Closed lead batteries are equipped with thin plates in which antimony has been replaced by calcium in the alloy, all bathed in an electrolytic solution of sulphuric acid and water.
The presence of calcium has the advantage of - almost - eliminating water consumption, making the presence of filling plugs unnecessary.
The 3 or 6 2.1 V elements are enclosed in a sealed "box" equipped with vents to ensure possible degassing during the charging phases.
They are not really waterproof like gel batteries, but remain so up to 55° of inclination.
These are closed batteries, which are not 100% waterproof and therefore different from the VLRA, the AGM and Gel battery category.
They are called "maintenance-free" because it is not necessary to top up electrolyte throughout the lifetime of these batteries. Even if it is a euphemism, because it is precisely the lack of electrolyte that will shorten their life span...
The low weight of the lead-calcium alloy allows the use of perforated strips for their construction, which is why it is sometimes referred to as "perforated plate batteries". They are therefore light enough and constitute excellent starter batteries, but they cannot withstand deep discharges that destroy them quickly enough.
Use of closed lead-acid batteries
They are used in the nautical or automotive industry, installed as starter batteries.
Setting the 3-phase charger
- Bulk 14,7V
- Absorption 14,7V
- Float 13,6V
Advantages of closed lead batteries
- Low weight
- Reasonable price
- Maintenance-free
Disadvantages of closed lead batteries
- Not really waterproof
- Cannot tolerate deep discharges
