My First MPPT Solar Charge and the Tracer 3215BN

[jrnymn7]

Well, second actually... first one got cut short due to heavy clouds... and a long ways to go to 'full'.

First, I'd like to thank those who were kind and patient enough to help me along this solar path. As BFL once put it, there's lots to learn about solar. All the debates/discussions over pwm vs. mppt, and such, have proven very enlightening and educational, so thank you!

So, here goes:

Bank... 430Ah, four 6's, ocv @ 12.44v, 74%soc, -111Ah's

Solar... two 140w 12v poly panels, in series, manually tracked, thru 50' of 6awg to a Tracer 3215BN MPPT charge controller and MT50 Remote Monitor.

10:50am:

- clear skies

- Isc at the moment was 'about' 9a (x2). (clamp meter not that reliable)

- Voc 20.6v

10:55am:

at Panels... 7.9a @ 31.2v,

at Bank... 18.9a @ 13.0v

The highest amperage I saw all day was at 11:05am, with 19a to the bank. Mostly in the mid 17's to high 18's up until about 3pm. I was a little surprised, given the conditions. A couple days earlier, under mostly cloudy skies, I saw amps in the high 21's several times... but that may have been an edge of cloud effect thing?

At 1:15pm, I switched over to the Solar30 pwm, and saw a difference of 1a to the bank, 17.3a vs 18.3a, for a 5.5% increase by the mppt controller.

Back on mppt, throughout the afternoon amps tapered to the mid 13's range by 6:40pm, and by 7:40pm, amps to bank were in the high 7's.

(At 5:15, I laid the panels flat, east to west, and saw a difference of 5.4a to the bank, 10.4a vs. 15.8a, for a decrease of 35%, compared to tracked.)


Tracer decided the bank was full at 7:50pm, at a little over 7a @ 14.5v. According to the Trimetric; which I believe is very close to being dialed in properly (...will know for sure next time I converter charge); 6.5Ah's were still missing at 99% soc. I usually take things down to less than 4a at 14.5v. This morning, (the next day), after a night of very light loads, ocv was at 12.73v... should be more like 12.77v, so I know the bank was not truly full.

10 minutes after it shut down, the Sun went down behind some distant trees, so the panels crashed, so it wouldn't have made it to full, anyway. And it was not able to go into float mode, so I've yet to see how that goes. But this raises a couple of questions:

? How does the Tracer decide when the bank is at 100% soc?

? Is there a way to re-calibrate it?

Any help would be greatly appreciated.

bn series manual

mt50 manual

In a couple days I'll be doing another run, less deep, and an earlier start, hopefully. That way I can see how the controller handles what it believes to be a full bank.

Another thing I noticed was, when set to 14.5v "max boost voltage", the monitor said 14.6v, and it took the bank up to 14.56v, according to the dmm. When set at 14.4v, it topped out at 14.5v (monitor) and 14.44v (dmm)... which is exactly the voltage I'm thinking will sync up well with my P10 CEF setting of 85%, on the Tri.

There are some other programmable settings I'm not sure about, but I'll post them, later. I'd like to get this '100% soc' thing sorted out first and foremost, seeing as this will be my main means of top end charging.

Thanxx!

[jrnymn7]

12thgenusa wrote:

jrnymn7 wrote:
Re; 100% SOC,

The controller has no idea at what soc the bank is at. Yesterday, it was showing 72%, but after I temporarily disconnected things to do a flat comparison, and reconnected, soc was 50%, meanwhile the bank was at about 95%.

I don't' know the process by which it would ever know. At least the Trimetric counts amps in and amps out with an adjustable discount for amps in. But it does not account for Peukert effect.

The controller has no way of knowing what portion of its output goes to the battery and what may go directly to loads. It doesn't know if amps have been added to the battery through other means. It doesn't know how many amps have been discharged from the battery. Determining SOC from battery voltage while charging or discharging is not possible. Does the manual say how it is supposed to work?

True dat.

No, the manual says very little, if anything about what constitutes full. I edited while you were posting... there is a 'voltage comp' choice in charge mode. My guess is, this will not affect anything, seeing as the controller switches to float once Vboost is reached, regardless.

[jrnymn7]

12thgenusa wrote:

jrnymn7 wrote:
Yeah, he does one with a bosch drill, as well, and although it's at float voltage, it is clearly in mppt mode, as input v & a are way different than output v & a. It appears maybe these things never go out of mppt? I have yet to see mine or any of the ones in the videos ever match input/panel amps to output amps, as I would expect to see in pwm mode.

No. Tracking and bucking are two separate functions. It is always bucking panel voltage down to battery voltage no matter what mode it is in. In fact, unless in poor light conditions the difference between panel and battery voltages will be greater during float and abs than it is when in mppt.

Thanks! I will keep an eye out for that.

But shouldn't panel and output amps be pretty much equal when only bucking?

[12thgenusa]

jrnymn7 wrote:
Re; 100% SOC,

The controller has no idea at what soc the bank is at. Yesterday, it was showing 72%, but after I temporarily disconnected things to do a flat comparison, and reconnected, soc was 50%, meanwhile the bank was at about 95%.

I don't' know the process by which it would ever know. At least the Trimetric counts amps in and amps out with an adjustable discount for amps in. But it does not account for Peukert effect.

The controller has no way of knowing what portion of its output goes to the battery and what may go directly to loads. It doesn't know if amps have been added to the battery through other means. It doesn't know how many amps have been discharged from the battery. Determining SOC from battery voltage while charging or discharging is not possible. Does the manual say how it is supposed to work?

