FAQ
TL;DR: For 48V ROV builds, step down to 10–12V using proven modules; a "2000 watt switching power supply is a major project" best bought off‑the‑shelf. This FAQ guides parts choices, sizing, and EMI control. [Elektroda, DAVID CUTHBERT, post #21670168]
Why it matters: Reliable power keeps thrusters and pumps running under pressure without burning time or budget.
Quick Facts
- Target conversion: 48V input to regulated 12V output for motors. [Elektroda, Amr Awny, post #21670171]
- Bilge pumps run at 10V; two operate simultaneously, so plan a 10V rail. [Elektroda, Amr Awny, post #21670166]
- Off‑the‑shelf is advised; a 2 kW SMPS from scratch is a major project. [Elektroda, DAVID CUTHBERT, post #21670168]
- Example pick: Vicor V48B12C250B → 12V at 21A; add FIAM filter for bus EMI. [Elektroda, DAVID CUTHBERT, post #21670173]
- Modular path: LTM8027 handles up to 60V in, 4A out; parallel with small series resistors and validate in LTspice. [Elektroda, DAVID CUTHBERT, post #21670172]
What is an ROV and why are we using a 48V battery?
An ROV is a remotely operated underwater vehicle. The competition mandates a 48V battery, so your power system starts at 48V and must feed lower‑voltage loads. [Elektroda, Amr Awny, post #21670164]
Do I really need a regulator if my source is a 48V battery?
Yes. Your bilge pumps need 10V, and two run together. A regulator or dedicated DC‑DC stage is required to supply that rail safely. [Elektroda, Amr Awny, post #21670166]
What output spec do my motors need from the regulator?
You stated a 48V to 12V conversion, delivering about 12A to the motors. Size the converter and wiring for continuous 12A at 12V. [Elektroda, Amr Awny, post #21670171]
Can I build a 48V to 10–12V SMPS myself?
It’s possible but not recommended for your first design. As one expert noted, a 2000W SMPS is a major project; reliability matters underwater. [Elektroda, DAVID CUTHBERT, post #21670168]
What off‑the‑shelf 48V→12V module fits 12A or more?
Vicor’s V48B12C250B outputs 12V at 21A, covering your 12A requirement with headroom. Add a Vicor FIAM filter to tame bus EMI. [Elektroda, DAVID CUTHBERT, post #21670173]
How do I cut EMI on the 48V line feeding my converters?
Place an input EMI filter on the 48V bus. The suggested Vicor FIAM filter is designed for this and pairs with their DC‑DC modules. [Elektroda, DAVID CUTHBERT, post #21670173]
Can I parallel smaller regulators to reach 12A?
Yes. The LTM8027 handles up to 60V in and 4A out. Parallel several with small series resistors (≈0.1Ω) and verify sharing in LTspice. [Elektroda, DAVID CUTHBERT, post #21670172]
Why is SMPS layout such a big deal?
High di/dt currents make layout critical. "SMPS design and construction is not for beginners" because poor layout causes instability and noise. [Elektroda, Garth Wilson, post #21670174]
How much current could the system pull at full thrust?
If each motor draws about 25A, two motors together mean around 50A from the battery. Size conductors, fusing, and connectors accordingly. [Elektroda, Mark Harrington, post #21670167]
What should I do about the 10V bilge pumps?
Provide a dedicated 10V buck stage from 48V or from 12V, sized for both pumps’ combined current. Keep it isolated from motor spikes. [Elektroda, Amr Awny, post #21670166]
Quick how‑to: pick a 48V→12V converter for my ROV
- Define outputs: 12V/≥12A for motors; 10V rail for pumps.
- Select module: e.g., V48B12C250B for 12V/21A headroom.
- Add input filter (FIAM), then validate under load on the bench before wet tests. [Elektroda, DAVID CUTHBERT, post #21670173]
What if I still want to design a custom multi‑module solution?
Model it first. Parallel LTM8027 uModules with small ballast resistors, tune values in LTspice, and confirm worst‑case current sharing margins. [Elektroda, DAVID CUTHBERT, post #21670172]
Is there a failure mode I should plan for early?
Watch for poor current sharing when paralleling modules. Mismatch can overload one regulator. Ballast resistors and simulation mitigate this risk. [Elektroda, DAVID CUTHBERT, post #21670172]
Why not overspec everything and be done?
Overspec costs and weight add up fast. A 21A, 12V module already provides margin over the requested 12A without unnecessary bulk. [Elektroda, DAVID CUTHBERT, post #21670173]
Who benefits most from off‑the‑shelf converters here?
Student or competition ROV teams gain reliability and speed. You avoid the steep SMPS learning curve and focus on mission tasks. [Elektroda, DAVID CUTHBERT, post #21670168]
Will layout still matter if I buy modules?
Yes. Keep short, wide high‑current paths and clean returns. Even with modules, layout discipline keeps noise and heat under control. [Elektroda, Garth Wilson, post #21670174]
