If your unit is experiencing power-related issues—such as touchscreen malfunctions, failure to power on or off, unexpected shutdowns, freezing, locking up, or loss of connectivity and other functions—we recommend using our Power Troubleshooting Tool. This tool can help identify and resolve common electrical problems. For further insight, you may also explore additional resources below covering voltage requirements, wire gauge recommendations, and battery specifications to ensure optimal performance and reliability.
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Troubleshooting your Fish Finder
To ensure your depth sounder or fish finder operates correctly, see the following steps. Cards in unit, voltage, bad connectors, weak battery or charging issues all can prevent your unit from turning on or staying on.
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Card(s) in Fish Finder
Please remove any cards from the unit and turn on the fish finder. For devices that power on, insert mapping card into unit and power cycle the fish finder. This tests to see if the problem is the card. If so, the card can be place inside the fish finder after the device is up and running.
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Try a Working Power Connector
You will need to try the fish finder on a known working power connector that powers the same size unit or larger. If this is not possible, skip to the next step. Remove any cards from the unit and connect the power cord. If the fish finder still does not turn on, the problem is inside the unit, Humminbird Repair Process and Service/Repair Fees. Devices that turn on means there is a problem somewhere else; with the battery, charger, alternator or wiring, please continue reading.
Note: HELIX and Legacy Models: Make sure the power cable has not been connected upside down. The notch on the plug (shown below) should point upwards for units with connections on the back. The notch should point towards the back of the unit for units with connectors on the bottom.
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Refer to the Operating Voltage Range
Consult your device's Operations Manual for the recommended voltage range, Operation Manuals.
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Load Test the Battery
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Load testing a battery with a battery load tester applies a calibrated load and displays how the battery responds. The load is applied for about 10 seconds and the batteries should be at a 75% charge, a battery below this should be charged before load testing. The battery not charging to 75% may indicate a need to test the charger. Charge battery 75% on a second compatible charger to see if the issue is the charger or the battery.
Note: When load testing, it is important to remove all cables from the battery and make sure the battery terminals are free of corrosion and/or dirt.
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12V Lead Acid Wet Cell Battery Voltage vs. State of Charge
State of Charge (%) Voltage (V) Notes 100% 12.60 – 12.80 Fully charged 90% 12.50 – 12.60 Healthy range 80% 12.42 – 12.50 Healthy range 70% 12.32 – 12.42 Healthy range 60% 12.20 – 12.32 Healthy range 50% 12.06 – 12.20 Midpoint 40% 11.90 – 12.06 Approaching low 30% 11.75 – 11.90 Minimum recommended 20% 11.58 – 11.75 Risk of damage 10% 11.31 – 11.58 Risk of damage 0% 10.50 – 11.31 Fully discharged Discharge Guidelines
- Recommended minimum charge level: 30% SoC (≈11.75V).
- Avoid frequent discharges below 30% to prevent sulfation and shortened battery life.
- Discharging below 10.5V can cause irreversible damage.
- Deep discharges (≥80% DoD) reduce cycle life by up to 58% in flooded lead-acid batteries.
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12V Lithium Battery Voltage vs. State of Charge
State of Charge (%) Voltage (V) Notes 100% 13.6 – 13.8 Fully charged 90% 13.4 Healthy range 80% 13.2 Healthy range 70% 13.1 Healthy range 60% 13.0 Healthy range 50% 12.9 Midpoint 40% 12.8 Safe zone 30% 12.6 Safe zone 20% 12.4 Minimum recommended 10% 12.0 Risk of damage 0% ≤11.5 Fully discharged -
12V LiFePO₄ Battery Voltage vs. State of Charge
State of Charge (%) Voltage (V) Notes 100% 13.6 – 14.6 Fully charged 90% 13.4 Ideal upper limit 80% 13.3 Healthy range 70% 13.2 Healthy range 60% 13.1 Healthy range 50% 13.0 Midpoint 40% 12.9 Safe zone 30% 12.8 Safe zone 20% 12.6 Minimum recommended 10% 12.0 Risk of degradation 0% <11.5 Fully discharged Discharge Guidelines for Lithium Batteries
Recommended operating range: 20% to 90% SoC for LiFePO₄.
Avoid discharging below 10% SoC to prevent lithium plating and cell imbalance.
Cycle life impact:
100% DoD: ~600 cycles (LiFePO₄)
80% DoD: ~900 cycles
40% DoD: ~3000 cycles
10% DoD: ~15,000 cycles
Use a Battery Management System (BMS) to protect against over-discharge.
