GPS Not Getting Enough Power?

[nickfox45]

I recently bought a used Garmin 441s, but I suspect it's not getting enough power to work properly. When I hook it up and power it on, the Garmin startup screen appears for about 5 seconds before the device shuts off.

A few more details/troubleshooting I've already done:
- I got the unit to work at home connected directly to a spare battery, so I know it's not the unit itself.
- The power source is a new marine deep cycle battery, so I don't think that's the issue either.
- The wires I'm using on board were existing, and I've trimmed them as much as I can to shorten the run. A multimeter readout on these wires says 11.3 volts. Garmin's support page says the device should work at 10+ volts, but does recommend getting closer to 12 for best performance.

Is it possible my single battery just doesn't have enough juice to power this thing? Is there anything else I should try? I feel like I've done all I can do at this point, but I'm far from an electrician.

[TheOffice]

Measure the voltage at the battery. Sounds like a corroded wire/connection along the way.

[rwidman]

Originally Posted by nickfox45

I recently bought a used Garmin 441s, but I suspect it's not getting enough power to work properly. When I hook it up and power it on, the Garmin startup screen appears for about 5 seconds before the device shuts off.

A few more details/troubleshooting I've already done:
- I got the unit to work at home connected directly to a spare battery, so I know it's not the unit itself.
- The power source is a new marine deep cycle battery, so I don't think that's the issue either.
- The wires I'm using on board were existing, and I've trimmed them as much as I can to shorten the run. A multimeter readout on these wires says 11.3 volts. Garmin's support page says the device should work at 10+ volts, but does recommend getting closer to 12 for best performance.

Is it possible my single battery just doesn't have enough juice to power this thing? Is there anything else I should try? I feel like I've done all I can do at this point, but I'm far from an electrician.

Measure the voltage at the battery with the GPS powered on. The GPS shouldn't draw enough power to affect the voltage of a good, charged battery. Look at the fuse. It's probably 5 or 7.5 amp and that's far more than the GPS actually draws.

If the battery is OK, rewire the GPS and use new wires and do it correctly, on its own circuit.

[nickfox45]

Originally Posted by rwidman

Measure the voltage at the battery with the GPS powered on. The GPS shouldn't draw enough power to affect the voltage of a good, charged battery. Look at the fuse. It's probably 5 or 7.5 amp and that's far more than the GPS actually draws.

If the battery is OK, rewire the GPS and use new wires and do it correctly, on its own circuit.

From what I recall, the voltage at the battery was something like 12.3 volts. What fuse should I be looking at? The GPS has a built-in fuse, which is 3 amps. Or do you mean the fuses behind the panel? I haven't ventured in there yet.

[Sailmonkey]

If you've got a volt of drop on your wire with no load, your wire is shot. Also, your battery is nowhere near fully charged.

I think you've got a lot of things to fix before worrying about the gps.


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[rwidman]

Originally Posted by nickfox45

From what I recall, the voltage at the battery was something like 12.3 volts. What fuse should I be looking at? The GPS has a built-in fuse, which is 3 amps. Or do you mean the fuses behind the panel? I haven't ventured in there yet.

If the GPS has its own inline fuse you don't need another, you can connect it to a positive buss bar or to an unused circuit. The negative wire is just as important so connect it to a negative buss bar.

Measuring the battery voltage with no load doesn't really say much. Turn on some lights or other loads and measure the voltage across the battery terminals. You should have about 12.6 volts. You say it's a new battery but has it been charged?

[nickfox45]

Originally Posted by rwidman

If the GPS has its own inline fuse you don't need another, you can connect it to a positive buss bar or to an unused circuit. The negative wire is just as important so connect it to a negative buss bar.

Measuring the battery voltage with no load doesn't really say much. Turn on some lights or other loads and measure the voltage across the battery terminals. You should have about 12.6 volts. You say it's a new battery but has it been charged?

Thanks, I'll give this load test a try, and hook up my battery charger this weekend and make sure that battery is topped up.

[W3GAC]

If you're going to be maintaining troubleshooting your boat yourself, I believe it's important to have the right test/ diagnostic equipment. Since electrical issues represent a significant percentage of issues that come up, can shutdown everything else... including starting your engine... I believe it's very important to have a very good understanding of your boat's wiring, a good understanding of low and especially very high circuit current troubleshooting techniques... and the two critical test instruments to make your testing, troubleshooting, preventative maintenance straight forward/ easy. That said, I always recommend every cruiser/ boat should have a VOM AND a Battery Load Test Meter.

Most hopefully know about a VOM and how to use it but I am amazed how few boaters have a battery load meter onboard... and USE IT. A battery load meter is a very simple device consisting of, in its simplest form, a volt meter and a switchable on/off internal 100a resistive load. This device is worth it's weight in gold in troubleshooting boat electrical/ possible battery/ terminal corrosion issues, alternator or electric charger issues. (A suitable battery load tester is available from Harbor Frieght Tools for about $49 but goes on sale for considerably less.). Almost every electrical problem starts out (as this original post does) with first determining if is it the battery, the battery terminal connection, or something in the branch circuit wiring, or the end device. To get the first four options out of the way... you simply clamp the black/ red battery load meter alligator clips directly on your battery and read your 'no load' voltage... then briefly turn on the charger (see if you see a bump up on voltage), then switch the 100a load on (kinda a toaster like heating element) that puts a BIG load on the battery... about the same as a starter would. If there is a big drop in voltage on its big easy to read meter you have a weak battery or bad terminal corrosion. By moving one clip at a time directly to its battery post you can even determine which (or both) terminal is causing the trouble. If the boat is in the water you can check your alternator by starting the engine and checking that you indeed have a increase in battery voltage indicating that the alternator is supplying sufficient changing voltage.

Even with daily monitoring/ awareness of battery in/ out of Amp hour drain/ charging, I still perform a monthly individual battery load test of my seven batteries to ensure that one or more batteries (some are in parallel) are not quietly developing a corrosion/ end of life issue. Sure you could watch your VOM while someone cranks your starter... or cranks up your inverter/ microwave for a load on inverter batteries, but as in recent examples, the boat was on the hard. And you need two people and you still can't test down to individual batteries w/o a lot of extra effort. I consider a battery load meter right up there with having spare engine oil on a cruising trip.


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