Freddmc
New Member
I have 3x 100w solar panels feeding 2x12V FLA's. Can I safely add an 12vAGM to this?
Thx
Thx
Combining FLA's and AGM's
- Thread starter Freddmc
- Start date
gnubie
Solar Wizard
- Joined
- Sep 20, 2019
- Messages
- 3,847
The outcome will be 3 x 12v batteries in parallel? If so, yes you can do that but there are some things to be aware of that will limit your battery capacity.
For open cell batteries where you are supposed to maintain the electrolyte level:
Flooded cells develop a problem called acid stratification, where the acid concentration in the electrolyte becomes uneven reducing the capacity of the cell. To combat this in stationary batteries they are periodically given an equalisation charge, which amongst other things literally stirs up the electrolyte via the gas bubbles given off. This is fine as you can top up the electrolyte to replace any that is lost.
For sealed (VRLA) flooded batteries:
These batteries should not be exposed to equalisation charging as there is no way to replace any lost electrolyte. The plate spacing is different to an open flooded battery to reduce the effect of acid stratification. Extended absorption charging can exceed the rate that the battery can recombine the electrolyte and this will result in lower service life.
AGM batteries:
AGM batteries are closed units where the electrolyte is not particularly mobile, it's contained around the glass. Any charging that results in excessive splitting of the electrolyte will quickly damage the battery. It is essential that an AGM battery is never exposed to equalisation charging. It is important that the AGM battery is not held at absorption charging for extended periods as this will reduce the life of the battery. If you have a load directly across the battery your charge controller may never detect end of absorption charge and over time fry your AGM battery.
AGM and flood batteries have similar normal charging voltages so they are largely compatible in bulk and absorption charging, but you can see that in order to not damage the AGM battery the flooded open cell battery will have a reduction in its capacity.
Are your existing flooded batteries sealed (VRLA)?
For open cell batteries where you are supposed to maintain the electrolyte level:
Flooded cells develop a problem called acid stratification, where the acid concentration in the electrolyte becomes uneven reducing the capacity of the cell. To combat this in stationary batteries they are periodically given an equalisation charge, which amongst other things literally stirs up the electrolyte via the gas bubbles given off. This is fine as you can top up the electrolyte to replace any that is lost.
For sealed (VRLA) flooded batteries:
These batteries should not be exposed to equalisation charging as there is no way to replace any lost electrolyte. The plate spacing is different to an open flooded battery to reduce the effect of acid stratification. Extended absorption charging can exceed the rate that the battery can recombine the electrolyte and this will result in lower service life.
AGM batteries:
AGM batteries are closed units where the electrolyte is not particularly mobile, it's contained around the glass. Any charging that results in excessive splitting of the electrolyte will quickly damage the battery. It is essential that an AGM battery is never exposed to equalisation charging. It is important that the AGM battery is not held at absorption charging for extended periods as this will reduce the life of the battery. If you have a load directly across the battery your charge controller may never detect end of absorption charge and over time fry your AGM battery.
AGM and flood batteries have similar normal charging voltages so they are largely compatible in bulk and absorption charging, but you can see that in order to not damage the AGM battery the flooded open cell battery will have a reduction in its capacity.
Are your existing flooded batteries sealed (VRLA)?
Freddmc
New Member
The existing FLA's are not sealed.
Freddmc
New Member
Thanks. Good to know.
victorpr
Solar Enthusiast
Correct
