Hi everyone,
I bought a kayak a year ago and now I want to put two T200 thruster on it for some trolling fishing. It’s for a finale school project in mechanic engineer, so for the mechanic stuff it’s all fine, but I want to use 2 dewalt 20V max Lithium 2.0 Ah (DCB203) to power the two thruster. I know it’s might not be enough, but I want it to be a low cost project and I only have thoses battery at home. Do you have any idea which low cost battery I could use to get the max out of thoses thrusters? 
I’d head over to the HobbyKing website and find the 4-series LiPo batteries and sort by price and try to get the most for my money. They have a 20ah 4s pack for $120 and that’s a great deal which would be pretty sweet for your setup. Supposedly the T200 can pull up to 25 amps, which doesn’t totally jive with its voltage/watt rating, but let’s say you need a pack that can dump 40-50 amps, that’s only a 5ah battery with a 10c rating, which you can get for under $50, but it probably wouldn’t last five minutes if you were working it. I’d really try to get a 4-series battery of at least 10ah and only hit full throttle for a few seconds just for fun, but mostly keep it under half throttle so you can get some decent time out of it. You could use your DeWalt batteries for proof of concept, but you definitely won’t get the max out of the thrusters.
@charlo your run time will be ~proportional to the amp-hours of your battery, the more amp-hours, the more run time you will get. You can use most any 12-20V battery, the one thing you need to make sure of is that the battery can provide enough current for the thrusters. Less expensive batteries will have lower current ratings and may perform poorly.