Common pack design mistakes, how to avoid?

[jdvmi00]

The picture didn’t come out.
Yes you want the current in all the cells to be nearly equal. With only 3p this won’t be hard.

Thoughts on this?

Terminal.jpg (121.41 KiB) Viewed 776 times

[papasapien]

i went on reddit and someone told me i need to not have all my output for the negative and positive terminals of my battery pack on just two tabs.( im using the vruzend 2.1 kit) i understand why and the diagram in the beginning of this thread but everyones batteries i see on here seem to do the opposite of what is suggested or am i missing something? can someone help me understand this? how to have good current flow and even draw. everyone seems to just have a slab of wire across their battery pack. i dont understand how thats different then just having it at the end if every cell is already connected.

here is my diagram vs what he suggested. which i know is the right way but how could i do this? pls help thank you. its the last thing i need to understand

[ItsOverRock]

Trying to wire 2 of these exact gotrax scooter batterys packs in parallel to double capacity of scooter. Dunno how to go about connecting them together. Need help, here are the pics from the bottom of battery pack to top & BMS.

[fechter]

Thoughts on this? Terminal.jpg

That looks fine. There won't be much voltage drop in the tabs.

[pwd]

I'm back with my 3rd battery build in sight. I'm aiming for a 20S6P configuration but am constrained by the shape of the bike. Here is what I have to work with:

Ignore the Nickle sheet

IMG_20200513_195746-v2.1.jpg (108.16 KiB) Viewed 596 times

Does anyone have an suggested layouts to make this 20S6P?

[RootedSuperuser]

I'm back with my 3rd battery build in sight. I'm aiming for a 20S6P configuration but am constrained by the shape of the bike. Here is what I have to work with:

Ignore the Nickle sheet
IMG_20200513_195746-v2.1.jpg

Does anyone have an suggested layouts to make this 20S6P?

You don't have to do a 20*6, you can do a 20*2x3 and get the same result. I did this with my 14*2x3 pack and got a perfit 1:1 power share, using nickel STRIPS .... your using sheet so it matters not.

[pwd]

I'm back with my 3rd battery build in sight. I'm aiming for a 20S6P configuration but am constrained by the shape of the bike. Here is what I have to work with:

Ignore the Nickle sheet
IMG_20200513_195746-v2.1.jpg

Does anyone have an suggested layouts to make this 20S6P?

You don't have to do a 20*6, you can do a 20*2x3 and get the same result. I did this with my 14*2x3 pack and got a perfit 1:1 power share, using nickel STRIPS .... your using sheet so it matters not.

Thank you for the suggestion. The numbers make sense to me but I'm having a hard time visualizing how to connect that. So I would make 3 X 20S2P packs and parallel the discharge leads together?

[pwd]

If I did spilt up the 20S6P pack into 20S2P sub packs and put them in parallel; would I also have to paralell all the balance leads for the BMS?

[john61ct]

If I did spilt up the 20S6P pack into 20S2P sub packs and put them in parallel; would I also have to paralell all the balance leads for the BMS?

No "have to" your call.

But yes that approach lets all the sub-packs to be protected and balanced by just one BMS

simpler is usually better.

Plus the cell/groups will naturally rebalance in use, counteracting the ill effects of unequal draws via the power leads at pack level voltage

[DogDipstick]

If I did spilt up the ...; would I also have to ... for the BMS?

I do. yes. I just built a 50Ah 2p Chevy cell pack that I did this so I could run 1 BMS... One 25Ah half, 21 sense lines, and one 25Ah half, 21 sense lines... into +/- discharge leads and a 25 pin DB connector.... Every cell has an output lead and the pairs of 2p come together in a connector to go to the BMS as one signal line.

[RootedSuperuser]

If I did spilt up the 20S6P pack into 20S2P sub packs and put them in parallel; would I also have to paralell all the balance leads for the BMS?

Yes

[john61ct]

Again, not have to

but certainly is the better way to go.

If only paralleled at the power pair, imbalanced flows creates extra monitoring / balancing headaches

and lower overall lifespan.

[pwd]

Thanks guys No free lunch as they say.