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How to Charge Generac Generator Battery

How to Charge Generac Generator Battery

Charging a generac generator battery is not always straightforward. How to charge Generac Generator Battery can be complicated and confusing for those unfamiliar with the procedure.   


Many factors can affect how long it takes to charge a generac generator battery.   

  • The type of charger 
  • The amperage output of the charger,
  • Temperature

Generac batteries have a long shelf life. If you plan to use your generac generator frequently, you must charge it at least once a month. Failure to do so can cause the battery to lose its ability to hold a charge over time.

To learn more about charging generac generator batteries, Check out this blog post. You will find information on the best ways to charge your generac generator battery, how long it should take, and the replacement guide.

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Generac Power Systems Charging Guide

Generac power systems require that batteries be charged monthly during periods of prolonged storage.

The battery voltage needs to be maintained above 9 volts, but not over 13 volts. Overcharging will cause premature deterioration and reduce the service life of the battery.

When connecting the charger to the generator, 

  • Ensure that there is at least one inch between the charger and an object before beginning to charge.
  • Do not operate the generator within 10 feet of a house, garage, or other structure. The exhaust gases may contain carbon monoxide (CO) and other toxic substances. 
  • Run the engine for 15 minutes before charging. Stay outside or leave the door open while the engine is running to ensure complete ventilation.
  • Charge the generac batteries monthly during periods of prolonged storage. 
  • After charging is completed, disconnect all cables in the reverse order they were connected.

Here are some tools to have on hand for battery testing. 

1. Schumacher Battery Load Tester and Voltmeter – 100 Amp

This digital load tester is designed to quickly and accurately troubleshoot the charging system of 12-volt lead-acid batteries.

It can test both starter motor draw, battery condition, and alternator output with a fully charged battery. In addition, it is capable of testing up to 1000 cold-cranking amps.

It is made with a rubber over-mold for shock absorbency and an insulated handle that provides extra comfort during use. The load tester has high accuracy and quick diagnosis of battery problems.

This coupled with its compact and lightweight design makes for easy transportability. The only downside is that it can be difficult to use if you are inexperienced with battery testing.

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2. Fluke 115 Compact True-RMS Digital Multimeter

The Fluke 115 provides accurate readings from DC voltage to 1000 volts AC. It’s designed for fast yet precise measurement testing.

The unit can measure up to 1000 VAC RMS without recalibration using the included temperature probe accessory kit.

A feature unique to this model of multimeters is its ability to display backlighted results automatically, making it easier to read your test data in poor lighting conditions.

The Fluke 115 provides a visual display of data for quick reading of results. It’s simple to use and operate. The only demerit is the calibration required for first-time use which can be burdensome to inexperienced users.

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3. Generac OEM 0G5744 Charger. AC Adaptor 12VDC Plug by Generac

This charger by Generac is compatible with all power systems. It can be used to maintain and recharge batteries for a full range of generators manufactured by the company.

The unit has been designed to prolong generator service life while protecting against overcharging and short circuit conditions. The visual interface(LED) makes it easy to read the status indicators. The compact and lightweight design makes it a durable material with extended life.

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The setup, however, may be challenging to a beginner with no battery charging experience.

To charge a generac power system battery, follow these simple steps:

  • Connect the positive cable to the battery’s positive terminal, and connect the negative cable to the generating unit
  • Open the DC breaker panel and turn on the generator
  • Turn off all power to the house except for one lighting circuit to which you have connected a CFL (compact fluorescent light) and leave it on at full brightness. This will provide enough charge current to keep your battery charged during this process
  • After three hours, turn off the alternate power source and turn on any other circuits you want powering by your generator
  • Once all power has been shut down, unplug appliances and put them back in their proper homes. This should leave only the CFL on
  • After about eight hours, go back to the DC breaker panel and turn off the generator.
  • Disconnect the negative cable from the generating unit first, then disconnect the positive cable from the battery’s positive terminal
  • You can now remove your generac power systems battery from its box and place it into a well-lit area to charge normally.

If you do not plan to use your generators for an extended period (one month or more), we recommend that you follow this same procedure every 30 days as a preventative maintenance task.

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FAQ’s on charging generac generator battery

1. How to charge generac generator battery?

The best way to recharge a power system is by using the trickle charger designed for your specific model of Generac Generator.

You should never attempt to use other batteries with your system unless otherwise stated in the user manual provided with your portable device. 

This prevents damage to both yourself and your equipment. It’s better to err on the side of safety when dealing with high voltage electrical systems. 

2. What does an uncharged generac generator look like? 

An uncharged power source will appear much darker than usual. You will likely not be able to get it to start up. 

This is always an indication that the battery has not been charged or used for a reasonably long period. It needs to be recharged before being put back into service again.

3. Can I use my car ac adaptor charger?

Unless otherwise stated in your user manual, you should never attempt to charge your power system using any automotive parts.

Using these kinds of chargers on generators made by Generac can cause irreparable damage, which may require you to spend hundreds/thousands on repairs.

4. Can I use my old gen charger on the new generator?

Do not attempt using your old chargers. This will help you avoid damaging your equipment. If you are unsure, contact the customer service representatives at any major retailer.

5. Can a generac power system start without being charged? 

Most generators can be started, whether fully or partially discharged. It is recommended that you fully charge your power systems before putting them away for more than a few days at a time. How to start a generator that has been sitting.

6. How often should I recharge my generator?

It depends on the frequency with which you use it and how long each session lasts. Partial discharges tend to have a less significant impact in prolonging service life compared to full ones. 

You should try recharging every 30 days, but this varies from one model/application to another, so make sure you check your user manual. 

When it comes to how to charge generac generator battery, there is no definitive answer. This is because it depends on how often you use your generator and how long each session lasts. 

Most generators can operate when fully or partially charged. Avoid using automotive parts unless explicitly advised in the user manual. 

References and Citations:

1. CISION PR Newswire: Generac Unveils New PWRgenerator, Designed to Dramatically Extend the Duration of Solar Battery Backup-

2. AutoBatteries: Cold Cranking AMPS (CCA)

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