There’s a myth that a common charger can be used instead even the best AGM battery charger. Let’s dispel it to exclude damages and to let the battery stay save for a long period.
AGM batteries are designed to charge them gradually not to overheat or boil battery acid. Normal chargers are not able to charge in stages. Besides, AGM batteries demand low voltage that is not the common units’ strength. They can’t control either voltage or amperage.
AGM charger is dedicated to AGM type of batteries and comes with the microprocessor to track the battery’s power and to set right both voltage and amperes based on the data obtained. Every modification of AGM battery has its own charge’s parameters and requires a proper AGM charger.
AGM Battery Charger Reviews
The following AGM battery charger reviews deal with advanced multifunctional devices that can power several types of batteries and are compatible with plenty of vehicles.
XS Power HF1215 – Versatile Model with 3-staged Charging
This 12-volt high frequency/15-Amp compact model can control the whole process providing accurate charging, excluding overcharging and breaking the battery down. It fits not only glass mat battery but also 2-volt deep cycle, maintenance free, and gel-cell ones.
One of its main features is 3 stages of charging. The first one delivers 80% of power allowing voltage floating but keeping the current fix. The second stage starts when the voltage has reached its correct level, and the cells have been equated providing 100% of power. The last stage adjusts the number of amperes and voltage to enhance the power of the battery.
The HF1215 has LED indicators to see the power on/off and charged status. Despite the absence of the display (some models in this price range have it), this model has a chance to become the best AGM battery charger due to the overload protection to escape endless checking the charge levels and full reverse polarity function.
It is not recommended to leave it connected to the battery without plugging it into the power outlet to avoid draining the battery.
- It is easy to use – just plug in and switch on. No extra settings and monitoring are required.
- It is available in 12, 14, and 16V versions.
- The clamp sometimes falls off from the wire because of some vibrations.
- Takes 2 hours to put on the first stage (it’s too long).
CTEK (56-353) MULTI US 7002 – Great for Diversity of Vehicles
This 12-volt/7-Amp unit fits both cars and other 12-volt vehicles – boats, dune buggies, ATVs, etc. The device is easy to carry and to store. Its cables are well insulated and very flexible. The CTEK (56-353) is safe because it can’t be activated in case of crossing connections.
It has 4 modes to use it in normal conditions, in colder climates with the average temperatures of 41 degrees Fahrenheit, for reconditioning heavily discharged batteries, and to provide a stable supply of 13.6 volts. Many drivers consider this model to be the best AGM battery charger due to its 8-staged system of charging; however, its alligator clips that are made of brittle plastic and can break easily.
- It can stay connected for several months without damaging the battery that makes the device perfect for seasonal vehicles.
- Simple plug – just supply jumpers to the charger, connect to the batteries + and – terminals and turn it on.
- Absorption phase overextends that provoke delays and make AGM battery charging too long.
- Too small positive clamps that are about one size.
Battery Tender 021-0123 – Keeps Batteries in Best Shape
The 12-volt/0.75-Amp battery charger is compact and lightweight enough to save space in the car or in the garage. It is compatible with different vehicles including airplanes, ATVs, motorcycles, scooters, watercraft, and lawnmowers. Ring terminals and alligator clip provide its easy connection. Its spark proof spec protects from current surges.
It comes with a 4-step program for charging AGM batteries and helps optimize the battery power. This model works great on flooded, wet-cell, lead-acid batteries, and AGM ones but except for the gel-cell battery.
Battery Tender starts floating voltage automatically after the power is full due to its ISM adaptive charging tech. The battery burning up or overcharging is impossible. The unit comes with reverse-hookup protection to avoid damaging when the battery is inserted incorrectly.
- A weatherproof connector on wires to use the charger for water vehicles.
- The charger can be stored and use in the unheated garage.
- Maintains fully charged batteries.
- Produces noise while operation.
- Its cord isn’t water resistant that requires to be cautious when charging watercraft.
- Hard to understand the indicators lights – green and red colors have several statuses.
