A DC connector
is an electrical connector
power. DC connectors are poorly standardized
, compared to domestic AC power plugs and
. DC plug
is a common name used for one
common type of cylindrical two-conductor plug available in a range
of sizes and used to power small pieces of electronic equipment. It
is also used to describe some older multi-pin plugs.
Several competing standards exist for DC plugs, and in some cases
incompatible plugs will fit together, to avoid damaging equipment
these conditions must be true:
- Voltage must be correct.
- Polarity must be correct.
- Current rating must be sufficient.
- Power supply filtering and stability must be adequate for the
equipment being powered.
- Connectors must be the correct matching types.
Common DC power connectors shown with
a ruler marked in cm/mm
Also known as barrel connectors
concentric barrel connectors
, small cylindrical connectors come in an
enormous variety of sizes.
The intended use of these plugs is on the cable connected to a
. The matching jack or
socket is then mounted in the equipment to be powered. Some of
these jacks contain a normally closed contact, which can be used to
disconnect internal batteries whenever the power supply is
connected, avoiding the risk of battery leakage or explosion posed
by incorrect recharging of the batteries.
Cylindrical plugs generally have an insulated tip constructed to
accept insertion of a pin. The outer body of the plug is one
contact, most often but not always the negative side of the supply.
A pin mounted in the socket makes contact with a second internal
contact. The outer plug contact is often called the
, and while the inner one is called the
There are a wide variety of different sizes and designs for these
power connectors, and many appear quite similar to each other yet
are not quite mechanically or electrically compatible. In addition to a
plethora of generic designs (whose original designer is unknown)
there are at least two different national standards—EIAJ in Japan and DIN in Germany, plus the
JSBP connector used on some laptop computers.
EIAJ standard includes five different sizes, with each supporting a
specified range of voltages. Most of the other coaxial DC power
connectors have no specified voltage association, however.
The most common plugs are 5.5 mm in outside diameter (OD) and
9.5 mm in length. Two pin sizes are common in the jacks for
this size plug body, 2.1 mm and 2.5 mm, and the plugs
should ideally match. Generic plugs are often named for the pin
diameter they are designed to take, so these types will be seen
described as 2.1 mm DC plugs
and 2.5 mm DC
respectively. These two sizes are easily confused unless
Contact ratings vary from unspecified (and probably less than 1 A
in practice) up to 5 A, with 2 A typical. Voltage is again often
unspecified, up to 48 V with 12 V typical. The smaller types
usually have lower ratings, both for current and voltage. The
ie the inner conductor usually
positive (+) pole.
Snap and lock DC power connectors
These connectors look similar to Mini-DIN
connectors, but have either 3 or 4 thicker pins and a slightly
larger mating shell. Because of this they do not mate with any of
connectors. They can usually
be identified by an engraved symbol on the backs of the plug,
consisting of two wide arrows pointing in opposite directions, but
parallel to each other, or sometimes one wide arrow inside a box,
pointing towards the end of the male connector.
- Also known as Power Mini-DIN or Power DIN
- The male plug's mating shell outer diameter is 0.394 inches,
10 mm and the pins is 1.5 mm diameter
- Standard may include a limit of 20 V at 7.5 amps
- Hosiden part number TCP8927-53
- Kycon part number KPP-3P (Obsolete) or KPPX-3P (RoHS)
- Kycon part number KPP-4P (Obsolete) or KPPX-4P (RoHS)
The connector design most commonly called Molex connector
has frequently been used to
supply DC power, most frequently on personal computers, for
supplying power to drives and other peripherals.
Mini IEC connector
(IEC) has produced a standard for a
system of plugs and socket-outlets for household and similar
purposes in fixed and portable applications. Safety extra-low voltage
(SELV) plugs and
socket-outlets for 16 Ampere 6, 12, 24, or 48 Volt AC
For use either indoors or outdoors.
The dimensions are as follows:
||7 mm +/- 0,1 mm
||3,5 mm +0/-0,075 mm
- Commonly used on radio-control (toy) vehicle battery packs and
- Also commonly used on airsoft guns.
As shown, the usual wiring has the positive (red) wire running to
the terminal with a square profile, and the negative (black) wire
running to the semi-rounded terminal. This is true for both Male
and Female connectors.
