Has anyone successfully charged AGM battery with the battery tender junior? I removed the battery and connected it - but the red light is flashing = the battery is not being charged...
My Battery Tender does that if I connect it to a severely discharged battery. Happened recently and I tried 2 different tenders on it. A regular battery charger was able to charge the battery. The tender has been maintaining it since then. My guess is that if the battery voltage is too low the tender won't try to charge it, but I haven't looked around for an explanation.
Verify the 'Tender' ok by clipping to auto battery. If flashing red good possibility 'Tender' defective. If not flashing, well, your cycle battery is toast.
+1 I had to take apart the 12 volt end when one of the wires inside came loose inside of mine. Easy to put back together. Just a couple of set-screw type clamps inside to hold the two wires.