If you’ve got an engine battery, a house battery, and a trolling motor battery on your boat, you already know how hard it is to keep track of all three. One of them starts going dead all the time, and you’re stuck guessing which one it is and why. I got my hands on the NewWire.com DEEX7 voltage meter to solve exactly this problem, and I wanted to show you what it can actually do once it’s wired into your electrical system.
Why It Matters
When you’ve got three or four batteries running different systems on your boat, a dead battery can sneak up on you. Without a way to monitor voltage and amp draw in real time, you’re troubleshooting blind — pulling connections, checking each battery individually, and hoping you find the problem before you’re stranded. A single display that reads all your batteries at once takes the guesswork out of it, especially if you’re dealing with a parasitic draw that’s slowly killing a battery while the boat sits.
Products
- NewWire.com DEEX7 – 7-in-1 compact voltage meter/display that monitors DC and AC voltage, current, and up to four flex inputs (battery voltage, bilge monitor, or hour meter); fits a standard 2-1/16″ dash cutout.
- Shunt tool – Included in the kit; installs inline with your ground to measure amp draw across your house battery system.
Step-by-Step Guide
Unbox and Set Up the Display
The DEEX7 uses Deutsch connectors on the back, so you just plug in whatever you want the display to monitor. I set up a test rig on a piece of siding just to demonstrate the wiring before it goes into a dash.
Wire Power and Ground
Power goes to the red wire, negative/ground goes to the yellow wire. That’s what gives the gauge power. The bottom two inputs are flex connections you can wire to whatever you want to monitor — batteries, float switches, other components.
Connect Your Batteries
I hooked up three batteries and the display immediately showed me the voltage on each: 13.3, 26.2 (trolling motor battery bank), and 14.3. This is the core function — a real-time glance at every battery on the boat instead of checking each one individually.
Install the Shunt for Amp Draw
To read amp draw, not just voltage, you need the shunt tool. It installs between your house battery’s ground and all the grounds in the boat — one side positive, one side negative. This lets the DEEX7 measure how many amps are being pulled across that shunt, which tells you your actual current draw.
Configure the Input in the Menu
Go to Menu > Setup > select the input number (I used input five for the shunt). Set it active, name it, set the alarm and output ratio — I used 150 amp by 50 mV since that matched my shunt. Once configured, running the bilge pump showed a real draw: about 9 amps.
Set Up Bilge Pump Cycle Monitoring
For a separate input (I used input four), you can wire in a float switch and bilge pump to track how many times the pump has cycled. In the menu, set that input’s type to “bilge monitor,” name it, and set your alarm cycle count. Every time the pump kicks on, the counter increments — I tested it and watched it go from 0 to 3 cycles as I triggered the pump repeatedly.
Read Voltage Drop Under Load
As a component draws power, you’ll see the voltage on that battery dip in real time — mine dropped from 14.3 to 14.1-14.2 while pulling 9 amps on the bilge pump. That’s useful for catching a battery or alternator problem: if voltage reads low (say 11.9) and you start your engine and it doesn’t climb, your engine isn’t charging.
Pro Tips
- Use the shunt for real parasitic draw testing. With everything on the boat turned off, if you’re still seeing amp draw on the shunt reading, you’ve found a parasitic drain worth chasing down.
- Wire the bilge cycle input straight to the battery, not through the shunt, if you want it to keep counting cycles even when the rest of the system isn’t actively monitoring amp draw. It needs constant power to log cycles.
- Do the math on your amp-hour rating. If your battery is rated at 120 amp hours and you know your draw rate from the shunt, you can actually calculate how many hours of runtime you have left at that draw.
Final Verdict
I think this is genuinely useful, especially if you’re running three or four batteries on one boat. It’s not complicated to wire — Deutsch connectors, plug and play for the most part — and the amount of data you get for the price is hard to beat. If I had four batteries in a boat, I’d wire all four into this and just watch the screen instead of guessing which one is going bad. The one thing I couldn’t confirm is what kind of standby power draw the display itself pulls when it’s just sitting there monitoring, since it doesn’t have stored memory like a computer.
FAQ
Do I need the shunt tool to use the DEEX7?
No — the shunt is only needed if you want amp draw data. If you just want to monitor voltage on multiple batteries, you can wire batteries directly into the flex inputs without the shunt.
Can this tell me if I have a parasitic battery drain?
Yes. With everything on the boat switched off and the shunt installed on your house battery ground, any amperage still showing on the display is power being pulled from somewhere it shouldn’t be.
Will this fit in my existing dash?
It’s built for a standard 2-1/16″ cutout, so in most boats you can pull your old voltage gauge and drop this in without modifying the dash.
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