC system, that will almost make me independant from grid power. Hence constructing a 12s100p lithium ion battery. I'm going to need 1200 cells. Can you recommend good cost effective cells? The above Lime scooter cells look very good, but not much info on them. Unlikely I will use them for the 48V system, I'd rather want new good quality cells, with capacity around 3000mAh each.

The idea is to buy the MPP 48V, 5kW solar inverter to use with the lithium ion battery (12s100p) I want to build. BUT I'm quite sure I will need a BMS to balance each of the 12 x 100p cell banks with each other? As mentioned I think I know how to wire the balance cable to the battery, but unsure how to connect the BMS into the system. I think it goes in series on the positive lead from the battery to the solar inverter.

ANYTHING else you believe I should know?

 

[stefangous]

When we talk about 48 volts we are referring to the system side of the device not the panel side.
They are separate domains.
We will determine which of 13s or 14s based on the charge and discharge parameters of the device.

Correct, the battery side will be 48V, i.e. 3s100p. But I could go to a 13s or 14s Batterie, however 12s seems more compatible with the MPP solar inverter?

The solar generation side will have at least 4 x 12V PV solar panels in series to ensure the PV voltage is above the 48V required to charge the battery. But if I add 1 or 2 additional solar panels in series, then the solar voltage is well above the 48V required. For 5 in series it will be 60V DC and 72V DC for 6 in series. That implies you will be able to generate and charge the battery under much lower light? I hope I have this correct. Therefore with my 12 panels, if I connect 6 PV panels in series with an identical 6 PV panels in series together in parallel, then I should have a reasonable solar generation capacity.

 

[stefangous]

I recommend following jehugarcia or Adam welch on YouTube if you are building a power wall with lithium ion cells. They cover the hookup and charging dangers and methods... jehu’s sells cell boards, etc... is kind of crazy at times... Adam is more methodical...
whatever you do, you need to have a plan first, you have to be careful, and have well researched plans. Watch a few videos of those cells burning down house,car,garage, etc...

Much appreciated. I certainly want to know as much as possible before I get started. My biggest concern is how to hook up the balancing component. Also how to set the upper and lower voltage at which you stop charging and stop drawing power from the system.

I also have a plan concerning fire etc. I am going to install the whole system in a flame proof cupboard outside in a shed, NOT in the house or garage, although I intend to make sure I do the best possible job and installation to prevent any chance of overheating and shorting out. That's one of the reasons for potentially connecting each cell to the main connecting cable via fuse wire. I've seen a few designs that looked very neat and impressive. Do you have any thoughts on that?