Part 1: Initial Observations
I picked up one of Mike's HobbyWing EZRun 80 ESCs he now has in his store and thought I'd provide my humble opinions on it.
Some spec highlights: 80A continuous/270A burst, 4s/12 NiMH cells voltage, 3A switching BEC, 0.0018 on resistance. We'll see about the probability of those specs later.
First, a pic of the box contents. Comes with the ESC with dual Deans-compatible connectors pre-soldered on the power wires (seems like it is meant for dual battery applications) and 4mm bullets on the motor wires. Wires are 12GA. There's extra heatshrink, a few zip-ties, and a couple 3mm screws for mounting. The throttle cable is wrapped around a ferrite ring near the servo connector for reduced RF interference. The ESC has two mounting tabs built into the plastic case.
A couple of pictures showing relative size compared to a MMM. Yeah, it's that big.
The next picture shows the side where the fan and throttle cables are located. The switch is in a little box along with the program button connected via a servo wire. The throttle and switch wires are glued in place to act as a strain relief to protect the traces. The fan connector/wire has an extra output for a motor fan if desired (optional item). This ESC probably isn't meant to be waterproof, but HobbyWing did a pretty good job in sealing the ESC because there is a rubber seal all the way around where the heatsink meets the PCB, and where the bottom case meets the PCB. And any exposed PCB has a conformal coating.
Now for the guts! The fan is held on via four 5mm hex head (3mm) screws. The PCB is sandwiched between the heatsink and bottom case. The switching BEC is located on the brains board inside a little metal case, presumably to shield nearby components from switching noise.
I was pretty anxious to see the FETs, so I was disappointed when I removed the heatsink and found none there! This side of the PCB has heatspreader bars which touch the heatsink via a thermal pad. I kinda like this setup because it helps protect the fairly delicate FET component cases from accidental damage from jarring the heatsink.
And a view of the actual FETs sandwiched between the main and brain boards, which are soldered together via jumper pin headers.
Now for the fun part. Due to the way the PCBs were arranged, I had a heck of a time getting the FET part number, but with the use of creative lighting and a makeshift jewelers monacle, I was able to make out one of the FET part numbers as IRF3709Z
. And there are 18 of these on this ESC.
Looking at the datasheet, we see that each of these FETs are rated for 30V, ~0.006 ohms (depends on gate drive), and 62A @ 100*C (212*F). Since there are 6 FETs on at any one time, 3 of which controlling each motor phase, that brings the current rating to 186A continuous and an on-resistance of around 0.002 ohms. Hmm, not bad at all. Seems like HobbyWing rated this ESC pretty realistically taking into account the temperatures we run these at. And the 270A burst rating seems possible judging from what the datasheet says based on the duration and duty cycle of the pulses. I really didn't want to calculate it out, but you are free to do so if you want.
The three input caps on the ESC are rated 470uF and 25v for a total capacitance of 1,410uF. The 4s rating on this ESC seems pretty conservative. Even running 5s lipo fresh off the charger, the caps would still run 16% below their voltage rating, and the FETs would be running 30% below their rating. But, even if the components might support 5s, I don't know if the firmware will let it arm at 5s, so it's just speculation right now. I'm not saying everyone should run 5s on this ESC, but we all know people will push them beyond the ratings - you know who you are! However, I would NOT
run 6s on this at all. That would be pushing the caps too far and the FETs would have hardly any headroom for any back-EMF spikes.
In reading the manual, I was pleased to see a well-rounded set of programming features: adjustable lipo cutoff, manual lipo cell programming (it will do auto-cell detect, but only for certain pack arrangements), etc. One really neat feature that stood out is the motor reversal. This can be done in three
ways; 1) swap any two wires, 2) via ESC programming, and 3) simply by activating the transmitter servo reversing function (have to recalibrate the transmitter after this one though). This ESC does work with an optional programming card if counting motor beeps is too taxing for you.
All in all, this looks and specs out to be a VERY solid ESC with realistic/conservative ratings. Construction is top-notch too. Unfortunately, I do not have a vehicle I can test this in at the moment, but I will soon. I wanted to get Part 1 of the review out first.
A couple more tests with my bench power supply at 14.76v DC:
- ESC current draw with switch "off": 0mA. Hmm, it seems that this ESC won't drain your batteries if you accidentally leave them plugged in as long as you shut off the switch, but I wouldn't want to find out the hard way.
- ESC current draw with no motor, no load on the BEC, and the fan disconnected: 21mA (373mW)
- ESC current draw with no motor, no load on the BEC, but with the fan connected: 177mA (2.61w)
- ESC current draw with no motor, 2.5 ohm load on the BEC, and the fan disconnected: 999mA (14.75w)
I also tested the BEC a little.
- With no load (fan disconnected), BEC voltage was 5.84v with 23mV of 1163Hz AC ripple.
- With a 2.5 ohm load, BEC voltage was 5.58v with 18mV of 394Hz AC ripple. This equates to 2.23A and 12.44w. Efficiency at this load was 84%.
Efficiency is on par with typical switching regulators. I found it interesting that noise decreased
with load. Odd BEC switching frequency though. I expected frequencies around 15kHz.
Part 2: Operation
I got a new motor mount and battery tray from Mike yesterday, and so was able to do a little running and offer my humble opinion on the performance of this ESC.
I hooked it up in my Hyper8 buggy: Neu 1512/2d (kv=2650) on 4s lipo (5Ah), geared 46/12. Top speed calculates to around 40mph.
First thing I tried was slow speed running. If you just lightly apply the throttle, the motor "chatters" similar to the MM/MMM at less than 1mph. When you give it a tad more, it stops chattering and starts to move, but does this surge/slow/surge/slow behavior. Here is a small (and I mean small) video of what I am talking about
I spoke with someone running a 7XL and it does the same thing, so it's nothing to do with the motor being slotted or 4 pole. So, it's not really good for slow running. Anything above ~3-4mph works fine though. Plenty of power when you goose it.
When I started out, I ran with the fan removed and the body on. Within 10 minutes of running at normal (fast) speed, the ESC thermaled. I re-installed the fan and once I let it cool, I was able to run the rest of the time without any more thermaling. Temps after the run was ~115*F (55*F ambient) with the fan. So, the fan IS
IMO, this ESC is too small to use on for 1/8 scale applications, but I think it would work great on a lighter 1/10 scale vehicle, geared right, and might even be able to get away with running without the fan. For 1/8 scale use, the EZRun150 would probably be a better bet for cooler running.