Re: draw, thrust, and components
Posted: Dec 14th, 2014, 8:12 am
That is impressive, but I have to ask about power draw and battery life.
I think the 4s is in the 4 Amp (4000-5000mAh) family of batteries, right?
So that means it can deliver 4000mA of power for an hour and then it's done. If you use more mA then you get less than an hour and if you use less mA you can go more than an hour.
So just like any vehicle your ability to continue to move (and how fast) is going to be a relationship of a LOT of factors with power to weight being one of the main ones. A Lotus is a fast car even though it's got a tiny engine because the car itself doesn't weigh much while a Corvette has to have LOTS more power to get the same performance.
I'm wondering where is the 'sweet spot' for thrusters and for ROVs in general when it comes to performance for a given weight of thruster and cost.
I'd say the average weight of a homebuilt ROV is just a few lbs to up to maybe 10-15 at the most (just guessing) and the ability to get where you're going is limited by lots of factors like visibility and your tether payout/drag data. No one (that I've seen) is cranking along very fast down there, so really the ability to hold position against a current or move just fast enough to keep up with what you're seeing seem to be 'enough' and long battery life is more important than the maximum amount of power you can generate at the top of the power band.
I guess what I'm saying is that I'd like more information from experienced ROV pilots/owners/builders about their experience with thrusters. Is there a performance hit to having thrusters that go zero to max in too short a time? Is there a case where you've felt 'overpowered' or 'underpowered' down there where control was just not fine enough? At what point does control become jerky and unmanageable where the main thing you are thinking of is control rather than just looking around/doing what you want to do?
Is there such a thing as too much power?
I think the 4s is in the 4 Amp (4000-5000mAh) family of batteries, right?
So that means it can deliver 4000mA of power for an hour and then it's done. If you use more mA then you get less than an hour and if you use less mA you can go more than an hour.
So just like any vehicle your ability to continue to move (and how fast) is going to be a relationship of a LOT of factors with power to weight being one of the main ones. A Lotus is a fast car even though it's got a tiny engine because the car itself doesn't weigh much while a Corvette has to have LOTS more power to get the same performance.
I'm wondering where is the 'sweet spot' for thrusters and for ROVs in general when it comes to performance for a given weight of thruster and cost.
I'd say the average weight of a homebuilt ROV is just a few lbs to up to maybe 10-15 at the most (just guessing) and the ability to get where you're going is limited by lots of factors like visibility and your tether payout/drag data. No one (that I've seen) is cranking along very fast down there, so really the ability to hold position against a current or move just fast enough to keep up with what you're seeing seem to be 'enough' and long battery life is more important than the maximum amount of power you can generate at the top of the power band.
I guess what I'm saying is that I'd like more information from experienced ROV pilots/owners/builders about their experience with thrusters. Is there a performance hit to having thrusters that go zero to max in too short a time? Is there a case where you've felt 'overpowered' or 'underpowered' down there where control was just not fine enough? At what point does control become jerky and unmanageable where the main thing you are thinking of is control rather than just looking around/doing what you want to do?
Is there such a thing as too much power?