Question for pouch cell battery pack (im a full on idiot)

[TheoneKnocker]

I was wondering since pouch cells last longer and are safer i was going to build a battery using them, problem is that the capacity isnt that big, I was planning on ordering 60 cells, 30 for a series battery pack and another 30 for pure parallel. Would i in theory be able to connect the battery packs together to create a monster battery back of 126v and 1890Ah? Or would i end up just burning everything to the ground or this plan not work at all. Yes both battery pack would have their seperate bms and I would have to figure out a way to connect them both but i think this plan is either really stupid and dangerous or smart, i want your opinion on this guys and thank you very much.

 

[TheoneKnocker]

Why did my brain even think of this idea, i just had the realization that i would need 900 batteries for this, this would never work thank you Chalo for your reply

 

[Chalo]

If you add one 30P cell group to a 30S 1P battery pack, in effect you get a 31S 1P pack but almost double the weight. You would waste the energy capacity of 29 of the cells.

If you need 126V and 1890Ah, you'll have to use 30S 30P or 900 pouch cells. Seems like a lot to carry. That would be 238 kWh of battery. For comparison, the Hummer EV's 205 kWh battery weighs over 2,800 pounds.

If this reflects the level of your understanding, I advise you not to mess around with cylindrical cells either, until you've firmed up your knowledge about how series-parallel batteries work. Or stick with 1P construction only; that's much harder to screw up.

 

[TheoneKnocker]

If you add one 30P cell group to a 30S 1P battery pack, in effect you get a 31S 1P pack but almost double the weight. You would waste the energy capacity of 29 of the cells.

If you need 126V and 1890Ah, you'll have to use 30S 30P or 900 pouch cells. Seems like a lot to carry. That would be 238 kWh of battery. For comparison, the Hummer EV's 205 kWh battery weighs over 2,800 pounds.

If this reflects the level of your understanding, I advise you not to mess around with cylindrical cells either, until you've firmed up your knowledge about how series-parallel batteries work. Or stick with 1P construction only; that's much harder to screw up.

I have little to no knowledge on these pouch cells thats why im asking, is it possible to just make a 30s 1p pack? Since these are 63ah with "10c" discharged they should be enough to run a powerful motor right? Its more realistic to just make a 30s 1p pack using these because of the high discharge and the low size they have, also how could i make a 30s2p configuration using these batteries?

 

[Chalo]

I have little to no knowledge on these pouch cells thats why im asking, is it possible to just make a 30s 1p pack?

Not only is it possible, it's the best way to build a pack.

 

[TheoneKnocker]

Not only is it possible, it's the best way to build a pack.

I am extremely new to these and would love to make one because of their longevity and power they have, do you have any sources for making one battery pack using these cells or should i search on my own?

 

[Chalo]

I am extremely new to these and would love to make one because of their longevity and power they have, do you have any sources for making one battery pack using these cells or should i search on my own?

I haven't built any packs with tabbed cells (I prefer threaded posts), but I've seen a few DIY versions on this forum over the years. Maybe start here and then check out the wider Internet for tips.

 

[TheoneKnocker]

I haven't built any packs with tabbed cells (I prefer threaded posts), but I've seen a few DIY versions on this forum over the years. Maybe start here and then check out the wider Internet for tips.

alright thank you very much

 

[lnanek]

The bad thing about budget pouch pack building is that reclaimed cells often have the tabs cut off. And it takes laser welding to put new ones on. So you are stuck buying new instead of old EV cells, or trying to clamp blocks of metal on the short tabs to make solid connections. Maybe they require strapping to keep them under pressure like prismatic cells too. Kind of a pain.

 

[TheoneKnocker]

The bad thing about budget pouch pack building is that reclaimed cells often have the tabs cut off. And it takes laser welding to put new ones on. So you are stuck buying new instead of old EV cells, or trying to clamp blocks of metal on the short tabs to make solid connections. Maybe they require strapping to keep them under pressure like prismatic cells too. Kind of a pain.

something like this video?

