Looks like you have a weak or dead cell. It should read 12.5+
Look for a swollen cell. Mine did the same thing. I still have several others that are still working fine, but I think Optima has priced their batteries out of the market now.
Here is some handy battery information I have compiled:
Voltmeter Reading State of Charge
12.84 Volts or higher 100%
12.50 Volts 75%
12.18 Volts 50%
11.88 Volts 25%
Warning: Gel and AGM (Absorbed Glass Mat) batteries
require a voltage-limited charger. Charging a Gel or AGM
battery on a typical shop charger – even one time – may
greatly shorten its life. It is imperative not to exceed 15.0V as this will cause the pressure valves to open and out-gas hydrogen, oxygen and water from inside the battery. This will shorten the life of the battery and cause premature failure.
Recommended charging information:
Alternator: 13.65-15.0 volts
Battery Charger: 13.8-15.0 volts; 10 amps maximum; 6-12 hours
Float charge: 13.2-13.8 volts; 1 amp maximum (indefinite time at lower voltages)
Rapid Recharge (Constant voltage charger): Maximum voltage15.6 volts. No current limit as long as battery temperature remains below 125°F (51.7° C). When current falls below 1 amp, finish with 2 amp constant current for one hour.
All Limits Must Be Strictly Adhered To
Recharge time (assuming 100% discharge - 10.5 volts):
100 amps - 35 minutes
50 amps - 75 minutes
25 amps - 140 minutes
Recharge time will vary according to temperature and charger characteristics. When using constant voltage chargers, amperage will taper down as the battery becomes recharged. When amperage drops below 1 amp, the battery will be close to a full charge. (all charge recommendations assume an average temperature of 77°F , 25°C)
* APPROX. BATTERY CHARGING TIME *
STANDARD OF TO FULL CHARGE AT 80°F/27°C
Maximum Rate at
12 V ---------- 50 Amps 30 Amps 20 Amps 10 Amps
12.6 100% – F U L L C H A R G E –
12.4 75% ---- 20 min. 135 min. 148 min. 190 min.
12.2 50% ---- 45 min. 175 min. 195 min. 180 min.
12.0 25% ---- 65 min. 115 min. 145 min. 280 min.
11.8 0% ------ 85 min. 150 min. 195 min. 370 min
I am currently trying a Deka Intimidator 34/78. The rep says the Deka Intimidator 34/78 dual terminal was built to compete directly with the Optima Yellow top. He said the ratings are under estimated and it will test higher than advertised.
It will be a while before I am able to give a good judgment of the value of this battery.
Keep in mind that I have been a diehard Optima advocate for a dozen years or more.
The Deka is built to the size an mounting considerations of the group 34/78 battery. The Optima meets these specs too , but doesn't fill all the space due to the cylindrical cell design. The Deka takes up all the available space.
I could not find warranty information, so I placed a call and sent an email. East Penn / Deka impressed me with their customer service.
I promptly received an email with the warranty information I requested. "Hello, below is the answer to your question.
36 months warranty and 12 months free replacement
Thank You and have a great day "
I also made a phone call to the 800 number. There was a message on my machine from last Friday. Today I received another call. The rep said, " Mr.Lehman?" , I said "Yes". "I understand you have a problem with your battery?". I said "No, I was just inquiring as the the warranty. I was told it was 12 months free replacement and prorated after that for a total of three years warranty." He said "That is correct".
I went on to ask about the recycling. That is true. They have their own lead and plastics recycling. 70% of the lead used is recycled and 30% new. 100% of the battery is recycled. The gases are made into fertilizer. This is one reason they have been able to keep their costs low.
I like the "Green" aspects of this battery.
The Intimidator yellow top was built to directly compete with Optimas Yellow top. The ratings on the Intimidator are said to be under rated. I was assured that they will out perform the ratings.
This may all be salesman BS, but I will see if they can back up those boasts.
Much of this post was copy/paste from a thread on the
S-10CREWCAB.COM Forum - Optima , Odyssey, Deka, Battery information