Some confusion exists in the market place between which is male or
female. The male housing has female pins and the female housing has
male pins. Some companies reference the housing gender while others
reference the pin gender.
There are two sizes of Tamiya connectors, small and large. The
rectangular portion of the small housing is approx 3/8”(9.35mm)
wide and the large is approx ½” (12.7mm) wide. They are not
compatible without an adapter.
- Popular with higher-end radio-control vehicle battery packs and
- W.S. Deans Web site
JST RCY connector
- Also known in RC circles as the BEC connector, or the P
Locking Molex connector
- Available in 3, 4, and 6 terminal configurations.
Inverter tabs - inverter lugs
- Available in 2,4, and 8 gauge. Designed to pass very high
amperages at voltages up to 600V DC to and from battery packs,
inverters, and other high amperage loads to a terminal bus.
Airline in-seat power supply system
Two different airline in-seat power supply system (ISPSS) standards
for DC power have been used in the past.
American Airlines has in the past used an automotive cigar lighter socket
but using 14.7 V instead of the automotive 12 V.
Most other airlines that provide DC power use the EmPower
system, which has a 4-pin Hypertronics'
D-series connector smaller in diameter and overall size than a
cigar lighter plug. And uses 15 Volt maximum 5 Ampere.
Anderson Powerpole connectors
The Anderson Powerpole
adopted by the amateur radio
as their standard 12-volt DC power connector for everything from
radios to accessories. It is a bit more expensive than the older
“standards” of the 2-wire trailer plug and Molex connector, but
provides a more reliable electrical connection (both mechanically
and electrically) and is easier to adapt to a wider range of wire
gauges. Powerpole connectors are physically and electrically
hermaphroditic, thus avoiding the need to worry about which end is
the plug and which the socket, or which end has the correct
polarity, as is the case with the physically but not electrically
hermaphroditic 2-wire trailer plug.
For use in amateur radio, the community has adopted a standard
polarity for assembling the Singlepole connectors, using one red
and one black housing, as well as a mnemonic for remembering the
arrangement: Red Right—Tongue Top
. Before this polarity
standard was adopted, some amateur radio groups had chosen the
opposite polarity, so it is wise to double-check the polarity
before blindly plugging devices together.
Although many sizes of the Powerpoles are available, the size most
commonly used is the 15/30/45 amp variety. These sizes all use the
same plastic housing, differing only in the metal contact inserted
into the housing (selected based on the current need and wire
size). Larger Powerpole connectors (the SB/Multipole series) with 2
or 3 contacts in one molded housing are commonly used in various
industrial settings, including as a battery connection for some UPS
devices, removable truck/Jeep winches, many electric forklifts, and
other electric powered vehicles.
For the larger Multipole design, each color is keyed so as to mate
only with a like colored connector, and Anderson publishes a list
of recommended voltages for each color:
- 12 V: Yellow
- 18 V: Orange
- 24 V: Red
- Used by Warn for its 12 V winches (should have used yellow
- Used by Tripp-Lite for some of its 24 V external UPS battery
- 36 V: Gray
- Used by Tripp-Lite for some of its 38 V external UPS battery
- Used by APC for some of its 24 V external
UPS battery packs (should have used red multipole)
- 48 V: Blue
- Used by Tripp-Lite and APC for 48 V external
UPS battery packs
- 72 V: Green
- 80 V: Black
- 96 V: Brown
- 120 V: Purple
- 144 V: White
Some manufacturers have ignored this color coding recommendation.
One should always test the connection with a voltmeter if unsure.
For example, winch manufacturer Warn uses a red housing for its
winches, even though they are powered by 12 V DC, not 24 V
The connectors are also starting to be used by Radio Control
hobbyists, including robot builders and the R2-D2 Builders
This connector design was created by Anderson, but the patent on
its design has apparently lapsed, and there are other manufacturers
of this connector now, including AMP and Sermos.
The SAE connector
is a hermaphrodite
two-conductor, DC connector commonly used for automotive
applications (also motorcycles
). It is so named for the Society of Automotive
who created its specifications.
