Crimping JST PH connectors using Engineer PA-09 Crimp Tool

Manual Crimping instructions on how to crimp JST PH series housing contacts using the Engineer PA-09

This is a crimp tool Digi-Key sells under Adafruit Part Number 350 which can be used to crimp many housing contacts ranging from 20 to 32 AWG wire.

This is the rectangular connector housing commonly used on popular single cell gray lithium ‘pouch’ batteries and many of the battery holders we sell, it also happens to be one of the most widely used contact housings on the planet.

These instructions are for JST PH series, however contacts from many rectangular connector housings are very similar so these instructions will work with many connector types, just pay attention to the recommended strip length of the wire for particular contacts.

Parts Used for these instructions:

Personally, I always buy a few extra crimp terminals in case there are any mis-crimps that do not pass a pull test.

Tools Used

Engineer Crimp Tool PN: PA-09 - Adafruit Part Number: 350

Wire Stripper - Seeed Technology Part Number: 404080001


Tweezers or fine tip needle nose pliers to seat the contact within the housing.

Prior to purchase, it should be noted the PA-09 crimp tool is not the manufacturer’s recommended crimp tool for these contacts.

It’s a non-ratcheting, manual crimp tool, if you’re assembling a fair number of these contacts this isn’t the recommended option, the repetitive motion of crimping these types of contacts would get hard on the wrist in production quantities.

This kind of tool is very handy to have around for crimping quantities commonly done in electronics enthusiasts or prototyping levels.

JST recommends stripping the wire anywhere between 1.9 to 2.5mm in length (or 0.075 to 0.098 inches) If you’re having trouble visualizing this it’s just a little bit thicker than a quarter (US coin).

You can always strip a little longer and then trim back the wire to the desired length.

Next, using your fingers twist the recently stripped wire together to avoid loose strands of wire.

Let’s familiarize ourselves with the terminology of the different parts of the crimp contact

Holding the tool in one hand, with the other hand insert the wire barrel section of the crimp contact within 1.4mm crimp and gently hold the contact within the tool.

Make sure the tabs of the wire barrel section are facing upward toward the numbers and the heart shaped curves of the crimp tool.

Now insert the stripped and twisted wire inside the jaws of the crimper so that the insulation is near or flush with the outer edge of the tool, taking care not to crimp any of the insulation within the wire barrel section and give it a good hard squeeze.

If you have a magnifier, your crimped contact should look something like this:

You don’t want frayed strands poking out and it helps if you can see a little bit of wire between the insulation and the wire barrel to make sure the insulation didn’t get crimped in the wire barrel.

At this point it’s a good idea to give a firm tug on the contact and wire to test that there is a solid mechanical bond.

If you are reading along crimping a different contact for a different connector and your pull test fails try jumping to the next size down on the crimper with a new contact to see if that fixes your issue.

Next pinch the longer insulation barrel tabs inward with the pliers end of the crimp tool. This step is easier to do with a needle nose pliers, otherwise a tweezers works for this, you want to fold the top of the insulation barrel inwards and down to get it started prior to crimp.

Now insert the insulation barrel tabs into the 1.9mm crimp jaws to crimp the strain relief section of the contact and squeeze.

The final crimp ideally should look something like this:

Finalize crimp by giving it another good firm tug test, and if needed it’s handy to have an eye loupe magnifying glass around to provide a visual inspection, watching for any loose stranded wires or improperly seated crimps.

In the side of the connector housing there are holes that are little tabs. When inserting contacts into the housing make sure the small protruding contact lance is facing the hole on the housing, like shown.

It helps if you have fine stranded wire to use a fine point needle nose pliers or tweezers to grip the back of the contact when inserting it into the contact housing connector to get it seated.

A list of compatible housings/contacts with this crimp tool can be found here: