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opinions/experiences on AGM vs flooded cell batteries?

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  • #16
    As a note I bought an Optima charger too right around $200 bucks, not cheap. Then the battery in my wife's old Miata went dead & me, a die hard CASO (no relation to Diehard batteries) took the battery out & put it on the Optima charger. It goes through a diagnostic check & then charges. It has a setting for regular lead-acid batteries & AGM's. Took that battery that wouldn't light up a test lamp up to starting the car without any problems. Car is back on the road now for over a month so if there were anything wrong it should have showed itself by now.
    59 Lark wagon, now V-8, H.D. auto!
    60 Lark convertible V-8 auto
    61 Champ 1/2 ton 4 speed
    62 Champ 3/4 ton 5 speed o/drive
    62 Champ 3/4 ton auto
    62 Daytona convertible V-8 4 speed & 62 Cruiser, auto.
    63 G.T. Hawk R-2,4 speed
    63 Avanti (2) R-1 auto
    64 Zip Van
    66 Daytona Sport Sedan(327)V-8 4 speed
    66 Cruiser V-8 auto


    • #17
      We have both Flooded Cell (lead acid) and AGM (Absorbed Glass Mat) batteries.

      Our 54 hardtop, the one in our avatar, has an old fashioned 6 volt flooded cell battery under the hood for the original look and a 6 volt Absorbed Glass Mat Optima battery in the trunk discreetly concealed by a piece of black felt.

      They are connected in parallel by a manual interconnect switch whenever the engine is running. They are not interconnected when not running because one battery will discharge the other when not being charged. The 6V Optima is for back up to the 6V system; it has rarely been needed.

      All batteries self-discharge and batteries connected in parallel discharge one another.

      The Flooded Cell and the AGM batteries have different charging needs so the AGM in the trunk of the Stude with its 6V generator system is a sacrifice battery in the long run; but in the long run it too has not yet failed.

      We have a small GMC motorhome that we use a large flooded cell 12V from Walmart for the engine battery and two large Southern golf cart 6V flooded cell batteries in series for the house batteries.

      We keep AGM batteries in the trunk of our cars that have trunk mounted batteries to keep the sulfuric acid fumes out of the trunk. These are all sports cars that see limited use. We also have an AGM on an airplane to keep out sulfuric acid fumes; it too sees limited use.

      We keep battery minders on the batteries of our intermittent use vehicles. Search on the brand "Battery MINDer" and check out how they charge, de-sulphate and maintain batteries in 24 hour cycles. These devices are life lines for batteries.

      Flooded Cell and AGM batteries have different charging needs. We use an AGM specific Battery MINDer on our vehicles with AGM batteries and a Flooded Cell Battery MINDer on our vehicles with lead acid flooded cell batteries. Both types go for long periods with the vehicles not being in use.

      The Battery MINDers pay for themselves in battery life and dependability. The batteries should be fully or near fully charged when the Battery MINDer is connected.

      From time to time I use an old fashioned parts store battery charger on the 54 Stude since there isn't a 6V Battery MINDer. The lead acid and the AGM batteries are charged separately.

      We've had one 12V Red Top AGM battery die and no amount of coaxing would bring it back.

      We've taken dead, flooded cell batteries, charged them for long periods, dumped the electrolyte out, filled them with distilled water, charged again, dumped the water and lead dust out and re-filled with new electrolyte and gotten some more service out of them; all in the name of fun and experimentation. The usually were severely sulfated.

      All batteries should be kept fully charged all the time. Flooded cell battery electrolyte should be kept up. Discharge cycles shorten battery life.

      Flooded cell batteries are actually more efficient than AGM batteries. Flooded cells are used in industrial battery banks.

      Battery life is of great value to us so we try to keep them charged.

      Don and Susan Jeffers


      • #18
        I always get over 10 years out of the lead/acid 6 volt batteries, and I don't use any battery tender when the cars set for 6 months of snow and road salt. The last 3 batteries came from a recycling yard over 10 years ago, and are still starting the cars. I think I paid about $8 for all three because the price for lead was down at the time. Unfortunately that recycling yard has a new owner, and he won't sell a thing.