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NOCO Genius G3500 6V/12V 3.5 Amp Smart Battery Charger and Maintainer

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NOCO G3500 6V/12V 3.5 Amp Smart Battery Charger and Maintainer

Wicked Features, Wicked Smart!

The G3500 is a smart, eight-step, fully automatic switch-mode battery charger and maintainer. The G3500 restores batteries to their original capacity, recovers slightly sulfated batteries, charges batteries in cold climates, rescues drained batteries and provides maintenance charging to increase battery life. A versatile battery charger that provides charging modes for both large and small batteries from 1.2 - 120Ah, such as Cars, RVs, Boats and Trucks, as well as for Motorcycles, ATVs, Jet Skis or Snowmobiles.

Powered by Noco's VosFX Processor
The VosFX Processor is a revolutionary smart processor utilizing sophisticated levels of intelligence to alter the charge process.


Rapid Charging Technology
Charges batteries 2X faster than traditional linear battery chargers.


High Frequency, High Efficiency
High-frequency, high-efficiency for a lightweight, compact charger.


Designed for Safety
Reverse polarity, short circuit, open circuit, spark proof, overheat, overcurrent & overcharge.

Five-Year Limited Warranty


Simple User Interface


Designed Tough


Comfort Cable Clamps
Ergonomically designed to make battery connecting and disconnecting effortless. Features a fully insulated over-mold casing with strain relief ends to alleviate unwanted tension on cable leads.


Extendable Connectors
Connecting and disconnecting accessory leads has never been easier! A uniquely designed interchangeable connector allows accessories to be properly mated and fastened with a snap-lock latch.


Built-In Fuse Protection
Each battery connection accessory features an over-molded inline fuse to increase user safety by protecting the battery charger from potentially dangerous short circuits.


Rugged Enclosure
Made from a rugged polymer for high-impact resistance for some of the harshest and most demanding working environments.

Wicked Smart Features


6V/12V Compatibility
Charges 6V & 12V batteries


Returns to last selected mode when restarted


Fully Interactive
Automatically adjusts itself to changing current needs


Designed for Safety
Reverse polarity, short circuit, open circuit, spark proof, overheat, overcurrent & overcharge


HF/HE Switch Mode Design
High-frequency, high-efficiency for lightweight, compact charger


Rapid Charging Technology
Charges batteries 2X faster than traditional linear battery chargers


Variable Input Compensated
100% full charge even with varying A/C input voltages


Recovery Mode
Recovers deeply discharged & sulfated batteries with pulse charging


Multiple Battery Chemistry
Safely charges Wet, Gel, MF & AGM batteries


Abnormality Protection
Automatically shuts "off" if charger remains in Bulk charge mode for an extended period of time


Extendable Connectors
Plug-n-play connectors for easy accessory changes


Cold/AGM Mode
Optimized charge mode for cold weather or AGM batteries

Input Voltage AC 110 ~ 120VAC, 50 - 60Hz
Working Voltage AC 85 ~ 130VAC, 50 - 60Hz
Input Current 1200mA RMS Max
Efficiency 85% Approx.
Power 60W Max
Charging Voltage 7.2/14.4, 7.4/14.7V (Cold/AGM)
Charging Current 3500mA (Large),
900mA (Small)
Back Current Drain <5mA
Ripple <2%
Ambient Temperature 32 - 104°F (0 - 40°C)
Charger Type 8-Step, Fully Automatic,
Type of Batteries 6V & 12V Lead-Acid
Battery Chemistries Wet, Gel, MF & AGM
Battery Capacity 14-120Ah (Large),
1.2-14Ah (Small),
Maintains All Battery Sizes
Housing Protection IP65
Cooling Natural Convection
Noise Level <50dB
Dimensions (L x W x H) 7.7 x 2.7 x 1.9 Inches
Weight 1.1 Pounds


Charging Times

The time required for the G3500 to charge a normally discharged battery is shown below. Deeply discharged batteries may take longer to charge depending on the depth of discharge (DOD). The charge time is based on an average depth of discharge to a fully charged battery.


Note: The above table is for reference purposes only. Actual data may differ due to battery conditions. The time required for the G3500 to charge a normally discharged battery is based on an average DOD of 50%.

Charging Steps

Step 1: Diagnostics
Checks the battery voltage to make sure battery connections are good and the battery is in a stable condition before beginning the charge process.

Step 2: Recovery
Initializes the Recovery process, if needed, for deeply discharged or sulfated (desulfation) batteries by pulsing small amounts of current.

Step 3: Soft Start
Begins Bulk charging process with a gentle (soft) charge.

Step 4 - 5: Bulk
The Bulk charging process continues using both a High Rate and Medium Rate charge and returns 80% of battery capacity, indicated by the 25%, 50% and 75% CHARGE LEDs.

Step 6: Absorption
Brings the charge level to 90%. The battery charger will deliver small amounts of current to provide a safe, efficient charge and limit battery gassing.

Step 7: Trickle
Battery is fully charged and ready to use, indicated by the 100% CHARGE LED being a solid Green. In this step, the battery charger will only deliver enough current to keep the battery full. If the battery tells the charger that more current is needed, the battery charger will switch to Maintenance.

Step 8: Maintenance
Continuously monitors the battery voltage to determine if a maintenance charge should be initiated. If the terminal voltage falls below 6.4V (6V) and 12.8V (12V), the charger will start the Maintenance cycle until voltage reaches 7.2V (6V) and 14.4V (12V) and then discontinues the charge cycle. The cycle between Trickle and Maintenance is repeated indefinitely to keep the battery at full charge, without overcharging. The battery charger can be left connected indefinitely.



