Power Bank on Garmin 3790T (electrical issue)

Welcome to the site, Gerald VG.

Can you describe the power bank? It is a term those of us in the U.S. are not aware of. If it has a switching power supply to change from one voltage to another, that could be the source of the noise in the windscreen mount with its speaker.

A switching power supply may not put out clean DC similar to a 12 volt battery. It may have a square wave output that generates electrical noise.

dobs108

Hi.Portable Charger.External Battery Pack you can use to charge up your mobile phone
Also found this online

Garmin Nuvi uses the cable to determine which mode, navigate or data, the GPS should be operating in.
Using a standard USB data cable to power a Garmin Nuvi will cause it to go into data mode for
transferring maps, route/track data, pictures etc.
The Garmin factory power cable is used to enable navigation mode. However, the Garmin power cable is
unsatisfactory for powersports applications as it is not weatherproof, is way too long and is only supplied
with a cigarette lighter-type of plug.
The 3BR Powersports Red Band GPS power cable looks like a standard USB power cable with a USB
Type A plug on the source end but it has internal circuitry to make it appear to the GPS as a Garmin
power cable. The USB Type A plug allows powering the GPS from any generic USB port and allows use
of 3BR Powersports patented TAPP CAPP cables for full all-weather protection.

If the Garmin factory power cable is plugged in to a cigarette lighter outlet in an auto, does the hissing noise stop? Then the source of the noise is the power bank.

dobs108

Yes it works fine with Garmins own power cable .ALL
i was trying to do was to see if the power bank would run the sat nav as an experiment .I will have to do a bit more research to see if i can get the power bank to power sat nav

The powered mount on the windscreen usually operates at 12 volts. I assume the small USB port on the satnav itself operates at 5 volts. The power bank is usually connected to a phone with a USB cable, so the power bank puts out 5 volts.

That's why it doesn't work, because the power bank is supplying 5 volts to the mount when it needs 12 volts!

dobs108

Thanks for that will have a look tomorrow. Hope you are well over there.
Gerald VG

We are well and isolated but we are at the epicenter of the pandemic: New York state, Nassau County, Long Island. The projected peak is now. Even in Ireland you should be able to see our governor, Andrew Cuomo, on television, clearly explaining what is to be done.

Can any POI Factory members confirm how the powered mount works? Does the traffic receiver cable supply 12 volts or 5 volts to the powered mount?

dobs108

If it goes through a USB connection, it's 5VDC.

So the small USB at the end of the traffic receiver cable is supplying 5 volts?

dobs108

Yes, that's correct.

phranc says the voltage is correct at 5 volts. That is what the power bank is supplying. That means the noise must be coming from the power bank.

dobs108