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MPT-7210A Questions
#31
So I still can't figure out why the ESP8266 is not reliably starting up/connecting, so my inelegant solution is of course to use more batteries... I gave it a 4p pack of junk bin cells (6.81AH total) which should be enough to keep it alive for ~2 days with no sun recharging it. It's charged back up via a buck converter powered directly from the panel. Voltage on the buck is set to 4.2V output, but it's going through a schottky diode, so it is going to be around ~3.85V at 100mA load. I also added a reset button which can manually reset the ESP8266 if it's still not working.

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#32
Now that logging is working consistently, here are a few captures:

3/17/18 - Overcast/mostly cloudy


3/18/18 - Sunny


3/19/18 - Sunny
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#33
Squiggles!!!!! Big Grin
Proceed with caution. Knowledge is Power! Literally! Cool 
Knowledge is Power; Absolute Knowledge is Absolutely Shocking!
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Certified 18650 Cell Reclamation Technician
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#34
It would probably make more sense if you had somewhat depleted batteries, so as all available power would be moved by the charger from the panels to the batteries.
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#35
The chart for the 19th looks beter than my unit performs as the clouds in the morning ramp would have seen it drop and reset to zero once or twice. Overcast day looks typical basic track, pulling the V down to get the power out.

I really like these charts and data as it also shows just how much energy is available but not being used - incentive for larger battery or additional use of the power.... :-)
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#36
Not sure what you mean by not being used, I've been waiting 3 weeks for my battery to get filled up! I can drain it in 45 minutes of charging my Nissan Leaf as I did a few weeks ago Tongue Otherwise I can use my pack to power other household loads for a much longer time, but I'm in an apartment so it's not a real powerwall setup and where my panel is I only get a couple hours of sun unlike a proper roof mounted system.
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#37
The data in the chart looks as if it should be charging a lot more than it is and as a guess you may have the upper voltage setting too low if your pack is not charging.... it would seem like it's charging up to a CV position and then backing off before the sun is lost...

Something does not look right in the data, for my unit at the end of day if it can pull power it pulls the panel voltage right down before the unit loses power completely. I would normally have 3 x 100W in parallel at 18Vmp going in and end of day it tracks down to 8-10V.

Your charts seem to be showing solar voltage up near Vmp and yet there is no output to the battery ?
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#38
(03-29-2018, 07:20 PM)completelycharged Wrote: The data in the chart looks as if it should be charging a lot more than it is and as a guess you may have the upper voltage setting too low if your pack is not charging.... it would seem like it's charging up to a CV position and then backing off before the sun is lost...

Something does not look right in the data, for my unit at the end of day if it can pull power it pulls the panel voltage right down before the unit loses power completely. I would normally have 3 x 100W in parallel at 18Vmp going in and end of day it tracks down to 8-10V.

Your charts seem to be showing solar voltage up near Vmp and yet there is no output to the battery ?

At those points the panel is partially shaded I believe, the open circuit voltage is high enough but as soon as it's loaded it drops significantly. It does look like there's some noise on the voltage, so i think the mpt7210a might be trying to ramp up but can't.
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#39
Hi there,

I am experiencing the same issue of MPT-720A controller shutting down every 5-7 minutes. I have connected a solar panel 120W, maximum power point voltage (Umpp) 27.6, open circuit voltage 32.2, IMPP 4.61 to a 48v lead acid battery (4x 12v batteries connected in series). Battery capacity is albeit very small 4.5ah. All 4x batteries connected in series show around 48v.

I have set the panel voltage to 27.6, battery voltage to 57, battery current to 4.5amp. After starting the controller, it keeps on ramping up the power from 20w to 75w, current from 0.45amp to 1.43amp, and voltage keeps dropping from 27.6 to around 22. Voltage then hovers around 22 and 21.9 and in few seconds the controller resets the current to zero. Controller starts up again in about 20 seconds and again ramps up to 75w. It keeps going in cycle.

I have tried setting the panel voltage to 30, 27.6, 27.4, 27, 26, 25, 24 to see if panel voltage setting is causing any issues, but the problem persists.

I was wondering if you were able to figure out a fix for this issue and share with me. I am in bay area, CA. Would be glad to do a quick phone call.

Greatly appreciate your help here!
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#40
So like many people that purchase these I'm not really using them all as intended.  I use it in conjunction with a 12v led power supply to charge 24v and 36v lithium packs for e bikes and off grid UPS kits.  At this point I have 3 of these things and I have the same issue with all 3.  I will set the amps to 9 or 10 then start charging my packs, but the charging amperage never goes above 3.5.  I've tried different voltage settings, running many battery packs in parallel, as well as setting the battery amp hour and charge time to very low.  I understand lowering the amperage as the batteries get fuller is good for the batteries, but why won't it give me more juice?
I purchased a 250W 12v led power supply to power this thing so I could get a fairly rapid charge (at least up to 80%) on my 16ah ebike battery bank, but now it takes 3 times longer than I had planned on.
The batteries for the ebike I'm charging are 25.9VDC 7 cell 20650 units with their own BMS and low voltage disconnect.
I've got the high charging voltage set to 28.8 in the MPT-7210A.
I've attached a photo of the setup and readout on the display.


Any advice would be greatly appreciated.
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