ESC / MAH and Ripple Current. Experts weigh in please.

[photohoward1]

OK....A friend of ours fried a controller. Running a Fighter Cat Cheeta, I think on a 4082 something about 1500/per volt and a 442 prop. No big deal of a set-up. Probably no more than 120 amps. He called for warranty info and they hooked him up with the "boat expert". The "expert asked what cells he was running. 3Sx5000mah in series for 6s 5000. The expert said that We should only use no less than 8400mah or 10,000mah or ripple current would be a problem. WHAT? How would the gas tank size on that set-up effect the ripple current? I bet most of us run about 5000mah on our smaller set-ups. In my spec stuff I run 4200mah for sprint and 6600mah for offshore. Please explain this or is the "expert" full of it?

[TheShaughnessy]

what controller? While I'm not an expert I can assure you that Mah is not simply a measurement of "fuel" capacity. What C rating were his batteries? I run 5200 mah in my spec cat set up and easily burn up 2500 mah if I actually finish the heat, even though I'm only using half the batteries capacity I still see voltage sag down to 13.5 volts by the end of a race these are batteries rated at 65 c mind you. They have a theoretical output of 338 continuous amps, my set up sees spikes of 70 and averages far less, no where near the rated output of the packs.

Your expert may have a valid point. Hard to determine without knowing the esc in question, the age, brand, and c rating of the packs in question. Set up and run time may have also contributed. Battery wire length? Extra cap bank? Ripple current is a real thing, not saying it's for sure what took out the esc but it is particularly hard on them

[photohoward1]

I can't tell the ESC manufacture. It shod not make a difference. Let's assume the best cells and a 45c rating. Also let's assume short wires. The expert said never run less than 8400mah under any circumstance. On any setup.

[TheShaughnessy]

Ok what was the esc rated at? I personally think that's good advice for a 4082.

[nmnorth]

to answer the question, the batts were dinogy 3s 5000 mah 65c and controller was a castle 240 less then a year old , 4082 1600 kv leopard

[nmnorth]

if this is true , how do we run smaller boats 6s?? and 2 batts

[MarkF]

The problem is the controller. I have run several of the Castle 240s on my 4s boats and I run 4s 2p for 10,000 mah and I still would crap out the controller. I have since changed to a seaking 180 and never looked back. That motor on 6s is a hot set up and should be run with more mah but still shouldn't kill the controller. Castle recomends that high of mah for people running crappy batteries which you were not.

Mark

[Doug Smock]

Just curious. Are you running the 4D?

[nmnorth]

no, running 2y, guys this is castles boat expert telling me this , i have run several boats with same setup for a long time , never had this problem , castle is basically saying i have to double my battery weight, is this true???

[RaceMechaniX]

Ripple current has a lot to do to multiple factors. The capacity of the batteries does help with ripple current, but equally important are the wire length(s), wire diameter(s), connectors(s), timing and operating points.

There is a good thread on IW where details are spelled out. http://www.intlwaters.com/index.php?...nt#entry555674

Since your friend did have a Castle ICE controller the data would be revealing on the actual ripple current, throttle percentage, etc. Hopefully the ESC still works to retrieve this.

In general for 1P set-ups you need very good batteries and even better connectors. The Dinogy's should have no issue in this department. Your friend needs to keep the wire short, have tight connections and should not run at partial throttle for prolonged periods.

Post the data if you have it or the file and I can show the details.

TG

[nmnorth]

Wires are short , excellent connectors , do not hardly run partial throttle , castle has controller

[TheShaughnessy]

Seems like it should be covered, expensive esc to have go up. When you say fried, what happened to it?

[nmnorth]

Stopped working

[f1rogers]

Wow, I thought I was the only one having this problem. I think I killed 5 separate ICE 240 esc's in 2013 doing the exact same thing. The CC guy said I was "blowing the legs off the caps" by not running the recommended MAH. I didnt know what he was talkin about exactly. I upped my MAH and no trouble since.

[RaceMechaniX]

Do you have the data from the runs?