Service

Molex & JST PH2

Molex Picoblade 2 pin (also called Pico and incorrectly micro JST) and the JST PH 2 pin connectors are very small and have 1 & 2 Amp ratings respectively.

You will see them primarily used on small micro single cell LiPo RC aircraft such as Blade & Walkera micro helicopters and Eflite/Parkzone micro airplanes. The 2 pin Picoblade is also a decent low cost connector I find for LED RC lighting systems or any other very low current application that needs a plug.

All in all, these are both very decent little connectors. You do however have to be very careful when soldering wires to the female connector as too much heat for too long will easily loosen the pins and they will then fall out very easily. A little trick I will use if I do run into this problem is to put a very tiny drop of medium or thick CA glue on the base of the connector to keep the pin in place. Just make sure the glue doesn't wick all the way up the pin and insulate it (why I don't recommend thin CA).

The male connector pins are crimped onto the wires and then slid into the connector housing so soldering heat is not an issue with the male connector. Most male Picoblade and JST PH connectors come with the wires already attached since not many RC'ers have the correct & expensive crimp tool for these tiny pins.

There is actually much confusion circulating on the internet regarding all these micro connectors. This stems from each brand such as J.S.T. (Japan Solderless Terminal Mfg. Co.) having many different series of connectors, but many in the hobby just reference the brand name and associate it with a particular connector (eg. JST connector).

Moreover, each series of connector comes in an assortment of pin numbers ranging from 2 up to as high as 20. So to be correct at micro connector identification, you need to know both the brand's particular series designation and number of pins when ordering.

There is a fairly good J.S.T write-up on Wikipedia showing all the various series of JST connectors and links to the data sheet on each one.

There are also lots of "copies" of RC connectors of all types out there and this obviously leads to even more confusion because they are often called different names. It's quite frustrating to say the least!

JST RCY Connectors

JST RCY Connectors are a small plug that is rated for 5 Amps of continuous load. I have pushed mine up to 10 Amps for short bursts without issue.

They are used on smaller battery packs (usually under 1500 mAh) for powering small park fliers and small electric helis & quadrotors, or for powering on board electronics (receiver, servos, gyros, governors, etc.) in larger models with dedicated RX packs or higher current BEC's. 

I personally love JST RCY connectors. They are easy to plug & unplug and are very robust (I've had to replace very few over the years). In fact, they are pretty much the only 5 Amp rated 2 pin connector I currently use anymore. They come both as crimp only versions or with wires already installed.

XT30

It's hard to determine where the "XT" line of connectors got their beginnings, but Amass Electronics CO. seems to be the originator.

There are lots of copies of these connectors on the market, most not as good as the original Amass so be cautious of "too good to be true" pricing (genuine Amass connectors have the name embossed right onto the connector body). That said, genuine Amass XT connectors are usually competitively priced.

Hobby King's XT versions are very good as well and are said to be built by Amass for HK. The XT line in the 30, 60, and 90 sizes are currently my favorite connector in these Amperage ranges.

The XT30 RC LiPo battery connector shown above is their smallest rated at 30 Amps sustained, 40 Amp burst. Like all XT style connectors, wires are soldered to small external hollow pins on the back of the connector that need to be insulated with heat shrink/similar afterward. This also makes them easy to unsolder and replace/reuse. The connector housing material used (nylon) is very heat resistant so XT style connectors are more forgiving to overheating and pin loosening while soldering.

One warning with all XT plug types even though they are polarity protected is they can be forced together backwards. It's hard to do and I've never had one actually make contact when I accidentally try to plug them in backwards, but some report it can be done with enough force. Maybe with the softer copies it's easier?

Deans (T) Connectors

The Deans Connector (also called "T" connectors) were one of the first on the LiPo connector block, and remain to be a popular connector type with a very loyal following (which unfortunately had driven the price up).

The Deans "Ultra" connectors are rated for 60 Amps of continuous load, up to 75 Amp & higher bursts. I have pushed mine to 100 Amp for short spikes without issue. I used these connectors for several years when I first got into electric powered flight, but converted over to AMASS XT60's since, and have never looked back to be honest.

Deans connectors use sprung flat tabs for the connector which is a departure from most other connectors that use "bullet" style pins. This in my experience makes the Deans one of the better plugs for consistent connectivity pressure as the sprung tabs don't seem to lose their contact pressure over time after many cycles like bullet connectors sometimes do. 

Like almost every RC LiPo battery connector out there, there are a good deal of copied/clones of Deans T connectors on the market, and some I actually like better than the original because they are textured making them easier to plug/unplug. Some on the other hand are complete garbage!

Other than pricing, I would say that is what I dislike the most with Deans/T style connectors is I find them difficult to connect, more so than disconnecting which is quite easy. They are actually quite small for their current ratings so in space conscious applications, could be a better choice over larger similar rated connectors.

Wires are soldered onto the back side tabs which requires heat shrink to insulate but makes removal/reuse easy. 

The plastic body on Deans plugs is fairly heat sensitive so you have to be careful while soldering to avoid softening the plastic which can loosens or miss-aligns the connector tabs. Some copies/clones actually have better heat immunity than the originals I have found.

EC3 Connectors

EC3 Connectors use 3mm long bullet pins and are rated for up to 60 Amps of continuous load, 75 Amp burst. 

