Hobbywing Ezrun Mini28 30A

Today's we will install the Hobbywing Ezrun Mini28, a popular micro ESC used in many 1:28 and 1:24 applications. Currently on my Reflex RX28K, it's got the GL sensored ESC. It's not bad but the throttle curve doesn't feel linear enough to me, and the reverse delay is long.

I picked up the Hobbywing Mini28 a while back. Physically it's even smaller. It's great, but not perfect. Let's find out. Thankfully, Hobbywing included all the cables needed. It's got both the JST-ZH and JR control cables, plus sensor cables with both the large and small connector. My older GL sensored motors use the large sensor connector, but the current ones use the small version.

Let's disassemble all the electronics from the chassis. A RWD chassis like this is pretty straightforward. It doesn't take long to strip it down. My supervisor Loki dropped by to check my progress. I'm taking the opportunity to upgrade the A06CLS servo v1 to this v2. V2 supports 7.4v BEC for a faster response.

Compared to the second gen, this first gen RX28 is more limited in electronics real estate. The Mini28 ESC can fit, but the wires must be resoldered to come out vertically rather than horizontally out of the factory. Luckily, my soldering skill has improved significantly. There's just enough room here to position the ESC in this optimal position in terms of weight bias.

I'm pairing the GL sensored 3500kv motor with the ESC. The biggest issue with the ESC is it doesn't play well with sensorless motor for some reason. I'm pretty happy with the tidiness of the motor wires.

As usual, let's do a quick test before taping everything down. Everything looks good here. Cristian at Reflex Racing designed the chassis to accommodate the servo and nano receiver like this for the lowest possible CG. The chassis looks much cleaner than before. The left vs right weight distribution should be improved as well.

As expected, the Hobbywing sensored system is smooth at the low end. Please remember to use this ESC only in sensored mode. Let's experiment with the ESC throttle response by disconnecting the sensor cable. What used to be smooth is now cogging heavily at start up. I don't know if this problem can solved by programming the ESC to use more power at startup. Please let me know if you know how. Thank you.

The ESC is programmed using this LCD Program Box. My older program box for the GL 1.2 ESC is not compatible. Use the JR connector included with the ESC to connect it to the program box. Use the middle socket as we are powering the program box using the ESC BEC directly. This ESC is extremely programmable. All the items are described in the manual (also available online of course). It can be programmed to output 7.4v BEC. I'm going to set this because A06CLS v2 and Easylap transponder can operate at 7.4v. I'm also setting drag brake to 50% now, but later I will reduce it to 35-40%. I max out the brake force setting since I use the transmitter EPA to adjust the amount of brake power. There are also a ton of settings around boost and turbo.

Before hitting the track, let's do some sanity check first. Throttle control feels comfortably linear. In fact, the linearity feels similar to the GL 1.2 ESC which I really like. Throttle response is also immediate. There's no lag.

I took the RX28 to Brooklyn Hobbies to test the ESC and car in a much more demanding environment. FYI, this is Hobbywing Mini28, GL sensored 3500kv, A06CLS v2, PN KS med slick front, Marka 15 slick rear. The body is a red Jomurema. I'd say this is a medium speed Reflex car with a driver who is not very fast at all. I'm not fast enough to test the limit of the ESC, but I can say it's very comfortable to drive. I don't get that non-linear feel of the previous GL sensored ESC setup. I get to feel the car more easily. And because inevitably, I crash a lot, it's nice to have a reasonable reverse delay that does not get in the way. This is a huge plus. Interestingly, the reverse delay is not programmable. Fortunately it's not a problem.

On this visit, I was able to exceed my personal best time with this Reflex car. It's so fun to hang out here at the Brooklyn Hobbies track!

At the track, Richie mentioned that the motor pod roll action seemed a bit stiff. Let's investigate further. The problem isn't look to be obvious. All the relevant ball joints are nice and free. But on a closer look, I think the side links do not have any bit of slack to easily allow the up and down movement. I have previously added a 0.2mm shim under the rear pod pivot ball. This was done to remove all yawing play. With the shim removed, the pod has a bit more play, but at the same time the pod rolls more freely. This fix should increase rear traction during cornering. It should perhaps reduce traction roll tendency by a little.

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