18650 battery build ideas - Vyaire LTV2

[hman88]

Greetings,

I am new to the community. I came to know about the forum through Will’s YouTube channel.

I have been wanting to build a LiFePO4 battery pack for some time now but even more so now that I have found some reputable US-based suppliers.

I recently purchased (117) Panasonic NCR18650A 2.9Ah cells for $143 after shipping. They are sourced from new stock Vyaire Li-Ion battery packs used for ventilators which are rated as 10.8 VDC 8.7 Ah 94 Wh. I originally paid around $32 for a single battery pack on eBay as I was planning to repurpose the cells for several electronics. However, when I saw this recent deal pop up I couldn't help myself as I was able to convince myself.

https://batteryhookup.com/products/new-case-of-108-panasonic-ncr18650a-2900mah-cells

I would ideally like to maintain the packs without fully disassembling them but not immediately sure how I would wire up 13 of these packs. It would be nice to know what the existing pins/positions on the factory power connector are used for. If anyone can help identify this information I would greatly appreciate it.

I couldn't find any other forums/threads of people repurposing these particular packs. If anyone is aware of any resources or documentation I would add me in my understanding and project I would appreciate it.

If I did fully disassemble I was thinking to do a 13s9p configuration for a 48V pack. However, I am still obviously undecided and open to suggestions/recommendations. A 12V pack seems the most practical but like the idea of having the option to use with an electric bike or similar. As I already own this inverter I was leaning towards a 12V configuration. https://www.amazon.com/gp/product/B07J4ZXVTS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I previously disassemble the first pack I got from eBay several weeks ago so knew what I was getting into before placing the larger order. As I am not an electrical engineer I do not know much about the components on the circuit board.

Panasonic NCR18650A specs:

• 2.9 Ah per cell
• 3.6V nominal
• Standard charging: 4.2V, 590mA, 60mA end
• Quick charging: 4.2V, 1475mA, 60mA end
• Standard discharging: 580mA (Constant current, 2.5V end)
• Continuous allowable discharging current: 3540mA (45°C or under)
• Maximum discharge current: 5800mA

• 12v
  • 4s29p (116) cells = 1211.04Wh
    • Standard charging: 16.8V, 17.11A
    • Quick charging: 16.8V, 42.77A
    • Standard discharging current: 16.82A * 12V = 201.84W
    • Continuous allowable discharging: 102.66A * 12V = 1231.92W
    • Maximum discharge current: 168.2A * 12V = 2018.4W
• 24V
  • 7s16p (112 cells) = 1169.28Wh
    • Standard charging: 29.4V, 9.44A
    • Quick charging: 29.4V, 23.6A
    • Standard discharging current: 9.28A * 24V = 222.72W
    • Continuous allowable discharging: 56.64A * 24V = 1359.36W
    • Maximum discharge current: 92.8A * 24V = 2227.2W
• 48v
  • 13s9p (117 cells) = 1255.41Wh
    • Standard charging: 54.6V, 5.31A
    • Quick charging: 54.6V, 13.27A
    • Standard discharging current: 5.22A * 48V = 250.56W
    • Continuous allowable discharging: 31.86A * 48V = 1529.28W
    • Maximum discharge current: 52.2A * 48V = 2505.6W

https://drive.google.com/file/d/0B_...WDA/view?resourcekey=0-OaGgYSbjrAlauatZkaGzTQ

Please let me know if there is a more appropriate forum where I should be posting this topic.
Does anyone else have experience with these particular battery packs and/or cells?
Does anyone have build recommendations and/or suggestions? 12V vs 24V vs 48V etc.

Thanks for stopping by and viewing/sharing!

 

[psykeus]

Hey Hman88,

I also purchased a case of these batteries from Batteryhookup for building some packs.
I personally will be harvesting all the cells from the packs and building them into custom modules.

