Frequently Asked Questions

All information contained in our FAQ section related to battery chargers and the charging process is for general, informational use only. Please refer to your Schumacher battery charger and user manual for specific product information, instructions, and features. If you still have questions about our products, visit our blog for additional resources and education or contact us directly via phone or email.

General Information

If you bought your Schumacher product from a third party retailer, please refer to their return policy. If you bought your Schumacher product from our website, you must return the product in its original condition, with the original receipt and packaging, within 30 days of the date of delivery to the original purchaser. We will happily exchange your product or provide a full refund of the original purchase price. All returns require a Return Merchandise Authorization (RMA) number, which must be obtained through Customer Service.

NOTE: The customer is responsible for all return shipping costs. We also recommend that you use UPS or FedEx Ground Service and insure the package for its retail price.

Schumacher offers a limited warranty for all our products. In order to file a claim against your warranty, your product must be registered. If you bought your product from a third-party retailer, be sure to have the receipt handy as you will need the purchase date to register your product. You will also need your product’s serial number and UPC code. The serial number can be found on the unit and the UPC code is located on the packaging.

About Battery Chargers

A microprocessor-controlled battery charger is designed to provide fast, safe, and efficient charging to a wide variety of battery types and sizes. The microprocessor collects information from the battery and adjusts the charge current and voltage accordingly, which allows the battery to be charged quickly, correctly, and completely without negative effects on the capacity of the battery and on battery cycle-life. 

An automatic battery charger stops charging and switches to 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. 

A manual battery charger won’t cycle or shut down by itself, even after the battery is fully charged. It will continue to put current at the selected setting to the battery until the charger is disconnected. 

When your charger’s “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 into charge mode until the battery voltage returns to the full charge level before switching back to maintain mode.

NOTE: The maintain-mode technology utilized in Schumacher’s chargers/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.

There are gases emitted when charging that increase the risk of sparking. To avoid this, UL recommends using a 24-inch, 6-guage battery cable that can be purchased in any hardware store.

A battery charger is not a power supply. The charger is designed to look for positive (+) voltage, which an appliance will never produce. Thus, the appliance will not operate when connected to the charger.

No! Any modification of the battery charger could create unsafe operating conditions and also void the warranty. Additionally, when using an extension cord, shorter is better. For optimum operation use an extension cord that is less than 20 feet long.

The cranking assist position is not meant to be a charging setting. The charger will wait for you to crank the engine. If the vehicle won’t start after cranking the engine for 5 seconds, charge the battery for 15 minutes before trying again.

We recommend using the engine start/cranking assist feature on your charger for 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 and begin the cranking process again by charging your battery for another 10 to 15 minutes.

NOTE: 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. 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 charger’s cranking assist cycle can cause damage to the charger’s internal circuitry.

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. However, most chargers aren’t designed to leave your battery connected indefinitely. The only chargers recommended for extended or storage applications are the 1.5-, 2-, and 3-amp charger/maintainers 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.

Most of Schumacher’s battery chargers no longer have a deep-cycle setting. Instead, find out what type of battery you have and use that setting (Standard, AGM, Gel, or Lithium). If you are not sure what type of battery you have, select the gel battery type, because it will not damage the battery.

Note: Schumacher does not recommend using the gel battery setting over a long period of time if you are unsure of your battery type. While the gel battery setting will not cause immediate damage if used on a different battery type, long-term use will eventually cause the battery to lose some of its capacity.

Today’s batteries usually need at least 14.5 volts to fully charge, although this can vary according to battery manufacturer. For example, your vehicle’s alternator continually outputs 14.4 volts to your battery during normal operation.

The plastic casing used in our products can have an odor when new. This smell should dissipate quickly.

All of Schumacher’s microprocessor-controlled chargers require 0.5 volts of output from the battery in order to start charging.

Standard wet cell batteries are still a 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 becoming very popular in the evolution of lead-acid batteries. They are sealed like gel cell batteries but are typically smaller and can be recognized by their more compact size. Lithium batteries are the smallest size vehicle battery and are also drastically lighter than standard, AGM, or gel batteries. Lithium batteries, or more typically LiFePO4 (Lithium Iron Phosphate) batteries, are lithium-ion based and offer good safety characteristics along with resistance to vibration.

