Garmin GPSMAP 441 cuts off whenever I start the engine.

rpengr · **Posted:** Mon Jul 21, 2014 9:11 am

My Garmin GPSMAP 441 seems very sensitive to the voltage drop when starting the engine. It is wired to the fuse block and does not require the key to be turned on, however, every time I crank engine the GPS turns off. Has done this since I had the boat. No other signs of bad/loose wiring or excess voltage drop. Happens with either starting battery.

I would think that a capacitor wired into the GPS power/ground wires would prevent this. Has anyone done this or could anyone suggest what size capacitor? Might need a diode also so that the capacitor is not feeding all accessories on the fuse block?

LouC · **Posted:** Mon Jul 21, 2014 9:33 am

I have a 441s and it does the same thing.
I usually start the engine first then turn on the Garmin. I don't recall the Humminbird I had before having this issue.

rpengr · **Posted:** Mon Jul 21, 2014 9:43 am

LouC wrote:

I have a 441s and it does the same thing.
I usually start the engine first then turn on the Garmin. I don't recall the Humminbird I had before having this issue.

I'm glad to hear it is not just mine, but I would like to figure out a solution. It is a nuisance when using it as a speedometer for tow sports, and constantly turning the engine on and off.

Thalasso · **Joined:** Tue Jan 18, 2011 8:45 pm **Posts:** 333

rpengr wrote:

LouC wrote:

I have a 441s and it does the same thing.
I usually start the engine first then turn on the Garmin. I don't recall the Humminbird I had before having this issue.

I'm glad to hear it is not just mine, but I would like to figure out a solution. It is a nuisance when using it as a speedometer for tow sports, and constantly turning the engine on and off.

Try wiring the Garmin to a battery that isn't being used by the starter.
My advice would be to have a battery for your engine only, then use a split charger relay to charge your house battery only when the engine is running.
This solves almost all of your problems, it gives extra capacitance to help stop erroneous signals making it back to your electronics, it supplies only clean grounds and feeds to your electronics as the charger relay will only operate when the charger is in charge mode (not turning over and not firing) as the engine needs to be running at idle or above.
Hope this helps.

rpengr · **Posted:** Mon Jul 21, 2014 10:20 am

Thalasso wrote:

rpengr wrote:

LouC wrote:

I have a 441s and it does the same thing.
I usually start the engine first then turn on the Garmin. I don't recall the Humminbird I had before having this issue.

I'm glad to hear it is not just mine, but I would like to figure out a solution. It is a nuisance when using it as a speedometer for tow sports, and constantly turning the engine on and off.

Try wiring the Garmin to a battery that isn't being used by the starter.
My advice would be to have a battery for your engine only, then use a split charger relay to charge your house battery only when the engine is running.
This solves almost all of your problems, it gives extra capacitance to help stop erroneous signals making it back to your electronics, it supplies only clean grounds and feeds to your electronics as the charger relay will only operate when the charger is in charge mode (not turning over and not firing) as the engine needs to be running at idle or above.
Hope this helps.

That sounds like a good solution, but being a Horizon, I do not have a house battery.

ric · **Posted:** Mon Jul 21, 2014 10:33 am

Check the settings, I had a 441 on my H180. I remember there being a starting feature

kd4pbs · **Joined:** Thu Sep 05, 2013 10:34 am **Posts:** 350

If you wire in a capacitor across the chartplotter power, be sure to put a diode in-line to prevent any issues. Go with a decent Schottky rated high enough to carry the maximum current of your chartplotter so that the voltage drop isn't so bad as compared to a silicon diode.
Maybe instead of a capacitor, you could use a small gel-cell which would also of course power the chartplotter in an emergency situation where you lose battery power? If so, I'd hook up the VHF radio here as well.

rpengr · **Posted:** Mon Jul 21, 2014 12:19 pm

kd4pbs wrote:

If you wire in a capacitor across the chartplotter power, be sure to put a diode in-line to prevent any issues. Go with a decent Schottky rated high enough to carry the maximum current of your chartplotter so that the voltage drop isn't so bad as compared to a silicon diode.
Maybe instead of a capacitor, you could use a small gel-cell which would also of course power the chartplotter in an emergency situation where you lose battery power? If so, I'd hook up the VHF radio here as well.

That looks like the way to go. It looks like it would take a $125 capacitor to run the GPS for only 2-3 seconds. It's rated draw is 15 watts = 1.25 amp x 12V. It would take a 0.66 Farad capacitor to achieve a voltage drop of 2v/sec.

What do you think of a small gel-cell powering the entire console fuse block. I would connect the gel cell to the main battery through a 35amp Schottky diode (such as this one for $14 http://www.newark.com/genesic-semiconductor/1n5831/schottky-rectifier-35v-25a-do/dp/06W4304?MER=PPSO_N_P_EverywhereElse_None)
Would I also need a 35 amp fuse?

kd4pbs · **Joined:** Thu Sep 05, 2013 10:34 am **Posts:** 350

Sounds like a great idea to me. Yes, you'll want to fuse the supply at whatever amperage capacity the wiring is rated for. My guess is that there's already an over-current protection device somewhere in the power feed from the battery to the fuse block though, so just leave that one be, and add a fuse or breaker as close to the add-on battery's positive lead as possible. One could rig up the whole system including a decent sized gel cell (think somewhere in the 15Ah range) for less than a large capacitor.
One thing though; I would leave this as separate from the engine system's power distribution as possible. Treat it as a totally separate power source, and don't run any engine-critical loads from this supply (ignition, fuel pumps, etc.) Also realize that the gel cell won't ever reach full capacity due to the forward-biased voltage drop of the diode. If you can keep it around 1/2 volt or so, I wouldn't worry too much about it though, and that diode fits the bill close enough.

ric · **Posted:** Mon Jul 21, 2014 4:05 pm

Without isolation this won't work. Maybe it's in your plan didn't read. On phone.

kd4pbs · **Joined:** Thu Sep 05, 2013 10:34 am **Posts:** 350

Ric is right. I guess we didn't think about that. You'd need to add some sort of "isolator" -- I think they call them a "diode" or something like that. Not sure though. Who knows how to hook that up though? I mean, you'd need a high current isolator, and probably a large heatsink for that isolator, and all that kind of stuff. Probably some wire too. :mrgreen:

rpengr · **Posted:** Tue Jul 22, 2014 11:37 am

ric wrote:

Without isolation this won't work. Maybe it's in your plan didn't read. On phone.

Well, it would be isolated by the Diode. That would prevent the little battery from ever backfeeding to the engine or starter or bilge pumps, etc. And it would only feed it's accessories when it's voltage is greater than the main system.

I think I should just power the GPS and radios from this battery, and maybe a few lights.

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Garmin GPSMAP 441 cuts off whenever I start the engine.

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