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- Verified Buyer
I've had mine for over a year and it's just perfect for what it is. Vastly better charging than the dumb threshold on/off units. Temperature compensation is excellent. Albeit not MPPT, it really gets your batteries charged to their peak charge by floating the proper temperature-compensated voltage/amps to them. I.e., cold mornings you'll see like 14.6v, hot summer afternoons 14.2-ish.How it works: When your battery needs charging, it directly connects your solar panel to your battery, so your solar panel voltage drops to battery voltage (below optimal, which is why MPPT is better). As the battery is charged, the voltage climbs to meet the target (say, 14.4v), it starts pulsing the current very rapidly to the battery to give it just the right amperage it needs to hold the target voltage. You'll see the solar panel voltage rise above battery voltage as this starts to happen. The target voltage is held and over time, the amperage taken from the panel decreases. Cool.My application is my first dip into solar to maintain two big batteries in my Dodge diesel pickup that isn't driven often and is not located near an outlet. And when it is driven, the system only puts out 14.0 volts, not 14.4 like many other cars do, so while batteries certainly get a charge while driving, short drives can't replace all the energy taken on start-up. Compare that to say my 2008 GM which puts out 14.7v for the first 15 mins or so, then 14.4.Even in the short winter days, a 10 watt panel is overkill, probably could have gotten by with a 5 watt panel. Again, my use is not "charging", it's "maintaining." I agree a 50W panel is about the max you can use on this, which is rated to be 4.5A at 12v (54 watts), or ~3.8A at 14V. That's still a pretty good charging rate for a single battery in applications where it is discharged.I might put the solar panel in the interior (factory tint side windows block quite a bit) and see how it goes. Then again, I might bring the batteries to the basement for the winter and treat them to weeks of desulfating from my BatteryMinders.I use a "Watts Up" on the solar side and battery side to monitor Whr, amps, volts, etc and a voltmeter on the batteries. Neat stuff![Dec 2016 update], mine's still working ok, but the voltage compensation seems to be not working (14.1 is common at low temps - reached out to support, just past the 5 year warranty though). It hasn't gotten much use in the last year or so. With my common flooded lead acid batteries, floating most of the day at peak charge voltage caused more water loss than I expected/wanted (then I over-watered them, they leaked...then I turkey-based out some out and put in a jar for later...hassle & mess). I updated to a smarter Tracer 1210RN MPPT with the MT-5 display and while additionally being MPPT, after the bulk charge, it has a lower float voltage, solving my water loss issue, and batteries are happy. Sure, the MPPT+display is more expensive (around $100), but I'm happier with it... and it's a hobby...note 100 watt panels have dramatically come down in price this year to ~$120 (fine for the Tracer, not for the SunGuard).
