T-500 Thrusters in Hyper Saline Water

Blue Robotics Products Thrusters and Motors
1

Hi all,

We just completed a survey with our ASV in the Salton Sea (abt. 60ppt salinity) and have been having an issue with the thrusters / batteries. Our current setup is two T500 thrusters in a skid steering configuration, T-500 Speed controls, and Navigator/ RPI4 running the control software. The system is powered with a 22v li-ion 22,000 MAH 25c battery for main power with step down converters for some of the survey gear.

We have successfully used this setup for about 3 years in freshwater lakes with no issues. However, both times we have used the ASV in the Salton sea it has immediately caused the battery to swell and short after about 10 min of operation. Using 2x blue Robotics 14.4 v batteries works though. We have run the ASV in multiple lakes between the Salton Sea job with no issues.

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Is it possible the salinity of the water is causing this and if so why with the 22v system and not the 14.4v system

3

Hi @ktweed -

Do you have autopilot .BIN logs for operating in the Salton Sea vs. freshwater? It sounds like the higher voltage is leading to more current being pulled by the thrusters - and if the stators of the T500s have been damaged they could be leaking voltage into the water, leading to over-discharge and “puff” of your battery.

If not the thrusters, some other load (sonar?) could be pulling more current with the salty water acting as a conductor…

Also, as noted in the battery care guide, pouch style packs once puffed, have lost capacity and are on their way out…