Ron

Not having been satisfied with my Optima battery I got an Odyssey and tested each.

I used brand new batteries of each brand. I charged them for 5 hours with a Guest 3 stage charger. I measured the voltage 1 hour later, Optima 13.07 volts and Odyssey 13.18 volts.

Results
7 days later: Odyssey--12.92 Optima--12.69

14 days later: Odyssey--12.81 Optima--12.67

50 days later: Odyssey--12.81 Optima--12.63


This difference may not seem significant but the state charge of a battery that is 12.8 volts is 100% and the state of charge of a battery with about 12.60 volts is only 80%.

GrantG

Ron - Wouldn't a more accurate test evaluate the batteries with a load attached? I assume from your post that you just measured them disconnected...

Monique

A friend, formerly a technical engineer at Bentley, is building a Cobra and he chose the Odyssey. He uses a Harley Davidson battery and it will fulfill all his needs. He convinced me to go Odyssey when my batt kicks the can.

Ron

Grant,

I don't know. I just tested them the way I did because it was simple. I don't have any way of attaching each battery to the same amount of load, but that may well be the proper way to test a battery. Maybe someone else with more knowledge will chime in.

That being said I would think a battery that holds its voltage better over time is better than one that loses its voltage. So I would conclude that a battery that loses its voltage without a load will also lose its voltage under load. But I really don't know if that's the case. However, I will say the Optima installed in my car sure loses it voltage with a very small draw.

Well at least that's my theory.