2600mah 4s lipo

[StephenLilly]

Building my first electric boat, a delta force 26" mono, I have built a few nitro riggers before, while different game. My question is will I regret buying a lower mah 4s lipo, a mojo 2600mah. I haven't used it and may be able to return it. What kind of run times may I expect with my set up, 26" mono, sss 3660 2070kv motor, 120a Seaking esc, 442 or 445 prop.

[Speed3]

You might be look at around 115 amps on 4s with the x442 and around 140 amps with the x445.

61 seconds of flat out running with the x442.

50 seconds of flat out running with the x445.

The setup is not good. You are looking at a lot of heat issues if you are planning to sail this boat hard.

Maybe low voltage might kick in when you give full throttle.

I would recommend returning the battery and get a higher capacity pack. Today you can get powerful lipos at a good price. A 5000mah 4s lipo can be hard for less than $100.

A better ESC by far is the ose raider 150. $60 from offshore electrics.

I would stick to the x442 with that motor and just sail around slow and fast. I say slow and fast because I don't think that motor can handle constant full throttle (excess of 100 amps constant).

[rol243]

on 4s we run 5000 to 6000 mah packs. yes go higher than 2600 for sure.

[HTVboats]

Buy a second 2600ma pack and make some parallel connectors. 2X2600=5200ma. For props X442 and X642 will work. An M445 is about as large as you can run. I generally reduce my 445's to 42-43mm. A cut 445 is similar to a 642. Highicer pitch 67mm vs 63mm on a 445 but less blade area.
M

[Speed3]

I would like to also mention that the idea of running 2 2600mah 4s in parallel would double the capacity and give the necessary power to run the sss 3660 2070kv and a 442, 640, 642.

Another option is to go with 2 2s 5000mah or 6000 man and connect them in series so you then have 5000 mah at 14.8 v or 6000 mah at 14.8v. I think 2 2s 5000 man in series would be a good choice.

The 5000 mah cells would likely be more powerful than the 2600 mah cells even when getting 2 of them 2600 mah cells in parallel. I would recommend turnigy heavy duty 5000 mah 60c cells.

I like 5000 mah over 6000 mah for a smaller 26 inches hull. Because when you put to much weight in some hulls they don't run good.

I would also consider going with an octura x640 for that size boat. 442 and 642 would also be good props.

I would caution not to go too big on diameter on that little boat.

[StephenLilly]

Ok great info to know! I really appreciate you pointing me in the right direction.

[rol243]

MAH give run time not extra power. the C rates of the pack decide better power. so for example a 5000 mah 20c - 4s lipo will have less power than say a 5000 - 60c -4s lipo and looking at mah with the same c rating , a 5000 pack will give a longer run time in water than say a 2600 pack.

[HTVboats]

C ratings are at best very unreliable. No industry standards and more hype than reality. One simple analogy is you have a 5 gallon bucket of water and the size of the hole in the bucket determines how fast it drains. Bigger hole more "C"s. you still get 5 gallons. Two buckets with 2 1/2 gallons with the same size holes will drain faster. (parallel). For a record SAW run that large C rated cell may make a difference. Over 6 laps the difference between 40 & 60c's may not be much.
Mic

[Speed3]

I though the c rating did not make a difference. Especially when trying to work out voltage under loader by internal resistance.

I learned the difference when I test different cells with the GPS in the boat. I was shocked to see the difference.

When a cell can give an extra 8mph over another it made me realize don't take c rating for granted.

Only one problem though some brands have cells with lower c rating that is more power than other brands with higher c rating.

The turnigy 5000 60c cells are really good cells at least a set that I have.