Epever charge controller.

[Loveshack]

Just of a bit of an update. On the 28 th Day my mppt was to equalize my batteries at my preset 15.6 v. It was a cloudy day and I was off grid. I monitored the mppt for the day and the voltage was unable to reach my preset of 15.6v. I week later I was plugged into shore power so my batteries were topped right up. It was a sunny day and the mppt equalized my batteries at 15.6 for the set 180min. I was glad to see that the mppt eventually equalized when the conditions were right.

[indygreg]

the internet is awesome - i found this post and i think it is exactly what is happening to me. i have an solarepic 40 amp controller and 4 lensun 100W panels on the roof of our van. I have 4 fullriver dc150-12 batteries and a xantrex freedom 3000 inverter/charger. when the solar was first installed and the inverter was turned off i saw the voltage go up into the mid 14's (i set it to boost at 14.7 and float at 13.7). then when i turned the inverter on and powered up the fridge i never saw the voltage get over 12.5. the inverter draws 4 amps at idle (wow that was a surprise) and the fridge draws .4@110vac so about 4 amps also. so on a sunny day i suspect the 8 amp draw is not leaving enough current to get the battery charged.

so i don't really have room for more panels. i think i will have to look at the solar as a range extender and continue to charge from the wall or the engine (i have a second inverter on the engine that fees 110VAC to my xantrex charger). i know that charging with the xantrex is doing a proper 3 stage charge where this solar controller seems less sophisticated. i see my voltage climb to over 14V if the sun comes out while my van is plugged in a charging so even though the xantrex has the battery fully charged and in float stage, the solarepic will start boosting. today i put a relay on the solar power input to the charge controller so that if i am charging off the xantrex the solar is disabled. my batteries are VERY hard to replace so i want to take no chances with them.

on the plus side we tailgated the purdue game last week and i arrived fully charged in the morning and at night i was still at 100% due to the solar system. i had hoped to never plug in again but i will have to settle for having the solar be a backup to my main charger i think.

greg

[Loveshack]

Thanks for your time and patients. I feel like I have a much better grasp of my new solar system.
Dave

[littleharbor]

That particular charge controller does have a 100 Voc limit although tracer does make 150 volt versions as well.

[sensij]

Yes, you are getting it! You may already be familiar with it, but for reference, here is the SOC vs specific gravity table that Trojan includes in their FLA user's guide.

SOC.JPG

(there is temperature compensation to consider too, but I'm going to assume you have that covered)

At 1.240, you are just over 80% SOC. At 1.225, you are at around 70%. The good news is that your loads is small enough that you aren't over discharging, but the bad news is that if the batteries never get to 100% SOC, sulfation will still be a problem.

I think your plan is a good one... using the generator in the morning when high current can be accepted by the battery should be an efficient use of fuel, and transitioning to absorb in the middle of the day when solar is most productive gets the good out of your panels when the high current isn't so important.

With more or higher rated panels, you *should* eventually be able to drive the voltage up to 14.8 (or higher) and hold it there using only PV, but as your system is now, it would probably take a couple days of charging with very little consumption.

Yes, the SOC reported by the charge controller is not worth much, it is a problem with any system that tries to guess SOC on lead acid using only voltage. As we've already covered, voltage alone can be really misleading. Once you figure out a routine that regularly gets you to 100% SOC based on the specific gravity reading, you'll be in a better position to figure out how much more solar you should be adding, relative to the cost and effort to run the generator. If you add enough panel capacity, you might find that a 60 A or 80 A charge controller is a worthwhile upgrade. A pair of 40 A Tracers might be ok too, and lighter on the wallet, although the 100 Voc limit will be constraining at some point.

[Loveshack]

Just as an experiment I shut off the solar and put on my 70amp ac charger. It is putting out about 55amps at 13.35 volts. When I force it into boost it was putting out 74 amps (70 amp charger ) and went up to 13.6, still not the 14.4 it is programmed for. All of your help is paying off. I am on the learning curve. I guess an upgrade in my solar size will be in the future. For now I would think that for my batteries putting on the generator in the morning to boost the batteries and than shut it off and let the solar top it up to 100 soc, what do you think.
Dave

[Loveshack]

So I checked the specific gravity this morning. We used a fair amount to energy last night. (Tv on) This morning the batteries were at 1.225

[Loveshack]

So what you are saying is that my solar is not powerful enough to reach 14.8v?
As well it won't be able to equalize at 15.6?

From memory I have checked my ac charger amperage at times and it is no where close to 70 amps when producing 14.4 v. I will check it again when I can to confirm.
I also understand that that is a false reading of 14.4 and when shut off it drops. I just thought the solar would give me the same false reading? It never shows 14.8v ?

I will ill check the specific gravity tonight after sun down and again in the morning and get back to you on thoughts figures.

My lap top connected to the mppt now 4pm is showing 100% soc

just checked the specific gravity and its about 1240 at 444pm
today we have had off and on rain and mixed sun and cloud. We are anchored
I will check it again in the morning.
I really appreciate your time and patients.
Thanks Dave

[sensij]

I really appreciate your time. I am new at this but trying to get my head around it and do it properly.
I have an ac 70 amp charger. It maybe a totally different situation, or the same you can tell me.
It has a boost mode. When the batteries are low say 50% 12.2, it raises voltage to 14.4. And keeps it there until it reaches about 85% of charge. Then it backs off the voltage to say 13.5 until eventually lowering it to float voltage when above 90%. (Approximate values)

You are getting fooled by the internal resistance of the battery. The open circuit voltage is not immediately raised to 14.4, but the measured voltage does rise because you are pumping so much current in. If you turned off your AC charger immediately after turning it on, you would see your battery voltage fall back down and rest at something close to where it started.

