Increase AH in this battery or bad idea?

[999zip999]

Here my cell
Samsung 40T 21700 4000mAh 35A Battery (40T3)
Sale price$6.99
That's 20s6p with BT bms
Battery can do 180amps @ 72v or 14,000 watts on paper use at 50 amps and charge @14amps.
I have a A123 20ah 24s as two 12s with balance wires 4-6s for balancing and checking with meter. No bms just me.
8yr old 1,480 charge cycles. Still works big and heavy. Used at 80amps

 

[Cyclomania]

DIY lithium battery build by Micah Toll
I don't know how to spell his name. But buy this book.
And buy name brand cells and not that no name JUNK. Or Fire cells
Do you have a spot welder ? Yes answer this question.

I am going to buy that book now. Do you have a link to some brand name cells on aliekpress or amazon? Seems it is almost more expensive to build than to buy when considering that brand name cells costs so much. Also the box and the bms is a lot of money.

But perhaps after building a few batteries it will get less expensive and you will gain in some of the expenditures?

By the way. The most dangerous part of building a lithium battery is when the voltages might equalise between the cells? But this could be mitigated by measuring all the voltages beforehand correct?

 

[Cyclomania]

Here my cell
Samsung 40T 21700 4000mAh 35A Battery (40T3)
Sale price$6.99
That's 20s6p with BT bms
Battery can do 180amps @ 72v or 14,000 watts on paper use at 50 amps and charge @14amps.
I have a A123 20ah 24s as two 12s with balance wires 4-6s for balancing and checking with meter. No bms just me.
8yr old 1,480 charge cycles. Still works big and heavy. Used at 80amps

You have a link to this one on ali or amazon or something? I think they all seem to be as expensive as buying the already finished battery. I am trying to find something that would allow me to cut the cost down a bit and build like a 52volt 26ah or something high like that, but not at the same cost as buying a new one.

 

[docw009]

I looked at your aliexpress cell links. In general, you do not buy cells from China. For example, those Daiweikala 6000mah 21700 cells are a lie. The max capacity of a 21700 is around 4800-5000 mah from Panasonic, LG, etc. The Chamrider cells are probably OK, but only rated 2500 mah, You need 130 cells to make a 25AH battery, and it will be huge and unwieldy. Not a good choice for a novice battery builder. The welds will probably break off from the twisting in the bike frame.

You may be better off just buying a commercial chinese battery from someone like UPP and getting 2-3 years life out of it.

 

[999zip999]

CHEAP NEW ORIGINAL 18650 21700 BATTERY CELLS, POUCHES AND PACKS - Endless Sphere" viewtopic.php?f=31&t=61608
This guy is in your neck of the woods
Don't buy cells ripped out of a pack with small pin holes in the top don't buy cells that have cut tabs don't buy pouch cells that have re-welded laser welds on tabs.
Buy new cells from same batch
Buy a high amp cell less resistance for discharge band charging and at higher rate of charge.
I can charge my 72v 20ah battery in one hour.
This is in poland so shipping is weird. But cheap.

 

[999zip999]

He's in the new for sale section of E.S.

 

[nicobie]

You never have stated if you are looking to go faster or go farther. Going faster will also require a change in controllers and wiring.

Seeing as how you are relativity new to this, the simplest and safest way to go is to just buy a second battery to carry so you can swap out the depleted one when taking trips too long for just the one battery to make.

You can always sell the individual cells you bought on the forum's marketplace.

 

[Hummina Shadeeba]

Get lifepo4 cells! They’re cheaper and you can’t blow your house and family up in fire while you learn. Batteryhookup.com or there’s another good used cell site I forget the name.

 

[Cyclomania]

Get lifepo4 cells! They’re cheaper and you can’t blow your house and family up in fire while you learn. Batteryhookup.com or there’s another good used cell site I forget the name.

Aha ok. Do you have a link?

 

[Cyclomania]

You never have stated if you are looking to go faster or go farther. Going faster will also require a change in controllers and wiring.

I want both of these. Faster and longer.

I have good controllers and motors. But I also want to be able to build the most expensive part myself. The battery. It would be cool to do it and understand how it works.

 

[Cyclomania]

By the way it seems Micah Toll often uses the kind of cells from Ali that I referred to above. At least some of them are linked below his videos. For example these cells, that are for flashlights as stated in the ad, but also works for ebike batteries then(?).

This one is below his video for example:
https://www.aliexpress.com/item/32432727321.html?spm=2114.8153825.cb0001.8.wF6Ne6&scm=1007.13409.76764.0&amp&pvid=1253e437-fd3c-4e97-9cf7-051541802f4b&amp&tpp=1&aff_fcid=fec96965ef244450b72fec8b78fd0ffa-1664716350925-01116-bYfI2zv&aff_fsk=bYfI2zv&aff_platform=link-c-tool&sk=bYfI2zv&aff_trace_key=fec96965ef244450b72fec8b78fd0ffa-1664716350925-01116-bYfI2zv&terminal_id=71421e40aae242c99ee1c79458027c59

 

[Hummina Shadeeba]

Get lifepo4 cells! They’re cheaper and you can’t blow your house and family up in fire while you learn. Batteryhookup.com or there’s another good used cell site I forget the name.

Aha ok. Do you have a link?

https://endless-sphere.com/forums/viewtopic.php?f=31&t=117375

I have a bunch of A123 26650 cells I could sell you for $1 each plus shipping. All within 96-100% capacity.


Other benefits of lifepo4 being high power (each cell can put out many amps comfortably) so then can use a very high voltage controller with many cells in series and few in parallel but still get the wanted amp output= high power system.
And high cycle-life.
And charge very fast.
The only downside is they are less energy dense by weight or size compared to lithium ion cells.
Cheaper too as u can see


https://endless-sphere.com/forums/viewtopic.php?f=31&t=117048&p=1734683#p1734683

What motor and controller u have?

 

[Cyclomania]

Get lifepo4 cells! They’re cheaper and you can’t blow your house and family up in fire while you learn. Batteryhookup.com or there’s another good used cell site I forget the name.

Aha ok. Do you have a link?

https://endless-sphere.com/forums/viewtopic.php?f=31&t=117375

I have a bunch of A123 26650 cells I could sell you for $1 each plus shipping. All within 96-100% capacity.


Other benefits of lifepo4 being high power (each cell can put out many amps comfortably) so then can use a very high voltage controller with many cells in series and few in parallel but still get the wanted amp output= high power system.
And high cycle-life.
And charge very fast.
The only downside is they are less energy dense by weight or size compared to lithium ion cells.
Cheaper too as u can see


https://endless-sphere.com/forums/viewtopic.php?f=31&t=117048&p=1734683#p1734683

What motor and controller u have?

I live in Scandinavia so perhaps the shipping could be a problem?

 

[Hummina Shadeeba]

If u want to pay shipping I’ll do it.

But forgetting my cells and lifepo4 in general is just better in my mind these days especially with the price. A lot less stress for Diy stuff. And I forgot maybe it’s best attribute: it has a consistent discharge voltage till empty so it has the same top speed and torque w the vehicle till empty. Lithium ion sucks in that regard. And they’re tough, so if you screw up and over discharge u can bring them back from the dead. God forbid u over-charge a lithium ion by mistake n could be a flamethrower. Overcharging these is at worst a smoke bomb as far as I’ve seen. A dangerous smoke bomb u don’t want to breath

https://jag35.com/search?q=Lifepo4+