Absorbed Glass Matt Batteries [A.G.M’s] are still lead-acid batteries but are sealed instead of vented. The electrolyte is held captive in a fibrous glass mat that cannot be spilled and therefore can be shipped without hazardous material restrictions. This glass matt also provides pockets that assist in the recombination of hydrogen and oxygen gasses (that are generated during charging) back into water.
A.G.M. batteries, give high CCA, a deep cycle and fast charging (up to 5 times faster) than other batteries. The construction of AGM batteries allow them to be used in environments where other batteries simply could not. They have a high vibration resistance which is why they are broadly used in the 4WD, motor home and caravan markets. AGM batteries have a very low self-discharge rate, up to about 3% per month so they can sit in storage for much longer periods without charging.
Battery Care and Maintenance
- For optimum performance always recharge your battery after discharging;
- Do not mix AGM with conventional lead-acid batteries (unless they are charged from a completely separate source) OR if mixing batteries, like in most battery dual setups, you can use the two together as long as the correct isolator is being used.
- Do not overcharge your batteries as this will void your warranty. Once the battery is fully recharged, remove it from the charger;
- Use only fully automatic chargers suitable for
AGM Deep Cycle batteries when charging your AGM batteries. Failure to use a fully automatic charger (specifically for AGM Deep Cycle batteries)
can lead to over-charging and failure of your battery. Please note this will void your warranty.
We have a range of 10amp and 20amp automatic chargers spcifically designed for AGM Batteries (which can be found on our website at
AGM Battery Chargers ;
- Store batteries in a cool, dry, well ventilated place;
- AGM Batteries can be safely discharged to about 40%. Failure to recharge this battery promptly after discharge or leaving the battery in a state of low charge may cause sulphation and damage to the cells. Please note this will void your warranty.
The reasons we do not recommend wet cell and AGM Batteries together are:
1. When charging, the AGM will reach full charge before the wet cell. This means that the charge system will do one of two things. It will keep charging until the wet cell is fully charged and may over-charge the AGM or it will switch off when the AGM is fully charged which means the wet cell is only partially charged.
2. The wet cell will try to draw power from the AGM and this will reduce the life of both batteries because of under-charging then draining them will naturally damage both batteries but will kill the wet cell quickly.
As said above, if both batteries are charged separately, like in most dual battery set ups you can use the two together. With a voltage sensitive regulator or blockout diode (used in most dual battery systems) the start battery is charged first then it switches over to the 2nd or house battery.
Charging of your AGM Battery
The storage life of your AGM battery is usually between 9 to 12 months at 20ºC starting from a charged condition. Always store your batteries in a dry, clean, cool environment. If storage of 4 months or longer is required supplementary charging will be required.
Correct charging of an AGM battery is essential in optimising battery performance and life. Although a constant voltage charge should be applied, optimum charging also depends on temperature (normally 20ºC), charge current (maximum ¼ battery capacity) and ripple current (minimum).
Battery Chargers
Cheap chargers will ultimately do more harm then good and here's the thing to remember. A brand new, good quality 12 volt battery, depending on size, will generate between 13.0 and 14.5 volts. That is because each cell will generate slightly more than 2 volts per cell when they are new. But as the battery ages, they will progressively generate less voltage and power per cell. Cheap battery chargers cannot adjust for these changes in total voltage over time.
ALWAYS use a battery charger designed for charging AGM Deep Cycle Batteries. Ensure that your installation has a charging system with a program for AGMs or ask us about our 10amp and 20amp automatic chargers specifically designed for AGM Batteries (which can be found on our website at AGM Battery Chargers
Solar
Any solar charging system must be regulated. Failure to regulate the charge from your panel will result in overcharging and subsequent damage to your AGM battery.
Generators
Petrol or diesel generators can be used to recharge your AGM battery. However, it is not recommended to recharge from the charge outlet (if fitted to your generator) as most generators have insufficient regulators. This will damage your battery and also void your warranty. It is recommend that you use an automatic charger (suitable for AGM deep cycle batteries) with a generator that is capable of delivering up to more than 4 or 5 amps, otherwise the battery cannot successfully be quickly or fully charged.
Float/Standby
This charging method is used for back-up applications. The battery is continuously on charge and consequently the recommended voltages are slightly lower than cyclic charging so as not to damage the battery. Float voltage for these batteries are about 2.25-2.3 volts/cell. These figures may vary.
Cyclic
Cyclic charging is used in applications where the battery is repeatedly discharged then charged. A higher charging voltage is used but should NEVER be left on indefinitely since it will overcharge and destroy the battery. The voltage is about 2.4-2.5 volts/ cell.
Each battery suited to cyclic use will have a prescribed quantity of cycles to end of life and is dependent on the depth of discharge. Near the end-of-life standby capacity of the battery will reduce. When this reduction becomes persistently regular, this indication can also be used for the time of replacement.
AGM batteries today can be charged at up to 14.7 volts, but at the expense of longevity, 14.1 volts however is adequate.
FirstStart AGM batteries are thus charged deeply and speedily by 14.2-14.4 volts from a standard charging system.
FirstStart AGM Batteries can be safely discharged to about 40% and can be routinely and quickly charged to well over 90%. Please remember that FirstStart Batteries must be charged by a fully automatic charger otherwise your warranty will be void.
For optimum performance always recharge a battery immediately after discharging.
Please take special note to:
Sulphation/Undercharge
WARNING – never leave a battery in a discharged state
If a battery has an open-circuit voltage lower than its rated value, then sulphation may well be the cause.
When a battery is left in a discharged state or for prolonged periods of storage lead sulphate crystals begin to form acting as a barrier to recharge and will prevent normal battery operation.
Depending on the degree of sulphation, a battery may be recovered from the condition by constant current charging at a higher voltage with the current limited to one tenth of the battery capacity for a maximum of 12 hours.
In extreme circumstances a battery may never fully recover from sulphation and must therefore be replaced.
Multiple Batteries
Please remember when changing batteries in your boat or vehicle DO NOT MIX batteries. If you are changing one or two to AGM Batteries change them all.
Warranty
FirstStart Deep Cycle Batteries from 7a/h up to 40a/h have a 12 month warranty,
55a/h up to 200a/h have a 24 month warranty. Mobility Scooter applications have a 8 month warranty. The warranty period commences on the
date of despatch. If you have misplaced your paperwork, the warranty will be based on the battery date code which can be found on the top of
each battery. The warranty does not cover incorrect charging and sulphation. It also does not cover neglect, breakage and freight.
Any warranty replacements need to be returned ‘back to base’ to our office in Kirrawee, Sydney.
First StartAGM Battery Special:FS-12V 90A/H
First StartAGM Battery Special:FS-12V 100A/H
