I’m considering powering my BlueROV2 using two separate batteries — one for the right-side components and one for the left. The configuration would look like this:
Before proceeding, I would like to know what kinds of problems or risks I should expect with this setup.
Some concerns I have:
Since the Navigator and other components are connected via signal lines to both sides, could differences in ground potential or voltage cause control issues or signal interference?
Could uneven voltage between the two batteries result in asymmetric thrust, causing the ROV to veer instead of moving straight?
Any risks of damaging the ESCs or Navigator if battery voltages become unbalanced?
Would you recommend diode isolation, a power combiner, or some other form of synchronization?
Has anyone tried a similar dual-battery setup for load balancing or redundancy? If so, I would greatly appreciate hearing your experiences or recommendations.
My Goal:
The idea is to reduce load on a single battery and possibly extend dive time, while still maintaining stable and safe operation.
Hi @Itaru -
Connecting the batteries like you describe isn’t going to accomplish the goals you have. It would lead to problems with the battery voltages going out of balance relative to each other, and generally seems risky. Keep it simple!
The best way to reduce the load on a single battery is to connect it in parallel! With the + and - of each battery connected together, each one only needs to source half the current it would if a single battery was connected. Thus, as long as you balance charge the batteries and connect them at voltages where they are matched (to 0.1V), you’ll be all set!
I’m currently using Blue Robotics batteries (BR-100842) with the parallel connection method you mentioned.
To minimize imbalance, I always use brand-new batteries as matched pairs.
However, after multiple uses, I’ve started noticing heat buildup, which I suspect is due to differences in internal resistance causing an imbalance between the batteries.
Also, there’s a safety concern when battery replacement procedures are done incorrectly.
For example, if a used battery is mistakenly left connected and then paired with a freshly charged one, it can be very dangerous.
Since we perform battery swaps onboard a vessel, a fire or thermal incident could be catastrophic.
That’s why I’m exploring a safer alternative configuration, even if it’s a bit more complex.
Hi @Itaru -
I understand - but balancing and keeping batteries connected to each other at the same voltage just comes with the territory. This is what the BlueBoat does to keep up to 8 batteries connected in parallel . If you’re concerned about mismatches in internal resistance leading to heat, connecting the balance connectors in parallel together can eliminate this to some degree, as all 32 batteries in each series set would maintain the same voltage. If charging or operating for days to weeks continuously, a battery balance module should be connected to all the cells at this point.
Lithium batteries are inherently dangerous!