They’re very water resistant, but they aren’t built to be submerged. Millertech Sport Series batteries are built with marine usage in mind. Yes, they are waterproof but not submersible or to be used in a direct spray of water for an extended period of time.

Millertech Sport Series batteries are built with marine use at the top of our minds. Yes, they're waterproof, but they aren't submersible, and they aren't made for direct spray over long periods. Every Millertech marine battery is sealed with a rubber gasket. The stainless-steel breather vent sits on top of the case, where rain and dirt can't collect, and lets air flow to prevent condensation. If your compartment floods, pump it out right away. If you have any doubts about your batteries afterward, call our Support Team at 855-MAX-LITH.

The batteries are very water resistant, with an estimated IP67 rating. This means they can handle rain, spray, and short-term exposure to water, like when washing a boat, but they are not fully waterproof. As long as they aren’t submerged or continuously sprayed for long periods, they should be fine.

Yes, with a Dual Purpose battery:
• 12V 135Ah and 190Ah: 1,500 cold cranking amps (CCA), rated for Mercury four-stroke engines up to 250hp
• 12V 100Ah: 1,000 CCA
• 12V 40Ah: 600 CCA

A standard Sport Series battery won’t take a charge below freezing. Built-in low-temperature charging protection stops it, which protects the cells. Store and charge it above freezing, or bring it inside the night before. If you charge on the boat in the cold, choose a heated model. Millertech offers several options that are heated.

Yes. Make sure your solar charge controller is compatible with lithium.

Yes, with the Dark Speed "On The Run" charger. While your outboard runs, it uses the alternator to charge your 12V cranking battery first. It then sends extra power to your 24V or 36V trolling motor battery. That can add hours to your day without shore power or a generator. It comes in 12V/24V (DS24) and 12V/36V (DS36) models.

Yes, in the same RV, but not in the same system. Never connect lithium and lead-acid batteries in parallel with each other, and avoid connecting them in series except in an emergency. Each type can still help the other in a pinch: a lead-acid battery can jump-start a dead lithium battery, and a lithium battery can jump-start a dead lead-acid battery.

Yes, on the same boat, but not in the same system. Never connect lithium and lead-acid batteries in parallel with each other. Avoid connecting them in series, too, except in an emergency. Each type can still help the other in a pinch: a lead-acid battery can jump-start a dead lithium battery, and a lithium battery can jump-start a dead lead-acid battery.

Yes! Millertech offers reliable lithium batteries for boats, trolling motors, RVs, and more. Our team can help you find the right replacement, backed by our 10-year, no-questions-asked warranty.

Yes. You can connect up to four Millertech batteries, in series or in parallel. Two 2480-BTs in parallel roughly double run time, to 12+ hours.

Yes. Millertech batteries perform “extremely well in cold conditions during discharge.” Sport Series batteries are rated to run from -4°F to 140°F. The limit is charging in the cold, not fishing in it (see question 25). Greg Hackney ran his while breaking ice: “nothing but raw power, the same as if it was 90° every day.”

It may work, but it could overcharge the battery or not have sufficient voltage to fully charge it. Before you hook it up, call Millertech at 855-MAX-LITH. A real person will tell you whether your charger fits your new batteries. We promise to never try selling you something you don’t need. Our goal is simple: you get exactly what you need and nothing you don’t. When you’re happy, we’re happy.

It may work, but it could overcharge your battery, or it may not have enough voltage to charge it fully. Before you hook it up, call Millertech at 855-MAX-LITH. A real person will tell you whether your charger is compatible with your batteries. We'll never try to sell you something you don't need. When our customers have exactly what they need and nothing else, they're happy, and that's what makes us happy.

It’s the cleanest way to run serious electronics. Millertech’s Electronics batteries are built to give “consistently clearer images and stronger signals” on your graphs all day. They also keep electronics off your trolling motor and cranking batteries. If you’d rather run one battery, the Dual Purpose line cranks your engine and runs graphs and accessories too.