How to initial charge of fla batteries

[MambaJack]

so finally getting around to setting up the fla batteries that i purchased in october in my bus conversion. They are 8 6v 235 ah gc2s that will be in a 24v setup. I havent done anything with them to this point except store them inside. The hydrometer shows them undercharged. What is the best way to charge / set them up. I put 2 in series and tried my car charger at 10 amps. But it is taking a while. Thoughts. Thanks

[inetdog]

FLA batteries which have been sitting around uncharged since October have permanently lost a good portion of their original capacity because of what is called sulfation. FLA batteries at a reputable battery dealer will either be trickle charged constantly or charged periodically (at least weekly) to preserve them.
By all means charge them any way that you can, either by putting them in series and using a 24V battery charger or getting a charger which can accommodate 8V batteries.
I fear that you will find that they charge up to a maximum voltage which is less than the expected voltage for a new battery and if you measure the Specific Gravity with a temperature compensated hydrometer you fill find that it is lower than the manufacturer's specification for a fully charged lead acid battery. This will be an indication that some of the initially spongy lead sulfate compound that builds up on one plate during discharge has converted into hard crystals which are difficult to impossible to break down again to fully charge the battery.

If you had asked here before buying the batteries, we would have advised you to have a plan in place for keeping the batteries charged before bringing them home.

[MambaJack]

Thanks inetdog, that is what i was afraid of (naive). Definitely wish i would have asked

I connected 2 yesterday and put my car charger on at 10 amps for a few hours. removed over night,
When i checked this morning, the voltage said 12.68 together, should i put it back on there to see if it will take more?

I also plan to charge the rest the same way.
There is a 50 amp charge option on my charger, should i use that?

Thanks,
dave

[inetdog]

Thanks inetdog, that is what i was afraid of (naive). Definitely wish i would have asked

I connected 2 yesterday and put my car charger on at 10 amps for a few hours. removed over night,
When i checked this morning, the voltage said 12.68 together, should i put it back on there to see if it will take more?

I also plan to charge the rest the same way.
There is a 50 amp charge option on my charger, should i use that?

Thanks,
dave

The regulated voltage from your car's charging system will not be able to charge the 16 volt series combination any higher than about 12V. It will NOT get the job done no matter how long you wait.

You need an 8V charger or a 24V charger with all 4 in series. This is one of the hassles of buying 8V batteries before you have the system you will use them in.

[MambaJack]

I fear that you will find that they charge up to a maximum voltage which is less than the expected voltage for a new battery and if you measure the Specific Gravity with a temperature compensated hydrometer you fill find that it is lower than the manufacturer's specification for a fully charged lead acid battery. This will be an indication that some of the initially spongy lead sulfate compound that builds up on one plate during discharge has converted into hard crystals which are difficult to impossible to break down again to fully charge the battery.

Thanks for the advise. I initially charged in pairs with my 12v charger, then hooked up the inverter charger over the weekend.
After what seemed like quite a bit of charging, the bank has been sitting for a day with the charger turned off and shows 25.7v
Also, i checked one of the batteries and the cells with a hydrometer and they were 1300,1275,1300.
What does temperature compensated means? What voltage should the battery bank get up to to be "full"?
Thanks,
dave

[inetdog]

Thanks for the advise. I initially charged in pairs with my 12v charger, then hooked up the inverter charger over the weekend.
After what seemed like quite a bit of charging, the bank has been sitting for a day with the charger turned off and shows 25.7v
Also, i checked one of the batteries and the cells with a hydrometer and they were 1300,1275,1300.
What does temperature compensated means? What voltage should the battery bank get up to to be "full"?
Thanks,
dave

Temperature compensated refers to the fact that thermal expansion affects both pure water and electrolyte mix, so the specific gravity, being a measure of weight per unit volume, will change with temperature for the exact same electrolyte concentration. A temperature-compensated hydrometer, either automatically or with multiple scale calibrations and a built-in thermometer, tells you what the specific gravity would be at the standard temperature used by the manufacturer and others as a reference (usually 68F).