For additional information on batteries and charge states please see the following links:
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Load Testing
Handheld Load Tester
Note: Follow instructions and settings supplied by handheld load tester manufacturer.
Computerized Load Tester and Readout
If you take your batteries to a Battery Dealer or Auto Parts Store to have them tested with their computerized system, it will create a Test Report for you.
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Battery's Load Test Voltage.
Lower Voltage than device supports: The battery may need to be replaced. You may need to go to your marine service shop or a battery store.
Higher Voltage than device supports: Check the battery terminal voltage is within it's normal battery voltage range. If so, the equipment will not turn on to protect itself. That battery may be too powerful and may need to be replaced. If battery terminal voltage is above its listed voltage range, this would indicate a problem with the charger or alternator on your main motor over charging your battery. You may need to go to your marine service shop.
Testing a Battery with a Voltmeter or Multimeter
Testing a battery with a Volt Meter or Multimeter gives a quick indication of the current voltage of the battery. Note: When testing, it is important to remove all cables and make sure the battery terminals are free of corrosion and/or dirt.
Icons on Volt Meters and Multimeters can vary though the most common is a V with a wavy Line
above the V for AC and a V with a Solid Line and Dashed Line
above the V for DC.
Note: We recommend following the instructions and settings supplied by the Voltmeter or Multimeter manufacturer.
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Power Cable
Measure voltage at both ends of power cable, if there is a severe drop off from the terminal end to the plug end, the power cable is likely defective.
See the images of our different power plug types below
PC 11/PC 10 (HELIX & PMAX) PC 12 (SOLIX & ONIX) PC 13 (APEX, XPLORE & MEGA Live) 
SAE Power Cables MEGA 360 PC -
Test System Under Load Conditions
Have all onboard electrical equipment is running, including the trolling motor at various speeds with the main engine off and charger unplugged. Wait 6 minutes before measuring voltage at power cable's fish finder's connection. Repeat the test with main engine on for 6 minutes. The voltage at the power cable terminals should be above the fish finder's minimum operating voltage and below its maximum. This helps identify:- Electrical interference
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Under-voltage - Wiring issues see Check Your Hardware and Connections
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Check Your Hardware and Connections
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Check the Connectors & Pins
Check the pins of all connectors, to make sure they have not been bent, broken off or pushed back into the connector plug. If any connector pins have been bent, you may try to straighten them with needle nose pliers. If any pins are broken, replace the entire accessory.
Note: There is a risk that while straightening a bent connector pin, it can break.
HELIX and Legacy Models: Make sure the power cable has not been connected upside down. The notch on the plug (shown below) should point upwards for units with connections on the back. The notch should point towards the back of the unit for units with connectors on the bottom.
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Check the Cables
Check all accessories and cables for nicks, cuts, or physical damage. Try to repair any nicks in the cable with electrical tape. If any cables have had the internal wires cut or separated, the entire accessory or cable should be replaced.
Try wiggling the cable leading into the connector of the power cord to show any intermittent connection. If the power cable is intermittent, replace it. On some fish finders, an intermittent power connection may cause the microprocessor to cease correct operation. This may make it impossible to turn the depth sounder off. If this is the case, return it to the Service Department.
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Check for Proper Grounding
Ensure the negative wires for your Humminbird products are not spliced into other negative wires. They need to be individually ran to a grounding terminal with the proper gauge wire for the device.
Products with drain wires, such as MEGA 360 and MEGA Live, must have the drain wire grounded.
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Run the power direct to battery
By running direct to your cranking battery (or 12 volt accessory battery), with the proper gauge wire and proper sized inline fuse. This could identify a bad connection to the fuse panel.
Fuse sizes, power draw and the recommended wire gauge can be found in Fuse Size, Power Draw and Power Cable Extension Requirements.
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Test for Bad Connections
To determine if there could be any crimps, nicks, cuts or poor splices in your existing battery to panel run. If the unit works correctly, directly tied to the battery, we recommend that you look at your existing panel/buss, fuse and/or panel to battery wiring.
If the wire gauge is too small for amperage or power draw, this can also create an issue. For a 15-20' run of cable, we recommend 12-14 gauge, tinned copper stranded wire. Pay close attention to the gauge recommended for your unit as seen in our article on the subject or the unit's installation guide.
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If you are still having problems after trying all of the suggestions on the Common Check guide, watch this video for additional tips. If you still have issues, please contact our Help Center.
Resources
- Humminbird Repair Process and Service/Repair Fees
- Operation Manuals
- Fuse Size, Power Draw and Power Cable Extension Requirements
- Battery University.com
- Solar Electric.com
