Beta 1498TB/ST Mode D'emploi page 11

GLOSSARY
Conventional Lead-Acid Batteries
Lead-acid batteries, which were invented back in 1859, are still the number one choice for cars, since they are robust,
can tolerate misuse, are popular and cheap. However, for high-capacity applications, with intermittent loads, lead-acid
batteries are usually too big and heavy; in addition, they have a shorter life cycle and usable power accounts for only
50%. Cell voltage is 2V. They are extremely reliable, have low internal resistance, thus being able to supply high
currents. However, they are very cumbersome and heavy; their efficiency accounts for 70% vs. 85-90% of more
modern designs, and risk getting overheated while being recharged.
Lead-Acid Batteries with Added Calcium
Lead-acid batteries whose electrodes are modified by adding calcium have a few advantages over conventional lead-
acid batteries:
– They are more resistant to corrosion, excessive charge, gas production, water-saving, and are connected with
slower self-discharge.
– They have a larger reserve area for the electrolyte on the plates.
– They have a higher CCA (Cold Cranking Amps).
– They require more occasional maintenance.
Lead-Acid Batteries with Added Antimony
Lead-acid batteries whose electrodes are modified by adding antimony have a few advantages over conventional lead-
acid batteries:
– The electrodes have a higher mechanical resistance - which is important in case of deep battery discharge.
– They reduce internal heat production and water loss.
– They usually have a long useful life compared to lead-calcium batteries.
– They are easy to recharge when they are completely run-down.
– They are cheaper.
Lead-antimony batteries have a very high self-discharge rate, approximately 2-10% a week, vs. 1-5% a month for lead-
calcium batteries.
VRLA (Valve Regulated Lead Acid) or SLA (Sealed Lead Acid) Batteries
These batteries are designed to prevent electrolyte losses through evaporation, dripping or boiling. This allows the
battery life to be prolonged and results in easier battery maintenance. VRLA batteries are fitted with Bunce pressure
valves which open only under extreme conditions, and not with vent plugs on the cells. In addition, the electrolyte is
designed to reduce the possibility of gas production, preventing oxygen and hydrogen produced through galvanic
battery actions during recharge from being released into the atmosphere. As a result, a catalyst is generally required
to combine hydrogen and oxygen in water. Hence it is called "recombining system". Dealing with acid loss makes these
batteries safer than conventional batteries.
Gel Batteries
This alternative recombining technology is used for VRLA batteries. These batteries have a disadvantage in that they
may gas if the charging rate/voltage is too high. Hence the charging rate should be reduced to prevent the cells from
being damaged. They should not be charged with a conventional car battery charger.
– Gel batteries are sealed and should never be opened.
– They are completely maintenance free.
– They use a recombining system to prevent hydrogen and oxygen, which are usually lost in a conventional lead-acid
battery (especially in heavy applications), from being discharged.
– It can be virtually used in any position. However, face-down installation is not recommended.
– Connection should be twisted, and batteries should be periodically cleaned.
AGM (Absorbed Glass Material) Batteries
Basically, AGM technology, used for VRLA batteries, is based on glass microfiber (Boron Silicate), which functions as
a separator between electrodes and absorbs the electrolyte more or less like a sponge. This makes it easier to
recombine hydrogen and oxygen, which separated during the charging process. Glass fibre absorbs and immobilizes
acid in its texture, while keeping it in a liquid form, and not a semisolid one, as is the case with gel batteries. Hence
acid is made available to the plates more quickly, thus allowing a quicker chemical reaction between acid and the
material of the plates and thus higher charging/discharging rates and higher capacity in terms of deep discharge
cycles.
This structure is very robust and can survive major shocks and vibrations; in addition, the cells will not leak acid, not
even when they are broken.
– AGM batteries are sometimes called "starved electrolyte" or "dry" batteries, because glass fibre is 95% saturated
with sulphuric acid, and there is no excess liquid.
– AGM batteries have a very low self-discharge rate, approximately 1-3% a month.
– AGM batteries are sealed and should never be opened.