12v and 6v lead-acid in series for T200 for electric boat drive

[EliotBR (Eliot)]

@captainkephart

I remember seeing a huge cabinet, that had once housed a large mercury-arc glass rectifier, replaced with a small plastic block - I couldn’t get my head round why it didn’t just melt with the current

Sounds interesting

@captainkephart

I realise I don’t need ESCs (?) as I’d like to control the T200s ‘directly’ with a mechanical throttle. I can see now that something like the Thruster Commander is best between throttle, battery(ies) and T200s.

Brushless DC motors (like those used in our thrusters) operate by charging coils in a particular sequence to attract and turn a magnetic rotor - they won’t run without an ESC. The Thruster Commander can be used as a convenient way to send meaningful control signals to the ESCs without needing custom circuitry, custom code, or a full autopilot board.

@captainkephart

• What kind of thing would do for the ‘mechanical’ throttle that’s not one of the devices shown in the Technical Specifications?

The Thruster Commander applies a voltage across its input pins and measures the voltage in the middle. It comes with potentiometers (variable resistors) that act as a voltage-divider, and can be turned to make the middle voltage higher or lower.

I’m not sure what exactly you’re asking about/for here, but if you’re after for example a larger thing to turn then that could be achieved by just attaching a larger knob to the potentiometer.

@captainkephart

• Do I have to use an ESC? I’m guessing the Thruster Commander replaces that?

As above, yes you still need ESCs (one for each thruster you want to control).

@captainkephart

• I’m not understanding where the battery voltage controllers sit in the circuit, or even what type to buy - especially want to avoid the cheap ones;

If you’re using some kind of voltage regulator it would serve as the load for the power supply (battery), and then you use its outputs as the supply for the actual load (e.g. your thruster commander + ESCs). Choosing a suitable type would be mostly dependent on your desired voltage input and output, and corresponding output current that you require.

@captainkephart

• I’d like to use 2 identical 12v ‘leisure’ batteries in series for simplicity (trying to avoid the mini-computer that sits inside every Lithium battery) … though understand from the power curves that 2 in parallel gives a thrust / endurance trade-off;

2x12V in series gives 24V output, which would require some kind of regulation because T200s have a maximum supply voltage of 20V. 2x12V in parallel gives a 12V output with double the current capacity, and since running T200s at a lower voltage also reduces the current draw then that would indeed mean the batteries would last longer, although likely at the cost of a slower vehicle (lower power input → lower thrust output).

@captainkephart

So, to avoid joining their numbers (!), have you produced any pages with sets of sample circuits for different applications to study?

Blue Robotics only sells one battery at this point in time, and we don’t actively support using several at once, so we don’t have sample application circuits for different setups (lithium-ion batteries are finicky, which makes it difficult to support combining them).

I’m aware that one of our distributors (@seaview) sells a battery/power supply manager, which is discussed here (their webpage has some high-level connection diagrams, if that’s of interest)