Looks like this is based on/clone of MyAirBot/iPeaka 4-1 ESCs. Looks pretty much the same as the now-discontinued iFlight-RC iPeaka 30A 4-1 ESC. Eachine rates it @35A but that's OK, the IR FH5301 FETs can do up to 100A burst when properly cooled (though that's not possible in an ESC like this one as there's not enough heat dissipating capacity in the PCB. However, they're rated @40A when case temperature is about 140ºC!
I've found the iPeaka version to be a very robust and reliable 4-1 ESC. So far it's worked great. I've been using it on my test-bed quad (flight video testing BrotherHobby R5 2306-2450KV motors = https://youtu.be/0xEdOFq8TGk?t=9m46s )

Banggood is now selling it for a very attractive price. If quality is as good as the iPeaka I've been using, that's a great price and could be worth considering.
This ESC uses the very robust/heavy duty IR Fets - check my video review for more info on those FETs. They're one of the best FETs as far as being able to handle very high loads and working smoothly.

Banggood product page: https://www.banggood.com/Eachine-Stack-X-F4-Flytower-Spare-Part-35A-4-In-1-ESC-2-6S-BLHeli_S-Dshot600-Ready-For-Racing-Drone-p-1220191.html?p=FR3104108021201212@4

Eachine Stack-X 35A/30A D-Shot 4-in-1 BLHELI_S ESC Review (15 min 40 sec)

It is the same as 35A anniversary edition that has been out for a while.
It is also the same is being used on the furibee darkmax stack and other 4in1 stacks in china RTF models.
Looks like they found a nice design which is reliable and now they're using it everywhere.

and I'm cool with that because it's cheap

Only complaint I find the 6s rating a bit optimistic since the fets are rated 30v (IR 5301 right?) which is too little headroom for reliable long term operation.

However I also have a couple of these (from banggood...) working reliably on 5s for now.

For instance I would have preferred IR h7440 fets that have a 40v rating (as used in fvt littlebees). Those are really war tanks.

Those FETs are fairly robust. True the Vds=30V but with a good 35V Panasonic FM/FR 1000uF capacitor it should be good to go on 6S. The other good spec is their Tc or how they get "de-rated" due to case temperature. Those FETs can still do 40A @140ºC. As they should - they're huge compared to other FETs (though size isn't everything) You're right, those IRFR7440 FETs would've been better, but for $28 if this 4-1 proves to be reliable it's quite a good bargain for 4S or even 5S use.

Same here, I've only used mine on 5S since motors are 2306-2450KV, that's plenty of speed for my skills.

Those FETs can still do 40A @140ºC

I'd like to clear an important misconception here. I know datasheets are a little pesky on these details, and it's not clear to understand what those ratings mean, until you really work on them.

That current rating is calculated (yes, only calculated, never measured) using only the thermal resistance of fet junction to the package, but supposing the package to air resistance being zero.

In this example 40A@140°C is equivalent of using an "infinitely good" heatsink on the fet, with an ambient temperature of 140°c.

Instead if you look at the Id @ TA 70°C (first page of the datasheet) it is only 28A.

this one instead is calculated only using the thermal resistance to package and package to air without heatsink, so neglecting the thermal resistance to the pcb, which is the main drain of heat.

in this example is equivalent to the FET flying in mid-air at 70°C, without the pcb nor heatskink attached.


nither of the two is the real case application of an ESC, It's something like a best case and worst case scenario, so the real rating is somewhere in between...

Very useful explanation! i'm not that knowledgeable on IC specs, (CE over here - we deal with beams and dirt LoL) Will definitely refer back to your explanation when needed. Thanks!

For those 4-1 ESC's you would think the 32x32mm PCB should have some decent heat dissipation capacity.