Remember, Measured voltage = OCV + (I * Ri)

Since you have three pairs in parallel, let's use 0.033 ohm as Ri, and this time with 70 A of charge current.

Measured voltage = 12.2 + (0.033 * 70) = 14.5 V. In this scenario, when you have that much charge current available, it will jump immediately to the constant voltage stage of charging, as you've observed.

The algorithms it is using to set the constant voltage from there are somewhat specific to your charger.

Again, with 19.2 A of solar instead of 70 A of charging.

12.2 + (0.033 * 19.2) = 12.84 V measured.

Do you see how 12.84 V and 14.5 V measurements can both represent the exact same battery (with different charging currents), which has an open circuit voltage of 12.2 V?

This conversation would be much more anchored if you have the ability to measure specific gravity, and think about state of charge in those terms instead of in voltage.

[Loveshack]

I really appreciate your time. I am new at this but trying to get my head around it and do it properly.
I have an ac 70 amp charger. It maybe a totally different situation, or the same you can tell me.
It has a boost mode. When the batteries are low say 50% 12.2, it raises voltage to 14.4. And keeps it there until it reaches about 85% of charge. Then it backs off the voltage to say 13.5 until eventually lowering it to float voltage when above 90%. (Approximate values)
if during boost mode I check the voltage it is 14.4 Right from the start.
I thought that the solar would be the same. Set the boost voltage to 14.8 and it would boost (charge ) at that until about 85% capacity and then taper off. Not use the 14.8 boost setting as an upper limit for when to taper off?

[sensij]

Each mppt is a 20 amp controller. I was thinking of putting another 100 w panel per pair next year.
Our needs. Our needs change daily depending on what we are doing. (Sailing, or at anchor or motoring )
The lowest battery reading in the morning before sun up has been 12.5. I thought that was good for the low point of the day,and therefore the solar system was keeping up with our needs?
Am I reading the display properly that when under the battery heading it reads
Battery (normal)
13.53v, 9.6A, 129.88 w, 23.75 C

13.53 v is the charging voltage at that time
9.6 A is what the batteries are accepting ( and that this number can be higher than the solar panel amp display ?)

so getting back to my original question, if my boost charging parameter is 14.8, this number should be displayed in the battery heading. Where the picture shows 13.53 it would be 14.8 during boost?

I am am trying to figure out if it is following my charging battery parameters or not.
Thanks

It is following the parameters correctly. The charge controller supplies current, the voltage is the feedback. Voltage will climb as battery charge increases... a charge controller does not (and can not) simply supply a fixed 14.8 V output and instantly bring the battery to that voltage. When you are setting 14.8 V, all you are doing is telling it at what feedback voltage it should switch from constant current charging (supplying maximum available charge current, up to the rating of the controller) to constant voltage charging (holding that voltage, and allowing current to taper off as the battery continues to charge).

That you never see 14.8 V means that you're not supplying enough charge to get to 100%. If you were getting to 100%, you would see voltage at 14.8, and current tapering off to nothing.

The fact that you aren't seeing less than 12.5 V on the battery in the morning means that solar may be keeping up with your demand, or that your generator/alternator are getting enough charge into it to keep SOC from dropping too low. Your PV isn't enough to get the battery all the way through the constant voltage stage to 100% SOC.

A 690 Ah battery would ideally be getting at least C/10 of charge current... 69 A. In your latest screenshot, if both controllers look the same, you are supplying only 19.2 A. Even if you were maxing out your charge controllers, you would only be generating 40 A, still lower than most would recommend, but maybe enough to meet your demand and get the battery closer to 100%.

That you aren't discharging below 50% SOC is good, but your inability to get to 100% SOC will cause early battery death due to sulfation, if you don't add PV or other sources to get to 100% routinely.

If you haven't done it yet, measure the specific gravity at the end of the charging day. That will tell you more clearly than I can what SOC you are actually achieving.

[Loveshack]

Each mppt is a 20 amp controller. I was thinking of putting another 100 w panel per pair next year.
Our needs. Our needs change daily depending on what we are doing. (Sailing, or at anchor or motoring )
The lowest battery reading in the morning before sun up has been 12.5. I thought that was good for the low point of the day,and therefore the solar system was keeping up with our needs?
Am I reading the display properly that when under the battery heading it reads
Battery (normal)
13.53v, 9.6A, 129.88 w, 23.75 C

13.53 v is the charging voltage at that time
9.6 A is what the batteries are accepting ( and that this number can be higher than the solar panel amp display ?)

so getting back to my original question, if my boost charging parameter is 14.8, this number should be displayed in the battery heading. Where the picture shows 13.53 it would be 14.8 during boost?

I am am trying to figure out if it is following my charging battery parameters or not.
Thanks

[sensij]

The short answer is that your PV system is probably too small to take care of that battery without help from other sources, especially since it sounds and looks like the panels might not be optimally oriented. Knowing more about your loads would help. Doubling to 800 W (at least) would be more aligned to a conventional C/10 charging current recommendation.

Do you have room for more panels? Replacing what you have with more efficient panels will help somewhat, even if you don't have more space. In the space of each of your 200 W pairs, you should be able to fit a 300+ W 72 cell panel. That would get you to over 600 W. With just a little more space, you could shoot for 4 x 275-290 W panels (60 cell), getting you to 1100 W or so, at which point solar-only should be realistic.

Yeah, the "equalizing" indicator doesn't make any sense, might just be a bug.

What is the output rating of each of your controllers?

[Loveshack]

The batteries are 6v

[Loveshack]

Here is an example while we had sunshine today. This is from one pair of 2 pairs. Please note it says equalizing. Not sure what that means. It does this several times a day but the voltage is not 15.6 which is the parameter I have set for "equalizing. " not sure if the icon should just be ignored