Yes!
An image of the main board:
Wow! Nice work, and I'm very excited to see the completed thing.
I built up one of the prototype boards. It needed a little hacking to fix a problem with the power MOSFET used to switch the battery on and off… I’ll need to order some more fixed prototype boards.
The battery switch FET is connected to one of the microcontroller PWM timer/counters. This lets you do all sorts of neat things… like implementing a constant-current load. Here is a plot of the device PWMing the power input to a XML T6 P60 drop in to produce a constant 1 amp load on a battery. I was rather surprised that the drop-in worked just fine while being fed pulsed 16 kHz power… I was expecting to have to use a load resistor to do this test.
I let it run until the battery voltage hit the programmed 3.0V low voltage cutoff. Voila! Battery capacity tester. It can also measure cell internal resistance by looking at the battery voltage change when a load is applied to/removed from the battery. The battery voltage is show in red since it hit the LVC cutoff and caused the battery to be turned off. The yellow numbers say that battery has been turned off and those numbers are probably not useful.
if you’re tracking # of seriously interested buyers, count me IN
popcorn. 
I added some code for charging lithium cells… scares the bejesus out of me to test it. Seems to be working though. It’s past the constant current phase and into the constant voltage phase. Hopefully it will end the charge at the proper place…
Interesting project - I’ll keep reading.
The first battery charge test went well. Only charged the cell to 4.05V because of voltage drop in the clip leads/crappy battery holder I was using and I had it stop the charge cycle when the charge current dropped to 200 mA (from a 1A constant current phase).
Texas, what is the voltage range this thing can do, also how much amperage?
50 volts, 20 amps (could be built with 30A sensors)
Wow! Do you have any plans to make this so it also can be used as a power supply? Either way, count me in for one! :D
+1000
Not specifically at this time.
There are four Deans Ultra type high current connectors on the board:
The first is a “battery (or power supply) input. The board measures the voltage and current flowing through the battery connector.
The next is the switched output of the battery connector. It uses a power FET to switch the battery on and off. The FET gate terminal is driven via one of the micro-controller PWM timers. The PWM freq is 16 kHz. The resolution is 10 bit (1024 steps). This connector is used to supply switched power to a driver.
The next connector is the driver output connector. It connects to the driver output leads. For applications that don’t use/test a driver you can connect the driver input connector to the driver output connector.
The fourth connector is the LED connector. You connect the LED or device under test to this connector. The board can monitor the voltage of the LED+ and LED- pins and the current flowing between the driver output connector and the LED connector. For battery capacity testing, etc you can connect a power resistor to act as the battery load.
You could use the FET switch in PWM mode to drive and inductor/diode/filter cap as a buck or boost converter.
In the constant load current mode, you can use it as a kind of buck converter/led driver. It requires a filter cap across the LED terminals, otherwise each PWM pulse dumps the full battery input voltage to the load. The filter cap (I was using a 1000 uF electrolytic) smooths out the PWM pulses (at 16 kHz) to a constant average voltage. For my battery charging test, I used a filter cap. Using a filter cap alone to make a buck converter is not very efficient, but is rather simple.
Also, you can set protection thresholds for the battery voltage (too low or too high), battery current, LED/load voltage (too high) and LED/load current, and temperatures. If any protection value is tripped, the battery switch is turned off and can’t be turned on again until the fault condition is removed.
are you planning to sell these - as a kit, or built?
Built…
This sounds so cool! :bigsmile: Do you have any pictures?
And when can I get my hands on one of these things? :P I really want one...
Interested!