Battery life for kayak electronics is a genuine constraint — you don't have a large starting battery or alternator charging the way a motorized bass boat does. Here's how to calculate your power budget and maximize time on the water.
Calculate Your Electronics Current Draw
Check the specifications page of each device for current draw (amps) at typical operating brightness:
- 5-inch fish finder: 0.5–1.0A typically
- 7-inch fish finder: 0.8–1.5A typically
- 9-inch fish finder with side imaging: 1.5–2.5A
- LiveScope transducer (if added): adds 1.5–2.5A on top of the head unit draw
- Trolling motor (kayak, 12V): 15–30A at full throttle, 5–10A at trolling speed
A 7-inch fish finder at 1.2A for an 8-hour day = 9.6 amp-hours needed. Add a small trolling motor at 8A average for 2 hours of use = 16Ah. Total = 25.6Ah. With a 20% safety buffer, a 32Ah battery is your minimum comfortable choice.
Battery Options for Kayak Electronics
7Ah sealed AGM (most compact): Runs a 5-inch fish finder for 6–8 hours. Weighs approximately 5 lbs. The minimum usable size for electronics-only (no trolling motor) on a half-day kayak trip.
18–20Ah sealed AGM: Runs a 7-inch fish finder for a full day or a small trolling motor + fish finder for a half day. The most common kayak electronics battery. 12–15 lbs.
12V lithium (LiFePO4): Same capacity in 50–60% less weight and faster recharge than AGM. Higher upfront cost but superior performance-to-weight for kayak applications where every pound matters.
Power-Saving Settings
Reduce screen brightness to 50–60% of maximum — the display backlight is the largest power consumer in the head unit. Many units have an auto-dim setting that reduces brightness below a set threshold. Turn off side imaging when you don't need it — actively pinging SI adds sonar channel draw. Lower ping rate in slow-moving shallow water situations where high ping rate isn't needed.
Lithium iron phosphate kayak battery — same amp-hours as AGM in 40-50% less weight. The best power option for weight-sensitive kayak setups.