18650 LG Li-ion battery cells good for ebike?

[fabieville]

Are the 18650 LG Li-ion battery cells good to use on a ebike. I currently have 60 of them that were recycled from used laptops and they are in very good condition and working perfectly. I am going to build a 24v 26ah pack from them. Will it perform similar to a lifepo4 battery. Will I be able to pull a constant current draw of about 20amp from it without causing any issues. In other words how will it perform in comparison to a lifepo4?

This is the specs:
http://www.batteryspace.com/lg-lithium-nmc-18650-rechargeable-cell-3-7v-2600mah-9-62wh---icr18650b4-un38-3-passed.aspx

Features
LG 3.7V 18650 (ICR18650 B4) size Cylindrical Li-Ion Cell.
Lighter weight and higher energy density than any other rechargeable battery
Voltage 3.7V (Nominal), 3.6V (Working)
Capacity 2600mAh Nominal, 2500 Minimum
Max. Charging current 2.5A Max.
Max. Discharging current 3.75A (1.5C, Continuous)
Dimensions(DxH) Diameter 18.3 mm (Max 18.4), Height: 64.9 mm (Max 65.1)
Weight 48.0g (1.69 oz)
Internal Impedance Internal Impedance: less or equal to 90 mirco-ohm (with PTC)
Cycle Performance 80% of initial capacity at 300 cycles

 

[d8veh]

If the cells are in good condition, they will be better than LiFePO4, but used recycled ones are difficult to assess. You have to spend a lot of time testing them to sort out the good from the bad.

A 24v battery for an ebike is 7S, so the biggest battery you can make is 7S8P, which would be 24v 20Ah.

It's a lot of work to make the battery, but you will learn a lot along the way. My advice is to only use those cells if they're known to be good.

 

[fabieville]

when i build the battery and equip it with a bms can i use a bulk sla charger that puts out about 4amp to charge the battery and it won't cause any issues?
Any bulk charger or smart charger for any battery chemistry can use on a lithium battery once the battery is equipped wit a bms?

 

[riba2233]

It must have standard CC/CV profile and correct CV or final voltage. Some sla chargers have additional float stage and shouldn't be used, but most cheap ones are CC/CV and if they have correct final voltage they can be used.

 

[Jonathan in Hiram]

Pulling 20A constant out of 8P 18650 laptop cells is going to get them toasty, definitely use a separator to space the cells apart and arrange for substantial air flow through the assembled block, a fan forcing air through would not be a bad idea at all.

I don't think your cells will last a long time doing that to them, I started with 12S6P and they didn't like much over 10A, I now have 12S12P and 20-22A is about the practical limit before heat becomes too much of an issue.

Laptop cells are really designed for about a two hour discharge period or .5C which is usually about 1.25A or so per cell.

 

[dogman dan]

Most lifepo4 nowdays is at least 2c, and your cells when new were 1.5c rate cells.

So no, it won't be "as good" as lifepo4. But if you build it 24 ah in size, it should still be able to put out a comfy enough 25 amps.