The numbers add up quickly:
• A 12-inch graph pulls about 2–3A.
• Forward-facing sonar adds 3–5A.
• With lighting and device charging, a full setup typically runs 6–8A.
Millertech’s 12V 135Ah and 190Ah Dual Purpose batteries are rated to run multiple power-hungry graphs for 8+ hours.

Keep the battery plugged into the charger whenever it’s not in use. For long-term storage (1 month or more), fully charge the battery, remove all loads, and store it with nothing connected. Following these steps will help maximize the lifespan of your lithium deep cycle battery.

For long-term storage, fully charge the battery, remove all loads or connections, and store it with nothing attached. This preparation helps maximize the battery’s lifespan during extended storage periods, such as over the winter.

No. Phones and laptops use lithium-ion cells built to pack the most power into the least space. Millertech RV batteries use lithium iron phosphate (LiFePO4), which is widely recognized as one of the most stable lithium chemistries. It gives off no gas while charging, and our batteries are UL certified to UL 1973. (Myths blog; UL certified page)

We lean toward one 36V battery, mostly for reliability. When three 12V batteries run in series, every one of them has to work perfectly, because if one fails, the whole system goes down. That gives you three times the chance of a failure compared with a single 36V battery. One weak battery also drags the others down: if one of three 12V 100Ah batteries only delivers 75Ah, the whole bank drops to 75% capacity.

Want a backup on the water?

The battery, a battery charger, an adjustable mounting strap and three connector cables that fit most major trail camera brands (5.5mm x 2.1mm, 4.0mm x 1.7mm and 4.8mm x 1.7mm). The USB hub, security camera adapter, splitter and 6V converter are sold separately.

The BMS is the battery’s built-in brain. It watches voltage, current and internal temperature, and it protects against:
• Overcharge and over-discharge
• Over-temperature
• Short circuit
• Reverse polarity and over-current (through a dual-blade fuse)
Millertech uses a commercial-grade BMS sized at least 20A above the battery’s rating.

The Millertech app for iOS and Android shows:
• Remaining capacity, total capacity and amp hours
• Voltage and current
• Temperature
• Recharge cycle count
• Battery status and an error log
You can also give each battery a name, like “Trolling” or “Cranking.”

Two things to check:

• Charger or converter: use one built for lithium. An old lead-acid charger could overcharge a lithium battery, or it may not have enough voltage to charge it fully.
• Terminals: use ring terminals, torqued to 10 ft-lb.

If you're not sure about your setup, call our Support Team at 855-MAX-LITH before you buy.

The Battery Management System (BMS) puts the battery into low-voltage protection (sleep mode) to protect the cells. To wake it, connect a lithium charger, a jump pack, or another battery that’s at least 50% charged. The Dark Speed and three-bank chargers have a built-in BMS wake-up. The app shows remaining capacity in real time, so you’ll see it coming.

A heated battery has a built-in heater that turns on when the charger is connected and the temperature is below 32°F. It warms the cells to 34°F, then resumes charging. That lets you charge in the cold and fish down to 0°F. If you fish late fall, winter or early spring and keep the boat outside, it’s the one to get.

Heated Sport Series models:

• 12V 100Ah and 135Ah Dual Purpose
• 12V 300Ah
• 24V 80Ah
• 36V 60Ah

It’s a compact, rechargeable lithium battery pack, designed by Millertech, that powers your trail camera for months at a time so you’re not hiking in to swap AAs. Hang it on the tree next to the camera and plug it in. Add the slide-on USB hub and the same battery becomes a power station for phones, tablets and other USB gear at camp, on the boat or in the blind.