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12V 235Ah Lithium Battery: One Battery to Crank and Run Electronics
Short answer: The Pro-Guide 31M235-DP is a 12V 235Ah lithium battery (12.8V LiFePO4) that starts your outboard at 1,000 CCA (lead-acid equivalent) and stores 3,008 watt-hours for big electronics packages, all in one Group 31 Tall case (13.07 x 6.93 x 10.83 in) weighing 52.91 lb. For anglers running four or five graphs plus live sonar, it can replace both a cranking battery and a separate electronics battery, with Bluetooth monitoring, a built-in heater and NMEA 2000 compatibility.
Modern fishing electronics are hungry. Multiple 12-inch and larger displays, forward-facing sonar, livewell pumps and bilge pumps add up fast, and the old answer was to stack more Group 31 AGMs in the compartment. This guide explains how much a 235Ah lithium dual purpose battery really runs, what customers are getting from it on the water, how it charges from your alternator and from shore power, and whether you need the tall 235Ah model or the standard-height 180Ah version.
Key Takeaways
- Big capacity, one battery: 235Ah and 3,008Wh, plus 1,000 CCA lead-acid equivalent for starting.
- Built for big electronics: about 23.5 hours on a 10A electronics load, and 404 minutes of reserve capacity at 25A before the Pro-Boost safety cut-off.
- One battery, one case: Group 31 Tall, 13.07 x 6.93 x 10.83 in, 52.91 lb (24 kg).
- Smart and cold-ready: Bluetooth, built-in heater (charges from -4°F), NMEA 2000 compatible, state of charge gauge, IP67.
- Long life: more than 3,000 cycles at 100% depth of discharge and more than 6,000 at 80%.
- Warranty: 3-year free replacement, 10-year pro-rata.
Why a 235Ah Dual Purpose Lithium Battery?
A dual purpose battery does two jobs: it delivers a short, high-current burst to crank your engine, and it delivers steady power for hours to run electronics and accessories. With lead-acid or AGM, doing both well usually meant two or more batteries, because deep discharges shorten a lead-acid battery's life and a drained house battery can leave you without enough voltage to start.
Lithium iron phosphate (LiFePO4) changes that. It holds its voltage under load, can use nearly all of its rated capacity and lasts thousands of cycles. Put 235Ah of it in one case and you have enough capacity that a full tournament day of electronics barely dents the cranking reserve.
The 31M235-DP uses a Group 31 Tall case. It shares the 13.07 x 6.93 in footprint of a standard Group 31, but it stands 10.83 in tall, about 1.9 in taller than our standard-height 31M180-DP. That extra height is where the extra 55Ah lives.
Pro-Guide 31M235-DP Specifications
| Model / SKU | Pro-Guide 31M235-DP (PGL31M235-DP) |
| Battery type | Dual purpose (starting + deep cycle), LiFePO4 |
| Nominal voltage | 12.8V |
| Capacity / energy | 235Ah / 3,008Wh |
| Cranking | 1,000 CCA lead-acid equivalent (PbEq); 800A for 8 s, 1,000A for 5 s |
| Reserve capacity | 404 min at 25A to the Pro-Boost safety cut-off; 507 min to the low-voltage cut-off |
| Cycle life | 3,000+ cycles at 100% DoD, 6,000+ at 80% DoD |
| Discharge current | 47A standard, 200A continuous, 10V cut-off |
| Charge current | 10A to 47A standard, 117.5A maximum continuous, 14.4V charge cut-off |
| Alternator charging | 200A charge acceptance, 14.8V maximum, peak 1.65C for 1 minute |
| Charging temperature | -4°F to 131°F (-20°C to 55°C), built-in heater |
| Discharge temperature | -4°F to 140°F (-20°C to 60°C) |
| Features | Bluetooth, NMEA 2000 compatible, state of charge gauge, BMS reset, removable handle |
| Protection | IP67 |
| Terminals | 3 x M8 internal thread |
| Dimensions | 13.07 x 6.93 x 10.83 in (332 x 176 x 275 mm) |
| Weight | 52.91 lb (24 kg) |
| Warranty | 3-year free replacement, 10-year pro-rata |
Download the 31M235-DP data sheet (PDF) or the safety data sheet (PDF).
