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The MPPT 75/10 manual and Victron Connect guide explain this differently.
Is it true that the panel V must exceed the bat. V to START charging? Once that day or as a pre-condition for the charger to charge? The first day, the difference never above 4.5V and it was charging all day. The Vic. Connect Status screen never showed "OFF" (vs. BULK or ABSORB.).
Thanks
Thanks. I was sort of following the guy until his last sentence. SOmething about when "off", it sill chargeswhen the panel volts is only 1 volt above battery volts. Could someone please clarify this +5V or +1V issue. Please.
Vpv > Vbatt +5V to turn on
Vpv < Vbatt +1V to turn off
If this is a problem then your solar panels are not well matched for a MPPT and your battery bank voltage.
For good performance with a MPPT solar charger the PV Vmp should be at least twice the battery voltage (but can be much higher).
Thanks.
I understand what you, the video and manuals are saying. My controller is not working that way.
My 100W setup is charging normally the entire day, every day while the panel V has never exceeded the battery V by even 4 volts? It is never "Off."
I have never changed any of the factory settings.
Thanks
Short answer: Replace the Victron with a different brand.
Victron doesn't consider it worth waking the MPPT up until there is +5V diff but considers it's worth operating as long as it is min +1V diff. This basically makes Victron useless for smaller installations, that is probably a business decision and not a technical one (simply because there are tons of other MPPTs that are doing just that). A Victron MPPT in a smaller system is at risk of damaging your batteries (no matter what type they are).
@PerStr All MPPT Solar Charge controllers, with a Buck Converter, require the PV Input voltage to be higher than the Battery Bank voltage. And when the Buck Converter starts running, the Voc of the PV Panels will drop down even lower, to the active Vmppt voltage. This is how all MPPT Solar Charge controllers, with buck converters, operate. Name one MPPT Solar Charge controller, with a buck converter, that can charge the battery bank when the PV volt is below the Battery Bank voltage. Actually this is called a "technical decision". No, there is no risk of damaging your batteries, in smaller systems when properly designed.
Example: Renogy 100 Watt 12 volt Solar Panel ( a very small system )
Open Circuit Voltage = 24 Volts
MPPT Voltage = 20 volts
That is a 4 Volt drop.
Then add the 1 volt drop for the Buck Converter = 5 Volts minimum.
If the Voc of the PV is not at least 18 Volts ( = 13 Vbat + 5 volts ) then
it makes no sense even trying to turn ON.
A smaller panel will output in the range of 16-17V. These installs are common among smaller yachts where deck design etc does not allow for larger or serial panels etc. Panels are installed where possible, often flexible and sometimes partly shaded by sails and other deck equipment.
The Victron MPPT require panel voltage to be +5V over battery voltage before even starting. Once started it will run until +1V above the battery (hence worth operating). In an LFP/AGM install this means that the Victron MPPT won't even start until the batteries are at 5-20% SOC (or possibly dead/ruined).
So put simply Victron MPPTs will not even charge the batteries on your boat at home port with everything switched off until the batteries have run flat. So in order to have an MPPT to maintain batteries on a smaller install/vessel, you need something different than Victron.
This might be a great feature for many use cases, but not for this user segment where it's a hazard.
Nobody buys panels that won't run up V to at least 20V with no current flow. Even in poor light, and then the true tracked Vmp might be only 60% of the Voc. With effectively zero current. Think about it..
I once had an expensive mppt (American made) that would wake me from sleep at the faintest hint of daylight with it's clicking carry on. That's from 3 rooms away and lasted 20 minutes. It didn't know there was no power to be had from a poor Voc in crappy light. My Victron does. And doesn't wake me either.
@PerStr No, you can NOT fully charge a 12 volt battery with any Solar Panel that has a Voc between 16 volts - 17 volts. As soon as, you put a load on that Solar Panel the active Vmp minus the 1 volt drop of the MPPT Charge Controller will make the output voltage way too low to do any reasonable charging. It appears that you have confused Voc, with Vmppt. If your Solar Panels have an extremely low ( 16v - 17v ) Voc, then you should really be using PWM, not MPPT. Do the proper engineering. Renogy's 50 Watt Solar Panel has a Voc = 22 Volts!
I am experiencing this right now in a sailing Vessel with two sunbeam flex panels of in total 135W connected to a Victron bluesolar 75/10 feeding one large AGM 12V battery. I prefer to have them connected i parallell to minimize impact of partial shading. After successfully getting the controller started I noticed that the yellow control indicator on controller had went out. Troubleshooting I noticed I did not reach the 5V margin between panel output (disconnected) and battery voltage and I can only assume the margin had dropped below 1V overnight. It was cloudy and late in the afternoon why the margin couldn’t be reached at the circumstances.
I opted to reconnect the panels in series to get the charging started again, but I am curious to know if the charging would have started again once 5V margin is reached.
I could not find this information in the documentation but suspect this is the case. I will do some tests to find out but I think it could be relevant information to point out in the manual.
If this is the case, I think It is still better on a sailboat to connect in parallel and I do believe there will be enough hours of charging for my needs, even given the amount of sun hours in Scandinavia.
I’m almost 100% positive that Victron hard coded this feature (limit?) in an FW-update sometime in 2020.
Sunbeam also has a nice app. My favorite Genasun is hard coded AGM or LFP-model (so no apps or settings). Only 6 mA power consumption (half of Victron/Sunbeam) and starts at only 5V panel voltage!
Would be a nice surprise if Victron added some of these skills in a future FW-update.
I’m almost 100% positive that Victron hard coded this feature (limit?) in an FW-update sometime in 2020.
No, all MPPT have that since the begining.
You will find that in old manuals. This manual is from July 2014:
https://www.victronenergy.com/upload/documents/Manual-BlueSolar-charge-controller-MPPT-70-15-EN_NL_FR_DE_ES_SE.pdf
I don't think Victron will change that for you.
Victron decided to make it that way, if you don't like that you can use other MPPTs.
This is bit like buying a sportscar, putting tiny tyres on it and then being unhappy that it is slow around the track.
It has already been stated in responses to you in numerous posts across different topics:
You choose the panel and mppt together, so they are properly matched.
If you want a really low end solution where there is next to no headroom between the battery and the panel voltage, you either need to use Victron's PWM charger which is designed for that, or to use the specialist chargers like you have referred to, that are built for these small environments. The hardware is made to perform in a specific way, it is not a software feature.
The MPPT calculators are free to use and will help you avoid disappointment.
The behaviour is thoroughly documented.
But if you choose to pair a low voltage panel with the wrong MPPT that has little to do with Victron products and R&D. It is just bad planning.
I now have the panels in parallel again and I think I can live with the function as is. As soon as the sky is fairly clear on one of the panels (during Swedish summer there is enough light even a cloudy day) charging will start. I added the bluetooth dongle which provides better possibility to monitor an follow up. I don´t have much electrical loads (refrigerator is on gas and all light is LED by now), it is mostly the phone chargers during night and I think this is normally recovered day-time during the period I use my boat.
I can confirm the hysteresis (start @5V and stop @1V) was there from start. My charger is at least 5 years old and the firmware was never updated until I added the bluetooth dongle.
