How to Make a 20S 2P 60v 12Ah Battery Pack Using 32650 Lifepo4

This will detail the steps on how to make a 20S 2P 60V Battery Pack using 32650 Lithium Iron Phosphate (aka LifePo4) batteries. I'm planning to use this to power my DIY electric cart (I'll post it once done). This is the one I chose because the LifePo4 Battery is kind of a middle ground between SLA (Sealed Lead Acid) and Lithium-Ion batteries. It has a higher usable capacity and faster charging than SLA as well as it is a lot safer than Lithium-Ion batteries.

(Update: 20/12/2022 )

I have changed the enclosure of the battery to plastic with a handle to make it more portable (as seen in the above 2nd and 3rd pictures. As also mentioned, I will use it to power my DIY electric buggy. Above is a preview of it. This DIY electric buggy project is now in working condition, though unfortunately, it's still not 100 percent complete. (I will continue this project when time permits and will upload details here once done ;-)

Parts List:

40 pcs 32650 Lifepo4 Batteries

30 pcs 32650 Battery Holders

1 meter Double Tabbing

20 pcs (each) M4 screws and Nuts

Solder

Tools:

Screwdriver - for tightening the screws in the positive terminal of the battery.

Scissor - for cutting nickel

Small Wrench/Spanner (recommended) - for tightening nuts

Soldering Iron - for attaching the BMS, Charge, and Output Port

Container (recommended)

The layout is simple. I will just stack the batteries 2 levels up and then once I get to the fifth column (at 10s), I will fold it and create the other half (10s). With this layout, I will have a relatively square shape battery pack when finished.

Before stacking the batteries together, make sure all the batteries are in working condition. The nominal voltage must be somewhere around 3.2V. It is also recommended that the voltage discrepancy in each battery be minimal.

Note: While doing this, we also need to put the metal tabbing before connecting each battery. It will be used later when we connect the BMS.

Using a multimeter, test each connection point. One side will be connected on the (-) negative terminal and then tap the positive terminal at each connection point. The voltage will increase by roughly 3.2v at each point until you reach the last where you will get the total voltage (which will be roughly between 64 -72 volts). While doing this, it will be a good idea to label it as well as seen in the picture. This will make it easier to solder the BMS wires on the next step.

In order to prolong the lifetime of the battery and protect it from overcharging and over-discharging, you will need to put BMS (Battery Management System). The wiring of BMS is almost always identical for most brands. But it's always a good idea to refer to the included manual or some picture of how the wiring should be. For me, I purchase a DALY brand BMS for LifePo4 60v battery.

Being organized and careful on how to layout the wires is very very important. You don't want any mixed-up on the connections.

Before hooking up the connector to the BMS, ensure that each terminal is properly connected. Test the voltage from the first hole up to the last. In general, the voltage of the current hole should increase by around 3.2v from the previous hole (e.g. first hole is 3.2v, and the second hole should be around 6.4v).

Once everything is ok, hook the connector to BMS.

Note: You also need to solder the battery (-) and (+) terminal wires. Usually, these wires should be thicker as they should handle higher Amps.

At this point, it's really up to you how you enclose it. I would have used a plastic enclosure if I have one, but for now, I opt to just use thick cardboard (as I will use this battery just for testing purposes). I will probably be going to change the case once I used this battery to power my DIY go kart.