I had the same question a couple of months ago. You need to emial the serial number on the side of the battery to the email address below. Below is the email address and information they sent me.
info@optimabatteries.com
What is the serial number from the 1" X 3" white "non spill-able" decal from the side of the battery?
The best method for consumers to maximize AGM battery performance or to recover a deeply discharged AGM battery is to use a modern AGM specific charger with a desulfation mode.
Since there are many great battery chargers on the market, we do not have the capability of testing each one. We do not “Officially” endorse specific chargers yet we will supply information about chargers that our customers and staff have used and liked. These are becoming more common and they work great for all lead acid batteries. In most cases these chargers will recover deeply discharged AGM batteries.
These units have the additional capability of doubling as a battery “maintainer” for storage. Some also come with additional wiring to permanently attach leads from your battery to an accessible spot on your vehicle. This makes it easy to hook up when you store the car, boat or RV. Here are a few that we have gotten feedback from consumers about:
Ctek, Multi US 7000 or 7002:
http://www.ctek.com/EN-US/Buy-US-Charger.aspx
Interacter, EX 12 volt model:
http://www.interacter.com/EX_Page.htm
For regular charging we recommend 2 amps with a max of 10 amps, 13.8-15.0V. For float charging we recommend 1 amp max, 13.2-13.8v.
However, for nearly all people (over 90%) who believe they have a "dead" Optima battery, the battery only needs to be charged. If the battery has less than 10.5v most battery chargers won't do anything to charge the battery using typical procedures, and most test equipment will erroneously indicate the battery has a bad cell.
If an Optima is deeply discharged (below 10.5 volts) most basic chargers will not supply a charge. Also keep in mind an Optima will not recharge properly if treated as a regular flooded or gel battery. To charge the battery, you can wire a 2nd fully charged automotive battery (12V+) to the discharged AGM in parallel (+ to + and – to –). Then hook up the charger to the discharged battery, setting the charger at 10 amps. Leave for 2 hours, monitoring frequently. When the discharged battery reaches 10.5 volts or more, remove the 2nd battery and continue charging the AGM until fully charged.
Typically we recommend charging at a relatively low current, such as 2 amps, but when the battery has been deeply discharged, some sulfation of the battery plates may have occurred. If you charge at 10 amps, the higher current will help to break up this sulfation.
If you have an automatic charger, let it run until the charger indicates charging is complete. If you have a manual charger, estimate charging time by multiplying the capacity (amp hours or Ah) of the battery by 1.2 for a rough estimate of charging time in hours.
In most cases these steps will recover the AGM battery. It’s okay for the AGM battery to get slightly warm during the charging process. Hot to the touch means there’s a short and the process should be discontinued.
