Group 24 Lithium Starting Battery Guide: 1,000 CCA Marine Cranking

Short answer: A Group 24 lithium starting battery like the Pro-Guide 24M100-ST is a 12.8V LiFePO4 marine cranking battery rated at 1,000 CCA (lead-acid equivalent), with 800 amps for 8 seconds and 1,000 amps for 5 seconds, in a standard Group 24 case (10.25 x 6.83 x 9.19 in) that weighs 28.7 lb. It also stores 100Ah (1,280Wh), so the battery that starts your outboard can run your graphs, and it accepts up to 200A of alternator charge.

Your starting battery has one job that matters more than any other: turn the engine over at the ramp, at the end of the day and after the boat has sat all winter. This guide explains what makes a lithium marine starting battery different from an AGM cranking battery, what the 24M100-ST's cranking ratings actually mean, how it charges from your outboard's alternator, and how it differs from our 24M100 deep cycle battery that shares the same Group 24 case.

Key Takeaways

• Serious cranking power: 1,000 CCA lead-acid equivalent (PbEq), with 800A for 8 seconds and 1,000A for 5 seconds on the data sheet.
• Drop-in Group 24 size: 10.25 x 6.83 x 9.19 in, with 1 SAE post and 1 stud terminal.
• Light: 28.7 lb (13 kg).
• Capacity to spare: 100Ah and 1,280Wh, so it can also run electronics; 172 minutes of reserve capacity at 25A before the Pro-Boost safety cut-off.
• Alternator friendly: 200A charge acceptance at up to 14.8V.
• Durable: IP67 rated, 3,000+ cycles at 100% depth of discharge, 3-year free replacement and 10-year pro-rata warranty.

What Is a Lithium Marine Starting Battery?

A starting (cranking) battery delivers a large current for a few seconds to spin the engine's starter, then gets recharged by the engine's alternator or charging system. Traditionally that meant a flooded or AGM battery with thin plates designed for high current, rated in cold cranking amps (CCA) or marine cranking amps (MCA).

A lithium marine starting battery uses lithium iron phosphate (LiFePO4) cells instead of lead plates. LiFePO4 holds its voltage under load, so it cranks at a steady voltage instead of sagging, it weighs far less than a lead-acid battery of the same group size, and it loses less charge in storage, so it is more likely to be ready after the off-season.

The Pro-Guide 24M100-ST packs that into a Group 24 case, one of the most common marine battery sizes. Its data sheet describes its LiFePO4 chemistry as designed for marine cranking use, and the battery label calls it "ideal for engine starting with deep cycle capacity." In other words, it is a starting battery first, with enough capacity to power electronics too.

Pro-Guide 24M100-ST Specifications

Model / SKU	Pro-Guide 24M100-ST (PGL24M100-ST)
Battery type	Lithium starting battery (LiFePO4) with deep cycle capacity
Cranking	1,000 CCA lead-acid equivalent (PbEq); 800A for 8 s, 1,000A for 5 s
Nominal voltage	12.8V
Capacity / energy	100Ah / 1,280Wh
Reserve capacity	172 min at 25A to the Pro-Boost safety cut-off; 216 min to the low-voltage cut-off
Cycle life	3,000+ cycles at 100% DoD, 6,000+ at 80% DoD
Discharge current	5A standard, 100A continuous, 9.6V cut-off
Charge current	20A standard, 50A maximum continuous, 14.6V charge cut-off
Alternator charging	200A charge acceptance, 14.8V maximum, peak 1.65C for 1 minute
Charging temperature	14°F to 113°F (-10°C to 45°C)
Discharge temperature	-4°F to 140°F (-20°C to 60°C)
Protection	IP67, built-in BMS, Pro-Boost
Terminals	1 SAE post, 1 stud terminal
Dimensions	10 1/4 x 6 13/16 x 9 3/16 in (260.4 x 173 x 233.4 mm)
Weight	28.7 lb (13 kg)
Warranty	3-year free replacement, 10-year pro-rata

See the full ratings in the 24M100-ST data sheet (PDF).

The 24M100-ST in its Group 24 case. The STARTING label lists 12.8V, 1,000 CCA (PbEq), 100Ah and 1,280Wh.

How Much Cranking Power Does the 24M100-ST Have?

