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May 08, 2010, 01:49 PM
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Turnigy 40A Esc's - Plush or Sentry?


Aside from the balance plug connector of the Sentry, the only other differences between the Plush and Sentry seems to be linear/switch mode bec and 55A/43A burst current. However in reading the comments, it seems the Sentry can easily be pushed well beyond the 43A burst rating - but at what long term affect?

Considering they cost about the same, can someone with experience with both these esc's please explain why the Plush series is so much more in demand?? Is it simply the rated burst of 55A, or is there some other design element that makes the Plush so much better than the Sentry?

Also, can someone explain in simple terms (the only ones I understand) the difference between linear and switch mode bec, and how it affects the performance of the esc in airplanes?

Thanks.

Steve
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May 08, 2010, 08:09 PM
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Bruce Abbott's Avatar
Both of these controllers are actually made by Hobbywing. As new chips (FETs, regulators etc.) have become available, they have upgraded the specs. The BEC in the old Pentium 40 (AKA Plush 40A) used a linear regulator, which was prone to overheating when using more than 3 servos on 3S Lipo (2 servos on 4S, 1 on 5S). The latest version uses a switch-mode regulator which is good to 6S. However it seems that Hobbyking are still selling the old version.

A switch-mode BEC works better at high voltage because it switches current through a coil to 'transform' the voltage down to 5V, rather than just wasting the excess voltage. On 3S Lipo a linear BEC is less than 50% efficient (it wastes more power than it delivers to the receiver and servos!) so it needs a heatsink and good airflow to avoid overheating, while a switch-mode BEC is 80~90% efficient so it has no trouble staying cool.

The Guard 40 (AKA Sentry 40amp) always had a switch-mode BEC, but originally it was only good for 5S Lipo (it can now handle 6S). Also the FETs have been upgraded, so it is now rated for 55A (same as the Pentium 40). Note that this is burst only (10 seconds max.) - for normal operation you should still prop for less than 40A at full throttle!

My guess is the Plush 40A is more popular because it doesn't have the balance connector, which is a pain to use and may damage the ESC if not plugged in correctly. In fact you do not need to plug it in at all, in which case it is just a useless appendage...
May 08, 2010, 10:11 PM
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Bruce, thanks very much for the thorough explanation. So, if I understand correctly, the 40A switch mode bec Sentry is actually a better esc than the old style40A linear bec Plush? And, you are saying the Hobbywing as offered by ValueHobby is the same as the Turnigy.

Good information to have. Thanks again.

Steve
May 09, 2010, 01:01 AM
Registered User
Sir,

Go over to Ebay and look up Pentium brushless speed controllers. Look at the selections and buy one of the Hobbywing Pentium version 3.1 40 amp speed controllers. Version 3.1 features the switch mode bec. Prices vary a little, but I picked up one for $25.00 shipped about a week ago. Got it yesterday. Nice....

I ordered another one because the price is so good. I have been using Pentium 3.1 60 amp controllers for awhile. So far, an excellet product at a great price.

Mickydee


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