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Battery Chargers FAQs

Battery Charger Frequently Asked Questions (FAQ)

FAQs About Battery Settings

When should I use a 2-amp, 10-amp, 12-amp, or 15-amp charge rate?

This depends on how fast you want to charge your battery and the size of the actual battery you are charging. The higher the amp setting, the faster your battery will charge. For smaller batteries like lawn/tractors and motorcycles, we suggest a 2-amp charge rate, as higher charge rates may create a dangerous condition. Check your battery specifications for the charge rate. Certain batteries like deep-cycle batteries with a Group Size of 27 or higher may require a 12-amp charge rate or higher to be charged.

Why doesn’t my battery charger shut off in the 2-amp position when charging my vehicle or deep-cycle battery?

The 2-amp charge rate is intended for small batteries such as motorcycles, snowmobiles and lawn garden tractors. Consequently, when trying to charge a larger battery at that rate, it will take a very long time and the battery may discharge at a greater rate than the 2-amp charge can provide. It is best to charge at a higher charge rate like 6-amps, 10-amps or higher.

Why does my deep-cycle battery overheat when my charger is in the deep-cycle setting?

Some deep-cycles batteries on the market will not sustain 15+ volt settings. If during charging the battery begins to emit gas, or if the battery becomes warm, use the Regular Battery Setting. This will better maintain the battery’s life.

FAQ About Meters

How do I read the amp meter?

The amp meter shows how much current the battery charger is outputting to the battery. When you turn on the charger, it outputs a high amount of current (electrical power). For example, if you select the 12-amp rate to charge the battery, the charger needle will be closer to the 12 on the right side. As the battery charges, the needle will drop to approximately half of the selected amperage rate indicating the battery is fully charged (For example: 6-amps).

Why is there more than one red area on the charger’s amp meter?

The red area represents the charge rate you selected at the beginning of battery charging. The red area on the far right is for the higher, amperage charge rate. The red area to the left indicates rates for the 2-amp position. In both instances, the needle starts in the red area, and as the battery becomes charged, drops to the left towards the larger green area.

What does it mean when the green LED blinks ON/OFF and the needle bounces?

All automatic battery chargers in the automotive market today have some sort of voltage regulation to prevent overcharging the battery. The rate of the flashing is dependent on the battery type, its rated capacity, the degree of discharge, its age, the temperature, as well as the amperage rating of the battery charger.

If the charger’s green LED begins blinking when you connect the charger clips to the battery, the amperage in-rush current to the battery is reaching the pre-set shut-off voltage and the charger is shutting down. The voltage will drop as soon as the charger shuts down, turning the charger back on. This may also mean the charger has detected a battery problem – for instance, its ability to take or hold a charge. Sometimes a battery may be sulfated (accumulation of lead sulfate on the battery plates), and the sulfation is creating a high resistance to the current flow (ability to accept a charge). Or, perhaps the battery is deeply discharged (below 8-volts).

There is no meter reading, but I hear a hum. How can I tell if my battery charger is working?

Hearing a slight humming noise is normal, and a sign that the transformer is powered up and working. If you don’t have a volt/amp meter or battery tester to check if the battery is charged, you can carefully open the caps of the battery. If the liquid is bubbling in the battery, the battery is almost at full charge. Any gasses emitted from the battery are normal and occur at the end of each charge cycle.

FAQ About Battery Chargers

Why doesn’t my automatic charger charge my battery?

An automatic charger is designed to power the transformer when you first plug it into a receptacle. The automatic charger needs to “see” at least 4 volts in the battery to power up the circuitry. This initializes the charge sequence. When a completely discharged battery, or one with less than 4 volts charge remaining, is attached to the charger, the charger never “sees” this battery and will not begin the charging cycle. It will also cancel out the Engine Start function. The yellow charging light will also not come on. The meter (where used) will remain in the default “100%” position.

In order to get past this mode, you can “jump start” the battery so to speak, by momentarily connecting another fully charged battery in parallel. This will allow the charger to “see” a higher initial voltage enabling it to begin the charging sequence.

NOTE: Batteries that remain lower than 4 volts state of charge are often defective or just worn out. It is always best (safer) to check the battery with a hydrometer or Schumacher tester before charging.

The charger’s green light is on, but I still cannot start my car – why?

In cold weather, a battery’s chemistry changes and gives the battery charger a false voltage signal. When this happens, remove the battery from the vehicle and move it to a warm location to warm up before charging. Never charge a frozen battery.

If the charger has a deep-cycle setting, try charging the battery for a short period of time at a higher, amperage charge rate. Then, try starting the vehicle again.

Why doesn’t the green light stay on when my battery is completely charged?

Three reasons

  1. The electronic control circuit board and LED lights use a minor amount of battery power to operate and to determine the battery’s state-of-charge. This results in the battery charger having to periodically charge the battery back to full charge. Consequently, the green light goes on and off as this process occurs.
  2. All batteries have some internal power losses, which the charger is replenishing similar to #1.
  3. The length of time that the green light is on is dependent on the battery type, its rated capacity, the degree of discharge, its age, and temperature.

Why don’t I get sparks when I touch the battery clips together, creating a short?

With electronic short-circuit protection, the battery charger must be able to measure a battery’s voltage before it turns on. There is no output power in the clips until they are hooked up to a lead-acid battery. This is a built-in safety feature not found on most automotive battery chargers.

How long can I use the Engine Start/Cranking Assist on my charger?

The engine start/cranking assist feature on your charger is for short duration only (typically 3 to 5 seconds ON and 5 minutes OFF maximum). See the front panel of your charger for the recommended crank time your charger allows. Charge the battery for 15 minutes before using engine start/cranking assist. After 15 minutes of charging, set the selector switch to the Engine Start/Cranking Assist position. Then try to start the engine using the ignition switch.

If the engine fails to start within 3 to 5 seconds, stop cranking. Set the selector switch to a regular charge mode for another 10 to 15 minutes before trying to start the engine again. This rating is a UL standard based on the amperage output of the charger at 7.2 volts for 5 seconds. Recommended cranking assist cycles less then 5 seconds are in place to allow the charger to dissipate the heat generated by the increased power output through the transformer. Exceeding the recommended time duration of your charger’s cranking assist cycle can cause damage to the charger’s internal circuitry.

How long can I leave my charger connected to my battery?

The type of charger you are using more accurately determines this, but generally your battery charger is safe to leave powered up and connected to your battery until the battery has reached a full charge. Manual chargers should be removed as soon as the battery has reached a full charge. These chargers will not cycle or shut down by themselves. They will continue to put a current through the battery until they are disconnected. The use of a hydrometer or voltmeter to monitor state of charge is recommended for use with manual battery chargers.

Automatic chargers are more forgiving on your battery than manual chargers, but they are not designed for indefinite use. They will begin a cycling process, as described above, to prevent overcharging of the battery. Continued cycling will cause premature wear on the electromechanical parts of the charger, causing the charger to fail prematurely. The only charger recommended for extended or a storage application is the 1.5 amp 12-volt charger specifically designed for long term, slow trickle charging/maintenance applications.

Why can’t I measure a voltage when connecting my volt meter to the battery clips?

No output power is supplied until the battery charger’s clips are hooked up to the battery. Then, it will measure and show the battery’s voltage.