The resistance of AGM and EFB batteries to deep discharges is the ability to fully charge after them without losing their previous capacity. What does not make a deep (or even full) discharge impossible is that it will not work to deceive physics.
What to do if the battery is completely discharged? There are different opinions on whether it is possible to “light up” an AGM Battery. Someone is sure that it is absolutely impossible, others believe that nothing terrible will happen. It is wiser to proceed from a specific situation: if there is some current left in the battery, but it is not enough to start the engine, it is quite acceptable to help it with a “light” if you do everything right and use high-quality starting wires . If the battery is set “to zero” – do not torment the equipment. A discharged battery must be removed and fully charged using an external charger. This applies not only to AGM, but also to EFBs and conventional wet batteries.
If the battery is set to “zero” – do not torment the equipment. The battery must be removed and fully charged.
Charging EFB And AGM Batteries
How to charge EFB and AGM batteries with an external charger? EFB batteries are no different from conventional batteries in terms of charging, since they also use a liquid electrolyte. The battery is charged with a current equal to 10% of the nominal capacity and a voltage not exceeding 14.8 V. On the digital charger for charging the EFB battery, select the mode for liquid batteries (WET or SLI). Temperature compensation (snowflake icon on charger) is not required for EFB.
With AGM batteries, things are a little more complicated due to their greater sensitivity to overcharging: the voltage should not exceed 14.4 V. To properly charge an AGM battery, it is better to use an electronic charger with a microprocessor that supports AGM charging mode and temperature compensation. When manually charging with a conventional transformer “charger”, there is a high risk of overheating the glass mats of the battery.
As for charging directly in the car, you should not worry: the generator of a modern car, especially a “green” one, will successfully cope with any type of battery.
Which Is Better: AGM or EFB?
Directly comparing EFB and AGM batteries is not entirely correct. Both types of batteries perform well in “green” cars with a “start-stop” system, but they are made using different technologies and for different tasks. AGM is an uncompromising solution capable of operating in extreme conditions, with strong vibrations and large rolls, delivering stable voltage without dropouts and quickly replenishing the charge. For this, they are respected by jeepers using powerful electric winches, and lovers of high-quality car audio. The high cost of AGM batteries is quite consistent with their level.
EFB batteries are an intermediate step between AGM and a conventional wet battery, they can be called a good compromise. Being structurally closer to the “classics”, EFB is not much inferior to AGM in terms of deep discharge resistance and charging speed. This solution is for those who are not ready to overpay for the extreme capabilities of AGM batteries, but simply want to ensure the normal operation of the start-stop system. In this case, buying an EFB battery is a smart choice.