Whether you’re running a 12v or 16v battery, off season maintenance is critical for proper performance and life expectancy. AGM or absorbed glass mat batteries are sealed, high performance lead acid batteries. This style of construction provides many advantages over traditional flooded lead acid batteries. Faster recharge times, higher discharge rates, higher resting voltages, more vibration resistant, sealed case design (multiple mounting options) and a low self-discharge rate are just a few. For these reasons, AGM batteries are an obvious choice in any racing environment. However, for a long life, they must be maintained correctly. This means using the correct charger for your specific battery model, keeping the battery charged when not in use to prevent sulfation and running the correct alternator for your application (if equipped).
All battery chargers are not created equal. Conventional lead acid battery chargers use a different profile as well as a higher overall voltage when compared to AGM approved models. AGM batteries are sealed, which tends to make them more sensitive to charge voltage and proper charge current. If they are overcharged (over 2.4v per cell), electrolytes will be released from the safety valves, which cannot be replaced. After several improper charge cycles the battery will dry up and poor performance will be experienced. Under extreme conditions the battery itself can swell from the increased internal pressure, often times combined with high battery and/or ambient temperatures.
XS Power 12v AGM batteries have to be kept over 12.6v when not in use, or 16.6v for 16v models. This generally means charging your battery with an AGM charger every 4-6 weeks when not in use. Another option is to leave the battery on an AGM battery maintainer (see XS Power part # HF1615, 1005). If left at a low state of charge, a chemical reaction can occur inside the battery. This reaction is called sulfation. Sulfate crystals will begin to form on the negative plates within the battery, leading to higher internal resistance, loss of cranking power and capacity. Once significant sulfation has occurred there is little that can be done to reverse the effect. If the sulfation is not yet severe, de-sulfation charging modes can restore battery function.
Most OEM and aftermarket alternators will correctly charge AGM batteries as long as they are large enough for the application and charging at the correct voltage. All previously discussed maximum charge voltage’s will still need to be met; maximum of 14.4v on a 12v, 16.8v on a 14v, or 19.2v on a 16v. We generally recommend running an alternator that will safely maintain charging voltage even at engine idle speed with all electrical devices running. Many manufacturers’ rate in maximum amperage, which often times do not provide the customer with realistic output or correct charge at idle. Making sure you have enough alternator power at all times will prevent the racer from relying on battery capacity to continue the vehicles operation. If your vehicle is total loss (runs no alternator) it is important to select a properly sized battery. It’s always a tradeoff; more weight means more capacity, less weight means less capacity. The most important rating for customers’ running total loss is the “RC” rating. This is the number of minutes a battery can maintain a 25 amp constant discharge until it is 100% discharged (10.5v on a 12v). Generally speaking, 25 amps should roughly reflect most circle track/asphalt vehicles running ignition, lights and helmet fan. With most racing applications we size 12v batteries to maintain over 11.5 volts (15.3v for 16v) even in a total loss situation.
Following these guidelines are key to a long and powerful .