I've decided to once again go with a 12V system. I had to take a step back from my prejudgment and ask myself why 12V? So, I thought I would ask a few professionals for their opinions. I had a long chat with the EE's that work in my company and my college profs. They each chose 12V DC. Why? I will write down as many reasons as I can think of. (remember, I was once trained as a EE.. how much I remember is another story! Reason 1: P = V*I (More accurately, Watt Hour = V * Amp * Hours) It will take a boat a finite amount of power to traverse a lake, no matter what voltage you run. So, assuming it takes the same amount of time & assume it will take 24 Watts to traverse the lake. @6V, you will be averaging 4Amps @12V, you will be averaging 2Amps So, assuming both the 12V & the 6V battery are rated @ 1Ah... The 12V will last longer. Great! But... the 12V battery is twice the size of the 6V battery! Well usually not quite (I checked all listed batteries @ battery mart), but the point still remains... what matters is which one can pack the most Watt*hours into a manageably small space. Additionally wires are only rated for a certain 'max' current... So lower voltage must use bulkier (lower gauge) wire.
RE: 12V vs 6V --> the discussion through the ages. Reason 2: I^2*R losses. Since metal conducting wires have a certain resistance, some power will be wasted as heat in the wires. This power loss is given by P = I^2*R. **Warning Math Content** Everyone knows ohms law: V=I*R (Volt = Current * Resistance) So, if the wire has resistance, and the motor is pulling current through the wire... a voltage drop will occur on the wire itself. I think everyone should know: P=V*I (Power = Volts * Current) The power wasted on the wire as heat is = the voltage drop on the wire * the current through the wire. -> P = V*I P = (I*R)*I P = I^2*R **END Math Content** --> OK, FINE. So? We are traveling 2 feet from battery to motor... Will the resistance on the wires be reallllly high enough to make a difference? I donno; guess it depends on your motor's resistance, operating current, and the wires you use... but sure could be. ---Discussion point--- Unfortunately, I cannot say for sure how each individual ESC works... But it stands to reason that even with solid-state 'switching' ESC's, there will be an internal resistance. Therefore, the same rules apply from the wire example above... The ESC should theoretically not get as hot on a 12V system.
RE: 12V vs 6V --> the discussion through the ages. Price: Again, is there much difference? I guess yes for some boats and no for others... depending on size & how much power you need. For my requirements it was exactly the same price. Weight: No difference for me... 15lbs. ---> So, all the differences seem pretty theoretical; so why 12V again? Every little bit counts? An amp saved is an amp generated? ehh...mostly cause I had one laying around.
RE: 12V vs 6V --> the discussion through the ages. Yes, but since most boats are 6v you have less in common with them, so in case of problems by either you or them, sharing batteries isn't an option.
RE: 12V vs 6V --> the discussion through the ages. Don't forget the zillion feet of wire in the motor windings for resistance... Also, unless you run an ESC on the pump, it'll spin much faster on 12V, so as long as your motor is rated for 12V, you can move some water! If you're in a club that restricts pump capacity, that may not be a plus. I have 6V and 12V ships. I like 12V because the batteries can serve as emergency power for my ham radios. Yes, I have a harness to connect 6V's in series for that purpose, but it's easier to grab one 12V in a hurry Boat-wise, not a big issue for me.
RE: 12V vs 6V --> the discussion through the ages. I have been collecting a number of 3 volt motors. And have been looking forward to trying them out. (Using them in some of the smaller boats) I have even been tempted to try them in something as large as the Mogador.
RE: 12V vs 6V --> the discussion through the ages. The major issue is drive motors @12 volts. There are plenty of motors for battleship that work nice on 6Volts, but few that do the job well on 12 volts.
RE: 12V vs 6V --> the discussion through the ages. Hmmm... I ran 12v in my Scharnhorst a few years ago. There were two reasons. First, my ship wasn't getting up to speed on 6v. I bumped it up to 12v, and boy oh boy did it fly. Easily 40+ knots, when all I needed was 32 knots. And no shortage of torque for grinding through weeds, rocks, and unfortunate destroyers [] The other reason was because I initially installed an air compressor in my ship, in place of a CO2 system. The air compressor required 12v to run. Unfortunately I found out that the RF from my particular compressor would disable my ship and any others that happened to be nearby, but I still stuck with the 12v system. I also used 6v bilge pumps. They never fried on me (fortunately) when I ran them on 12v, and when they pumped, they really moved some water. There was at least one time when they brought me back to life when I had less than 1/8" of freeboard remaining []