Reusing the attached BMU (the circuit board in the pack) and trying to connect the packs together would likely not be worth the trouble.
I find the best method is to determine what you are using the pack for and build around that.
I'm not sure about your use case, but it sounds like more of an experiment for having backup power if needed.
If that is the case, and you are wanting to re-use some 12v inverter you have, then I would just build out some type
of 3sXp solution to meet your needs. Just keep in mind that 12v wiring requires very large gauges if the amperage draw is high.

If you are considering a larger build for a powerwall, I would suggest using 48v or at least 24v packs,
as they are much easier to work with for carrying larger loads.

Also, keep in mind these are not high-current batteries, so the sum of your current draw across the "P" side of the pack needs to be balanced.
E.g. If you build a 12volt battery pack out of the cells, the P side needs to equal at least 1.5 times what your maximum current draw will be.
A 600-watt draw on a 12 volt 3sXp requires 50 AMPS of pull across the batteries, and I would set up everything to handle 900 watts of power
to compensate for differences. That would mean having a 3s5p minimum build size. Then consider how long you need to run at this wattage to determine how many more batteries to add to the P side of the pack.

Hope this makes sense!

Psykeus

 

[hman88]

Hey Hman88,

I also purchased a case of these batteries from Batteryhookup for building some packs.
I personally will be harvesting all the cells from the packs and building them into custom modules.

Reusing the attached BMU (the circuit board in the pack) and trying to connect the packs together would likely not be worth the trouble.
I find the best method is to determine what you are using the pack for and build around that.
I'm not sure about your use case, but it sounds like more of an experiment for having backup power if needed.
If that is the case, and you are wanting to re-use some 12v inverter you have, then I would just build out some type
of 3sXp solution to meet your needs. Just keep in mind that 12v wiring requires very large gauges if the amperage draw is high.

If you are considering a larger build for a powerwall, I would suggest using 48v or at least 24v packs,
as they are much easier to work with for carrying larger loads.

Also, keep in mind these are not high-current batteries, so the sum of your current draw across the "P" side of the pack needs to be balanced.
E.g. If you build a 12volt battery pack out of the cells, the P side needs to equal at least 1.5 times what your maximum current draw will be.
A 600-watt draw on a 12 volt 3sXp requires 50 AMPS of pull across the batteries, and I would set up everything to handle 900 watts of power
to compensate for differences. That would mean having a 3s5p minimum build size. Then consider how long you need to run at this wattage to determine how many more batteries to add to the P side of the pack.

Hope this makes sense!

Psykeus

Thanks for commenting and sharing!

What materials will you be using to build out your modules/packs? I still need to decide on a BMS and charging source. I am thinking this could be a suitable charger:

Amazon.com: 16.8V 20A Charger 16.8V Li-ion Battery Charger Output Alligator Clip Used for 4S 14.8V Lithium Battery Pack : Electronics

Amazon.com: 16.8V 20A Charger 16.8V Li-ion Battery Charger Output Alligator Clip Used for 4S 14.8V Lithium Battery Pack : Electronics

www.amazon.com

For the BMS I was reviewing these if you have any recommendations? https://www.amazon.com/s?k=4s+12v+bms&crid=2SMC37V43JGHX&sprefix=4s+12v+bms,aps,276&ref=nb_sb_noss_1

I think for me, the most practical application would be to have a portable 110v power source for camping, emergencies, etc. I would like to replicate something like these products: https://www.amazon.com/s?k=portable+power+station&sprefix=portable+power,aps,244&ref=nb_sb_ss_ts-doa-p_2_14

As the cells nominal voltage is 3.6 would it not be most appropriate to have have a 4sXp configuration for 14.4V vs a 3sXp at 10.8V?

If I am not mistaken these cells are rated for 5.8A max discharge. However, I would plan to draw 600w using the below configuration which should be approximately half of the rated continuous allowable discharge rating if my math is correct.

• 4s29p (116) cells = 1211.04Wh
  • Standard charging: 16.8V @ 17.11A
  • Quick charging: 16.8V @ 42.77A
  • Standard discharging current: 16.82A * 12V = 201.84W
  • Continuous allowable discharging: 102.66A * 12V = 1231.92W
  • Maximum discharge current: 168.2A * 12V = 2018.4W

 

[psykeus]

Hey hman88!