  • G3500 Charger
  • Battery Clamp Connectors
  • Eyelet Terminal Connectors
  • Owner's Manual & User Guide




Battery Charger and Maintainer

Quick Info

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  • John F.
  • 3/31/2015 9:37:28 AM
  • Tech Level: Somewhat High
  • Ownership: 1 month to 1 year
  • Verified Owner

1 out of 5 eggsCannot be trusted unattended, may drop into error mode & stop charging

Pros: Works most of the time.

Cons: Random charge operation failures, switches to error mode wherein it slowly drains the battery instead of charging, does not automatically reset and start charging again. This was not due to a bad battery, possibly too sensitive to AC power line fluctuations.

Other Thoughts: Keeps battery charged when it works, but every week or 2 it stops charging and instead starts slowly draining the battery, with all LEDs rapidly blinking, indicating that it switched to error mode. It does not automatically reset, so you have to unplug and replug it to the AC line, making it impossible to leave unattended for long periods. The FAQ says this indicates a bad battery, but the battery is not old and anyway the same thing occurred with a new one.

I have no such problems with 4 other charger/maintainer brands that I have, so it's something peculiar to this NOCO G3500. Another owner with this same problem said it's vulnerable to brief dropouts or noise on the AC power mains - could be, but if there were any here they must have been very short because none of my digital clocks stopped, which they always do with power interruptions even if less than a second. If this G3500 requires a power line conditioner to be able to operate continuously then you can add that substantial cost to the purchase price.

This problem became apparent 35 days after buying from Newegg, so I can't return it to them due to the 30 day limit. BOO!

Did you find this review helpful? Yes No

  • Stephen L.
  • 3/25/2015 5:04:46 PM
  • Tech Level: Somewhat High
  • Ownership: 1 day to 1 week

4 out of 5 eggsThis is version 1

Pros: Unit seems to be well made and has a series of optional accessories that fit nearly any situation. This is my second unit.

Use of LED's is a plus, precise switches.

Cons: fixed AC cord, removable one will be better. This unit shipped to me was a version 1, there is a version 2 that allows for battery repair as well as compatibility with lithium.

Other Thoughts: Since the seller is NOCO and NOCO claims they only stock version 2, not sure why they shipped out version 1.

Did you find this review helpful? Yes No

  • Mike S.
  • 3/16/2015 6:34:19 AM
  • Tech Level: Average
  • Ownership: 1 month to 1 year
  • Verified Owner

5 out of 5 eggsNoco g3500

Pros: Great price at the time. Very well packaged. Fast safe charging

Cons: None

Did you find this review helpful? Yes No

  • Steve T.
  • 2/27/2015 9:00:34 AM
  • Tech Level: Somewhat High
  • Ownership: 1 day to 1 week
  • Verified Owner

4 out of 5 eggs

Pros: It's a NOCO, top of the line quality and performance. Great price for this quality.

Cons: Not impressed by the short battery hookup lead. Not sure how any truck owner is supposed to connect this for external hookup to the charger, which is a shame.

Did you find this review helpful? Yes No

  • Stephen M.
  • 12/26/2014 8:04:06 AM
  • Tech Level: High
  • Ownership: more than 1 year
  • Verified Owner

5 out of 5 eggsG3500

Pros: Small and compact, easy to use, high quality locking connector, water resistant, charges AGM batteries and has cold weather setting. Remembers settings during power outages and automatically restarts. Can leave it on and connected for years with no damage. I have 10 of this brand of charger and use them on all my batteries all winter (cars, ATV, motorcycles, Jetski, lawn mower). Comes with connectors (clamps and permanent wired harness. It is also fused for safety. Reverse connection protected.

Cons: Would be nice if it had a hanging hook. Other than that, it is perfect.

Other Thoughts: The G3500 is a very good size. I also use the 1100 size for smaller batteries like in Motorcycles and Jetskis. The 3500 does all size batteries from small to large.

3 out of 4 people found this review helpful. Did you? Yes No

  • Raymond P.
  • 3/12/2014 7:01:15 AM
  • Tech Level: Somewhat High
  • Ownership: 1 week to 1 month
  • Verified Owner

4 out of 5 eggsPleasantly surprised

Pros: I hooked this up to an OEM battery from 2006 (Toyota) which was in a vehicle which is not driven that much. It had been successful in starting the truck, but seemingly barely. I had been informed that I needed a new battery, but got this charger to give it a chance - and I would need it in the future anyway. Hooked up the charger for a day and the unit indicated full charge. Next day was the coldest day of the year and the truck started without hesitation. I am not saying the charger saved the battery for all time, but it certainly revived it in the short run. Once unit is set for the battery voltage it is a fire and forget unit.

Cons: Wish the unit was weather proof. Having the extra cables (battery clip on and bolt on) able to be stored in or clipped to the charger would have been a nice feature.

Other Thoughts: Charger is compact and seems well made with a sturdy plastic case. Plug in connectors are idiot proof. Power cord is 6 ft. Note in instructions about extension cords concerns power usage, i.e., don't use a lamp extension cord. The is a provision for the unit to be permanently mounted (screws provided) to presumably a wall, but the charger-battery leads are not long enough (4 ft.) to make this seem practical.

5 out of 8 people found this review helpful. Did you? Yes No

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