Read the manual thoroughly and understand all of the instructions, cautions, and warnings before using this equipment. If any section of the manual is not understood, contact your nearest authorized dealer, or contact Generac Customer Service at 1-888-436-3722 (1-888-GENERAC), or www.generac.com with any questions or concerns. 

Portable generator charging guide 

Environment 

Contents 

• General guidelines
  
• Battery health and testing
• Potential hazards of overcharging
• Portable generator battery charging FAQs

Models 

GB Power Stations

• GB 1000
• GB 2000
• Solar Accessories 
• Charge Enhancer Accessories 

Portable Inverter Generators

• 2500i
• 3300i
• 3500i
• 3500iQ
• iQ3800 / iQ5200

Portable Generators 

• GP3600
• GP6500
• GP8000E

Large Format (15.5kW-18kW) Portable Generators

• GP15500 (EFI)
• GP18000 (EFI)

XT Series Portable Generators

• XT 8500 (EFI)

Dual Fuel and Tri Fuel Portable Generators

• GP6700E Dual Fuel
• GP7500E Dual Fuel
• GP9500E Tri Fuel

Diesel Portable Generators

• XD5000E Diesel

Note: If you do not see your portable generator listed above, owner's manuals for all models can be found here. This list is intended to cover most current models but is not exhaustive. 

• Where can I download a user manual for my Generac portable generator?

General guidelines

Always refer to the owner's manual:

• Each generator has specific requirements for battery charging and maintenance. Consult the owner's manual for detailed instructions. 
• Replacement battery part numbers are available in the owner's manual.

A note on charging safety:

• Avoid leaving batteries on chargers indefinitely. Overcharging can lead to overheating, potential fire hazards, or battery damage. 

Battery health and testing

• Multimeter testing 
  • A multimeter can be used to check the battery's health While this is not the best method for accurately gauging a battery's performance, it is good for confirming that voltage is present in the battery.
• Load testing 
  • To precisely gauge battery health, load testing with a carbon pile or digital load tester is recommended. this method evaluates the battery's performance while under load.
  • Load testing can be done at most battery and automotive stores, i.e., AutoZone. 
• Outage readiness
  • To help ensure the battery is ready to start the generator in an outage scenario, we recommend charging the battery each month for 24–48 hours.

Potential hazards of overcharging

• Fire Risks: overcharging can cause batteries to overheat, leak, or ignite. 
• Battery damage: Leaving a battery on a charger indefinitely can reduce its lifespan or render it unusable.
• Preventative measures: 
  • Always use the recommended battery charger for your specific unit.
  • Always read and follow the guidelines outlined in the manufacturer's owner's manual for the charger. 
  • Never charge a battery for longer than 48 hours, as battery damage can occur.  

 

Portable generator battery charging FAQs

Why do portable generators with EFI need the battery to be charged to operate?

• The battery powers the generator's electronic fuel injection system, which regulates the fuel-to-air mixture. Even if you use the recoil to start the unit, a sufficiently charged battery is still required to operate the EFI system. 
• EFI units require a minimum of 10.6V DC for starting, even when utilizing the recoil. 

Why isn't my generator's battery charging?

• If the battery is not charging, check for loose connections or corrosion on the cables or battery terminals. Clean the cables or terminals if necessary and tighten as needed.
• Confirm that the outlet where the charger is being connected has power present.

I just purchased my portable generator. Do I still need to charge the battery?

• While batteries are fully charged from the factory, they can lose charge during storage or transit. It is best practice to complete a full charge cycle on the battery before the first startup. 

What should I know about outage/storm preparedness and battery charging?

• Before a potential outage/storm, check your portable generator's battery health and charge status to ensure it's ready when needed. Allow for a full charge cycle and verify that it can successfully start the generator.
• Some portable generator models require the unit to be under load to charge the battery. If this applies to your model, a battery maintainer can be used as an alternative.
• Always refer to your owner's manual for specific battery and maintenance requirements. 

I don't see my portable generator listed? 

This page covers most current models but is not exhaustive and is for informational purposes only. Owners should always refer directly to their owner's manual. If you do not see your model listed, owner's manuals with model-specific charging guidelines are available for download here. Enter your generator's serial number or model number to access the manual. 

• Where do I find the serial and model number on my portable generator?

How do I know if my portable generator's battery is low?

• If an electric start or EFI generator has trouble starting, or clicks when attempting to start, the battery may need to be charged.
• Some portable generator models include a low battery indicator or fault light to indicate a low battery. Consult the owner's manual for your specific model to understand the low battery warning system, if present.

Battery and charging guidelines by model

GB Power Stations

Charging guidelines

• The Power Station is equipped with a battery State of Charge (SOC) indicator bar, and a low battery power indicator.
  
  • Indicators will allow you to check the status of the charging and provide an estimate on time until the full charge.
• Always use the charging cord(s) supplied with the unit. 
• Discharge and charge the battery every 3 months.
• Charge the battery as soon as the display reads 20% state of charge or less.

Note: Beware of the dangers of unattended overcharging.

