Frequently Asked Questions

What is Microprocessor Controlled Charging?

A microprocessor controlled battery charger is designed to provide fast, safe and efficient charging to a wide variety of battery types and sizes. Advanced microprocessor controlled algorithms monitor the charging process to avoid battery damage caused by overcharging. Simply put, the charger collects information from the battery and adjusts the charge current and voltage based on this information. This allows the battery to be charged quickly, correctly, and completely when using a microprocessor controlled battery charger. Because of this, fast charging does not have negative effects on the capacity of the battery and on battery cycle-life. The multi-phase charging process ensures that each battery gets the power it needs in a manner that is best for the health of the battery ensuring that all of the energy is properly absorbed by the battery whether it’s a Conventional, AGM, Gel Cell, Marine or Deep Cycle battery. Microprocessor controlled battery chargers can remain connected to the battery indefinitely and will not overcharge or damage it. Microprocessor controlled battery chargers are faster, safer and certainly more efficient than "old school" transformer type battery chargers.

What is Automatic Charging?

When an automatic charge is performed, the charger stops charging and switches to the Maintain Mode (Float-Mode Monitoring) automatically after the battery is fully charged. Automatic chargers are more forgiving on the battery than manual chargers but are not designed for indefinite or maintenance use. Automatic chargers use a cycling process (see Maintain Mode) to prevent overcharging the battery.

What is Maintain Mode?

When the CHARGED LED is lit; the charger has started Maintain Mode. In this mode, the charger keeps the battery fully charged by delivering a small current when necessary. If the battery voltage drops below a preset level, the charger will go back in to Charge Mode until the battery voltage returns to the full charge level, which at this point the charger will return to Maintain Mode. The charger automatically switches between Charge Mode and Maintain Mode as necessary. The CHARGED LED will cycle on when the battery is at full charge and off when the voltage drops below a preset level and the charger goes into Charge Mode. The cycle will continue, and the CHARGED LED will stay on for longer periods of time as the battery becomes more fully charged. The voltage is maintained at a level determined by the BATTERY TYPE selected.

NOTE: The maintain mode technology utilized in Schumacher’s maintainers allows you to safely charge and maintain a healthy battery for extended periods of time. However, problems with the battery, electrical problems in the vehicle, improper connections or other unanticipated conditions could cause excessive voltage draws. As such, occasionally monitoring the battery and the charging process is recommended.

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.

Why doesn't my automatic 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 better to charge a deep cycle battery at a higher charge rate like 6-amps, 10-amps or higher. However, check your battery specifications for the proper charge rate.

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 chargers 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. Use a volt/amp meter or battery tester to check if the battery is charged.

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.

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 batterys 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:

The electronic control circuit board and LED lights use a minor amount of battery power to operate and to determine the batterys 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. All batteries have some internal power losses, which the charger is replenishing similar to #1. 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 batterys voltage before it turns on. There is no output power in the clips until they are hooked up to a lead-acid battery.

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). 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. (You should not attempt to charge your battery on the engine start setting. Doing so could cause damage to your battery or cause other property damage or personal injury.) 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 than 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 chargers cranking assist cycle can cause damage to the chargers 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 utilize a cycling process, as described above, to prevent overcharging of the battery. The only charger recommended for extended or storage application is the 1.5 amp 12-volt charger specifically designed for long term, slow trickle charging/maintenance applications. However, problems with the battery, electrical problems in the vehicle, improper connections or other unanticipated conditions could cause excessive voltage draws. As such, occasionally monitoring the battery and the charging process is recommended.

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

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

How do I tell what type of battery I have; Flooded, AGM or Gel?

Flooded or Wet Cell batteries are the most common lead-acid battery type in use today. They usually are not sealed and electrolyte can be added through holes in the top casing of the battery. Gel Cell batteries are sealed and cannot be re-filled with electrolyte. Therefore they have a smooth top with no access holes. AGM (Absorbed Glass Mat) batteries are the latest step in the evolution of lead-acid batteries. They are sealed like Gel Cell batteries but are smaller and can be recognized by their compact size.

What is the correct charging voltage for my battery?

That depends on the battery. While most of today’s automotive and marine batteries are 12 volt, some motorcycle and lawn tractor batteries are 6 volt. Check the battery and the owner’s manual of the vehicle the battery came out of for the correct voltage. The value of the charge rate voltage is determined by the battery manufacturer. Deviating from the recommended values will under or overcharge the battery – both of which will reduce the battery’s life and performance.

What is a trickle charger?

The difference between a float charger and a trickle charger is that the float charger has circuitry to prevent overcharging the battery. It senses when the battery voltage is at the maximum level and temporarily shuts off the charge (floats voltage at zero or a very minimal charge until it senses that the battery output voltage has fallen and then resumes charging). It may be kept connected indefinitely. A trickle charger, on the other hand, will charge no matter whether the battery is fully charged or not, so it needs to be connected and disconnected periodically. If left in place too long, it will eventually boil the electrolyte out of the cells or damage the plates. Trickle chargers will work to keep the battery charged, if used once a month or so for a day or two, but the float chargers can be left connected longer without potential harm to the battery.

The portable power unit is not charged and I just took it out of the box, is it defective?

No. Every Portable Power Jump-Pack unit’s battery is fully charged when it leaves our factory. One must factor in the amount of time the unit has spent sitting in warehouses and on store shelves, before it was purchased. The more time a unit sits idle, the greater the decrease in battery power. We recommend charging the battery immediately after purchase, before placing the unit into service.

Does my power inverter have to be wired directly to my car battery?

It depends on the model of the inverter and what you intend to run with it. For electrical loads up to 200 watts, the power-inverter can be plugged into the car’s cigarette lighter. This allows you to power laptop computers, small power tools, most small appliances, and even a small (13") TV directly through the cigarette lighter. If you want to power larger equipment, or if you want to run more than one item at a time, a direct connection to your car battery is necessary. Generally, if you intend to power loads of more than 200 watts, your inverter should be direct-wired to the battery to ensure safe operation.