Horizon Hobby use the EC style connectors pretty much exclusively, and have made them very popular in their eFlite & Blade line of airplanes and helicopters. These are therefore the very first LiPo battery connector many are introduced to, myself included. One of the biggest complaints with EC3's by myself and others is they can be very difficult to plug/unplug, at least compared to the other connectors in this current range, not to mention they are fairly pricey.

Wires are soldered into the hollow end of the pins and then the pins are snapped into the connector so no worries of melting the plastic housing. Another advantage is the EC's don't require heat shrink insulation as the wire insulation runs into the connector housing which is nice. The draw back is it can be difficult to remove the pins from the housing for replacement or reuse. I find a small drift punch while supporting the housing on the edges so the pins can be tapped out the back side will work most times (but not always).

XT60

XT60's as I already stated are one of my favorite RC LiPo battery connector / s in this current range and I use them even on fairly large birds without issue. They are rated for 60 Amps sustained and 90 Amps for short bursts (why I can get away using them on larger models that are not flown too aggressively).

They are fairly easy to plug/unplug and why I like them better than Deans or EC3's.

Like I mentioned in the XT30 description, the genuine Amass ones are constructed out of high temperature nylon so they don't melt/pins loosen if you get a little carried away.

External soldering "cradle style" pins on the back require heat shrink insulation, but make them easy to remove/replace/reuse.

Traxxas plug

As the name suggests, Traxxas battery connectors (TRX connectors) are used exclusively on electric Traxxas RC vehicles/boats but can be fit to any current application up to about 60 Amps.

These are a very nice connector that many say are one of the nicest to plug and unplug. I just tried a set out and am very impressed with the ease of connectivity. They use a flat contact tab like Deans over a bullet style connector pin.

Like the EC3 connector, the Traxxas connectors don't require heat shrink for insulation as the wires are soldered onto the ends of the contact tabs and inserted deep enough into the connector housing afterward that the wire insulation offers full protection, also prevents melting the connector housing.  Similar to the EC style connectors, pin removal can be very difficult without a special pin release tool/key.

TRX connectors are also one of the most difficult to solder properly because if you let even a small amount of solder wick down the connector tab, it will prevent the tab from clicking into the housing correctly. This is where good tinning skills and quality solder really come into play for a sort duration solder melt. Just enough heat to make a solid mechanical & electrical bond without enough heat migrating down the pin cause the solder to flow down as well.

EC5 Connectors

EC5 Connectors are a larger/ longer version of the EC3 and because the bullet pins are longer (5mm) they have an even greater surface area for contact. EC5's are rated for up to 120 amps of continuous load, and bursts of upwards of 150A. Perfect for large 1/4 scale electric planes and 700-800 size electric helis.

Like the EC3's, the wires are soldered into the back of the pin and pushed into the housing far enough that heat shrink insulation is not required, but pin removal afterward is very difficult for replacement/reuse. My drift punch method on EC5's is seldom successful and I generally destroy the housing or the pin in the process.

The EC5 Lipo battery connector used to be the only large current connector I trusted on my larger 12S powered 700 & 800 helicopters, but I'm slowly switching over to XT-90's after a crash which I talk about later on in this article under the heading "connector life span".

XT90

The XT90 is rated for a continuous 90 Amp load with bursts up to about 120-130 Amps.

As I just mentioned above, I'm currently converting all my EC5 batteries & ESC's over to the Amass XT-90 RC LiPo battery connector. I have not used these high current connectors long enough for any practical usage feedback, but like the XT60, I do find them a nicer connector to plug/unplug than the EC5.

Soldering connections on the back side of this plug are exposed so heat shrink must be used; however, there are now versions of this plug that have a plastic insulation cap that snaps on the back end of the plug if you don't want to use heat shrink.

Banana plug

Last up we have stand alone "Bullet Style" connectors, sometimes also called "Banana Plugs". Various sizes (measured in diameter) for various current ratings. Listed below are some approximate continuous current values based on bullet size. There are of course variations dependent on bullet length (more length = more contact area) as well, but this list should get you in the ballpark for most of them.

2mm Bullet = 25 Amps

3.5mm Bullet = 50 Amps

4mm Bullet = 90 Amps

5mm Bullet = 120 Amps

5.5mm Bullet = 130 Amps

6.0mm Bullet = 150 Amps

6.5mm Bullet = 160 Amps

8.0mm Bullet = 200 Amps +

Most of the RC LiPo Battery connectors I have listed above (other than the few that use flat tab contacts), all use bullet connectors within the housings. However, some folks just like to use stand alone bullets as they are less expensive without the housing, weigh less, and take up less room.

I use stand alone bullets pretty much only for ESC to brushless motor connections (3 used), and would much rather have a nice housed connector on my LiPo packs and ESC's for ease of connectivity and safety. It's much easier for example for stand alone bullets (even when coated with heat shrink) that are not housed in a connector housing to short out.

There are essentially two styles of male bullet connectors, split & sprung. In the above photo, the male 2 to 5mm are the sprung design, the 5.5 to 8mm are the split type. The female side are all the same, basically a hollow tube that the male end fits into.

The sprung connectors have a sprung sleeved section that wraps around the inner pin and that is what makes contact with the inside of the female tube. The split style has the pin divided into two or more quadrants that are sprung outward, slightly wider than the internal diameter of the female end. As they are plugged in, the "quadrants" are squeezed and held tight again the inside of the tube under tension making good electrical contact.

Generally speaking, the split style are able to handle larger current loads than the spring style. I talk about one "hidden" weakness that all spring sheathed bullets have after the next section of this article.