Charging guidelines for long-term storage:

• For long-term storage, the power station should be charged between 30-60%.
• To maintain battery life, it should be recharged every three (3) months. 

GB Power Stations

GB1000

• Charge cycle life: 800 cycles to 80%. 
• Charge shelf life: Charge every 3 months. 
• Built-in MPPT controller - No controller accessory is needed. (Solar panels sold separately).
• Includes AC Charge cord, car charger, and solar adapter cord (XT90 to MC4). 
• Power stations support 10-28V DX, 30A Max up to 4687W of solar input. 

GB2000

• Charge cycle life: 1000 cycles to 80%.
• Charge shelf life: Charge every 3 months.
• Built-in MPPT controller - No controller accessory is needed. (Solar panels sold separately).
• Includes AC Charge cord, car charger, and solar adapter cord. 
• Power stations support 10-28V DX, 30A Max up to 4687W of solar input. 

Power Station solar accessories

GS100 Solar Panel

• A 100W max power solar panel can be connected to the Power Station for recharging.  
• Up to four (4) solar panels may be connected in parallel by utilizing the provided parallel cable(s). this provides faster charging speeds for the Power Station.
• Parallel cable included

Power Station charge enhancer accessories

200W Charger

• Available for the GB1000 and GB2000
• Capable of recharging the GB Power Station up to 25% faster when used in combination with the built-in charger. 

 450W Charger

• Only available for the GB2000 Power Station.
• Capable of recharging the GB2000 Power Station up to 50% faster when used in combination with the built-in charger.

Car Charging with the Power Station 

• Car charging the Power Station will drain the vehicle's battery. It is recommended to only charge the Power Station while the car is running to prevent depletion of the vehicle's battery. 
• Always disconnect the Power Station when the vehicle is turned off. 

Pass-through charging 

• Power Stations support simultaneous charging and discharging of the battery during operation (pass-through charging).
• Power Stations are not designed to be used as an Uninterrupted Power Supply (UPS). 
• Pass-through charging can reduce battery life. 

Portable Inverter generators

2500i 

• There is no battery/ electric start with the 2500i - charging guidelines are not applicable.

3300i

• There is no battery/ electric start with the 3300i- charging guidelines are not applicable.

3500i

Battery:

• A battery is included with the 3500i.

Note: Battery cables are disconnected from the battery when shipped.

Charging:

• The generator charges the battery while running and under continuous load of a sufficient size (~5% of rated power output) 
• How do I know if my generator is currently under load?
• A battery charger is not included.

What type of charger is recommended?

• Generac recommends a battery tender.
• Battery tenders are available at most battery stores and big box retailers for under $15 USD.
• For charging guidelines and recommendations, refer to the battery tender's manufacturer guidelines.
• If using an after-market battery charger or battery tender, the battery should be disconnected from the generator while charging.

3500iQ

Battery:

• A battery is included with the 3500iQ.

Note: Battery cables are disconnected from the battery when shipped.

• Troubleshooting the electric start on the 3500iQ

Charging:

• The generator charges the battery while running and under continuous load of a sufficient size (~5% of rated power output).
• How do I know if my generator is currently under load?
• A battery charger is not included.

What type of charger is recommended?

• Generac recommends a battery tender for charging. 
• Battery tenders are available at most battery stores and big box retailers for under $15 USD. 
• For charging guidelines and recommendations, refer to the battery tender's manufacturer guidelines. 
  
• If using an after-market battery charger or battery tender, the battery should be disconnected from the generator while charging.

3500iO

• There is no battery/electric start with the 3500iO - battery charging guidelines are not applicable.

iQ3800/ iQ5200

Battery:

• A battery is included with both the iQ3800 and iQ5200.

Note: Battery cables are disconnected for shipping and must be connected before first use. For instructions, see: Why isn't the electric start working on my iQ3800 or iQ5200 portable inverter generator?

Charging:

• Both the iQ3800 and the iQ5200 charge the battery while running and under continuous load of a sufficient size (~5% of rated power output) 
• How do I know if my generator is currently under load?
• A battery charger is not included.

What type of charger is recommended?

• Generac recommends a battery tender for charging. 
• Battery tenders are available at most battery stores and big box retailers for under $15 USD. 
• For charging guidelines and recommendations, refer to the battery tender's manufacturer guidelines. 
  
• If using an after-market battery charger or battery tender, the battery should be disconnected from the generator while charging.

Open frame portable generators

GP3600

• There is no battery/electric start with the GP3600 - battery charging guidelines are not applicable.

GP6500 (electric start units only)

Battery:

• A battery is included with GP6500 electric start models.
  

Note: Battery cables are disconnected from the battery when shipped.

Charging:

• A 12V battery charger is included.
• The battery does not charge while the generator is running.
• Charge time varies based on the battery's state of charge. If the battery is very low or has not been used for a long time, it will need to be charged for longer. Depending on the state of the battery, charging may take 8-12 hours.
  

Note: The generator can charge its own battery while running by plugging the included battery charger into one of the generator's duplex outlets.

GP6700E (Dual Fuel)

Battery:

• A battery is included with the GP6700E.

Note: Battery cables are disconnected from the battery when shipped.

