Dimension Engineering Park BEC Test

[BrianG]

Mike sent me a Dimension Engineering ParkBEC switching BEC to test.

Meant for smaller-scale projects (1/18-1/12), the ParkBEC is specified to provide 6v at 1.25A continuously, and 1.5A bursts for 60 seconds. If you happen to have two of these, and need more current, Dimension Engineering says you can parallel these units. However, the output voltage will be slightly reduced. This BEC can also accept voltage levels up to 8s.

Here are a few pictures for size comparisons.

So, I hooked it up to my 12v power supply and ran various loads through it to test this little regulator:



Observations:

• Voltage output is very close to the rated voltage, and is very stable across all tested loads.
  
  
• Peak efficiency is quite high at almost 90%. Even at the extremes where there is no load and then exceeding its current rating, efficiency is still over 70%.
  
  
• Temperature stayed a very reasonable level as well, despite my attempt to overload it. Plus, there is a little heatsink as part of the BEC, so that helps keep temperatures down.
  
  
• This BEC supplies a very clean DC voltage, even at high loads. AC ripple on the output was below measureable limits for my Fluke true RMS meter. I did read 1.4mV AC, but I get that value even when I short together the meter leads. So, that noise must be coming from my flourescent bench light.
  
  
• Dropout voltage is almost 2v. So, this is NOT meant for systems running only 2s (6 NiMH cells). For best results, use no less than 3s or 8 cells with this unit.
  
  
• No ESC throttle cable modifications are necessary (cutting/removing the red wire). You plug the ESC into the BEC, and then plug the BEC plug into the throttle channel on your receiver. This allows you to keep the battery and AUX channel slots free. However, if you don't want to insert this device in line with the throttle cable, it can also function perfectly fine when hooked up isolated like any other BEC.

Yea, the ParkBECs are nice. How much current does a high performance standard servo draw? I would think a ParkBEC will be plenty even for cars upto 1:8.

Another nice BEC for cars would be an SBEC by Firmtronics. Small, 2A continuous, and it has a switch!

[GorillaMaxx360]

Brain i am not much into the technal stuff but if i do say so my self i like the look of this better than the kool flight one that mike sells. do you think that i could use this bec to run on my maxx or will this only work for the smaller vehicles.

[MetalMan]

This BEC looks to be a solid unit (I wouldn't expect much less from Dimension). What I'd be more interested in, though, is the Sport BEC.

[BrianG]

Yeah, this BEC surely is itty-bitty compared to the Koolflight. And it's built well too.

In a later thread, I plan to test several servos that I happen to have under idle, typical load, and stall conditions. People can then use this info to select whatever BEC that will work.

[Serum]

the eagletree flight recorder can record this IIRC

[BrianG]

Yeah, but I don't have one. My Fluke multimeter has a record function so I can get the various measurements.

[bdebde]

I think they would work fine with single servo, all but the real high torque ones maybe. I just put one in my 1/8th buggy, running old hitec 605mg. Works fine on 3s, only because I don't have 4s pack yet.

[Serum]

Heya, so does my Fluke. IIRC, i've got the 87mkII or something like that..

[hyperasus]

wow. That's tiny. Too bad it isn't good for 2 cell applications.

[sjcrss]

good info...im actually looking into getting the sport bec...but im not to sure about it .....

[BrianG]

bdebde: Yeah for single servo 1/10 scale applications, I think it would work fine. And don't forget, the only time a servo will pull a lot of current is under heavy load, or mechanically stalled. When the vehicle is moving, there is a lot less servo load when you try to turn than if you were stationary.

Serum: I'm using the Fluke 87. It's old, but I just had it recalibrated a couple years ago so it should be quite accurate. For some of the non-critical measurements, I also use a couple of el-cheapo multimeters from HarborFreight. Sometimes you just gotta mave multi-multimeters. :)

hyperasus: Well you could use it for 2s, but the high dropout voltage would not allow to get 6v, especially when the pack is close to depleted. But really, a linear regulator works fine since the supply voltage is so close to the output voltage. the efficiency of a linear regulator gets very close to a switching one at low input voltage. It's when you get to 3s+ when the power loss becomes more drastic.

sjcrss: If you are running a single servo in 1/10 scale application on anything above 2s, than this should work just fine. I'd use it in my CRT.5 if I was running 3s. I believe Mike has more so if you do decide to get one, let him know...

[Serum]

LOL, not working for Xerox, are you? got mine from them..

[BrianG]

Actually, I did get mine from a previous employer. The manager was trying to use it and the display would flash on and off. He tried a new battery and it didn't help, so he was going to throw it away. I told him I'd fix it so he gave it to me. I got it home and installed a fresh battery and it works like a charm. I even told him the workday that all it needed was a new battery, but he had already gotten another one and said to keep it.

[BrianG]

Since this isn't the first (and I don't think will be the last) BEC test I do, I made a constant current circuit that let's me dial in exactly the current I need. Pretty simple, and will let me test currents from 0.5A to 10A with infinitely variable currents in between. Just an Op-amp, a couple transistors, a heatsink, and a few other small parts. :)