NOCO Genius G7200 – Many Functions to Charge Vehicles and Devices
It is a 7.2-Amp, 12/24-volt device that charges and maintains lead-acid and lithium-ion batteries up to 230Ah, as well as deep-cycle batteries for automotive, marine, RV transport, as well as lawn and garden equipment. It is also possible to apply it for 120-volt 50-60Hz electrical systems.
This AGM battery maintainer is remarkable for its rubber cabinet to provide the non-slip effect and protection from UV rays and water. The NOCO is portable – it can fit into the palm of the hand. It is also very reliable to let it work for 24/7 without any control. The unit is energy efficient due to the auto-optimization of the flow of charge. Its LED indicators display not only the charging status but also real-time diagnostics to inform about the battery condition.
- Large clamps make them easier to use.
- The inline fuse is easy to access.
- Low power consumption up to 132W.
- Can’t revive dead batteries but need a bit of charge to start.
- No alligator cable in the box requires extra spending.
Battery Tender 022-0148-DL-WH – 4-step Charging, 4 Vehicles Are Available
This AGM charger is designed for 12-volt batteries and it fits different types of AGM batteries – sealed, maintenance free, and flooded. It is a perfect unit for owners of more than one vehicle including the recreational ones. It is possible to charge up to four batteries simultaneously (1.25 amp per charging bank) without a danger to overcharge or ruin them. There’s no need to supervise the charger – it can be hooked up for a long time and provide the necessary level of power. All the toggling between stages proceed automatically.
The device comes with 4-staged charging system – initialization, then bulking charging process, further absorption, and entering a float mode.
It comes with the reverse-polarity function to stay turned off in the case of incorrect polarity. Spark-proof connectors will keep you safe from being electrocuted.
- The mounting system is well-advanced mount it to the wall of a garage or a trailer for easy access.
- Diverse LED indicators for different vehicles.
- Not for an emergency, it is for slow charging only.
- Connectors can be damaged in rainy or snowy weather.
BatteryMinder 128CEC1 – Smart Device for 6 Vehicles Charging Simultaneously
This model is a 12-volt and 2/4/8-Amp battery charger for AGM battery (dry-sealed and wet modifications) that can charge, maintain, make disulfate, and condition it. It operates with low amp rates (2,4 or 8 Amps) that gives the batteries longer life. It enhances batteries’ performance without either undercharging or overcharging due to brand Auto-Temp Compensation Sensor. The unit is designed to operate flawlessly between the temperatures of 33°F to 130°F. It comes with a 5-step charging system:
- Check the battery to reveal bad cells.
- Charging up the maximum.
- Absorbing stage to confirm 100% capacity.
- Check the ability to hold power.
- Desulfation (if necessary) while keeping the battery at full charge.
The 128CEC1 can charge up to 6 vehicles at once that is not typical for the chargers in this price range.
- A setting option for Odyssey/PLT batteries with the charging voltage of 14.7V.
- Durable construction with top-quality cables.
- All the batteries have to be at the same level to charge them simultaneously.
Optima Digital 1200 – for Recovering Dead Batteries
This 12-volt/12-Amp AGM battery trickle charger contains many features including a USB adapter to charge the mobile devices and cameras. Its back panel has storage for cables. The model is compatible with 2V AGM and flooded batteries. On the top of the charger, there is a large circle display to show the charging process and error messages. Quick set controls for maintaining and choosing the type of battery to charge LED backlight button and pre-charge status sensor are also there. The unit informs about the quality of its connection to the battery.
It comes with 6 stages of charging to completely recharge and maintain a battery for 12 hours. The 1200 recovers even a deeply discharged battery.
- Separate setting for High-Performance AGM battery, regular AGM, and flooded types that are used in motorcycles, automotive, and marine.
- It works very quietly.
- It can’t charge several batteries at once.
- LED light for the charging status is a bit dim.
TPE 12V 5A – Water/Dust Resistant Device to Charge Fast
This 12-volt/5-Amp model has a sturdy corps that is able to resist water and dust that make it possible to use the charger outdoors in any weather and in a harsh environment. The unit has protection against short circuits, overloading, and overcurrent.
