GPS shuts down when starting engine

[NickNap]

My Garmin 128 shut down each time I started the engine last weekend. Don't think it's happened before (but can't swear to it).
Is there a gizmo I should fit to prevent this, or am I a bit low on volts? (Battery had been recharged the day before though)

 

[duncan]

indicative of a poor conection in the circuit somewhere - engine drawing current is reducing the voltage to the gps below it's acceptable level

or

your battery is struggling to deliver the cranking and maintain the volts

mine started this on Friday...........Sunday morning the battery switch failed completely when I went to start! Fortunately I have a back up plan that coped............

 

[Poignard]

I had that problem and replacing my very old battery with a new one cured it.

 

[philip_stevens]

fit a small 12v battery (as in intruder alarms - lead/acid or gel batteries) in parallel, between the main battery and the GPS. The positive feed should have a Schottky (3 to 5 amp) diode inline to prevent the small battery back-feeding the main battery.

When you next start the engine, the small battery will continue to supply the GPS with no voltage drop.

I had the same problem on my previous boat until I fitted the small battery and diode.

 

[hlb]

Why worry about it. Mine closes down sometimes on restarting. Just start it up again and carry on.

 

[guernseyman]

If it worries you deeply, connect your GPS to the same battery as your VHF, if that is different to your starting battery. Otherwise, don't power up your GPS till your engine is started, like the rest of us.

 

[ShipsWoofy]

not unusual, my Garmin also shuts down, but my Raymarine plotter on the same circuit does not!

Garmins seem very sensitive to any spikes etc during engine start, the same as the car stereo going silent during start up, that is normal isn't it?

 

[cliff]

I don't know your setup but I have two battery banks, one for engine start and one for leisure use - all leisure items are connected to the leisure bank so when starting I set the selector to bank 1 (engine start) and away I go - no volt drop across the Leisure bank (bank 2) so no problem with gps shutting down (connected to bank 2)
--------------------

"Artificial intelligence is no match for natural stupidity"

 

[savageseadog]

Sometimes it's not just a pure voltage drop that causes the problems, a starter motor has large inductance which means there is spiking as well. I would suggest a diode in series with your electronics supply and a largish electrolytic capacitor anything from say 1000 to 10,000 uF across the supply after the diode. Remember that the capacitor has to have correct polarity. If you want belt and braces put a ferrite ring round both legs of the supply as well. The inductance in the supply leads will filter spikes and interference out.

 

[Guest]

This is common where the engine cranking pulls the voltage down enough for GPS to effectively turn off.

There are various small circuit additions you can fit to augment the power supply while cranking - but best - which is what I did to stop it (and I had good batterys depsite what others have posted ....) was to have supply to nav equipment dedicated to domestic battery and only use engine batt for starting.

Later when I stopped using the Magellan and used the eTrex and later the Lowrance 3500 ... the problem never appeared again and I can start with either battery and not lose GPS. It seems they are more tolerant of the volt drop on starting.

My suggestion is to lead a direct feed from domestic battery via fuse / switch to GPS ...

 

[duncan]

funnily enough my Garmin 225 suffered badly but last weekend it was fine but the L3500 went out every time.

As we were drift fishing banks, and because of the way it records tracks, this was a right pain!

These things are sent to try us............

 

[Guest]

I have considered ...

As another above with the Sealed Lead Acid Alarm 12v battery.... but separate not with diode etc.
I am thinking so as to have a dedicated power supply independent of engine / domestics etc. - and of course that style cannot be charged via normal alternator or car charger ... so would have own 240v stepdown charger suited.

This way VHF and GPS can be independent ........

You could always if necessary insert an inverter etc. into system to top it up when engine running if shore power not available etc.

 

[duncan]

Re: I have considered ...

all these points are excellent but I have a really simple system that doesn't involve shorepower let alone chargers etc!

in my last post I was simply highlighting that my 3500 was kicking out when my Garmin (and in fact my L LCX-15MT) wasn't - in response to your post suggesting the new units were less sensitive.........

 

[Guest]

No prob Duncan ...

Like most things everyone experiences different - "0thers" tend to forget that !!

I mentioned the 12v alarm battery solution - as it has crossed my mind to do ... would be simple and is effective.

 

[dalex]

I take it your set-up has not always done this? If this is the case, it could be an early warning of something going towards a disconnection.

When I first took delivery of my set up, I had to power up the radar before the GPS, or the GPS would not come up. Powering the GPS followed by the radar, the GPS turned off. Traced this to some duff wiring, and a corroded terminal.

Try connecting a digital volt meter to the cranking battery when turning over the engine. Compare this reading to another, taken at the GPS, when cranking (GPS turned on, of course).
Unless something is very wrong, these should be within 1/2 a volt of each other. Anything more, points to a problem between the distribution panel and the GPS.

 

[NickNap]

Brilliant. Thanks guys - loads to go on now.