Lots to discuss here, so I'll dive right in.

First, you can use a 4s configuration for Li-ion cells, it's just not optimal and a bit more costly for parts.
Just make sure you don't get a LifePo4 BMS Also, you need to ensure your 12-volt inverter has the proper
voltage swings to work with a 4s Li-ion configuration.

I personally like to use a variable voltage power supply for charging cells. This gives me the ability to charge to different levels,
for example, charging a pack to a storage voltage, or if I want to only charge a pack to say 4v instead of 4.2v to give more cycles.
Here is one I use: https://www.amazon.com/DROK-110V-220V-Converter-Adjustable-Transformer/dp/B08GFQZFC1/
It may take a bit longer to charge at 10 amps, but it's better on the battery long-term.

For the BMS, I highly recommend a DALY BMS. Especially if you are going to purchase a smart one. JBD BMS'are ok too.
For a 4s configuration, your math is solid. A 600w draw from a 3s38p would also have no issues. As always make sure your BMS and wiring are rated for at least 20% more than the maximum current draw from the pack. In this case, I would go with a 75A - 100A BMS.

Lastly, when it comes to the inverter, make sure it is a pure sign-wave inverter! Stay away from modified sign-wave!

Now all that said above, I try not to use 12v battery packs. The wiring needed and the amount of current needed is too much of a pain to work with.
I almost always build 24v or higher battery packs that use much smaller gauge wiring and amperage BMS.

Hope this helps a little!

 

[Ampster]

I have been wanting to build a LiFePO4 battery pack for some time

The Panasonic cells are not LifePO4. Those are more dense, higher voltage and do not have the same low risk of fire that traditional LifePO4 cells do. i have used packs of similar cells for some ebikes so they work well because of their energy density.

 

[hman88]

Hey hman88!

Lots to discuss here, so I'll dive right in.

First, you can use a 4s configuration for Li-ion cells, it's just not optimal and a bit more costly for parts.
Just make sure you don't get a LifePo4 BMS Also, you need to ensure your 12-volt inverter has the proper
voltage swings to work with a 4s Li-ion configuration.

I personally like to use a variable voltage power supply for charging cells. This gives me the ability to charge to different levels,
for example, charging a pack to a storage voltage, or if I want to only charge a pack to say 4v instead of 4.2v to give more cycles.
Here is one I use: https://www.amazon.com/DROK-110V-220V-Converter-Adjustable-Transformer/dp/B08GFQZFC1/
It may take a bit longer to charge at 10 amps, but it's better on the battery long-term.

For the BMS, I highly recommend a DALY BMS. Especially if you are going to purchase a smart one. JBD BMS'are ok too.
For a 4s configuration, your math is solid. A 600w draw from a 3s38p would also have no issues. As always make sure your BMS and wiring are rated for at least 20% more than the maximum current draw from the pack. In this case, I would go with a 75A - 100A BMS.

Lastly, when it comes to the inverter, make sure it is a pure sign-wave inverter! Stay away from modified sign-wave!

Now all that said above, I try not to use 12v battery packs. The wiring needed and the amount of current needed is too much of a pain to work with.
I almost always build 24v or higher battery packs that use much smaller gauge wiring and amperage BMS.

Hope this helps a little!

Thanks again for sharing! This is most helpful. After watching several videos on YouTube of 18650 battery pack builds it seems most use 3 cells in series instead of 4 for 12V.

That is the same power supply I had in my Amazon shopping list as I saw someone else using it and recommending it in their video.

Thanks for the BMS recommendation too as I was leaning towards DALY as well.

I was more inclined to go with a 24V or 48V design for that very reason and that is largely why I posted to inquire about what others recommended. Higher outputs with smaller wire gauges are ideal for sure.

A pure sine wave inverter is the only way to go for sure!

 

[hman88]

The Panasonic cells are not LifePO4. Those are more dense, higher voltage and do not have the same low risk of fire that traditional LifePO4 cells do. i have used packs of similar cells for some ebikes so they work well because of their energy density.

