AGM (absorbed glass mat) and VRLA (valve regulated lead acid) are in essence the same. And a charger which can charge them, can also charge a flooded battery, but not the other way around.
An
Enhanced
Flooded
Battery is a normal battery with extra acid so it does not need topping up, but AGM and VRLA only have just enough acid, there is a valve to release pressure if over charged, but over charging will wreck the battery. However unlike the flooded, the active material can't fall off the plates, so treated correctly will last longer.
This
is the charge rate of my jump start unit which also has a VRLA in it, I got it from my late father-in-law so at least 15 year old, and still going strong. But over charging causes this
it was in a mobility scooter, and one cell in the other battery of the pair when short circuit, so even at only 5 amp the charger cooked this battery.
So the Lidi smart charger starts at 3.8 amp, and at a set voltage reduces to 3 amp, and then at 14.4 volt reduces to 0.8 amp and it will not auto revert to 3 amp, so it will not cook a battery even with a shorted cell, then it will drop further to 0.1 amp, when set to over 12 Ah, and alternate between 0.8 and 0.1 amp, under 12 Ah it alternates between off and 0.1 amp. So each time battery reaches 14.4 volts it turns down charge rate, and each time it drops to 12.8 amps it raises charge rate.
So you can put on charge and forget. The Ctec battery charge will return to full charge rate, so can bake a battery with a shorted cell, but the battery would be no good anyway, just don't really want the bad eggs smell. The Ctec will charge from a lower voltage as 12 volt only, the Lidi is 6 and 12 volt, so under 7.5 volt it assumes it's a 6 volt battery, the Lidi one has built in Volt meter, the Ctec one does not.
You can get large versions, we have this
one at work, 12 and 24 volt, and a lot higher amps available, up to 40 amp charging rate, and price to match around £330, and still designed for AGM batteries, but in the main chargers for AGM are not over 5 amp, and are designed to connect and forget, typically it can take a week to recharge a battery left to go discharged, it may get enough to start car in a few hours, but to fully recharge the battery in extreme cases can take two weeks.
Lidi, Aldi, Ctec, Ring, and Durite all make the small smart battery chargers, each has some slight different features, the first two depends if they have their special offers, and if so cost around £15, the next cheapest seems to be
Maypole MP7404 from screwfix, but the instructions seem to be some what lacking saying what it does. The Lidi one shows exactly what it does
I therefore would get the Lidi if I could, prefer one where the manufacturer is open as to how it works.
