What Size Battery Runs a Highbanker Pump? 12V Sizing Math

Every highbanker and recirculating sluice hides the same gotcha: the pump. The sluice itself needs nothing but gravity — but the pump that feeds it wants electricity all day, in a place that has none. Undersize the battery and your dig day ends at lunch. Oversize it and you hauled forty unnecessary pounds up a canyon.

The fix is twenty minutes of arithmetic, and you only do it once. I run an 1100 GPH pump on my own setup — the workhorse class for hobby highbankers — so that's the number this guide is built around, and the method works for any pump once you swap in your own figures.

Step 1: Find Your Pump's Real Draw

Flip your pump over or check its spec sheet. You're looking for the amp draw at 12V — not the GPH rating, which tells you about water, not electricity.

For the 1100 GPH class, manufacturer spec sheets cluster around 3 to 4 amps at 12 volts — call it 40–50 watts running. Some high-efficiency models pull under 2 amps; older or hard-worked pumps drift higher. Two honest cautions:

Head kills flow, not amps. Lifting water six feet up a bank, that "1100 GPH" delivers a lot less water — but the motor draws roughly the same. You may find yourself running the pump *longer* to move the same gravel, which is a sneaky way to burn more watt-hours than the math predicted.

Read your plate, not mine. The spread between a 1.5A pump and a 4A pump is nearly 3x on your battery math. Thirty seconds with the spec plate beats any guide's assumption — including this one's.

For everything below I'll use 45W as the working number for an 1100 GPH pump. If yours differs, scale accordingly.

Step 2: Count Honest Pump-Hours

Nobody runs the pump every minute of a dig day. You shovel, you classify, you clean out riffles, you eat, you stare at a promising crevice. In practice the pump runs half to two-thirds of your active hours. A "six-hour day on the water" is usually three to four pump-hours.

The core equation:

pump watts × pump-hours × 1.3 = watt-hours you need

That 1.3 is headroom — for cold mornings (batteries deliver less below 50°F), battery age, inverter losses, and the extra runtime the head-height problem above quietly adds. Skip it and the math works until October, then doesn't.

Step 3: The Table

For a 45W (1100 GPH) pump:

Half-day session — ~2.5 pump-hours: 45 × 2.5 × 1.3 ≈ 150Wh. Almost anything handles this, but a 300Wh day-tier unit is doing real work once you add phone and detector charging — it's the floor, not a comfortable fit.

Full dig day — ~4 pump-hours: 45 × 4 × 1.3 ≈ 235Wh for the pump alone; ~300Wh with camp charging. A ~1kWh unit runs the day without thinking about it and holds reserve for a second morning.

Weekend camp — 2 dig days: two full days of pump plus lights (an LED lantern is ~10W — 5 evening hours is 50Wh/night) and charging lands near 800–900Wh. This is exactly why the ~1kWh class exists.

Week on the claim — 5 dig days: ~1.2kWh of pump plus ~500Wh of camp is 1.7–2.5kWh depending on how hard you run — multi-day-tier territory (2–4kWh), or a smaller bank plus solar input.

Running a bigger pump? A 2000 GPH class unit draws roughly 7–8A (~90W) — double every number above. Running a 120V AC pump through the station's inverter? Add ~10–15% for inverter loss on top of the pump's own draw.

Step 4: Watch the Chemistry Trap

Battery ratings lie by omission. A "100Ah" wet or AGM lead-acid battery is a ~600Wh battery in practice — draw lead-acid below half charge routinely and you're buying a new battery next season. A 100Ah LiFePO4 pack delivers 1,000Wh+ of its rating, tolerates partial charge, and shrugs off the truck-bed life that murdered every wet cell I ever owned. When you compare a lead-acid price tag to a lithium one, compare *usable* watt-hours — the gap shrinks fast. The full ten-year version of that lesson is in the off-grid power guide.

Step 5: Solar Changes the Week Math

For day trips, solar is dead weight. For a week on a claim, it changes the equation: a 200W panel in honest field conditions — angled at the sun some of the time, shaded some of the time — returns roughly 600–800Wh on a summer day, which is a full dig day's pump budget flowing back in while you shovel. That's how a 2kWh bank covers a week that the table above prices at 2.5kWh. If you drive between sites, an alternator DC-DC charger does the same job from the truck.

Putting It Together

Read your pump's amp draw off the plate — don't guess

Estimate honest pump-hours per day (half to two-thirds of active time)

Watts × hours × 1.3, times your number of dig days

Compare against *usable* watt-hours, not the sticker rating

For multi-day stays, let solar carry part of the load

Our off-grid power lineup is organized by exactly these tiers — day, weekend, multi-day, and charging gear — so once you have your number, matching it to a unit takes a minute.

Related Guides:

Off-Grid Power for a Gold Claim: Batteries, Solar & Sizing

Sluice Box Setup and Optimization Guide

Beginner's Guide to Gold Panning