Hey Ampters! Thanks for commenting. Yes, I am aware of this. I was just noting my preference is to eventually build a LiFePO4 battery pack. Since I got such a good deal on the NCR18650A cells my first battery build will be using these cells.

 

[Tallguy]

Greetings,

I am new to the community. I came to know about the forum through Will’s YouTube channel.

I have been wanting to build a LiFePO4 battery pack for some time now but even more so now that I have found some reputable US-based suppliers.

I recently purchased (117) Panasonic NCR18650A 2.9Ah cells for $143 after shipping. They are sourced from new stock Vyaire Li-Ion battery packs used for ventilators which are rated as 10.8 VDC 8.7 Ah 94 Wh. I originally paid around $32 for a single battery pack on eBay as I was planning to repurpose the cells for several electronics. However, when I saw this recent deal pop up I couldn't help myself as I was able to convince myself.

https://batteryhookup.com/products/new-case-of-108-panasonic-ncr18650a-2900mah-cells

I would ideally like to maintain the packs without fully disassembling them but not immediately sure how I would wire up 13 of these packs. It would be nice to know what the existing pins/positions on the factory power connector are used for. If anyone can help identify this information I would greatly appreciate it.

I couldn't find any other forums/threads of people repurposing these particular packs. If anyone is aware of any resources or documentation I would add me in my understanding and project I would appreciate it.

If I did fully disassemble I was thinking to do a 13s9p configuration for a 48V pack. However, I am still obviously undecided and open to suggestions/recommendations. A 12V pack seems the most practical but like the idea of having the option to use with an electric bike or similar. As I already own this inverter I was leaning towards a 12V configuration. https://www.amazon.com/gp/product/B07J4ZXVTS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I previously disassemble the first pack I got from eBay several weeks ago so knew what I was getting into before placing the larger order. As I am not an electrical engineer I do not know much about the components on the circuit board.

Panasonic NCR18650A specs:

• 2.9 Ah per cell
• 3.6V nominal
• Standard charging: 4.2V, 590mA, 60mA end
• Quick charging: 4.2V, 1475mA, 60mA end
• Standard discharging: 580mA (Constant current, 2.5V end)
• Continuous allowable discharging current: 3540mA (45°C or under)
• Maximum discharge current: 5800mA

• 12v
  • 4s29p (116) cells = 1211.04Wh
    • Standard charging: 16.8V, 17.11A
    • Quick charging: 16.8V, 42.77A
    • Standard discharging current: 16.82A * 12V = 201.84W
    • Continuous allowable discharging: 102.66A * 12V = 1231.92W
    • Maximum discharge current: 168.2A * 12V = 2018.4W
• 24V
  • 7s16p (112 cells) = 1169.28Wh
    • Standard charging: 29.4V, 9.44A
    • Quick charging: 29.4V, 23.6A
    • Standard discharging current: 9.28A * 24V = 222.72W
    • Continuous allowable discharging: 56.64A * 24V = 1359.36W
    • Maximum discharge current: 92.8A * 24V = 2227.2W
• 48v
  • 13s9p (117 cells) = 1255.41Wh
    • Standard charging: 54.6V, 5.31A
    • Quick charging: 54.6V, 13.27A
    • Standard discharging current: 5.22A * 48V = 250.56W
    • Continuous allowable discharging: 31.86A * 48V = 1529.28W
    • Maximum discharge current: 52.2A * 48V = 2505.6W

https://drive.google.com/file/d/0B_...WDA/view?resourcekey=0-OaGgYSbjrAlauatZkaGzTQ

Please let me know if there is a more appropriate forum where I should be posting this topic.
Does anyone else have experience with these particular battery packs and/or cells?
Does anyone have build recommendations and/or suggestions? 12V vs 24V vs 48V etc.

Thanks for stopping by and viewing/sharing!

Did you break up the packs or use them as is? I have 6 I need to get useful. I thought about trying to use them as is. Did you get any wiring info from anywhere?