The taller 31M235-DP lined up beside three Group 24 deep cycle 24M100 batteries. The dual purpose battery handles cranking and electronics; the deep cycle batteries are built for trolling motor duty.
How Long Will a 12V 235Ah Lithium Battery Run Your Electronics?
For a rough estimate, divide 235Ah by your average load in amps:
| Load | Typical draw | Estimated runtime on the 31M235-DP |
| Single fish finder / chartplotter | About 2A | About 117 hours |
| Multiple graphs plus live sonar | About 10A | About 23.5 hours |
| Heavy accessory load | About 30A | About 7.8 hours |
| Steady 25A (reserve capacity test) | 25A | 404 minutes to the Pro-Boost safety cut-off |
What customers report on the water lines up with that math:
- One angler runs four 12-inch Garmin units and LiveScope and uses about 30% of the battery in a 10-hour fishing day. On 235Ah, that works out to roughly a 7A average draw, and he now charges every other trip instead of putting units in sleep mode to make it through the day.
- Another replaced two Group 31 AGMs with one 31M235-DP to crank the motor and run pumps and five graphs. After a 13-hour day, the battery still showed 64%.
- A third runs three Garmin 8600-series units and had more than 85% left after 6 hours.
- Another ran a 15-inch Garmin, two 12-inch units and a LiveScope setup for the better part of two and a half days without charging.
Your results depend on screen brightness, sonar settings, pump use and temperature, but the takeaway is consistent: with 235Ah on board, you stop rationing electronics.
One 31M235-DP vs. Two Group 31 AGM Batteries
A common setup on bigger boats is two Group 31 AGMs: one for starting, one (or both) for electronics. Here is how one 31M235-DP compares.
| Factor | One Pro-Guide 31M235-DP | Two typical Group 31 AGMs |
| Usable capacity | Nearly all of 235Ah | About 50% of each battery's rating to protect life |
| Weight | 52.91 lb total | Typically well over 100 lb for the pair |
| Compartment space | One Group 31 Tall footprint | Two Group 31 footprints |
| Cycle life | 3,000+ at 100% DoD | Typically a few hundred cycles each |
| Voltage under load | Stays flat until nearly empty | Sags as the batteries drain |
| Monitoring | Bluetooth, NMEA 2000 compatible, onboard gauge | Separate voltmeter or battery monitor |
| Wiring | One battery to connect and maintain | Two batteries, more cables and connections |
Fewer batteries also means fewer terminals to corrode, less weight in the stern and room in the compartment for other gear.
What Is the 31M235-DP Best For?
- Tournament bass boats with big electronics packages: multiple large displays, forward-facing sonar, livewells and pumps, plus engine starting from the same battery.
- Consolidating a two-battery cranking and house setup: one battery instead of two, if your compartment clears 10.83 in. Still prefer separate batteries? Read Should You Run a Separate Battery for Your Boat Electronics?
- NMEA 2000 networks: it is NMEA 2000 compatible. See What Is NMEA and Why Does It Matter for Your Battery Setup? One reviewer had trouble getting battery status to appear on a Garmin display, so if network data matters to you, call our team before you install.
- Full boat systems in one order: the 12V 235Ah & 36V 75Ah Bundle pairs it with a 36V trolling motor battery and a PGC-1236X 2-bank charger, and the 12V 235Ah & 24V 115Ah Bundle pairs it with a 24V trolling motor battery and a PGC-1224 charger. Compare trolling motor layouts in One Pack or Three?
- RV and off-grid systems: 3,008Wh of deep cycle storage.
A 31M235-DP wired into a bass boat compartment, sharing space with the onboard charger.
How to Charge a 235Ah Lithium Battery
From your alternator: the data sheet lists 200A charge acceptance at up to 14.8V, with a peak acceptance of 1.65C for 1 minute, so running time between spots puts charge back in.
