I am putting a 400w solar system running to a single 300ah 12v lifepo4 battery. What my concern is with all the battery protection circuits in my design including the the BMS there is the potential that at some point the battery will auto disconnect it self from the system. So say the BMS has an over temp or something and disconnects the battery what happens to the MPPT? How do I keep the PV from frying the MPPT if the battery disconnects?
New to solar MPPT Lifepo4 question
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I am confused what is the don't connect your panels to the mppt until the battery is connect thing about? Is this just about initial connection?
mberding
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Most MPPT controllers won't power on until there's a battery connected. I think the instructions say to wire it up that way so you can see the MPPT come alive right away. People have the belief that if there's power going into the MPPT (from the panels) that it should power it, but it doesn't, and they get confused.
Also, there's no need for a battery-driven isolator for the solar cables. If it makes you feel better, that's fine, but I've never seen it actually set up like that before, and I've had lots of experience with batteries being completely physically disconnected from RV systems while the solar is still connected and wired up and nothing bad happened to the MPPT controllers.
Also, there's no need for a battery-driven isolator for the solar cables. If it makes you feel better, that's fine, but I've never seen it actually set up like that before, and I've had lots of experience with batteries being completely physically disconnected from RV systems while the solar is still connected and wired up and nothing bad happened to the MPPT controllers.
TCgreg
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I would consult with the manufacturer of the solar charge controller. This is from Renogy for their controllers. On my Victron the manual states to connect the battery before solar panels but doesn't go any farther with warnings. When the battery was disconnected my MPPT monitor screamed at me due to over voltage the controller was seeing compared to my charge settings. That happened once and it did not seem to damage the controller but I definitely disconnect panels now first before disconnecting the battery.
https://www.renogy.com/content/Manual/RNG-CTRL-RVR203040.pdf
https://www.renogy.com/content/Manual/RNG-CTRL-RVR203040.pdf
Thank you that was a perfect answer! After searching I have been unable to find anything on the MPPT and this don't connect your panel first thing other then don't do it. It didn't make a lot of sense unless maybe surge thing when the unit powered on. To top this off I see no one doing anything to protect there MPPT. This will be a mobile system and can end up in extreme hot/cold areas and so I am sure at some point the system will disconnect the battery.
Rider
Solar Addict
On my EPever, if you disconnect the batteries, the SCC will continue to operate and complain. It will not shut off until the panels go dark. Turning off the battery does not turn off the SCC if there is panel voltage.
gnubie
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Victron controllers can start from solar alone, handy if you need to lift a battery that has gone low enough that the BMS has gone into low voltage disconnect.
I have tested quite a few charge controllers for a project I'm involved in. There are controllers out there that react quite badly to having the battery disconnected. MakeSkyBlue is one of them. The MakeSkyBlue won't start unless it has > 11.7 volts on the battery input and if the battery goes away the voltage on its output starts jumping around a lot even with a non-battery load. It didn't get to the smoke coming out stage but I didn't leave it connected in this manner for long.
I suspect the warning is given as there are controllers out there that will put excessive voltage on their output if the battery is removed, potentially damaging its own components.
I have tested quite a few charge controllers for a project I'm involved in. There are controllers out there that react quite badly to having the battery disconnected. MakeSkyBlue is one of them. The MakeSkyBlue won't start unless it has > 11.7 volts on the battery input and if the battery goes away the voltage on its output starts jumping around a lot even with a non-battery load. It didn't get to the smoke coming out stage but I didn't leave it connected in this manner for long.
I suspect the warning is given as there are controllers out there that will put excessive voltage on their output if the battery is removed, potentially damaging its own components.
I am using a Victron 100/30 for my solar charge controller
FLA?
How would that work?
Nice find gonna study that
Think I will just put one of these in pv line and run the remote to the battery. That should cut power from the panels if the battery disconnects. https://www.amazon.com/Victron-BPR0...rds=BatteryProtect&qid=1570415162&sr=8-1&th=1
I tried this by having a relay connected to line between battery circuit breaker and the SCC so if battery beaker shut off the relay would shut off the PV power problem is that the SCC still had power between SCC and breaker. Not sure if this is capacitators or PV still feeding controller.
So PV to controller before battery connection does not turn on SCC.
Battery disconnected while SCC active and solar Connected SCC maintains power
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