Hello all,

This is a quick review of the Makerbase VESC 75100, which I have been using nearly daily on my EBike for the past ~2 months. So far, this VESC has been fantastic and has put up with peaks of ~4kW and motor currents up to 140A; however, this device could likely take more! But, before getting into that, we have to start with the downside,

This ESC can not, or at least should NOT be used in its stock condition from the factory. As has been pointed out here on Reddit and on the forum.esk8.news forums, the 3x bulk capacitors inside are not secured to anything and are free to bounce around inside the enclosure. This is a ridiculous design flaw. Fortunately, this is quite easy to fix! The two options for fixing this are to either pot the entire device in a firm potting compound or epoxy, or to 3D print a bracket to which the capacitors are glued/epoxied. A user on Thingiverse has designed a 3D printable mount to secure the capacitors inside the enclosure. This model can be found here: Flipsky 75100 Capacitor Mount

I chose a combination of these two fixes, using the 3D printed bracket, and potting the entire device in SYLGARD 527 Dielectric Gel. I can't recommend using this compound as it remains very gel-like; I would have preferred something more viscous, but it has worked well thus far and is theoretically removable. However, once these capacitors are secured, the device is quite solid. If you don't feel comfortable investing the time in disassembling the device (relatively easy), securing these caps, and potting the ESC, I would recommend one of the newer VESC 75100 variants like the Pro V2 instead.

Once this has been remedied, you have quite a nice, waterproof, ESC which I have tested up to 140A of motor current pushing almost 4kW while remaining under 50°C. Another video of a similiar VESC 75100 from Flipsky shows it sustaining 200A of motor current at nearly 5kW, but their device overheats after ~20s, however this is due to the Flipsky design using a piece of Kapton tape between the TO-220 MOSFETs and the aluminum block, resulting in horrible thermal transfer between the FETs and the outer case. The Makerbase version instead has all of the TO-220 MDP10N027 MOSFETs, soldered to an aluminum-clad PCB, which is then directly mounted to an aluminum block and then onto the outer enclosure casing. This is a far more effective thermal solution and is why my device remains under 50°C in my demo video and in all of my most intense riding outside of it! For more firmware info and teardown pics of my ESC, refer to this thread.

In my demo video here, you can see my own personal test using this Makerbase VESC 75100 on my EBike. From timestamp 0:47 to 1:37, the ESC temp only rises by 5°C at an average of 1.5-2kW of output over the entire 50s interval.

If you are interested in potting this ESC, I have designed a simple potting fixture to hold the ESC upright while curing. I have also designed a simple mount for attaching the ESC to a bike tube. Both models are linked below:

• VESC 75100 Potting Fixture
• VESC 75100 Bike Tube Mount

Additionally, the ESC is currently on sale from AliExpress and can be had for under $47 shipped using the promo code USMS05 for $5 off. For under $50, the value really can't be beat. And no, I haven't been paid or compensated in any way for this post.

TL;DR: NV14 + external 2S 18650 power + ES24TX Pro + EdgeTX v2.10.6 = a surprisingly capable long-range transmitter. Most of the difficult hardware mods can be skipped with external power. Full modification doc and 3D models linked below.

The Flysky NV14 Nirvana (aka UndergroundFPV Dark Knight) first launched almost 8 years ago, in late 2018, to mixed reviews and plenty of bugs. I purchased mine in April of 2019 for ~$160 and only used it a few times before I fell out of the hobby, and it sat in a box for many years... until recently, when I finally got it back out and became determined to make it a usable transmitter!

I'm happy to say that after many hardware mods, a few 3D models, and a lot of trial and error, my NV14 is finally a very capable transmitter I've used for long-range FPV planes and quadcopters. Albeit with one remaining software bug, I'll cover at the end.

