Originally Posted by ignatz72
A few posts above make me think clarification is needed here - Gel and AGM batteries are not the same thing. They are similar Valve Regulated Lead-Acid technology, but the electrolytes completely different. They do have similar pros and cons.
You can use a regular Deltran Battery Tender on an AGM, you should not use these on a BMW or other Gel. Etc., etc.
It's like saying a biodiesel wagon and a gas car are both road vehicles, since neither is a train, but you shouldn't swap the fuels around.
You are absolutely correct. Mine was an AGM that failed. It was not a Gel.