Renogy Shunt 300 Review: Battery Monitor Setup

Renogy’s Battery Shunt 300 is a Bluetooth battery monitor that tells you what a voltmeter can’t: how much charge is actually left in your battery and how long it will last at the current load. Renogy’s user manual (version A2, November 2024) rates it for 8–120V systems, 300A continuous and 500A for under 10 seconds, with ±1% current accuracy and a 0.01A resolution. It was listed at $120.99 on Renogy’s US store when we checked in October 2026. There’s no display on the shunt itself; everything shows up in Renogy’s DC Home app or on a Renogy ONE monitor. Here’s how it installs, how to set it up so the state-of-charge reading is trustworthy, and how it compares with a Victron SmartShunt.

As an Amazon Associate I earn from qualifying purchases, at no cost to you.

Renogy Battery Shunt 300 on Amazon · Shunt 300 on Renogy

Why a Shunt Beats a Voltmeter

Lithium iron phosphate batteries hold an almost flat voltage from about 90% down to 20% charge, so a voltage reading tells you very little about how full a LiFePO4 battery is. A shunt measures every amp going in and out of the battery and counts them, the way a fuel gauge would. Renogy’s manual describes the Shunt 300 as calculating state of charge (SOC) and remaining run time from that measured current and voltage. It also logs history such as charge cycles, deepest discharge and battery temperature.

Specs

Spec	Renogy Battery Shunt 300 (RSHST-B02P300-G1)
System voltage	8–120V DC
Continuous / peak current	300A / 500A for under 10 seconds
Current accuracy / resolution	±1% / 0.01A
Voltage resolution	10 mV
Battery capacity setting	1 to 6,500Ah
Self-consumption	Less than 0.1W
Connectivity	Bluetooth LE and Bluetooth Mesh (DC Home app, Renogy ONE)
Terminals	M10 (3/8 in) bolts
Temperature sensor	Included, 1.5 m lead; -4°F to 176°F range
Starter battery input	Yes, via the B2 wire (voltage only)
Operating temperature	14°F to 122°F (-10°C to 50°C)
Size / weight	5.27 × 3.82 × 1.22 in, 0.57 lb
Warranty	1 year

Renogy says it works with lead-acid (AGM, gel), LiFePO4, lithium-ion and nickel-metal hydride batteries.

What’s in the Box and What You’ll Need

Renogy’s manual lists the shunt, a quick guide, two 1-meter 22 AWG sense wires (B1 and B2), a 1.5-meter temperature sensor and mounting screws. Battery cables aren’t included. Renogy’s recommended tools: a 17 mm wrench, Phillips and small slotted screwdrivers, a wire stripper, a hydraulic crimper, heat shrink and a heat gun, plus insulating gloves.

Sizing the cables

The shunt carries your full system current on the negative side, so its two main cables must be sized like your battery cables. Renogy’s manual includes this ampacity table, citing NEC Table 310.17 for 90°C copper at up to 86°F ambient:

Gauge	Ampacity	Gauge	Ampacity
8 AWG	80A	1 AWG	220A
6 AWG	105A	1/0 AWG	260A
4 AWG	140A	2/0 AWG	300A
2 AWG	190A	4/0 AWG	405A

Renogy adds that runs longer than about 13 feet may need thicker cable for voltage drop. Our wire gauge chart and battery cable crimping guide cover both steps.

Installation, Step by Step

Renogy’s manual asks you to follow its order exactly. Turn off every device in the system and make sure no current is flowing before you start.

1. Pick a spot. Clean, dry and ventilated, out of direct sunlight, and away from large metal objects that can weaken Bluetooth.
2. Remove both covers from the shunt.
3. Battery negative to B-. Run a cable from the shunt’s B- terminal to the battery’s negative post. Renogy specifies 173.5–224.8 in·lb (19.6–25.4 N·m) of torque on the M10 terminals.
4. System negative to P-. Everything else that used to connect to battery negative (loads, chargers, inverter, DC-DC charger) now connects to the P- terminal instead.
5. B1 sense wire to battery positive. This lets the shunt read voltage and power itself.
6. Plug in the temperature sensor and attach it to the battery.
7. Optional: B2 to the starter battery positive, if you want to see the vehicle battery’s voltage too.
8. Mount the shunt and refit the covers.

The most common mistake with any shunt is leaving something connected straight to battery negative. If a load or charger bypasses the shunt, its current never gets counted and the SOC reading drifts. Everything except the B- cable must go to P-. Our SmartShunt wiring guide shows the same principle with diagrams.

Multiple batteries

The manual shows parallel and series banks connected through one shunt, with no limit on battery count, as long as the combined continuous current stays under 300A and the total voltage under 120V.