Intuitive interface has 4 LED indicators to show the charging percentage – 25%, 50%, 75%, and 100% respectively. It provides a 4-step charging that can last from 3 to 24 hours. The charger works as a maintainer to recover dead batteries.
- Very compact and easy-to-install.
- Fits not only AGM batteries but sealed, VRLA, calcium ones as well.
- No fuse compartment.
- No power switch. To add ON/Off switch or an inline connector for the power cord is highly recommended.
AGM Battery – Rules of Charging
Acid glass mat batteries are sensitive to overcharging. How to charge AGM battery to prevent heat and damages? They should be charged minimum in three stages with the aid of an appropriate charger. If the battery is deeply discharged, it may take more stages, including desulfation. Main stages’ are the following:
- Constant-current stage of the charger powers a battery up to 80% of its energy capacity operating at the maximum voltage and current amp rating.
- Topping charge makes absorption after an AGM battery’s got 14.4V. During this process, the voltage stays stable and the amp is getting lower until the battery reaches 98% of charge.
- Float charge makes no more than 13.4V and no less than 1 Amp providing the battery with 100% of charge.
AGM technology – the Basic Principles
AGM (Absorbed Glass Mat) batteries or starved electrolyte, as they are also called, have fiberglass mat wedged between 2 plates that are impregnated with acid. Those plates are welded to the battery and compress the mat. This tight connection provides the battery’s resistance to the vibrations. The plates contain enough liquid to keep the mat wet but not enough to leak out if the battery is broken.
Can Normal Chargers Charge AGM Batteries?
Originally, normal chargers can’t charge AGM batteries because they demand diverse voltages than conventional ones. They are usually used in deep cycle situations and need special kind of charging that consider the ratio of voltage to amperage and the necessity of slow charging. When using normal chargers, there’s a threat of overheating that force the driver to track the charging process all the time. Besides, they aren’t able to maintain the AGM battery to revive the dead one.
Still, there are some battery chargers designed to charge both lead-acid and AGM batteries by having charging mode selection feature.
Correct Voltage for Charging AGM Battery
The optimal charging voltage is from 14.6 to 14.8V for deep cycle use and from 13.6V to 13.8V for standby use. The accurate output voltage is used when turning on a special mode to a certain AGM battery (for example, automotive charging systems for flooded lead acid require 14.40V).
Charge Time – When is It Enough?
The time depends on the level of discharge. The average period is 4 – 6 hours. It takes near 12 hours to power heavily discharged battery. Completely dead ones may demand 24 hours to recover. Slow charging is required – up to 20-amps.
When comparing AGM vs standard battery charging, time and temperature control is necessary in case of using a normal charger to stop charging when it is hot (up to 125 Fahrenheit). AGM chargers need no control because they cannot overheat the battery.
The time of charging depends on the battery’s reserve capacity that is usually given in manufactures specs. You can determine the number of amp-hours in a battery multiplying the battery’s reserve capacity by 0.6. The result is for the 20-hour rate. If using the 10-hour rate, 36 amp-hours should be replaced in the battery. Divide 36 by 10 to get 3.6 hours for charging.
Recovering a Dead AGM Battery
Choose the AGM charger that performs as a maintainer and can proceed desulfation to restore the discharged battery.
If such a charger is not enough, take additional equipment:
- Jumper cables
- An AGM/Wet Cell battery above 12.2V
- The discharged AGM battery
Steps to recover:
- Make parallel connections between two batteries via jumper cables but leave the charger disconnected for a while.
- Then hook up the charger to the terminals of the extra battery (not the dead one) and switch it on to start the process.
- Switch the charger off in one hour and disconnect it from the extra battery.
- Detach the jumper cables completely.
- Check the temperature to avoid overheating and stop the charging if the battery is hot (that means the battery may be broken).
- Stop charging if the battery hisses that means the start of its inner overheating.