Eight-Cell 21700 Lithium Battery Emergency Car Jump Starter

Following the release of the mini four-cell 21700 jump starter—see the link: Mini Four-Cell 21700 Car Emergency Jump Starter from @xiaotielong - MakerWorld, I still felt a little regret. Therefore, this eight-cell 21700 lithium battery car emergency jump starter was created, adding battery voltage display and DC and XT60 output interfaces to alleviate concerns about insufficient battery capacity and output current.Its dimensions are 65.7*71.7*117.7 (MM). Here's a family portrait:

Materials required for this model:

1: Eight 21700 cells with high discharge capabilities (Recommended: EVE 21700 JP40 cells and CALB 21700 4000MAH cells. I personally use CALB 21700 batteries; their performance is slightly weaker than EVE's, but they are cheaper)

2: One PD 100W power bank module (65W charging, 100W discharging)

3: One 4S ternary lithium battery charge-discharge protection board

4: One set of EC5 female connectors with battery clips and mounting brackets and protective covers, and one set of EC5 male connectors (using 10AWG silicone wire)

5: Two copper wire lugs

6: Several M2*10 and M2*6 black iron pan head self-tapping screws

7: Several M3*12 and M2*4 stainless steel self-tapping screws

8: One DC power jack, one XT60E-F (optional)

9: One 0.28 voltage meter, one 5.8*5.8 self-locking switch

Installation instructions: See the attached document

Finished product shown below:

Power Test:The jump starter shows 92% power, 16.2V voltage. At an outdoor temperature of -12℃, after being left for over a week, disconnecting and reconnecting the battery, the vehicle started on the first attempt.

After starting the vehicle, if the buttons don't display, simply plug in the charger to activate it. This is likely due to the high current draw during vehicle startup, causing a momentary drop in battery voltage and triggering the low-voltage protection of the lithium battery protection board.

To ensure the longevity of the jump starter, here are some precautions:

1: Each ignition attempt should not exceed 10 seconds

2: The interval between ignition attempts should ideally be more than 1 minute

3: Avoid disconnecting the original vehicle battery when jump-starting

4: Do not attempt to start the vehicle if the jump starter voltage is below 12V.

The above are my thoughts on creating this eight-cell 21700 battery jump starter. Please feel free to point out any errors. Download and print if needed, and please offer your support. Thank you!!!