This connector is typically used for applying a maintenance charge
to a vehicle battery. The polarity of the connector, when installed
in a vehicle and attached to a battery, is always such that no
short circuit will occur if the exposed terminal were to touch the
vehicle chassis. In most vehicles, this means that the exposed
terminal connects to the negative terminal of the battery.
Conversely, the positive terminal on a battery charger is exposed,
to mate with the concealed one on the vehicle side.
Although there is a risk of short-circuiting a battery charger, the
risk is minimal and often mitigated by the circuitry of the battery
charger itself. On the other hand, the power-to-weight ratio
of the lead-acid batteries
installed in vehicles
is sufficiently great, that a short circuit could result in a fire
or explosion. The priority is therefore given to avoiding short
circuits of the vehicle battery, rather than of the charger.
Cigar lighter sockets and plugs
The car cigarette lighter socket is technically called a cigar lighter receptacle
, since it
was originally designed as a lighter
cigars—hence its rather large size (and unheated center barely
large enough to light a cigarette).
These sockets were not originally designed to provide DC power, and
are not an ideal DC connector for several reasons, notably the fact
that three sizes exist (one for 6 V DC and two for 12 V DC) and the
mating of the different sized 12 V DC plugs and jacks is
problematic. Because of this, and the small gauge wiring sometimes
used, they can sometimes provide only unreliable and
current-limited power connections.
The polarity for 12V DC sockets is center pin positive (+), outer
collar negative (-). Reversed polarity will damage some electronic
DIN 4165 connector
Similar in concept to an automotive cigar lighter, the DIN 4165 connector
is shorter and
smaller, and found most frequently on motorcycles.
- Also known as Powerlet connector, BMW Accessory connector or
XLR connectors used for power
In the broadcast, film and television industries, the 4-pin
is the standard for 12v
power. The connectors are wired pin 1 negative, pin 4 positive.
Often pins 1 and 2 will be negative, 3 and 4 positive for a higher
current rating. Female connectors are used as supply and male
connectors are used on loads. Most battery belts and power supplies
output 13.2v, but equipment can usually handle a range of 11-18
volts to accommodate battery packs of varying voltages and charging
The readily-available XLR3 is also used by some manufacturers as
power supply plugs despite their being a well-accepted standard for
Other DC connectors
- Fly RC magazine: Connectors Connection describes most or all of the
connectors used by RC users.
- There are a number of similar design PC board power connectors,
including Molex Mini-Fit SR, Molex Mini-fit jr., MOLEX MICROFIT and
Molex SABRE connectors, and AMP DUAC connectors that look similar
to each other.
- Some plugs with three, four, five or more pins are also called
DC plugs. These were common on vacuum tube equipment and continue to be used
where several voltages are supplied. On vacuum tube equipment the
pins are normally on the equipment side of the join for safety
- Many cell phones use DC connectors
that are unique to the manufacturer, or even a specific phone.
- Many manufactures make special-purpose DC power connectors for
battery packs, instruments, medical equipment, communications
equipment and other devices.
In Australia, a T-configuration socket is used for DC power
outlets, such as in Stand-alone Power Systems
or on boats. For this use, the horizontal slot is on top and is
positive. This is also used for temporary equipment in emergency
vehicles. In Victoria the top of the T is taken to look like a
minus sign, and is therefore negative. Outside Victoria the
vertical pin is meant to be earth/chassis ground, consistent with
Australian Standards for Type I 240 volt outlets; therefore, the
top of the T is positive on a negative-earth vehicle. Older
positive-earth vehicles are still in service, so actual polarity at
the outlet can be random.
- Hosiden product guide
- Adapters: output plug/cord options See for pin
- Access Communications Snap and Lock plug
- ElectriFly: Adapters and Connectors shows converter
cables for connectors commonly used in the RC community.
- Battery Junction: Tamiya Connectors shows that
Tamiya connectors are used for airsoft guns.
- Trinity Airsoft: Chargers and Dischargers shows a
converter between the two sizes of Tamiya connector.
- "Powerpoleing Your Power Connections" by Stan
Horzepa, WA1LOU, 2003: "the Anderson Powerpole is the emerging
national ARES/RACES standard"