,i would love to know how he connected the batteries step by step as he explains it but im having a little difficult time understanding how he connected all of his batteries together and i cant understand the design, he says he folds one tab over the other but the ends are just not even connected to any other cell. ill keep searching for an answer to this

 

[LewTwo]

... pouch cells last longer and are safer ....

Say what ? Says who?

 

[TheoneKnocker]

That is what i have read, but i might be mistaken again, ill be switching to giant LFP cylindrical cells 32140 batteries so i get the most lifetime out of them since size isnt an issue anymore.

 

[TheoneKnocker]

Say what ? Says who?

If you have any suggestions on good cells i should use that last longer and are compact please let me know, i want to run this bike as long as it can (at the end ill end up switching to lithium ion cells and realize the error in my ways)

 

[electric_nz]

You could look at an automotive module - some are 12S I think but large capacity and ultra long life. It will be cumbersome to fit to a bike frame or luggage rack. If you mounted it on a rear rack suggest a front hub motor to counterbalance the weight!

But seriously, newer 18650s and 21700s now last many hundreds or thousands of full discharge cycles - check the tests in this forum under the high power batteries. The LG HG2 or Molicell variants are exceptional. A standard e-bike pack made of those will cost a fair bit but probably last for a decade of daily use.

 

[LewTwo]

If you have any suggestions on good cells i should use that last longer and are compact please let me know, i want to run this bike as long as it can (at the end ill end up switching to lithium ion cells and realize the error in my ways)

Pouch cell is a physical form (vs a chemistry). They come with their own problems (some mentioned above). They swell and need separation between the cells. They also need a enclosure that protects them from physical damage. Some people build them with nothing more than plastic panels and shrink wrap for enclosures. I have never seen or heard anyone claim that they were safer or had better longevity.

LiFePO4 (lithium iron phosphate, LFP) are know for their longevity and tolerance of abuse. I think that Headway might be one of the better brands. They have steel cylindrical shells and M6 female terminals on each end. However they do not have the power density of some more popular battery chemistries (i.e. Nickel Manganese Cobalt, NMC).

Li4Ti5O12 (lithium-titanium-oxide, LTO) have a higher charge/discharge rates and better longevity but they tend to be expensive.

ALL of the above are Lithium-Ion batteries.

Pouch cells are very popular in small electronic devices. EV batteries pack a lot of capacity into a confined space with much larger power draws. It is a bit like comparing a petrol car and a zipo lighter. Very few if any Zipos have been know to explode or catch fire. Petrol fuel vehicles frequently catch fire and burn and/or explode. You can also ask Russians about trying to put out fires in large oil storage facilities. The point here is 'size does matter'.

 

[TheoneKnocker]

You could look at an automotive module - some are 12S I think but large capacity and ultra long life. It will be cumbersome to fit to a bike frame or luggage rack. If you mounted it on a rear rack suggest a front hub motor to counterbalance the weight!

But seriously, newer 18650s and 21700s now last many hundreds or thousands of full discharge cycles - check the tests in this forum under the high power batteries. The LG HG2 or Molicell variants are exceptional. A standard e-bike pack made of those will cost a fair bit but probably last for a decade of daily use.

Might probably try an automotive pack as you say thank you for suggesting these batteries

 

[TheoneKnocker]

Pouch cell is a physical form (vs a chemistry). They come with their own problems (some mentioned above). They swell and need separation between the cells. They also need a enclosure that protects them from physical damage. Some people build them with nothing more than plastic panels and shrink wrap for enclosures. I have never seen or heard anyone claim that they were safer or had better longevity.

LiFePO4 (lithium iron phosphate, LFP) are know for their longevity and tolerance of abuse. I think that Headway might be one of the better brands. They have steel cylindrical shells and M6 female terminals on each end. However they do not have the power density of some more popular battery chemistries (i.e. Nickel Manganese Cobalt, NMC).

Li4Ti5O12 (lithium-titanium-oxide, LTO) have a higher charge/discharge rates and better longevity but they tend to be expensive.

ALL of the above are Lithium-Ion batteries.

