4-wire Cell Holder

Description

Over the past several years, I’ve used many different cell holders for testing batteries. I’ve tried many options from the cheap leaf spring cell holders to expensive aluminum-framed universal cell holders, but none of them got everything right. So I designed my own to try and get as many things right as possible.

This is aimed at product designers looking to verify cells from a manufacturer, people hoping to expand battery lab testing channels while keeping costs low, or for people like me that just like getting their own accurate data without breaking the bank on proprietary cell holders from large organizations.

The cell holders are NOT ASSEMBLED unless you selected the fully assembled option. You must do the assembly yourself. See the Assembly section below.

Looking for other cell sizes – send me a message! We are happy and able to create holders for any size cells. For the 3D printed (5A) versions, a single piece can be made, but a minimum of 10 will be required for a custom PCB version (15A).

Features

• 4-wire contact for accurate voltage and internal resistance measurements
• Fixed position frame – don’t need to adjust every time you put a new cell size in
• Installation guides to center the cell before it is clamped in at the terminals
• Airflow channels through cell holder base for easier cooling without affecting adjacent cells
• Single connector connection to test equipment – easily swap between equipment and cell holder configurations
• Push Release for spring-loaded cell contacts – don’t need to push on the cell when installing (optional)

Versions

1. 5A 3D-Printed with PETG filament
   • • Best for low-current, ambient temperature testing only. Ensure cells will not heat above 45C under applied loads
     • Max temperature 45C
2. 15A 3D-Printed with ABS filament
   1. • Upgraded cell contacts, 16AWG wires for current path, and material with higher temperature rating
      • Max temperature 60C
3. 15A made from fiberglass (PCB material)
   • • Includes larger cell contacts, thicker 16AWG wires for current path and equivalent traces through PCBs
     • Max temperature 90C
4. With Push Release 3D-Printed with PETG/ABS filament
   • • Includes a tab at the end that you push to release the spring loaded cell contacts for easier cell installation and removal
     • The push release tab is 3D printed, but the cell holder is made from the material selected
5. With 3D Printed Parts
   • • The required 3D printed parts are included or not. The files can be downloaded below

Connectors

To connect to this cell holder, a connector with screw terminals is included. Supported wire gauge of the included connector is 12-24AWG.
When using screw terminals, please install wire ferrules on stranded wires to prevent accidental short circuits and loosening over time.
Connectors have 5.08mm pitch, and are a standard ‘pluggable terminal block’.
Additional connectors that fit the connector on the cell holder are available here: link

Compatible models also available from other connector manufacturers:

• TE Connectivity 796634-4
• Amphenol TJ0451530000G
• Molex 0395300004
• Phoenix Contact 1757035

Dimensions

18650 5A 3D Printed Version
Base: 147.5x40mm (push release adds 27mm when fully pushed down, total length required 174.5mm)
Height: 35mm (40mm with push release)
Mounting holes (M3): 135.5x31mm, 5mm depth

18650 15A PCB Version (2.5mm longer than 3D printed version)
Base: 150x40mm (push release adds 27mm when fully pushed down, total length required 177mm)
Height: 35mm (40mm with push release)
Mounting holes (M3): 138x31mm, 5mm depth

21700 15A PCB Version (2.5mm longer than 3D printed version)
Base: 152.5x40mm (push release adds 27mm when fully pushed down, total length required 182mm)
Height: 35mm (40mm with push release)
Mounting holes (M3): 143x31mm, 5mm depth

Assembly

Assembly instructions for the 3D printed version are available here and the PCB version here. The process is relatively straightforward, and takes around 15 minutes to complete. If you have experience with assembling electronic kits, you should be able to assemble it just from the pictures, though it might take a little longer.

You should be comfortable soldering, crimping screw terminals, stripping wires, using epoxy (and have some on hand), and have some standard size wrenches/sockets.

Includes:
Wires, cut to length but not stripped
Terminal block and screw terminal connector
4-terminal spring-loaded contacts
Wire crimp terminals for power contacts and push release handles
Nuts, bolts, standoffs, washer, for connecting wires and mount locations (including to embed in the 3D printed base)

Does not include:
Solder (to attach sense wires to 4-terminal contacts, and all wires to terminal block)
Epoxy (to fit the 2 sides of the push release tab, and hold the terminal block in the 3D printed version)
M3 bolts to mount the cell holder to a surface

3D Printing Files

If you chose to print the parts yourself, you can download the files that I uploaded to Printables here.
I printed everything on my Prusa Mini in standard PETG with a 0.6mm nozzle. The parts use about $2 of filament and take about 4h.
The cell holder base needs a pause after completing the holes for the captive nuts so you can insert 4x M3 nuts (included). For a guide on pausing a print after a specific layer in Prusa Slicer, see here.
The files include a single object with many parts. All except the large base piece are modifiers. The modifiers should be changed to 100% infill, except for the ones at the bottom under the cell which needs 15% hexagonal infill and 0 perimeters, 0 top layers, and 0 bottom layers. For a guide on using modifiers in Prusa Slicer, see here.

Stock Levels

Please note that stock levels on variations does not accurately reflect the available stock due to many common parts used between them. If an order is placed for all the stock available in all the variations at the same time, we will contact you with an expected lead time.

Allow for up to 3 weeks for backordered items to ship.