Yes, the ESC’s will still draw about 3 Watts according to earlier posts, but simply having ability to turn off controls and reboot without opening still has a lot of value. I do like the idea of topside on off capability though even if just to reboot while subsea.
Hello all,
I am considering adding a 100A SSR to the battery compartment, with a Blue Robotics external switch in the endcap. I have the BR battery pack. Any issues with using the charge balance connector as power source for the control circuit? The datasheet for the SSR states 15mA maximum input current for the control circuit. Also they say inductive loads must be diode suppressed, but I assume that because the motor loads are managed through the ESCs that doesn’t apply in our application… is that a correct assumption?
Here is the datasheet: Solid State Relays | Sensata Technologies
Thanks,
Tim
In The Case of Reboot Idea the Idea is Perfect as Per Earlier Post Is Considered.
BUMP this up from 2017. Is BR working on something for all of us so we conserve our expensive Li batteries???
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I know power switching is being considered for our next ROV version, as part of a broader electronics overhaul. Beyond that, I don’t believe we’re working on a self-contained power-switch that could be added to an existing ROV.
The biggest issue with an ROV power switch is being able to handle the significant current levels that the thrusters can draw. If “low power” is an acceptable “switched off” substitute then you might want to consider using a switch to control a MOSFET that can switch the power inputs for everything other than the ESCs, or possibly just the input to the 5V converter. Both those options mean the flight controller can be switched off, at which point it cannot send any control signals to the ESCs (which means they’re safely stopped), and should reduce most of the idle current draw.
Hi all,
I thought I’d share this solution. My preference would be to keep the SSR in the power enclosure (vs. the electronics enclosure) so have used:
- BlueRobotics wet switch
- SSR 100A 30VDC
- 1N4002 diode as flyback
- Mounting plate made from 3mm phenolic board (artwork PDF under photos).
- 4 x BlueROV2 short standoffs
- 4 x M3 x 8 bolts
- 2 x M4 x 8 bolts / nuts / washers
- Longer AWG11 (ideally) or 12 red/black DC power wire.
This solution JUST fits the 15Ah battery with the standard enclosure length. Battery access is from the front of the ROV with the longer power cord fitted.
NOTE: The flyback diode needs to be mounted in the electronic enclosure across the bus bars (earlier photos had it across terminals on the SSR - daw!).
SSR mounting plate - Rev B.pdf (112.6 KB)
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Hi @PeterM, welcome to the forum! 
Thanks for sharing - it’s always interesting to see the different ways people approach problems
I’ve updated you from ‘new user’, so you should be able to upload photos now. Feel free to add them in a new comment, or by editing your original one
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Thanks @EliotBR. Super impressed with the BlueROV2 product. Well done to the whole team - and big ups to Matt at Bay Dynamics, your NZ distributor, for great support.
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@PeterM @EliotBR
This thread helped me a lot I myself used a 120a constant duty 12v relay with a diode across the coil like you have there. I then send 12v down my tether to activate the relay, I haven’t had much real world usage so it could fail on my one day but I am positive buoyant so hopefully I can pull her back in from up top.
I really wanted to do SSR like you did but I only know of crydom and they are wow expensive for 100amp. I used some china ones 40amp for my printer and nearly burned my house down.
I’ve been using these: TL-SSR – 12V / 100A DC Unidirectional Solid State Relay (SSR)– Thornwave Labs
I put a switch on the front of the BR surface box and use a spare pair in the tether to turn it on/off. No issues after a few years of use so far! The SSR fits easily in the main enclosure.
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Now that is slim and pretty, Kinda surprised heat is not an issue, but I guess quality of gear matters. the china 40a DC relay when operated at 10amps got hot enough to char wood, however the crydom 20 AC relay that powers my 1500watt heater remains cool with nothing more than a small 40mm fan.
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Yeah - I enquired but those Thornwave Labs SSR’s are not approved for export to NZ unfortunately…
Finally went into work to put together on/off switch with 100A relay, built on ideas from this forum. I have not tested it fully. Just on workbench.
This would defiantly ease my mind in the field not to open and close the battery tube. 
I will then add a flyback diode to the circuit.
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I’d be interested in the community opinion on this solution!
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Looks useful Tony - thanks for posting a ready made solution. Certainly be convenient not to have to open the battery compartment in the field to start/stop the ROV - particularly when the ROV is wet or after vacuum testing the enclosure.
Limiting factor would be that its not that difficult to open the enclosure and is required to charge/replace the battery anyway.
Slightly off topic but wondered if its worth inserting some padding in the battery enclosure to stop the battery moving. Always wondered whether this significantly affects the stability/operation of the ROV?
Hi @BillyBudd -
I haven’t noticed the battery shifting much fore/aft, usualy the cable holds it pretty securely to the front of the enclosure? In the case of the heavy configuration, any pitch instability is corrected out when in stabilize mode, but this can impact efficiency. Generally I don’t think shifting the weight of the battery affects the stability much…
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Hi Team
As a follow on from this thread.
Bay Dynamics has been adding power switches to our BlueROVs for around 5 years now. We dont sell any without them. The post above from Peter Miles is a variation on what we normally make for customers. Using a SSR inside either the 4" or the 3", triggered by the BR Switch works great. Many units in NZ have these installed and not had one come back with a problem.
In the 4" Standard housing, there is space next to the Fathom X for a 100A SSR if you rotate the fathom X 90 degrees. We also have a redesigned electronics plate, more recent, that is a plug n play replacement for the BR standard one which is pre-drilled with holes and standoffs so its an easy install.
As mentioned by Peter Miles above, they can also fit in the 3" Battery housing behind the battery, albeit with a snug fit. We have done several of these recently also. Frees up a little more room in the 4" Housing. One downside to this way is that the battery is easier to get out the front, which can be a slight pain if you have a grabber installed as it always sits in the way of getting the end cap off. Just a minor point to consider.
A point to consider is that putting the SSR in the 3" battery housing allows you to electrically isolate the power lines to the main housing. This may be relevant for some who are using disconnects (Like Cobalts) on their power cables. If you put the SSR in the 4" the power cables are always live between the cans. This is often not an issue if you are using Wetlinks, but the pros and cons of each should be weighed up either way.
If anyone wants more info feel free to drop us a message.
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Hi
I can confirm that Bay Dynamics has made 3 BlueROVs now with the power switch installed in the BR Topside Box, allowing for remote on/off. It works nicely however a safety point should be noted around possible tether damage.
Its important you install a safety fuse in case the tether is damaged causing your live wires, in the tether, to be exposed to water. This will short out your relay and likely cause damage. This system does not strictly, under all conditions, allow you to isolate your battery supply.
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This is exactly what I need. Thanks for posting
I think the cable used to hold it reasonably well but recently I’ve noticed it rattles around when lifting the ROV - guess the cable has gotten compressed over time. Would there be any issue with adding some polystyrene or similar to the battery compartment to stabilise the battery?