From shore power: charge time is roughly capacity divided by charger output:
- 10A bank (such as the 12V bank of a PGC-1224, or the 12/16V 10A 1-Bank Battery Charger): about 23.5 hours from empty. Most days you won't be starting from empty.
- 20A bank (the 12V bank of the PGC-1236X): about 12 hours from empty.
- 30A with the Pro-Guide 12V 30A Lithium Battery Charger: about 8 hours.
- 47A, the top of the standard range: about 5 hours. 117.5A maximum continuous: about 2 hours.
Rules from the battery label:
- Both the vehicle and the battery charger should limit charging voltage to 14.0V to 15.0V. Never exceed 15.0V.
- Don't use a charger with an automatic "desulfation" function.
- If the battery gets hot to the touch, stop charging and let it cool.
- The label lists 13.8V as 100% charged and 13.1V as 20% charged.
The built-in heater allows charging from -4°F up to 131°F (-20°C to 55°C). Store it between 23°F and 113°F (-5°C to 45°C).
Install and Setup Tips
Measure the height first
At 10.83 in tall, the 31M235-DP needs more vertical clearance than a standard Group 31. Measure from the tray to the underside of the hatch or lid, and allow room for the cables on top.
Wake it from sleep mode
Hold TEST for 3 seconds until the green lights (75%-100%) flash three times and the battery turns on. For storage, hold TEST for 3 seconds until the red light flashes three times. Quickly press TEST any time to check state of charge.
Use the app
Bluetooth monitoring works with the Pro-Guide Power app (iOS).
Secure it
At nearly 53 lb, it needs a solid tray and hold-down. The NOCO Group 31 Battery Tray is a matched add-on, and the Bass Tank Power Harness keeps electronics wiring tidy.
31M235-DP vs. 31M180-DP: Which Should You Choose?
Both are 12.8V dual purpose LiFePO4 batteries at 1,000 CCA lead-acid equivalent with the same footprint and features. Choose the 31M235-DP for the most capacity (235Ah vs. 180Ah) and a 200A continuous rating vs. 180A, if your compartment clears 10.83 in and you can handle 52.91 lb. Choose the 31M180-DP if you need a standard 8.9 in Group 31 height or want to save about 11 lb.
Frequently Asked Questions
How long will a 12V 235Ah lithium battery last on the water?
Divide 235Ah by your load: about 23.5 hours at 10A or 7.8 hours at 30A. The 31M235-DP's reserve capacity is 404 minutes at 25A before the Pro-Boost safety cut-off.
Can the 31M235-DP start my outboard?
Yes. It is a dual purpose battery rated at 1,000 CCA lead-acid equivalent, with 800A for 8 seconds and 1,000A for 5 seconds on the data sheet.
Can one 31M235-DP replace two Group 31 AGM batteries?
For many cranking-plus-electronics setups, yes. One customer replaced two Group 31 AGMs with a 31M235-DP and still had 64% left after a 13-hour day of cranking, pumps and five graphs.
Will the 31M235-DP fit a Group 31 battery box?
It has a Group 31 footprint (13.07 x 6.93 in) but is a Group 31 Tall at 10.83 in. Check height and lid clearance before ordering.
How much does the 31M235-DP weigh?
52.91 lb (24 kg).
Can I charge it in cold weather?
Yes. The built-in heater gives it a charging range of -4°F to 131°F (-20°C to 55°C).
What warranty comes with the 31M235-DP?
A 36-month (3-year) free replacement warranty and 120 months (10 years) of total pro-rata coverage.
Power Your Whole Day With One Battery
If your electronics have outgrown your batteries, the Pro-Guide 31M235-DP gives you 235Ah of lithium capacity and 1,000 CCA of starting power in a single Group 31 Tall case. Run every screen at full brightness, keep the livewell going, and still turn the key with confidence at the end of the day, backed by a 10-year warranty.
Want help sizing your system? Call our team at 1-800-827-3232 or browse all dual purpose lithium batteries and the full lithium lineup.
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