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Dramatically improve a DC-DC converter: Add WiFi and color display:

rin67630

Solar Enthusiast
Joined
Apr 29, 2020
Messages
1,066
Location
Nort-Rhine-Westphlia Germany
A buck-boost converter is really a nice thing to have, when you have a solar battery bank.
With such a device you can load secondary batteries e.g. from tools, laptops, eBikes, even with different voltages: lower or higher.
That Chinese 38V/6A DC-DC buck-boost converter is well manufactured and damn cheap.
It has that digital seven segment display to show the voltage or current and 4 miniature push buttons to set the voltage/current.
Well, it is usable, but not really comfortable...

I decided to change that and replaced the pluggable control unit by a self-build one consisting of a prototyping board and a TTGO ESP32 microcontroller with an integrated color display.
Juntek&TTGO.jpg
The BOM for the modification amounts to ~20$, just the TTGO module, a prototyping board and a few resistors/condensators.
Everything is self contained, no wires, cables, additional power supply, server, database, extra computer required.

Now the cheap buck-boost converter is transformed in a versatile networked programmable power supply:
- accessible from everywhere over the cloud
- programmable
- with charging profiles for many battery chemistries
- and a couple of additional functions like battery evaluation, internal resistance evaluation and so on...
Juntek Dashboard.jpg

the whole project is described at Github.
Enjoy!
 
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Wow.... Excellent project !!!

1. Very nice concept. Control a solid power converter using an off-shelf ESP32 device with on board status, with network interfacing.

2. Very good documentation, both in the project description, implementation and the code base.

I'm a retired firmware engineer, maintaining numerous battery systems on my off-grid retirement playground.

After a lot of playing around I decided on using the RD Tech DPS 6018 as described below


I have to hack their protocol into my MPPT local server based system.

After reviewing your system, I see 1/2 cost of materials and full source cost code.

When I get a little more spare time I'll fire up one of your systems....

((hopefully by that time somebody will offer a $25 pre-build proto interface board ;-} ))

Great Work !!!
 
I almost pulled the trigger on the "Drok high power (80V/12A buck converter)" that is listed in your GitHub. But then I noticed that it was only a buck converter. I'm confused as to what is the best path to take. Can a boost converter perform as a CV/CC limiter if you wanted to use a higher input voltage than the output you need? What happens if you were to try such a scenario?

Would it be best to look at the compatible ones that are labeled as buck and boost?

Very neat project.
 
A buck boost converter is very versatile and can convert up/down. In fact it is a compound of two converters, therefore it has two coils.
Its first converts up, then down. Of course it can perform as a CV/CC limiter in both situations.
The caveat is that its efficiency is lower: With a good buck converter you can achieve 96% efficiency, with a buck boost converter considerate yourself happy, if you get 90%.
The Juntek it the only buck boost converter I could test. It is not very powerful, but from my purpose: Charging devices and portable tools + testing small batteries it is absolutely perfect.
 
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