This short Tech article is to help with Myth Busting the inaccuracies on the Internet and Facebook about Optima and other AGM style batteries AND which Optima is best for winching and daily driving.

I started using "Gel" type batteries (not saying that Optima's are "gel" batteries. They aren't) back in the late '70's to reduce the acid/water leakage that caused corrosion on cables and battery terminals. My driveway back then was 1/2 mile long, extremely bumpy and across 2 farm fields. Every couple weeks I would have to physically clean the terminals and cables with baking soda or corrosion would get so bad the Bronco wouldn't start or my Warn 8274 wouldn't work.

So I started using dual "gel" type batteries (all that was available) and what a difference for maintenance! I became hooked on using anything other than a lead acid battery in my Bronco so I wouldn't be scraping green corrosion from my battery terminals.


stands for Absorbed Glass Matt construction. Optima's use pure lead in construction. The more pure the lead is, the better the performance of the battery. There's no liquid, they don't leak, they can be damaged and still work. Makes them ideal for off road type use. AGM batteries are usually identifiable from the design of the top of the battery. Lead acid batteries have caps that unscrew, plastic pieces that pop off or some other way to allow you to add water and allow fumes to escape. An AGM battery will look completely sealed. No way to open it without damaging it.


Biggest mistake we all seem to make when running Optimas and AGM style batteries is how we charge them. Alternators are NOT battery chargers I've been told by Optima reps! If your battery won't start your car don't rely on your alternator to charge your AGM/Optima style battery. Put your charger at 10 amp or lower, yes- 10amps is the MAX amperage you should ever charge an Optima battery-direct from Optima. You do not need a special charger but they work better and more efficiently than just a typical low amperage charger. 10 amps is the max I was told directly by Optima tech. All batteries sulfate, Optimas do also and start at 12.4V.
Optima stresses that their batteries should never sit "at rest" under 12v. Charge slowly- they said it over and over to me. An Optima doesn't last nearly as long in a vehicle that sits and is used seldomly compared to a daily driver..

Inactive for 5 days or more? Once again, I'm quoting Optima tech and they said that their batteries need a maintenance charger (battery tender) whenever they are idle for 5 days or more.

If your Optima is below 10.4V you should always use a charger designed for an Optima/AGM or you can charge the Optima this way. Hook your 10 amp or less charger on another battery in parallel with your Optima. The other battery must be 12V or higher. Turn it on and you're good.

Here's an example of why an alternator isn't a charger and why an alternator won't charge a dead Optima. I was 1100 miles away from home at a Moab Bronco Safari event and left my seat heaters on one night. Next morning not even a click could be heard from the starter when turning the key. I jump started my Bronco and after 15-20min at fast idle with my 4G alternator I thought I'd be good for the day. Nothing, zero, a dead battery still when I tried to restart. Bronco buddy drug out his week old garage sale special Walmart charger, slapped it on and in a couple hours (at very low rate of charge) my engine would crank and started. Used my rig that day and finished charging it on his charger that night.

Life span

AGM batteries do not last as long in extreme temperatures as a lead acid battery. Example, an AGM won't last as long in Alaska as it would in San DIego since the repetitive cold days in Alaska.
Start/stop features on new vehicles is harder on lead acid batteries than an AGM battery. In this type of use an AGM battery will last much longer. Typical Optima lasts 2-3 times as long as a flooded lead acid battery- no guarantees but typical lifespan.


Battery voltage

Red Top Optima fully charged is 12.6-12.8V
Yellow Top Optima fully charged is 13.2V

For off road use you can't beat an AGM style battery. If you select an Optima do you choose Red Top or Yellow Top?

Optima rep told me when I specifically asked about which battery would be the choice for the majority of us who use their battery for winching, off roading and daily use was to use a Yellow Top. Use a Red Top when your off road vehicle doesn't have an electric winch.


Use the top terminals for your heavy accessory use like a winch. Never use the side terminals for any load that draws more amperage than a typical starter. So- top posts for winch, side posts for starter and/or other accessories.