Quick Disconnect for Battery

We are planning to provide a quick disconnect for ROV power. We are using 18Ah bluerobotics battery. This is to provide an option for the swapping battery hull.

For tether disconnect, we are going with Seacon MC Series.
Any suggestions for underwater connectors for the battery cable?

Assuming we require per contact current of 50A or higher.
Some available options we are exploring are
Birns Heavy Duty Connectors (Eg.HDBH4M)
Subconn High Power Contacts (Eg.HPBH4M)
Seacon - couldn’t find one yet


Hi Johns,

This is actually a really tough question. The battery cable has to carry substantial loads. At high power bursts that could be upwards of 100 amps. You’d need a massive connector to support that.

I would recommend searching for a something with a reasonable current rating per pin like 10-15 amps but get a connector with multiple pins, maybe 8, and use multiple pins for + and multiple for -. That will end up being fairly expensive, unfortunately.

I’m not very familiar with high power connectors so I can’t say much more than that.


Thanks @rjehangir


Has there been any more discussion about this topic (quick disconnect for the batteries)?

Just that I saw the other day that the SRV-8 Oceanrobotics, which seems to have a lot of Blue-ROV components, and has hot swappable batteries. Might be a simpler option than a battery switch to turn the ROV off in between dives?


A simple battery switch is a magnetic reed switch (like the type of magnetic switch used in a security system to tell if a door is opened) on the inside surface of the hull, closed by a magnet placed directly outside the hull. Reed switch operates relay, opening circuit.

High-current battery connector can be an XT90 hobby RC connector (or 2), inside the same kind of hardware-store Pex swivel, rubber-cone compression gasket used in this DIY tether connector, assembled immersed in a pan of mineral oil, to fill the void in the fitting so water has no space to invade.
2017 Pro Mini Logger Build: Potting Sensors & Waterproof Housing Pass-Through Connections - YouTube 11:40

from A Simple DIY Underwater Connector System - Homebuilt Rov Forum

Thanks - but looking for something I can buy (rather than make) and that disconnects the battery outside of the canister. So something like on the SRV-8 RJE Oceanbotics™ SRV-8 ROV System Set-Up - YouTube (at 3:57).



Hi Craig,

My company, Blue Trail Engineering, makes a 4-pin connector rated at 20 amps continuous per pin. You could double-up the pins for 40 amps continuous. My customers have used this before in this exact application. They put the cable with penetrator on the battery and the bulkhead connector on the main electronics enclosure.

Let me know if you have any questions.



Fantastic - thanks Damon, I might email you directly at Blue Trail engineering with a couple of questions.


Hi Rusty and Damon,

We often power the 4 horizontal thrusters on the BlueROV2 at 1000% gain and full throttle forward or sideways during 30 minutes. It is hard going (against strong currents) but has work for us so far. Only thing that we noticed is that the battery is hot at the end.

Is it actually dodgy to power it 100%+full throttle for so long (even with default BlueROV2 cabling)?

Assuming it is OK to do that in the first place, would it be possible to use a Cobalt 4-pin for the + cable and a 2nd Cobalt 4-pin for the - cable?



Hi Eloi,

I do have customers who have done as you suggested (use one Cobalt 4-pin cable for + and another for -). I also have done some custom 1-pin cables for this purpose. Each connector uses a Castle Creations 5.5-mm bullet connector as the contact. These bullets are rated at 150 amps max. I might offer these as a standard product at some point down the road.