I will go for the best option that you recommend me to improve the life of my batteries, 24V, 13A with this charger I can do the Cv that you mention? or do I need something additional?
A charger is simple. A 2 or 3 stage charger does the following:
1. It charges at its max Amp level, (or the one you chose so it doesent melt the chairs loom or connecting plug) and the battery voltage is gradually lifted at this CC (Constant Current) stage. This is known as BULK by ignorant people. It does this until the voltage reaches the voltage you have choosen. In the case of the MK gel that is a MAX of 14.1V (28.2V for a pair in series). The battery is about 80% charged.
2. As soon as this voltage is reached, a good charger then HOLDS IT SOLID at this 28.20V level (for your MK gel battery). This is the CV stage. This is Constant Voltage. Also called absorption by dummies. During this time, the battery is gradually pulling less and less amps quite naturally. The Amps will drop from the CC maximum Amp stage, over time, usually 8 hours approx, down to a very low level. When it reaches 8 hours of CV or when this current drops to approx 70 to 140mA, whichever occurs first, the battery is 99% charged. At this point the battery is ALMOST fully charged. Now the battery enters FLOAT.
3.The 3rd stage is another constant voltage stage. But at a lower voltage. It completes the charge over another 8 to 20 hours. Depending on battery type/condition etc. This is typically 13.8V (x2 for 2 batteries in series). Most use 13.5 to 13.6V instead because than it can be left indefinitely connected.
4. But on the victron charger I linked to, theres also a long term storage FLOAT level. An even lower voltage that can be left connected indefinitely. This is around 13.4V per battery. So 26.8V on your MK gel. It keeps te battery from discharging, and doesent charge it. Just keeps it at 100%.
So a 3 stage charge looks like this: