dc-dc module/bench supply/solar controller/milliohm meter?

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EternityForest
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Joined: Mon Apr 19, 2010 3:20 am

dc-dc module/bench supply/solar controller/milliohm meter?

Post by EternityForest » Sun Aug 21, 2016 5:45 pm

There's a lot of things that are just an MCU,a switching regulator, and a display. So why not a little board with a teensy or an Arduino-like chip, a display, some rotary encoders, and 1 or 2 fully controlled buck boost converters plus a 5v converter to power the teensy and display.

Linear makes a chip with full input and output current monitoring and limiting and input current regulation thst works up to 80 volts. The output current is based on choosing the size of the sense resistor which is hard to control digitally, but you could use an external feedback loop and probably still have well enough bandwidth for charging batteries and driving LEDs as long as you didn't hot swap the LEDs, plus you would still have the internal current limit to protect the fuses.

80 volts is IIRC just high enough to be able to use 60 cell solar panels and still use TVSS protection, but even with a different chip with less voltage capability a module like this would be useful for a lot of things.

Such a thing would make a great UPS for a raspberry pi, it could serve as a solar charge controller without the annoying requirement to connect the battery before the panel which is inconvenient for portable use, you could put some protection resistors on the analog inputs and do 4 wire measurements.

A solar charger with the ability to not only do MPPT but implement whatever charge algorithm you wanted would be amazing for anyone with lots of random batteries just lying around, and being able to do CC/CV charging with suitably protected lithium cells and an external balancer would be great.

In a power outage or offgrid scenario something like this would let you run almost any DC appliance on whatever was power was on hand. You could power guitar effects pedals with a bit of filtering, you could run a laptop, etc.

You could probably even make an acceptable DC powered soldering iron or hot glue gun or foam cutter by using the 4 wire resistance to measure temperature of the heating elements.

Plus, they are always working on new battery chemistries, and something like this would remain useful when current tech is obsolete.

And at the moment, combination electronic load and power supply units are pretty expensive. With the 2 switcher version it would just be a matter of putting a big resistor on the output of a switcher, setting the output power limit appropriately to protect the resistor, and then using the input current limit to control the load. You could do automatic battery cycle life testing, or automatically create graphs of switcher efficiency or diode Vf.

Also, with a teensy or some such fairly powerful controller on board you could add features with extra add on modules pretty easily. You could use the display and UI to control external stuff. You could even have a balancer add on that made it equivalent to a real RC hobby charger. With the MCU running an RTOS there shouldn't be too much of an issue using it for other features besides the main power supply functionality. At the very least making a portable power pack with the UI also controlling a lantern or something seems reasonable.

If there was 2 buck/boost regs you could use them for motor drivers and use the 5v output to power a raspberry pi and have a robot!

The ham crowd would probably love having a truly open solution to solar charging an monitoring that didn't require building from scratch, but could still handle MPPT. At the moment MPPT controllers usually require you to connect the battery before the panel, which is one extra not-user-friendly feature for portable use if you are going to be charging multiple batteries with one panel and controller.

I think something like this would be worth at least the price of a low end dual output bench supply plus a load, which is not exactly cheap. The only real issue I can think of is the possible safety issue with charging Li batteries, but especially with protection circuits and community reviewed firmware I can't imagine this being much worse than a no name clone hobby charger.

skimask
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Re: dc-dc module/bench supply/solar controller/milliohm mete

Post by skimask » Mon Aug 22, 2016 9:13 pm

So...what's the question?
I ignore "one post wonders".

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