[jrnymn7]

Controller Rebooting;

I tried doing an 89-100% run, yesterday morning, but a thunderstorm rolled in. But before shutting things down, there were fairly light grey clouds of various thicknesses passing by. Sometime between 1 and 1 1/2 hrs in, I found the controller shut down. Not sure how long it was in that state... but less than a half hour, for sure. I disconnected both the array and bank, and then reconnected. Unit went back to normal operation. So it may be struggling with ever changing conditions, like the one in the video. I need to review that video... as I recall it took over a 1/2hr to reboot.

[12thgenusa]

jrnymn7 wrote:
Yeah, he does one with a bosch drill, as well, and although it's at float voltage, it is clearly in mppt mode, as input v & a are way different than output v & a. It appears maybe these things never go out of mppt? I have yet to see mine or any of the ones in the videos ever match input/panel amps to output amps, as I would expect to see in pwm mode.

No. Tracking and bucking are two separate functions. It is always bucking panel voltage down to battery voltage no matter what mode it is in. In fact, unless in poor light conditions the difference between panel and battery voltages will be greater during float and abs than it is when in mppt.

[jrnymn7]

Re; 100% SOC,

The controller has no idea at what soc the bank is at. Yesterday, it was showing 72%, but after I temporarily disconnected things to do a flat comparison, and reconnected, soc was 50%, meanwhile the bank was at about 95%.

So, there is another choice for what constitutes full, as I originally thought. (round and round we go). Charge Mode can be either 100%soc, or 'voltage comp'. Not sure what that means though? Perhaps once Vabs/Vboost is reached?

[jrnymn7]

Yeah, he does one with a bosch drill, as well, and although it's at float voltage, it is clearly in mppt mode, as input v & a are way different than output v & a. It appears maybe these things never go out of mppt? I have yet to see mine or any of the ones in the videos ever match input/panel amps to output amps, as I would expect to see in pwm mode.

[red31]

couple of videos I watched show the controller in boost and float, as the different screens were scrolled through, 'pv mode: mppt'

Solarista Na Ako Ngayon has several mt50 videos, mt50 in float w/850 w vacumn
https://www.youtube.com/watch?v=6CvMWSTsfMM

it apprears to never go below boost reconnect V so it stays in float pv mode: mppt.

[jrnymn7]

Red,

Good point. Things were getting a little sketchy at the end, and the controller may very well have gone a little bonkers. 🙂

Are you speculating, concerning the pv mode in mppt thing, or did you find some info on that?

At this point, tomorrow morning is looking good. I plan to do a gen charge to about 90%, and then run the solar to 100%, between 9am and 1pm-ish.

btw, thanks for your help!

[red31]

The mt50 will show pv mode: mppt when connected to a mppt controller.

after boost set point v is reached, the 2 hr or used defined clock starts, after such time it goes to float.

I believe your 7:50 shut down was the controller loosing its mind to the clouds and rescanning the panel, more fun in full sun will help you find the answers.

[BFL13]

I am not familiar with the adjustable Tracer details, but I can say my controller has no idea how high in SOC the batteries are.

Late in the day after the bank is at Baseline SG, True Full, and the Trimetric is saying plus 15AH (I have not tried to correct for that), the solar just keeps chugging away, providing about 2 amps or so, which the batteries are "accepting" but must be throwing off as heat.

Note that I choose my Trimetric to not show the "Percentage Full" but that is not the same thing as with the Tracer apparently.

[jrnymn7]

O.K, I've compared solar charging notes with converter charging notes, and it would appear the Tracer was in boost from about 5:30pm, and around the 96-97% soc range.

It's often much more difficult to decipher what's going on with solar, with it's continual ups and downs, at times. And I'm still figuring out which data to keep track of... although I generally write down everything I can think to, and toss out what's not important... which is usually very little. But, I do have a few missing pieces of the puzzle, here and there, so I need to be more organized in my solar logging. There is definitely a learning curve involved.

So, I have two issues, it seems... this issue of the monitor remaining in mppt, when the controller is not, and the 100% soc thing. I'm pretty sure I had boost time at 180 minutes, but I may have changed it? I'll check that first thing, next run. I'm wondering if boost time effects the controller's idea of when it has reached 100%? Surely something tells it when the bank is full? Time in boost? and/or x amps at y volts? and/or ???

[jrnymn7]

red31 wrote:
this video show @ ~ the 5:20 mark shows boost to float, shortly after a scroll though batt (battery charge:float) and pv shows pv mode: mppt, I don't believe the pv mode: mppt will change but do the research!

https://www.youtube.com/watch?v=KHvLWjNwVwM

Yeah, how come it still says mppt mode when in float? I'll have to search for more reviews, and see if someone mentions this issue.

[jrnymn7]

No float... just stayed in mppt mode, and I'm assuming bulk mode. Amps appeared to be tapering a few times, but then they would rise back up, rather significantly, when there was a break in the clouds. I checked which mode it was in several times, under both conditions.

There is a setting for 'full'... SOC, which has a fixed value of 100%. I thought there was another option, as well, but on further review, it appears not.

As stated in the OP, the unit simply shut down once it's display reached 100% soc, which was well below full. While I was trying to figure things out, the panels crashed. It looks like it'll be a few days before the weather cooperates again, but I'll do an earlier, less deep run and see how things go.

[red31]

this video show @ ~ the 5:20 mark shows boost to float, shortly after a scroll though batt (battery charge:float) and pv shows pv mode: mppt, I don't believe the pv mode: mppt will change but do the research!

https://www.youtube.com/watch?v=KHvLWjNwVwM