Cranking ratings for lithium batteries can be confusing, so here is what each number on the 24M100-ST means:

• 1,000 CCA (PbEq): the cold cranking amp rating expressed as a lead-acid equivalent, so you can compare it with the CCA figure on a conventional starting battery.
• 800A for 8 seconds: the data sheet shows this meets the aftermarket lithium starting requirement of 800 amps for 8 seconds at 20°F (-7°C) listed on the same sheet.
• 1,000A for 5 seconds: the peak burst the battery is rated to deliver for a short start.
• Reserve capacity, 172 minutes: how long it can deliver a steady 25A before the Pro-Boost safety cut-off, a useful measure of how long it can run accessories if your charging system stops working.

How many CCA do you need? Check your engine owner's manual for its minimum CCA or MCA rating, then choose a battery that meets or exceeds it. Because a lithium battery holds its voltage under load, the 24M100-ST cranks at a steady voltage instead of slowing as it drains, which is where lead-acid starting batteries tend to struggle late in the day or on a cold morning.

The 24M100-ST also has Pro-Boost built-in jump starting. And because it stores 100Ah, a quick estimate for electronics runtime is 100Ah divided by your load: about 50 hours on a 2A fish finder or about 10 hours on a 10A electronics load. One customer runs LiveScope and three graphs all day from a 24M100-ST.

Lithium Starting Battery vs. AGM Cranking Battery

Factor	Pro-Guide 24M100-ST (LiFePO4)	Typical Group 24 AGM starting battery
Cranking rating	1,000 CCA (PbEq)	Varies by model; check the label
Voltage while cranking	Stays steady until nearly empty	Drops as the battery discharges
Weight	28.7 lb	Often noticeably heavier
Capacity for electronics	100Ah, nearly all usable	Lower; deep discharges shorten a starting battery's life
Off-season readiness	Low self-discharge; sleep mode for storage	Self-discharges faster; usually needs a maintainer
Cycle life	3,000+ at 100% DoD	Typically a few hundred deep cycles
Warranty	3-year free replacement, 10-year pro-rata	Usually 1 to 3 years

The biggest practical difference shows up when you use your starting battery for more than starting. Run a graph or two off an AGM cranking battery all day and you are asking a battery designed for short bursts to do deep cycle work. The 24M100-ST handles both, and it accepts a fast recharge from the alternator once the engine is running.

What Is the 24M100-ST Best For?

• Outboard starting on bass and fishing boats: drop into the Group 24 cranking battery spot and save weight.
• Starting plus front or console electronics: one customer runs three 24M100 deep cycle batteries on the trolling motor and a 24M100-ST for starting and electronics, powering two 12-inch Garmin graphs and LiveScope. If you're deciding whether to isolate electronics, read Should You Run a Separate Battery for Your Boat Electronics?
• Boats that sit between trips: lithium's lower self-discharge and the built-in sleep mode help it be ready when you are.
• Weight-sensitive boats: at 28.7 lb, it trims weight from the stern compared with a typical lead-acid starting battery.

Matched accessories include the NOCO Group 24 Snap-Top Battery Box, the NOCO Group 24 Battery Tray and the 12V 1000A Jump Starter for extra peace of mind.

The 24M100-ST top label lists its charging cautions, the 13.4V full and 12.9V 20% charge voltages, and the sleep and wake-up steps.

Charging From Your Alternator and Shore Power

Alternator: as a starting battery, the 24M100-ST is built to be recharged while you run. The data sheet lists 200A charge acceptance at up to 14.8V, with peak charge acceptance of 1.65C for 1 minute.

Shore power: charge time is roughly capacity divided by charger output:

• 10A: about 10 hours from empty, for example with the 12/16V 10A 1-Bank Battery Charger, which has a 12V lithium profile and an Activation Mode for waking a sleeping lithium battery.
• 20A standard: about 5 hours from empty.
• 30A: about 3.5 hours with the Pro-Guide 12V 30A Lithium Battery Charger.
• 50A maximum continuous: about 2 hours.

Rules from the battery label:

1. Use a smart lithium-specific charger with a charging voltage between 14V and 15V. Below 14V the battery cannot be fully charged; above 15V it will be overcharged.
2. Avoid chargers with an automatic "desulfation mode."
3. Don't discharge it below 12V, which may damage the battery.
4. Let it rest 1 to 2 hours after charging before checking voltage. The label lists 13.4V as 100% charged and 12.9V as 20%; below 12.8V after resting, it needs more charging.
5. Charge between 14°F and 113°F (-10°C to 45°C). It can discharge down to -4°F, so it can start your engine in colder conditions than it should be charged in. One reviewer brought the battery inside to warm up before charging on a cold day, which is the right approach.

