I got in the EpSolar Tracer 1210A charge controller + MT50 monitor I ordered off eBay ($80 shipped). It’s a great little piece of kit. Substantial feeling with serviceable build quality. Confidence-inspiring wiring ports. Packed lovingly and arrived safely from the land of green tea in 2 weeks.
I hooked the controller to the battery, which was already in Absorption stage on a different charger; it came online. Then I plugged in the MT50 monitor and it jumped to life. Wired in and turned on the 24v power supply (currently set to 23vdc) and with a couple of seconds it had entered the default charging mode (SLA) and the appropriate absorption phase. Note: Absorption stage is called Boost in the monitor. I don’t think that’s an accurate term though I have seen it used elsewhere. It’s especially misleading in an MPPT controller where “boost” has a distinct meaning.
At that point it was running something like:
23.0v @ 1.1A --> 14.5v @ 1.8A
I disregarded the instructions (of course) and poked through the monitor. It took about 2 minutes to figure it out and config custom setpoints and durations. I dropped Vabs to 14.4v so I could see the difference, dropped duration to an hour, set the capacity, and reduced Vfloat to 13.4v.
Then I added some 12v loads I had hanging around: started charging a phone, charging a pair of headphones, running a small 12v compact flourescent. With each addition the controller used more power instead of converting it to heat in PWM cycles.
Right now it is running:
23.0v @ 1.5A --> 14.4v @ 2.4A
Adding and subtracting load doesn’t phase it; Absorption voltage stays steady. I assume that would last until the load outstripped the controller’s ability to hold Vabs (or Vfloat).
I’ll update with more finding later. Must sleep. Changed work shifts (again!) this week and I am a zombie. Blargh.