Where dose it say that please as I cant see it in the description
Specification tab on the advert you linked to
as to
It doesn't need to - if it didn't switch off once the battery voltage drops, then it would permanently ruin the battery.
That was always what I was taught, however I found 2 x 7Ah AGM (VRLA) batteries that had been changed on a stair lift after my father-in-law had unplugged it and let them completely discharge and I could not at the time find where he had put them.
On his death they were found, so by this time had been left flat for a year, my smart charger will not charge a battery under 7.5 volt, it assumes it's a 6 volt battery if under that voltage, so to charge it needed to cheat, and put it in parallel with another battery. I was charging in the garage so to save going to view it all the time I plugged the charger into a computer linked energy monitor so I could view from my PC.
The donor battery charged to 14.4 volt and then it dropped to 12.8 volt and stopped there, with no current being drawn, and it stayed like that for 11 days, then as if some one had flicked a switch it started to charge, and went through the whole charge sequence, and on testing the battery it seemed A1. This was repeated with the second battery, and a few others, I had one fail, clearly a shorted cell in the battery, but since the maximum charge rate was 0.8 amp this was not a problem. So 4 out of 5 batteries I had found kicking around recovered.
However the point is it took 11 days, so a battery which has been left part discharged will need to sit on the smart charger for at least a couple of weeks to ensure all the sulphur has returned into the acid, there is no fast fix.
This has been a problem with narrow boats, the domestic battery is only charged while the engine is running, which is around 7 hours per day, which is simply not long enough to ensure the battery is fully recharged, if they manage to connect to a shore supply for 24 hours, then this is often enough to get the battery fully charged again, the answer is move away from lead acid, the metal iron batteries found in some buses and milk tankers were far better, but so expensive, today we have the lithium battery, but the problem is the charge rate needs such careful monitoring and they are so expensive.
The absorbed glass mat is still a lead acid battery, but the construction stops the active material falling off the plates, the flooded battery there is an area below the plates designed to catch the active material there is a trade off, the more current one can draw the easier the active material can drop off, so we have three classes of flooded lead acid, the traction battery is designed to be deep cycled, fitted to fork lifts, golf trollies, milk floats etc. Then the leisure battery is a half way stage it holds the active material better than a vehicle start battery but not as good as the traction, but can give more amps to traction battery but not as much as a vehicle start battery, and then we have the vehicle start battery which is designed to give high amps but never to be deep cycled.
So for an engine needing a 60 Ah battery we can fit a 90 Ah leisure battery and still start engine but allow it to be used for lights etc.
When the start/stop technology came along we started seeing the AGM battery being used in vehicles, smaller versions were called VRLA which is really the same type of battery it stands for valve regulated lead acid or absorbed glass mat. These will work well with inverters as they can stand deep cycling better than the flooded type, but wife's jag has an AGM and my Kia has a flooded both 90 Ah the Jag battery costs around £200 and the Kia around £80. And to look at they seem nearly the same.
So you should be using a traction battery for your inverter, one designed for a golf trolley would be fine, but I use AGM 35 Ah for the mobility scooter, they would also be fine. But a car or wagon battery is simply not the right type. The MPPT charge controller is specially designed to charge lead acid batteries from solar and wind power generators. The input and output voltages are not the same. However you can use a simple zeror diode. Well not really a zenor it works on the avalanche effect over seem to remember 3 volt, but we tend to call them all zenor diodes.
I have a jump start unit with a 12 Ah AGM battery in it plus compressor, lamp, and inverter, I have this for emergency power, think the inverter is around 200 watt, but clearly would not last long, so the freezers and central heating are now integrated with the solar panels, and have a 3.2 kWh battery, around 50 volt. I can draw I think 3.5 kW from the battery, it is lithium type, and they cost around £1.1k not really worth it just for the UPS system, but is worth it I hope to use the solar power to the full, but that is a whole different scale to what you are doing.
