BTW; do NOT use a higher amperage charger or sure death to the battery will result. These batteries like a slow methodically charge and then will live a very long time.
Takes care
Shadowman
Here is the charging info from Optima's site. No problem to use 10amp charger it just needs to be automatic so it reduces the amps as the battery charges and shuts off when charged.
OPTIMA REDTOP CHARGING INFORMATION
OPTIMA RedTop Charging Information
The following charging methods are recommended to insure a long battery life - always use a voltage-regulated charger, with voltage limits set as described below.
RedTop Type: 34 & 34R - 34/78 - 78 - 6V - 25 & 35 - 75/25
These batteries are designed for engine starting applications. They are NOT recommended or warranted for use in deep cycle applications.
Recommended charging information:
Alternator:
13.3 to 15.0 volts, no amperage limit.
Battery Charger:
13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate.
Rapid Recharge:
Maximum voltage 15.6 volts (regulated), no current limit as long as battery temperature remains below 125°F (51.7°C). Charge until current drops below 1 amp.
Float Charge:
13.2 to 13.8 volts, 1 amp maximum current, time indefinite (at lower voltage).
All limits must be strictly adhered to.
Safety Information:
Always wear safety glasses when working with batteries.
Always use a voltage regulated battery charger with limits set to the above ratings. Overcharging can cause the safety valves to open and battery gasses to escape, resulting in premature failure. These gasses are flammable! You cannot replace water in sealed batteries that have been overcharged. Any battery that becomes very hot or makes a hissing sound while recharging should be disconnected immediately.
Failure to fully charge a battery can result in poor performance and a reduction in capacity