Continuous current draw of T200 Thrusters and BMS rating required

[Syon]

Hi everyone,

I’m looking to add a BMS for a custom battery pack but am unsure of the current rating required for the BMS, specifically regarding the max continuous current draw of the T200 thrusters. I’m using the heavy config of the BlueROV2, with 8 thrusters.

On the product page for the T200 Thrusters, is the full throttle current in the technical details continuous current or the max current draw for a short duration?

If the specifications list the max current draw in an instant, then what would be the continuous current draw of a T200 thruster?

I’ve been looking through the forums for answers but I’ve found conflicting information and would like some clarification on which is correct.

@EliotBR

A T200 at ~15V draws ~22A at max thrust, so two of them would draw 44A. Our battery has a “Maximum continuous current draw” of 60A, and each ESC can handle a constant current of up to 30A (depending on cooling), so that shouldn’t pose any issues.

From my understanding, this comment suggests that the thruster’s continuous current draw is ~22A at max throttle. Would that mean I’d require a BMS rated at least 176A continuous?

@adam

On a recent practical ROV dive, we logged current draw over time, and found the average was about 20 A. Sure, there were short spikes up into the 60-90 A range, but these last no more than a second or two. In synthetic (tank) testing with all thrusters at max throttle 100% gain, a BlueROV2 heavy will draw around 110-120 A in an instantaneous spike, but this will quickly drop.

This comment is pretty self-explanatory. If this is the case, would a 100A rated BMS be suitable?

Just some further details:

• I’m looking to have the battery pack and BMS fit in a 400mm 3" WTE. Would the size of the BMS being unable to fit inside the enclosure be a concern?

• I’m planning on using Molicel P42B cells (4.2Ah, 45A max discharge current) in either a 4S7P or 4S8P configuration, depending on how many cells can fit inside the enclosure.

Any advice is greatly appreciated.