The correct charging voltage for your battery depends on the type of battery you have. Most of today’s automotive and marine batteries are 12 volts, while some motorcycle and lawn tractor batteries are 6 volts. Check the battery or the vehicle owner’s manual to find 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.

If the power goes out while you are charging your battery, a manual charger will keep charging as if it was just turned on, but an automatic charger may or may not continue charging depending on where it was at in the charging process when the power went out. If the battery is still sufficiently discharged, the charger will continue to charge the battery, but if the battery was almost fully charged, the charger may go into maintain mode early. This only affects the battery in how long it will take to be fully charged. You may also have to readjust the settings because the charger will come back on with the default settings.

If your battery won’t accept a charge or won’t stay charged as long as it used to, it’s time to replace it.

For certain models of battery chargers, it is normal for the fan to be on all the time in order to keep the transformer and electrical circuitry cool during normal charger use. Keep the area near the charger clear of obstructions to allow the fan to operate efficiently.

Our new energy-efficient models are designed with lightweight, high-efficiency transformers.

About Solar Panels

Yes, Schumacher solar panels can be used to charge AGM and gel batteries. However, we recommend all Schumacher solar panels be used with a charge controller. The solar panel can output a maximum voltage of 19 volts and a charge controller will limit the output to 14.4 volts, preventing battery damage.

About Meters

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, or 6 amps in this case, of the selected amperage rate indicating the battery is fully charged.

About Portable Power Units and Inverters

Our portable power jump starter includes an internal charger. Use a household extension cord (18 AWG or larger) to power the internal charger. Once you plug the extension cord into an outlet, connect the cord into the receptacle on the unit to charge.

We suggest charging your portable power jump starter’s internal battery immediately after you purchase it, every 30 days, and after every use. Frequently charging the battery maximizes the power potential of the unit and ensures your unit will be ready whenever you need it. Keeping the battery fully-charged can also extend the life of your unit.

No. Every portable power jump starter’s battery is fully charged when it leaves our factory. However, we don’t know how long it will sit in warehouses or on store shelves before you purchase it. During that period, it may lose some or all of its charge, which is why we instruct users to charge the unit before using it for the first time.

Yes, you can store your Schumacher jump starter in a vehicle during the winter, as long as you make sure the internal battery is fully charged and maintained. We recommend fully charging the unit once a month and after every use.

We recommend that you do not run your air compressor for more than 10 minutes at a time as it may overheat. After running the compressor for 10 minutes, allow the unit to cool down for 10 minutes before running the air compressor again. Some models may automatically turn the compressor off if it begins to overheat.

The “o2” message is only a revision code programmed into the unit and should disappear almost immediately. It has no effect on the function of the unit or the inverter.

When coupled with a power inverter, a Schumacher portable power jump starter can be used to operate appliances normally powered by 110V AC. This should be limited to inverters rated at 400 watts or less.

To troubleshoot your power inverter, please see the chart below listing the common errors your power inverter might display with the associated reason and solution. If you continue to have issues with your power inverter, please contact customer service for assistance.

ERROR CODE DESCRIPTION REASON/ SOLUTION
bAd The inverter is not functional. See warranty and call Customer Service at 1-800-621-5485 (Hours: 7 a.m. to 4:30 p.m. CST).
HiB The vehicle’s battery voltage is more than 15.5 volts. The inverter will automatically restart after the voltage drops below 15.5 volts.
HiP The continuous load demand from the device exceeds the inverter’s wattage output. Use a higher-rated inverter or a lower-rated device.
Hot The inverter is overheated and automatically turns off for a period of 1-3 minutes to cool. Make sure the inverter is well ventilated. It will automatically restart after it cools.
Lob The vehicle’s battery voltage is less than 10.5 volts. Recharge the vehicle’s batter
SC There is a short circuit, power surge or overload in the device being powered. Have the device checked.

We cannot guarantee that our inverters are compatible with your medical device. We recommend that you contact the manufacturer of your medical equipment to ask what brand/model of inverters work best with your device.

No! Under no circumstances should you use longer input cables than those that came with the device. Instead, we recommend that you use an extension cord on the output side.

Yes, a period of extended use will drain the battery.

The inverter does not produce a pure sine wave like a household outlet. Instead, the inverter produces a modified sine wave that is unable to power all of your fan’s speed settings.

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