Oh No ! I bought a Mppt Solar Controller
I don't believe it ! I bought it and I don't really even want it ! I was sure this would go for more than 12 bucks. Fooled me, oh well. Whats w/ links not working ?
Forum Discussion
Been running the new controller on just one battery (135AH approx. at 81% approx. at start) to see how it works.
Started at 9am, 13.0v getting max amps (around 8.2) on the 130w panel mounted on swivel tilted. Reached 14.3v by 1pm and hold ing there for three hours.
So, 14.3 is the high set point, and there is no two hour time limit like with the LS2024 at 14.6v.
Controller is PWM, not MPPT, in that charging amps never go over panel Isc. Also, once the set point is reached, it stays there, no up and down like with the Shunt type controller, so it acts like the Series type, and amps do taper while batt voltage is held.
However something interesting happens once you reach 14.3v. The spread between array voltage and batt voltage on the controller terminals changes drastically. On the way to 14.3, it stays at about 0.24v as reported earlier.
On first reaching 14.3 batt, array was going between 15.1 and 14.8 and the red "solar" lamp on the controller had started flickering.
30 min later, still at 14.3 batt, array 16.10 and jumping around down to 6.99, back to 16 etc.
30 min more (1 hour) now array is steady at 17.17v, batt 14.28, amps 3.1 (still tapering)
another 30 min and array is 18.13v batt is 14.37 and showing 14.4 Trimetric
another 30 min and now Tri is showing 14.3v and 1.3a. Controller has 16.45 up and down to 6.7 whatever, batt 14.27
Disconnected to check panel--Voc 19.7 Isc 8.09
Ok, what the heck? It looks like the controller is controlling that voltage to stay at 14.3 by playing with its "array" voltage.
The controller manual says when the solar lamp is flickering like it has been all this time since the batt voltage reached 14.3,
"When red LED is flickering, battery is MPPT charged up in constant voltage."
So we learned before that with MPPT, array voltage and batt voltage is quite different with MPPT and with PWM is is nearly the same (actually array is a tad higher but not a lot - under a volt let's say)
So instead of calling this a "fake MPPT", maybe we should be giving them some credit and just find some different terminology that does not deceive English speaking people as to just what this thing is?
Note--I am not sure if this test can run long enough to see what happens next as the battery gets to "full" It is still in "absorption at 14.3 , 1.1 charging amps three and a half hours since reaching 14.3.
Sun is getting lower. On controller, batt voltage, 14.28, array voltage 15.94 down to 3.9 etc back and forth.
Anyway, either this thing will drop to Float or not or else batt voltage will fall off anyway due to the sun going down. So I will report on that later.
--Add in, at four hours since reaching 14.3, batt voltage rose a bit about 20 min ago to 14.4 and is holding there! Trimetric shows 14.4v, 1.1a. Controller has batt voltage 14.37 and array voltage is 18.29 dropping to 6.x whatever off and on. ----Getting weirder folks! Meanwhile the sun keeps going down, so this story might not have an ending. :(
I have to hook up the other batteries and get back to what passes for normal around here.
Last little test--four and a half hours since 14.3, now 14.4 for an hour, went panel -direct (no controller). Tri jumped to 15.8v and 4.3a. Back to controller and back at 14.4, 0.9a.
Got to stop the test, sorry. Need all four batts!
Started at 9am, 13.0v getting max amps (around 8.2) on the 130w panel mounted on swivel tilted. Reached 14.3v by 1pm and hold ing there for three hours.
So, 14.3 is the high set point, and there is no two hour time limit like with the LS2024 at 14.6v.
Controller is PWM, not MPPT, in that charging amps never go over panel Isc. Also, once the set point is reached, it stays there, no up and down like with the Shunt type controller, so it acts like the Series type, and amps do taper while batt voltage is held.
However something interesting happens once you reach 14.3v. The spread between array voltage and batt voltage on the controller terminals changes drastically. On the way to 14.3, it stays at about 0.24v as reported earlier.
On first reaching 14.3 batt, array was going between 15.1 and 14.8 and the red "solar" lamp on the controller had started flickering.
30 min later, still at 14.3 batt, array 16.10 and jumping around down to 6.99, back to 16 etc.
30 min more (1 hour) now array is steady at 17.17v, batt 14.28, amps 3.1 (still tapering)
another 30 min and array is 18.13v batt is 14.37 and showing 14.4 Trimetric
another 30 min and now Tri is showing 14.3v and 1.3a. Controller has 16.45 up and down to 6.7 whatever, batt 14.27
Disconnected to check panel--Voc 19.7 Isc 8.09
Ok, what the heck? It looks like the controller is controlling that voltage to stay at 14.3 by playing with its "array" voltage.
The controller manual says when the solar lamp is flickering like it has been all this time since the batt voltage reached 14.3,
"When red LED is flickering, battery is MPPT charged up in constant voltage."
So we learned before that with MPPT, array voltage and batt voltage is quite different with MPPT and with PWM is is nearly the same (actually array is a tad higher but not a lot - under a volt let's say)
So instead of calling this a "fake MPPT", maybe we should be giving them some credit and just find some different terminology that does not deceive English speaking people as to just what this thing is?
Note--I am not sure if this test can run long enough to see what happens next as the battery gets to "full" It is still in "absorption at 14.3 , 1.1 charging amps three and a half hours since reaching 14.3.
Sun is getting lower. On controller, batt voltage, 14.28, array voltage 15.94 down to 3.9 etc back and forth.
Anyway, either this thing will drop to Float or not or else batt voltage will fall off anyway due to the sun going down. So I will report on that later.
--Add in, at four hours since reaching 14.3, batt voltage rose a bit about 20 min ago to 14.4 and is holding there! Trimetric shows 14.4v, 1.1a. Controller has batt voltage 14.37 and array voltage is 18.29 dropping to 6.x whatever off and on. ----Getting weirder folks! Meanwhile the sun keeps going down, so this story might not have an ending. :(
I have to hook up the other batteries and get back to what passes for normal around here.
Last little test--four and a half hours since 14.3, now 14.4 for an hour, went panel -direct (no controller). Tri jumped to 15.8v and 4.3a. Back to controller and back at 14.4, 0.9a.
Got to stop the test, sorry. Need all four batts!
