Happymodel ELRS Hardware
• Chris Landa
Happymodel was the first manufacturer to seize the opportunity for a quick buck and produce ELRS hardware. ELRS is an open source control link and I am pretty sure you have heard about it by now. I am a big fan of ELRS - been watching them basically since the beginning.
I am super stoked seeing more and more manufacturers implementing this Open Source hardware and I am confident that sooner or later it will replace FrSky D8 compatible SPI receivers on AIO boards.
Although Happymodel was the first manufacturer to produce ELRS hardware, BetaFPV was quicker with distribution of their review samples, thats why my BetaFPV ELRS hardware article was released earlier.
The Happymodel line up is very similar to what BetaFPV released, but I only got a sub-set of items for review, that’s why I will stick only to those that I actually have on hand:
- ELRS transmitter modules
- ELRS receivers
- AIO flight-controller
Banggood was kind enough to send me those items for review - thank you for that.
I draw your attention to the fact that there are already discontinued Happymodel ELRS products, so double check what you are buying.
Happymodel ELRS Transmitter Modules
Happmodel provides a couple of different transmitter module options, depending on the radio that you have. There are a couple of things you need to keep in mind when selecting a transmitter module:
- Not all modules are available in either 2.4GHz or 868/915MHz
- Output power - the smaller modules “only” go up to 500mW output power
Slim ELRS Module
The slim module is made for all radios with a slim module bay, like the TBS Tango 2 and FrSky X-Lite. I do not like the design of this one at all - why rip of intellectual property that is so unrelated to the TX module? Sticking two extra bright LEDs into it also makes no sense to me. The module has a fan to prevent it from overheating which is really a nice touch.
The module sticks out in a weired way from the module bay, instead of overlapping it like any other slim module
Sure, it does what it has been designed for and works without issues, but I would have preferred a more neutral design, sticking to the form factor of all other slim modules.
The module itself does not have buttons to change output power. It comes as a kit and you will have to assemble it yourself. This is actually pretty straight forward and you don’t even have to hook up the LEDs.
An antenna is included.
T-Lite ELRS Module
IMAGE: https://www.thingiverse.com/make:948930
The T-Lite module is very similar to the Slim module, but comes with power adapter boards to properly power the external module. Without the need for a power mod.
The downside of this module ist, that you have to install it permanently, so you cannot easily swap between external modules. I am not sure why they opted to go this way instead of simply allowing for the external module bay to be plugged into their power distribution board.
This is the module I got, but I printed a custom back piece, so that I can use it like a regular slim module since I have my T-Lite modded and want to be able to switch between different modules, especially since I want to keep running Crossfire.
I went for this module in 2.4GHz and modified it with a 3D printed part to use it as a classical Slim module. Please note that if you want to run it like this on the T-Lite, you will have to do the power mod or rewire the included PCBs accordingly.
JR ELRS Module
The JR module is made for all “big” radios that have the JR module bay. The big upside of this module ist, that you get the maximum output power. The slim modules only go up to 500mW. With this you can blast your control signal out with up to 1W.
If your goal is to go to the maximum possible range, you should go with the JR modules, they are capable of pushing the highest output power when flashing a spezialised firmware.
Comparison
The ELRS TX product line is a bit confusing, some of the TX modules are discontinued before they even hit the market. I will only list the ones that are not discontinued yet, basically the ones you should buy if you decide to go with ELRS from Happymodel.
| Model | Bay | 2.4GHz | 915MHz | 868MHz | Power |
|---|---|---|---|---|---|
| ES24TX-Lite | T-Lite | Yes | No | No | 250mW |
| ES24TX-Slim | Slim | Yes | No | No | 250mW |
| ES24TX | JR | Yes | No | No | 250W |
| ES900TX | JR | No | Yes | Yes | 250W |
Happymodel ELRS receivers
The happymodel receivers are the smallest ELRS receivers currently available. Most of them have WiFi and all of them come with an antenna. You need to supply your own heat shrink and wires - would have been really cool if that was included with the receiver.
The models with the U.FL antenna have way better range, but the ones with Ceramic antenna are the perfect fit for a 1S whoop - especially to retrofit your D8 SPI AIO boards with ELRS. And the range will still be higher than what you would ever need with your whoop.
There are a lot of different versions and I think it is easiest to compare their functionality in a chart:
| Model | 2.4GHz | 915MHz | 868MHz | Antenna | Weight | WiFi |
|---|---|---|---|---|---|---|
| EP1 | Yes | No | No | U.FL | 0.42g | Yes |
| EP2 | Yes | No | No | Ceramic | 0.44g | Yes |
| PP | Yes | No | No | Ceramic | 0.47g | No |
| ES900RX | No | Yes | Yes | U.FL | 0.60g | Yes |
Weight measurements are of the PCB only, without external antenna.
I am not sure why the PP receiver exists at all: it seems to be heavier than the EP2 and not being able to update it via WiFi seems to be rather inconvenient. Maybe someone could enlighten me as to why one would like to chose this one.
AIO boards
Happymodel is currently offering two different AIO boards: one for whoops and one with a 20mm mounting pattern. Unfortunately I have neither of those, so I can’t really comment on them.
The one with the 20mm mounting pattern seems to have a rather strange layout. It is intended for toothpicks but I don’t know of any frame that would support a flight-controller with this layout. I can only imagine that the flight-controller will be used in one of Happymodels upcoming products.
The AIO board for whoops has been available before, only with FrSky compatible SPI receiver, I guess that is the only change that Happymodel made - a different receiver. I really wanted to like this board since it is a true AIO: VTX, receiver, ESCs - everything on one board, but I had three of them and two of them died very quickly. The third one is still working but the video transmitter is not reliable anymore.
I would be super stoked if the issues that I had with those boards were resolved with the ELRS version - for now I have not yet heard from anyone using this board, so only time will tell.
Compatibility
The beauty of the ELRS system is its cross compatibility - you can mix and match components form other manufacturers: You can have a ELRS TX module from Happymodel and use it with an ELRS receiver from BetaFPV - the only important thing is, that they are all running the same ELRS firmware version.
Conclusion
I really like the size of the EP2 with the ceramic antenna. This is a perfect choice if you want to retro fit your D8 SPI boards with ELRS. You will get soo much better range for only adding about half a gram of weight - totally worth it for me. With a price of $16.99 on banggood there is also nothing to complain about.
For bigger quads, I would probably still go with the BetaFPV ELRS receivers with integrated PA & LNA.
As mentioned above I am not a big fan of either of their slim modules. If you want a Slim module, in my opinion it is your best option to get the T-Lite version and go with a custom 3D print. It will fit nicely into the module bay and does not have an IP infringing design. From fit and finish I definitely prefer the BetaFPV Slim ELRS module.
It seems to me as if the 2.4GHz system will be the prevailing one. I think the pros outweigh the cons, especially when it comes to micros: smaller antennas, lighter builds in total and only one system to maintain worldwide.
Chris is a Vienna based software developer. In his spare time he enjoys reviewing tech gear, ripping quads of all sizes and making stuff.
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