Lead Acid

Lead Acid, Lead Antimony, Maintenance Free, Sealed Lead Acid, AGM (Absorbed Glass Matt), EFB (Enhanced Flooded Battery), Calcium, Calcium / Calcium, Gel - these are all batteries that contain lead and acid and form a class of battery referred to lead acid batteries. Another example might be Lithium batteries and all their variants.

Each of these battery variations has been designed for a specific application/purpose. But many applications can take advantage of these characteristics so this is why you end up with batteries being used for starting applications even if they were primarily designed for Ah storage bank applications like house batteries in a boat or motor home.



Lithium Ion class includes Lithium Polymer, Lithium Iron (not to be confused with Ion) also known as LiFePO4, Lithium Cobalt, Lithium Maganese and many other variations.

Fundamentally Lithium charges almost opposite of Lead Acid which is why you can't use lead acid chargers on Lithium batteries despite which some lithium resellers say. Lithium has a lower internal resistance as it nears full capacity meaning it will keep absorbing more energy at a time when it should be slowing down, voltage should also be reducing but that's not how lead acid chargers work. So the end result is over charged batteries or worse.

CTEK have one Lithium Charger for LiFePO4 called the Lithium XS, it's a 12V, 5A charger with Lithium specific charge profiles.


Maintenance Charging

The term maintenance charging comes from being able to keep charged a battery that has already been bulk charged back to 100% state of charge. A battery in storage will lose voltage/capacity over a month (actual loss differs depending on type of battery & storage temperature) so a maintenance charge is needed to replace these losses. In a wider scope maintenance can be used to replace the top 20% of capacity of a battery because that's what a float charge on a battery is doing.

A float charge will require approx 5% of the batteries AH capacity so a 5A charger can maintenance charge a 100AH battery but it can't maintenance charge a 200AH battery. All CTEK chargers have a maintenance profile which goes one step further than explained above. Once the charger has returned voltage to 12.8V (AGM mode) it effectively turns off DC power, but uses mains power to keep monitoring the battery. This saves even more power and some manufacturers coin this as eco-friendly mode.