I'm currently using an Epever mppt controller. (one of their "higher end" units but they all seem similar in design)
The problem I have is if I get several cloudy days (normal) and my batteries deplete, the controller shuts down. Then the sun comes out finally but the controller stays dead. It only gets its power from the battery and not the panel. Really stupid design imo.
Seems like accurate specs /basic operation info for controllers is hard to find so hoping someone out there has come across what I'm searching for, which is :
An mppt controller that can power itself back up when the sun comes out and charge the batteries.
Maybe I'm crazy but isn't that their only job?
And I refuse to believe that it's only a "feature" available on a unit costing $1000+
My setup is minimal and I can't justify that much expenditure. Maybe $250 tops. (40amp range)
Thank you in advance!
Seems to me you might either have a faulty charge controller or are draining down your batteries more than is healthy for them or for the charge controller to power itself. How depleted, what voltage, are your batteries when the controller shuts off? If you are using a inverter they often have a built in LVD, low voltage disconnect that protects the batteries. If not using a inverter you can get LVDs on Amazon or eBay to protect your batteries.
Fully discharging the batteries is a bad no-no for battery health. Your system definitely needs some sort of disconnect. On top of that, you may wish to consider a generator set up to charge the batteries in times of need. Hubby & I live where we don't always get good sun. We check our battery readings daily and will tup them up with the generator as needed. We get 5-7 good years out of a battery bank before they start showing signs of failing.
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I bought a Outback Flexmax 80 it defaults to 24v, my setup is 24v it only needs the battery for the initial setup. It was a bit pricey at a little over 500 but has some nice features. Frog mountain on Amazon if I remember right.
The Flexmax80 can be setup for 12, 24, or 48v systems with a Max of 80 amp input.
posted 3 weeks ago
Thanks for the great replies.
Small 200w/100 amp-hr 12v system.
Regarding disconnect, I have load disconnect, but I hang a few devices directly off the battery. Since I can run those things at a little lower voltage, I do, and it gives me more 24/7 reliability. It is a remote and unattended application so I can't tend it at all.
Actually it is only during the couple of dismal low sun angle and snow months that I have any issue at all, nothing that doubling my battery capacity and panel count won't solve, but once again trying to spend less not more. I am currently not severely discharging as I have a bypass system that continues to charge up to a point, but the controller is the weak link because it can't recover from a slightly low voltage condition.
A controller that can power itself from either the panel input and/or the battery would solve my dilemma. I figured such a thing might exist, but I guess not.
Thanks for the tip re the Outback controller, they do seem highly rated, but hoping for a lower priced option that'll do what I'm looking for.
I'll probably just bite the bullet and double the capacity since I could benefit from a little more reserve power anyway.
posted 1 week ago
So I added a timer module on the Load output from the Epever Controller and it now delays the transition from the solar panels bypass (direct to batts), to being managed by the controller, to prevent the drain/loop issue. Now my system recovers nicely once the sun comes out from the thick cloud cover! Total cost of the timer module and bypass relay and misc connectors around $25. But since I could benefit from increased capacity for both storage and charging I still plan to double those things. I'll probably get an Outback controller eventually as I think it will just do a better job with the increased capacity, and also eliminate the need for the bypass mode patch.
Thanks again for all the good suggestions.
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