New 3.8v 4500mah 17.1wh Lithium Ion Battery w/ BMS - $73/kWh
New 3.8v 4500mah 17.1wh Lithium Ion Battery w/ BMS - $73/kWh
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New 3.8v 4500mah 17.1wh Lithium Ion Battery w/ BMS - $73/kWh

Regular price $1.25 $0.00 Unit price per

These batteries make DIY projects easy and affordable. At just $73/kWh, every battery is new and in the original zip bag. Each battery has a BMS already which will act like a smart fuse to protect against over current, over voltage, and under voltage. The dates on all the cells we checked were around 2021.

The red and black wires are your positive and negative. The cell itself is rated for 4500mah at 3.8v nominal. This particular battery can be charged up to 4.35v however you can also use it up to 4.2v and down to 2.8v like any other lithium ion battery.

The best design for a pack, since the BMS on these units has a 4.35v cutoff, is to build your pack then add an overall BMS for your pack. It doesn't get any easier. If you want to build a 24v 45ah battery you can buy 70 of these cells. Make 7 groups of 10 cells in parallel, series those groups, then add a 7s BMS. Nominal voltage will be 26.6v (7x3.8v), 45ah, 1.2kWh. You can build this battery for under $100 with a 30a BMS.

The BMS on these batteries appears to be a 1a or 2a BMS. The wires are pretty thin so make sure if you build a pack you are building one that you plan to last 5 hours or longer. Should probably keep it under 1a per cell based on the thickness of the wire. The cells themselves can discharge up to 4.5a per cell. So if you want to bypass the BMS on the cells to achieve a higher discharge rate you have easy access to the tabs which you can spot weld or solder to.

At this price, you have a chance to build an affordable battery large enough to provide power over a long period of time at a low C-rate. You can build a pack that lasts and doesn't strain the batteries.

The 2nd photo shows the BMS unit, the yellow wire is not needed for your project. The tabs are right there and easy to spot weld or add solder to. Or just use the wires and crimp connectors to build your packs. You have the two tabs on the sides, that runs through the BMS, and out the wires. Charge and discharge through the red and black wires.

Note: these batteries were made for a popular product that only required up to 1a charge and discharge so that's why the wires are so thin. If you build a pack large enough the wire thickness will not cause any issues. If you want to power a 100w device you should build a battery that is at least 500wh. This way you can power that device for at least 5 hours and you will be drawing under 1a per cell. If you need more power, again, just make your connections right to the cell tabs.

Either way, if you are building a pack with any cells in series you will still want to add an overall pack BMS. The BMS on the cells will protect each cell like a smart fuse but it will not do what an overall pack BMS will do. You still need a BMS to monitor the entire pack and all the groups of cells.

Dimensions per cell are 0.25" x 2" x 3". Wire length is 2.25".

Weight is around 2 ounces (0.1 lbs) per cell.

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