Setup in the DC Home App

1. Power on the system. The shunt starts automatically and its Power LED lights.
2. Add the device. In DC Home (or on a Renogy ONE), choose “Add Devices,” then scan and pair. Keep the phone within about 10 feet during pairing, Renogy says.
3. Set “Rated Battery Ah” first. Renogy says to do this before anything else, using your battery’s rated capacity. For two 100Ah batteries in parallel, that’s 200Ah.
4. Sync the SOC. Under Settings > Battery > SOC sync, choose 100% after a full charge, or enter your battery’s actual state of charge.
5. Review the alarms. Renogy’s defaults include a Low SOC alarm that triggers at 50% and releases at 55%, and a 12V High Volts alarm at 14.4V. LiFePO4 users often lower the Low SOC trigger to 20% to match how they actually use the battery.

When to re-sync

Renogy recommends SOC synchronization on first install, after the app or monitor loses power, when the battery hasn’t been fully charged for a while, and as the battery ages. Its manual gives the example of a 100Ah battery that only charges to 90Ah after a year; at that point, use 90Ah as the new reference. A monthly full charge followed by a sync keeps the gauge honest.

To pair with a different phone or monitor, remove the shunt from the app, or hold the RESET button for 5 seconds until the Bluetooth LED goes out, then pair again.

Remote Monitoring

On its own, the Shunt 300 talks to your phone over Bluetooth, so you need to be nearby. For monitoring from anywhere, Renogy’s manual describes pairing it with a Renogy ONE Core, which links to DC Home over Wi-Fi. Renogy’s store also lists the shunt bundled with a Renogy ONE Core at $292.99. If you already run other Renogy Bluetooth gear, such as a DC-DC charger, it can show up in the same app.

Reading the App: What Each Number Means

• SOC (%): the shunt’s running count of charge left, relative to the rated Ah you entered.
• Current (A): positive while charging, negative while discharging. A small negative number with everything “off” reveals phantom loads.
• Remaining time: an estimate based on the present current. It jumps around when loads change, so treat it as a rough guide.
• Voltage: still useful for spotting a charger that isn’t reaching its absorption voltage.
• Temperature: from the included sensor; worth watching on LiFePO4 batteries in cold weather, since most shouldn’t be charged below freezing.
• History: charge cycles, deepest discharge and discharged capacity, per Renogy’s manual. Handy for seeing how hard you actually use the bank.

Renogy Shunt 300 vs Victron SmartShunt

	Renogy Battery Shunt 300	Victron SmartShunt 500A
Continuous current	300A (500A peak, under 10 s)	500A (300A, 1000A and 2000A versions also sold)
Current accuracy	±1%	±0.4%
Voltage range	8–120V	6.5–70V
App	Renogy DC Home	VictronConnect
Remote monitoring	Renogy ONE Core over Wi-Fi	Victron GX device + VRM
Second input	Starter battery voltage (B2), plus a dedicated temperature port with sensor included	One aux input: starter battery, midpoint or temperature (sensor sold separately)
Best fit	Renogy-based systems, budgets, 36–48V golf carts and boats	Victron ecosystems

The Renogy’s wider voltage range and included temperature sensor stand out. The Victron lists tighter current accuracy and fits better if the rest of your system is Victron. Our SmartShunt vs budget shunts comparison covers the trade-offs, and our shunt sizing guide explains when 300A is enough.

Is 300A enough? At 12V, 300A is roughly 3,600W. A 2,000W inverter at full load draws around 170–190A at 12V once you allow for losses, which fits. A 3,000W inverter at 12V can pull more than 300A, so it would need a larger shunt or a higher-voltage system.

FAQ

Does the Renogy Shunt 300 work with non-Renogy batteries?

Yes. Renogy lists support for lead-acid, LiFePO4, lithium-ion and NiMH batteries, from any brand, as long as the system is 8–120V and under 300A continuous.

Why is my SOC reading wrong?

Usually because the rated Ah is set incorrectly, the SOC hasn’t been synced after a full charge, or a load or charger is wired straight to battery negative instead of through the P- terminal.

Does it have a screen?

No. You read it on the DC Home app or a Renogy ONE monitor.

How much power does the shunt use?

Less than 0.1W, according to Renogy’s manual.

Can it monitor my starter battery?

It can show starter battery voltage through the optional B2 wire. It measures current only on the auxiliary battery bank.

What warranty does it have?

Renogy’s manual lists a 1-year warranty.

Bottom Line

The Renogy Battery Shunt 300 is a straightforward way to get a real fuel gauge for an RV, van or boat battery bank, especially a LiFePO4 bank where voltage is no help. It covers 8–120V systems up to 300A, includes a temperature sensor, and costs less than many alternatives at Renogy’s list price. Wire every load and charger through the P- terminal, set the rated Ah first, and sync after a full charge. Luis’s install and app walkthrough video is planned.