knewblewkorvette

AGM and gel batteries are closely related but not identical. Even if you Google "GEL batteries", Optima batteries pop up.

Do not confuse AGM batteries with GEL batteries

These days AGM batteries are often mistaken as Gel batteries due to their numerous similarities –

1. Both are recombinant – meaning that the oxygen produced on positive plate is absorbed by the negative plate. Now instead of producing hydrogen, the negative plate produces water, thus maintaining the water content in the battery.
   1. This is the reason why AGM and Gel batteries are valve regulated, sealed, spill proof, maintenance free, resistant to vibration and can be installed in any position.
2. The striking difference between the two is that of the electrolyte. Electrolyte being used in Gel batteries has a look of jelly whereas the AGM batteries have electrolyte absorbed in glass mat like separators. Due to the properties of electrolyte used in gel batteries the battery loses power fast at temperatures below 32 degree F whereas AGM batteries work efficiently in cold temperatures.
3. Finally, gel batteries are best suited for deep discharge as they are more acid starved, protecting plates better compared to AGM batteries. The AGMs are more compatible where high current is required.

grinder11

I agree. I didn't mean to imply they were the same, because they are not. Sorry if my post was confusing. I've never owned an Optima, so I didn't know if they were AGM, or Gel type. As for Gel batteries losing their capacity under 32° F, I never saw that. I used my snowmobile many times in below zero temps, sometimes -15°F, no issues. BUT, cranking over a 3 cylinder, 2 cycle engine is much easier than a V8 four cycle engine!! Still, the battery was much smaller than an automotive battery, too, sooo.... I'm not positive if you can actually mount a Gel battery on its side or upside down, but I've been told that they can be mounted in any position you desire, as you stated.......