Hello, I have three 100W panels on my camper trailer. I recently installed a Victron IP22 and a 100/30 MPPT solar controller to charge my three brand new battleborn Lithium 12V batteries. I live in Denver CO and today is a beautiful clear day, however my controller is only showing 53W from all three panels. Any idea what may be going on? They are clean so any help or suggestions would be helpful given the investment I just made. Thanks.
Either your batteries dont need a charge, (they have not drained to the rebulk offset voltage) or your loads are not high enough, or you could have connected them up incorrectly, possible a bad connection somewhere so not all the panels are contributing?
If you think it is the last one then how have you connected them?
Series, parallel? If you take a meter what do you read there voc on the panels?
Regardless if my batteries need a charge or not, it should show the power coming from the panels as being greater than 53W correct? Or am I misunderstanding what the app is showing me? I went up to the top and disconnected the panels and reconnected them, looked at the app and it was at 155W. Now, its back down to 22W. I'm confused by what this thing is telling me.
Disconnecting the panels like this will start the charger from zero. They tend to push a higher current fr a hort while before adjusting to what's needed.
Lithium batteries aren't like lead. When full, they're full and the internal BMS will usually stop the charge. If your MPPT is 'smart' you can use Victron Connect to see the actual values from the MPPT. It shows input volts, current, Output volts, current. As said by the others, if there's no load, there will be little current.
Try disconnecting the panels, put a decent load on the batteries to discharge them a bit. Then reconnect. You should see the MPPT current increase, Multiply by output voltage for power.
Thank you for the feedback. So is it safe to assume, then, that when I view the MPPT 100/30 via bluetooth and in the solar section on top, that wattage will only show something higher than zero when it needs it? Other wise the solar input is something less? To your point, I want to be sure I understand what I'm seeing because right now its next to impossible to know how much battery I have left or how well the charger is working.
The app shows you the power that is used from the panels not the power that is theoretically available.
If you turn on some loads the power from the panels should rise.
Interesting. As I said, it was at 53W earlier, all I did was disconnect and then reconnect the panels and it was showing 155W. I never changed the load.
The voltage is 12V as described in my original post, MPPT was in Bulk state when it was at 155W and I think it was in float state when it showed 20W from the panel. No loads connected other than the controller itself. I'm just surprised there is no easy way to determine how much my batter bank is charged and why I wouldn't get to see the total power being gathered by the panels.
It sounds like your batteries have been fully charged, seeing how the mppt has gone through the bulk>absorb phase, and is resting at float.
Did you set up the charge controller as per Battle Born FAQ?
You can see all sorts of interesting stuff if you look at the detailed history.
My controller was set to lipo.
But I also think that your battery is just fully charged. Switch on all loads you have and the power from the PV should go up.
The battery gets discharged overnight, and requires charging the next day.
You can not refill your battery, without first taking a bit out first.
In any event, thank you all again. You have been much more helpful than some others in another thread so i appreciate it.
And how should the MPPT know the SOC of your battery?
Sorry, but no. You cannot get an accurate state of charge with a voltmeter. Basic fact. For example you charge an AGM to 14.4V, this will bring it to about 85%. Charger holds constant voltage. SOC increases. As SOC increases, current drops, voltage doesn't change. Eventually current drops to a low value, known as tail current. At this point battery is deemed 100% charged. Disconnect the battery. Voltage will drop to around 12.7V, no change in state of charge. (We can ignore self discharge, it's negligible over a day or two). Now put a reasonable load on the battery. Voltage drops immediately and significantly. Take the load off. Voltage will recover close to it's previous value over the next 20 minutes or so. Lithium has the opposite problem - during most of the cycle, voltage hardly changes.
Net result is that battery voltage can, at best, give an approximation of SOC. Which is why shunt based monitoring was developed.
For many battery voltage is good enough without trying to guess state of charge. Any maker, not just victron, can develop chargers which can display state of charge. However it increases product cost. And in a multi charger system, would lead to duplication of charge calcs. Many people don't want the extra cost. Plenty of systems built without battery monitors.
Hope this helps.
If you understood how these systems work, you wouldn't be disappointed.
You may see charge controllers that offer a % charged number, but this number is complete junk. It's purely voltage based and has no meaning in an actively operating system.
The only way to reliably compute state of charge is to track the current flowing in and out of a battery. The MPPT only knows what's being sent TO the battery. It has absolutely no way of knowing how much is coming out of the battery. Therefore, NO charge controller can reliably report SoC without additional hardware.
You should be disappointed in the $2500-$3000 you spent on batteries with a built-in BMS that have this capability, but Battleborn chose not to allow the user to access this feature/information.
What I said is I understand that the controller can't fill a battery that is charged. If I understood how these devices worked, I wouldn't be here, would I. But thanks for the pep talk. Very useful.
Now you know what it takes to calculate SoC.
Now you know that the Victron devices you purchased have no means of calculating SoC.
Now you know that even while charging a premium, BB chose to not provide the information you seek even though the key circuitry is already there.I already knew how to calc SoC and I already knew that BB has a BMS that does quite a bit. I wasn't here for either of those, but again, its great to know you chimed in for no particular reason. Just so very helpful. /sarcasm.
The only way to find out the available power from a PV panel or array at any moment is to "scan" it with an increasing load from open circuit to almost short circuit. This is what an MPPT controller does. During the scan or sweep, it constantly records the Voltage and current for each stage and multiplies the two figures to find the power. The combination of figures which produces the highest power figure is the maximum power point and so the controller loads the panel up by that amount and charges the battery. It does this regularly as the conditions of the sky and sun angle change over the course of the day.
You see, it could not simply figure the maximum power point of the panel if it can't scan the whole range. If the energy has nowhere to go because the battery is full, then it can't load the panel up and will only report what it was able to scan.
Where the energy goes next is anybody's guess. It goes towards the battery of course, but whether or not there is a load on the battery too is completely unknown. The MPPT could be charging at full power and the battery is actually discharging still because the load is more than the MPPT can produce, but how could the MPPT know this? It's just a charger at the basic level.
This is where you need a battery monitor. A proper battery monitor actually counts the amount of energy that flows into and out of the battery and takes account of the charge inefficiencies of the battery type.
Using Voltage to try and estimate the condition of a battery is almost useless. There are too many other factors at play, the load on the battery, the charge rate of the battery and the temperature being the main ones. Lithium batteries make Voltage readings even more useless since their discharge / charge curve is pretty much flat between ~20% - 80%. Counting the energy in and out is essential if you really want to know how full your battery is, The shunt of the battery monitor is where the current flows in and out and this is constantly monitored. Your handheld mobile telephone has a shunt for its battery too to give a decent idea of battery level.
I hope that helps a little bit to give a better understanding of why these systems are more complicated that you might think they should be.
The best thing I think to get the most understanding is power, the Watts as a relationship between Voltage and current. You need both Voltage and current to charge your battery and power your lamp. Thinking about the Voltage only is going to get you lost.
A Voltmeter is an essential tool to have to diagnosing problems or figuring things out, but you've got to think about the current too, and try to think in Watts.
I hope those pointers will help you on your new adventures. It's quite a bit of fun once you get your head around it all.