Pouch cells are very popular in small electronic devices. EV batteries pack a lot of capacity into a confined space with much larger power draws. It is a bit like comparing a petrol car and a zipo lighter. Very few if any Zipos have been know to explode or catch fire. Petrol fuel vehicles frequently catch fire and burn and/or explode. You can also ask Russians about trying to put out fires in large oil storage facilities. The point here is 'size does matter'.

Extremely grateful for this info i had no idea what i was talking about earlier so i might just go with an expensive pack just to be safe

 

[TheoneKnocker]

You could look at an automotive module - some are 12S I think but large capacity and ultra long life. It will be cumbersome to fit to a bike frame or luggage rack. If you mounted it on a rear rack suggest a front hub motor to counterbalance the weight!

But seriously, newer 18650s and 21700s now last many hundreds or thousands of full discharge cycles - check the tests in this forum under the high power batteries. The LG HG2 or Molicell variants are exceptional. A standard e-bike pack made of those will cost a fair bit but probably last for a decade of daily use.

Do you have any recommendation where i should go to purchase such cells?

 

[harrisonpatm]

Do you have any recommendation where i should go to purchase such cells?

batteryhookup.com

 

[TheoneKnocker]

batteryhookup.com

Ive seen everyone recommend them and i see that they have good cells, ill take a look at them and probably buy from them, thank you so much

 

[wturber]

Ive seen everyone recommend them and i see that they have good cells, ill take a look at them and probably buy from them, thank you so much

I like batteryhookup.com. In fact, I've bought pretty much all of my batteries from them. But you need to read their descriptions fully. It helps to have some background so you can more fully understand what they are offering and the potential shortcomings.
Also, regarding safety and fires, you might want to watch Grin's video on the subject. I think they give a practical real world insight into the issue that involves a lot of direct and indirect experience.

 

[TheoneKnocker]

I like batteryhookup.com. In fact, I've bought pretty much all of my batteries from them. But you need to read their descriptions fully. It helps to have some background so you can more fully understand what they are offering and the potential shortcomings.
Also, regarding safety and fires, you might want to watch Grin's video on the subject. I think they give a practical real world insight into the issue that involves a lot of direct and indirect experience.

Thank you very much for the video i am still looking for good batteries but i am indeed a little scared about lithium ion and the explosion factor so im looking at something else, like the LiFePO4 IFR 32700, since i dont care that much about the voltage (even thought im going to make a 30s pack) ill be using these cells due to the long cycle life and almost no risk of bursting on fire

 

[wturber]

Thank you very much for the video i am still looking for good batteries but i am indeed a little scared about lithium ion and the explosion factor so im looking at something else, like the LiFePO4 IFR 32700, since i dont care that much about the voltage (even thought im going to make a 30s pack) ill be using these cells due to the long cycle life and almost no risk of bursting on fire

My limited experience jibes with what Justin is saying. If you have brand name cells in a battery that was professionally assembled, the odds of a fire become vanishingly small. That said, LiFePO does have a reputation for greater safety and longevity. They are just generally heavier.

 

[TheoneKnocker]

My limited experience jibes with what Justin is saying. If you have brand name cells in a battery that was professionally assembled, the odds of a fire become vanishingly small. That said, LiFePO does have a reputation for greater safety and longevity. They are just generally heavier.

True, i see that they hold less energy and the dont have the same discharge as the lithium ion cells but yeah i think thats a safe bet for me

 

[TheoneKnocker]

You could look at an automotive module - some are 12S I think but large capacity and ultra long life. It will be cumbersome to fit to a bike frame or luggage rack. If you mounted it on a rear rack suggest a front hub motor to counterbalance the weight!

But seriously, newer 18650s and 21700s now last many hundreds or thousands of full discharge cycles - check the tests in this forum under the high power batteries. The LG HG2 or Molicell variants are exceptional. A standard e-bike pack made of those will cost a fair bit but probably last for a decade of daily use.

One more question, if i kind of cheap out and buy some INR 21700-40p cells for their 10c discharge and their small size so i can make a huge battery, would i notice the performance impact from not buying name brand/tested cells? since these claim 500 charge cycles and are cheaper, but i do not know if i should buy them?