Charging:

• The generator charges the battery while running and under continuous load of a sufficient size (~5% of rated power output).
• How do I know if my generator is currently under load?
• A battery charger is not included.

 Note: A battery may lose some charge when not in use for prolonged periods of time. If battery is unable to crank engine, use the recoil starter to start the generator, power a load, and charge the battery.

GP7500E (Dual Fuel)

Battery:

• A battery is included with the GP7500E.

Note: Battery cables are disconnected from the battery when shipped.

Charging:

• A 12V battery charger is included.
• The battery does not charge while the generator is running.
• Charge time varies based on the battery's state of charge. If the battery is very low or has not been used for a long time, it will need to be charged for longer. Depending on the state of the battery, charging may take 8-12 hours.

Note: The generator can charge its own battery while running by plugging the included battery charger into one of the generator's duplex outlets.

GP9500E (Tri-Fuel)

Battery:

• A battery is included with the GP9500E

Note: Battery cables are disconnected from the battery when shipped.

Charging:

• The generator charges the battery while running and under continuous load of a sufficient size (~5% of rated power output).
• How do I know if my generator is currently under load?

GP8000

Battery:

• A battery is included with the GP8000

Note: Battery cables are disconnected from the battery when shipped.

Charging:

• A 12V battery charger is included.
• The battery does not charge while the generator is running.
• Charge time varies based on the battery's state of charge. If the battery is very low or has not been used for a long time, it will need to be charged for longer. Depending on the state of the battery, charging may take 8-12 hours.

Note: The generator can charge its own battery while running by plugging the included battery charger into one of the generator's duplex outlets.

XT8500EFI

Battery:

• A battery is included with the XT8500EFI

Note: Battery cables are disconnected from the battery when shipped.

Charging:

• A 12V battery charger is included.
• The generator charges the battery while running and under continuous load of a sufficient size (~5% of rated power output).
• The battery charging circuit is protected by a 3-amp replaceable in-line fuse. If the charger is not charging the battery, check the fuse (located behind the control panel).
• To order a new fuse, contact a Generac authorized service dealer.

Starting considerations:

• The electronic fuel injection (EFI) system requires a minimum of 10V for the pull start to work.
• Electric start and EFI are not mutually exclusive.
• To check if your battery is sufficiently charged, first ensure the positive and negative are connected on the battery terminals. Next, move the key to the RUN position. If the battery is NOT sufficiently charged, you will see the fault light begin to flash. This is unique to the XT8500EFI. To resolve, charge the battery for 3-6 hours using the provided 12V battery charger.
• Charge time varies based on the battery's state of charge. If the battery is very low or has not been used for a long time, it will need to be charged for longer. Depending on the state of the battery, charging may take 8-12 hours.

GP15500 (EFI)

Battery:

• A battery is included with the GP15500EFI.

Note: Battery cables are disconnected from the battery when shipped.

• The battery charging circuit is protected by a 10- and 15-amp fuse. If the charger is not charging the battery, check the fuses and replace if necessary. (See image below for fuse locations)
• To order a new fuse, contact a Generac authorized service dealer.

Charging:

• The generator charges the battery while running and under continuous load of a sufficient size (~5% of rated power output).
• How do I know if my generator is currently under load?
• A battery charger is not included.

What type of charger is recommended?

• Generac recommends a battery tender for charging. 
• Battery tenders are available at most battery stores and big box retailers for under $15 USD. 
• For charging guidelines and recommendations, refer to the battery tender's manufacturer guidelines. 
  
• If using an after-market battery charger or battery tender, the battery should be disconnected from the generator while charging.

GP18000 (EFI)

Battery:

• A battery is included with the GP18000EFI.

Note: Battery cables are disconnected from the battery when shipped.

• The battery charging circuit is protected by a 10- and 15-amp fuse. If the charger is not charging the battery, check the fuses and replace if necessary. (See image below for fuse locations)
• To order a new fuse, contact a Generac authorized service dealer.

Charging:

• The generator charges the battery while running and under continuous load of a sufficient size (~5% of rated power output).
• How do I know if my generator is currently under load?
• A battery charger is not included.

What type of charger is recommended?

• Generac recommends a battery tender for charging. 
• Battery tenders are available at most battery stores and big box retailers for under $15 USD. 
• For charging guidelines and recommendations, refer to the battery tender's manufacturer guidelines. 
  
• If using an after-market battery charger or battery tender, the battery should be disconnected from the generator while charging.

*XD5000E Diesel

Battery:

• A battery is included with the XD5000E Diesel.

Note: Battery cables are disconnected from the battery when shipped.

Charging:

• The generator charges the battery while running and under continuous load of a sufficient size (~5% of rated power output).
• How do I know if my generator is currently under load?
• A battery charger is not included.

What type of charger is recommended?

• Generac recommends a battery tender for charging. 
• Battery tenders are available at most battery stores and big box retailers for under $15 USD. 
• For charging guidelines and recommendations, refer to the battery tender's manufacturer guidelines. 
  
• If using an after-market battery charger or battery tender, the battery should be disconnected from the generator while charging.