Wake-Up, Sleep Mode and Storage Tips

How the 24M100-ST goes to sleep

According to the label, it enters sleep mode in three ways: when you hold TEST for 3 seconds (the red light flashes 3 times), when it has not been used for 60 days after its first start and charge in your boat, or when its capacity drops below 15%.

Three ways to wake it

1. Hold TEST for 3 seconds until the blue light flashes 3 times.
2. Turn the key to the "ON" position and wait 1 minute. Make sure doors and accessory switches are off for 1 minute before turning the key.
3. Use a charger with a boost or activation mode. If capacity is still below 15% after charging, it will go back to sleep when disconnected from the charger.

Check state of charge

In wake-up mode, quickly press TEST: 3 lights means ready to use, 2 lights means charge soon, and 1 red light means recharge immediately.

Wiring limits and mounting

The label says not to connect more than 4 batteries in series or parallel. Mount the battery in a tray or box with a hold-down, and keep terminals clean with battery corrosion preventative spray. For a full seasonal routine, see our marine battery maintenance guide.

24M100-ST vs. 24M100: Starting or Deep Cycle?

Both are Pro-Guide 12.8V, 100Ah LiFePO4 batteries in the same Group 24 case, which is why they get mixed up. The difference is the job they are built for.

Spec	24M100-ST (starting)	24M100 (deep cycle)
Primary job	Engine cranking, with deep cycle capacity	Trolling motors, electronics, house power
Cranking rating	1,000 CCA (PbEq)	Not designed for engine starting
Size / capacity	Group 24, 100Ah, 1,280Wh	Group 24, 100Ah, 1,280Wh
Weight	28.7 lb	23.8 lb

Choose the 24M100-ST for the battery that starts your outboard. Choose the 24M100 deep cycle for your trolling motor bank or a dedicated electronics battery. Many boats use both, like the angler above with three 24M100s on the trolling motor and a 24M100-ST up front. For the deep cycle side, read our Group 24 lithium deep cycle battery guide.

Frequently Asked Questions

Can a lithium battery be used as a marine starting battery?

Yes, if it is built for cranking. The Pro-Guide 24M100-ST is a LiFePO4 starting battery rated at 1,000 CCA lead-acid equivalent, with 800A for 8 seconds and 1,000A for 5 seconds.

How many cranking amps does the 24M100-ST have?

1,000 CCA lead-acid equivalent (PbEq). The data sheet lists 800 amps for 8 seconds and 1,000 amps for 5 seconds.

Will the 24M100-ST fit in a Group 24 battery box?

Yes. It measures 10.25 x 6.83 x 9.19 in, a standard Group 24 size. Check height and terminal clearance in your compartment before installing.

Can my outboard's alternator charge the 24M100-ST?

Yes. The data sheet lists 200A alternator charge acceptance at up to 14.8V. The label recommends keeping charging voltage between 14V and 15V.

Can the 24M100-ST also run my electronics?

Yes. It stores 100Ah (1,280Wh): about 50 hours on a 2A fish finder or about 10 hours on a 10A load. Reserve capacity is 172 minutes at 25A.

Why won't my new lithium starting battery power on?

It is probably in sleep mode. Hold TEST for 3 seconds until the blue light flashes 3 times, or turn the key to "ON" and wait 1 minute.

Can I charge the 24M100-ST in cold weather?

Charge it between 14°F and 113°F (-10°C to 45°C). It can discharge, and start your engine, down to -4°F (-20°C).

What warranty comes with the 24M100-ST?

A 36-month (3-year) free replacement warranty and 120 months (10 years) of total pro-rata coverage.

Upgrade Your Starting Battery to Lithium

If your boat has a Group 24 starting battery, the Pro-Guide 24M100-ST is a straightforward way to get 1,000 CCA of steady cranking power, shed weight and gain 100Ah of capacity for your electronics. It is built to start your day at the ramp and finish it the same way, and it is backed by a 10-year warranty and a team that knows boat systems.

SHOP THE PRO-GUIDE 24M100-ST

Questions about cranking ratings or wiring? Call our team at 1-800-827-3232 or browse all lithium starting batteries and the full lithium lineup.

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