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By Glen Konorowski….
Since most of us let our cars sit for the winter, it is inevitable that the battery will run down over the course of the winter. I have been lucky enough for the past 4-years that my battery has not ever had to have been replaced, but I expect I will have to replace it soon. Unfortunately, there are those who are not as lucky and have to replace their batteries every 2-years. This can be a pain when you charge up the battery after sitting only to find that it doesn’t hold a charge.
One solution to constantly replacing batteries is to get one that lasts longer and holds a better charge. Presently the best way to do this is with an AGM battery and not just a bigger battery. AGM or Absorbed Glass Mat batteries work like conventional lead-acid batteries but use better quality material.
AGM sealed battery technology was originally invented in 1980, and developed and introduced in 1985 for military aircraft where power, weight, safety, and reliability were paramount considerations.
Instead of plates of alloy lead in rows with liquid acid in between, AGM batteries use high quality and almost pure lead closely wound with thin ultra-fine fibreglass mats sandwiched between the plates that are saturated with battery acid to about 95% of what they can hold. They are packed in between the plates and slightly compressed, then welded/soldered in place. (In cylindrical cell batteries like those made by Optima, the matting is wrapped).
Because the plates and mats are packed fairly tight, they are almost immune to vibration. The liquid acid is absorbed by the glass fibre wrapped around the lead so nothing is sloshing about. By using a better quality lead, electrons flow better giving the battery more cranking power and allowing it to last longer.
In the conventional batteries, the separation material used for the alloy lead does not effectively allow the electrons to flow as well, so there is less cranking power. The lead/alloy composition of the plates when inactive will sulphate over time diminishing the effectiveness of the battery. One other key factor to the life cycle of the conventional lead-acid battery is the evaporation of the liquid (distilled water) as compared to an AGM which is basically sealed.
Two other advantages to the AGM construction are that in case of a crack in the wall of the battery they will not leak. A colleague of mine did happen to get into an accident with an AGM battery installed. The AGM did crack and didn’t leak and I saw the damage just after the accident as a leaky battery could cause extra damage. In fact, he started the vehicle and drove away. This did perk my interest and I found out later that AGM batteries are also less prone to damage if the vehicle is driven over rough terrain.
So why haven’t all the major automotive companies not switched over to AGM batteries? Well, cost is a big factor. The conventional batteries we all use in our day to day vehicles work fine as these vehicles, for the most part, don’t sit inactive for long periods of time. In today’s modern vehicles there is a flow of power at all times for a host of things like radios, clocks and alarms. Driving your vehicle constantly replenishes that draw of power. But, if a new vehicle is allowed to sit for a long time, it will take less than a year to fully drain the battery. In a test that some friends made on a new car the battery, it lasted just nine months.
Things we have to contend with in older cars is inactivity and nagging little electrical shorts that cause the battery to drain. As AGM batteries have more power they will not run down as quickly as the conventional battery. They also have the ability to recharge better when the charge is low due to the better flow of electrons within the battery.
The one downside that Citroën owners with 6-volt cars face is that the size of an AGM battery may not fit in the same manner as a conventional lead-acid battery. (6-volt 2CVs for example, take a 19L size battery [L: 8.25″ x W: 6.75″ x H: 7.5″] and the only AGM 6-volt battery is made by Optima – part # 8010-044 which measures L: 10.06″ × W: 3.63″ × H: 8.13″. Because of its height, it needs to be mounted on its side and secured in a custom manner.)
If you are installing a conventional shape modern maintenance-free battery, you may not be thrilled that the top of the battery does not have old-style filler caps. For some sizes of batteries, there are options to put covers on that give a vintage appearance.
Two companies that offer such a product are Battery Toppers (for AC Delco 24 Series) and Tartopper.