First, I owe all of this to Stefan73, qba667, Michael Pastor, Viktoras Šidlauskas, zandorsp, and any other authors who worked and posted on the original RC Groups Forums, and elsewhere, about this radio and helped create some of the modification documents. Without them, I would have never dug deeper into improving this radio. The first document I stumbled upon was the "Fixing the Power Switching of the Flysky Nirvana NV14 Module Bay" PDF; however, this was replaced by the improved "Power Mod & Bay Mod of the Flysky Nirvana NV14" version, which is what I followed to get the JR Bay on the remote working with my ES24TX Pro module. After completing all of these mods, I went through and updated the entire document. I improved formatting, updated images, wording, links, and added Appendix 1 and 2. This improved document can be found at the link below:

Power Mods & JR Bay Mod of the Flysky Nirvana NV14 - V2

However, even after performing all of these hardware mods, my radio still had issues powering my ES24TX Pro module above 100mW of TX power, so I decided to externally power it. To do this, I created the 3D model linked below, and shown in the images above, to mount 2x 18650 batteries in a 2S1P configuration with a USB-C charger and switch. I also remixed a model to replace the ES24TX Pro case to fit properly in the NV14 and provide a cutout for a 2-pin JST connector.

The upside of powering your JR Bay module externally is that the majority of the complicated hardware mods can be skipped! The only mod required is Step 7: Removing pull-up on S.PORT line. For more information, refer to Appendix 2 of the document linked above. This significantly lowers the barrier to entry for someone looking to fix up their NV14, and I highly recommend this path to others.

3D Models:

• Flysky NV14 Nirvana External Battery Holder 2S 18650
• Happymodel ES24TX Pro 1W JR Bay Box FlySky Nirvana NV14 Mod - JDA

Issues

With all of these HW issues taken care of, the only major bug the NV14 still suffers from is EdgeTX issue #6112 "Flysky el18/nv14 Switch Function Lost". Due to this bug, I do not recommend using any EdgeTX version later than v2.10.6. I have been running v2.10.6 for many hours of flight time and have experienced no issues. While it's a bummer I can't use the latest and greatest EdgeTX versions, there is nothing major I have found myself missing in v2.10.6, yet.

Other Notes:

• The NV14 idle power draw with the built-in AFHDS 2A module off, no external module connected, and the display in standby mode (dimmed), is ~1W with a 4.2V supply.
• The Happymodel ES24TX Pro draws a max of ~6.4W at its max 1W TX power with a supply voltage of 5V.
• The EdgeTX GPS widget I am using is from https://github.com/dbarrios83/edgetx-widgets; however, my PR adding the plus code generation is still open at the time of writing.

Hello all!

I recently acquired a HOTA T6 from AliExpress for $40. Over the last few weeks of testing, I have been very impressed with this little charger! First, the balance voltage accuracy stock from the factory is phenomenal; every channel I tested (1-4) was within roughly 0.001V (1mV) of its true reading when compared to a calibrated Keithley 2000 DMM. The charge current accuracy was pretty good, all measuring lower than stated, from 1.8% at low current (1A) to 2.5% at high (9A), however, I can't guarantee the accuracy of my Amprobe AM-530 DMM. I was only able to test up to 150W of XT60 input power (my own PSU limitations) and 90W of USB-C charging power, but it worked great under both conditions. The small 40mm fan on the rear of the unit is relatively quiet and does a good job of keeping the unit cool, even under a max 10W discharge load. At steady state, I didn't see its internal temperature measurement rise above 62 °C. Due to my mediocre test setup and unknown AM-530 accuracy, I can only estimate that the charger has a conversion efficiency of ~86% to ~96%. To properly test this, I will need to use a calibrated current meter/shunt and measure the input/output voltage simultaneously. If this is something people are interested in, please let me know below.

Overall, this tiny charger has exceeded my expectations and is a big improvement over my previous Toolkit M8, which had poor voltage accuracy, loud fans, and kept blowing fuses.

USB-C PD

The USB-C PD interface works well. I was able to test with a 20V 5A (100W) USB-C charger and had no issues charging at the full 90W peak as advertised. Do note your USB-C power supply must support a higher voltage PD spec of at least 9-12V. I had success with a 12V 1.65A PD charger, but did not have a 9V max PD charger to test with. It will NOT work with a typical 5V only USB-C charger, at least in my testing.

My HOTA T6 System Info:

(Listed for reference in case firmware updates change anything)

HW: 1.0.2 | LD: 1.0.3 | SW: 1.0.14

I will make sure to come back to this post and edit or comment below if this charger has issues in the future.