Powering the GPS ???

[David Rive]

This coming weekend I want to install a new Raymarine A128 MFD on my boat. The installation manual says not to connect it to batteries that are used to start the engines. So here is my problem - the boat has two Group 31 AGM batteries, one for each engine. There is no separate house bank, because the previous owner was always connected to shore power - he never anchored out. High on my to do list is the creation of a new house bank, but it just has not been done yet. So if I connect the new electronics through the panel to my 2 starting batteries, am I going to damage the Raymarine unit, as its instructions seem to suggest?

 

[mbevins]

This coming weekend I want to install a new Raymarine A128 MFD on my boat. The installation manual says not to connect it to batteries that are used to start the engines. So here is my problem - the boat has two Group 31 AGM batteries, one for each engine. There is no separate house bank, because the previous owner was always connected to shore power - he never anchored out. High on my to do list is the creation of a new house bank, but it just has not been done yet. So if I connect the new electronics through the panel to my 2 starting batteries, am I going to damage the Raymarine unit, as its instructions seem to suggest?

No your fine connect away.
However you should make a point of NOT starting that engine with the GPS turned on. Odds are you'd still be fine but better safe than sorry.

 

[winty]

I have a a78 on my start bank. The worst that has happened is sometimes it reboots on engine start. More often it presents an alert stating low battery or voltage, I forget which. I never read the manual.

 

[David Rive]

Thanks folks. I guess I need to stop reading manuals and worrying so much. LOL Cheers.

 

[Nomad Willy]

David,
If you anchor out why not install a start batt?
I just found out someone had wired our electric head to the start batt. Unlikely that we should run the start batt down flushing the head at night so I'll probably leave it that way. I'll measure the start batt voltage while turning on other things. A drop in voltage would indicate something else is wired to the start batt. The whole idea and a good one is to insure one has power availible in the morning to start the engine. I could spend a night in the marina using lots of power switched to house batts and see if the start batt is fully charged in the morning.

 

[David Rive]

Hi Eric,

I understand - my intent is to set up a separate start battery and create a new house bank. My boats current configuration only makes sense if one is always plugged into shore power.

David

 

[menzies]

Can you not just buy a single deep cycle battery for now and stick it somewhere where you can connect it to the charger/alternator and GPS?

For ~$100 you can then rest assured that your GPS will be OK.

 

[dimer2]

Every small fishing boat out there uses a start battery for their GPS's/fishfinders, as they have no alternative and appear to be fine.

 

[Heron]

No your fine connect away.
However you should make a point of NOT starting that engine with the GPS turned on.

This...No Power draw re-boot due to the voltage drop when starters engaged.
Easier on the electronics.

 

[bayview]

The maker said that because starting will drop the voltage below the reboot voltage of the GPS. All that will happen is a reboot so unless you are starting the engines in a critical location it wont matter. even a small motorcycle battery connected through an isolation diode will keep it up but I never bothered and over 15 years the occasional reboot didn't bother me.

 

[Codger2]

No your fine connect away.
However you should make a point of NOT starting that engine with the GPS turned on. Odds are you'd still be fine but better safe than sorry.

I completely agree! Especially with NOT starting the engines with the chart plotter turned on.

 

[jskinner30PII]

You will be fine.
The problem I have is when starting engine and or using my bow thruster is my Raymarine C80 unit reboots and I get an annoying alarm.

 

[ranger58sb]

This coming weekend I want to install a new Raymarine A128 MFD on my boat. The installation manual says not to connect it to batteries that are used to start the engines. So here is my problem - the boat has two Group 31 AGM batteries, one for each engine. There is no separate house bank, because the previous owner was always connected to shore power - he never anchored out. High on my to do list is the creation of a new house bank, but it just has not been done yet. So if I connect the new electronics through the panel to my 2 starting batteries, am I going to damage the Raymarine unit, as its instructions seem to suggest?

Perhaps each of your batteries supplies separate house functions, too?

We have two battery banks that each do triple duty: start, half the house, and bridge (one for electrics like nav lights and so forth), one for electronics. These batteries can be paralleled on demand in case of starting issues, and we also have a separate stand-alone genset battery. It's apparently quite a common set-up.

Rather than creating a separate house bank, I just added capacity to each bank. What started as 2x Group 29s (I think) each bank from the builder is now 3x Group 31s each.

Our plotter -- and all other electronics -- are connected to our starboard bank. We (mostly) remember to have all that stuff turned off when starting that engine. The few times I've forgotten, it's caused a reboot on the MFD and a low voltage alert on the A/P, so far nothing worse.

I might change that starboard bank to 4x golf cart batteries whenever necessary to replace the current G31s -- even more capacity, and enough cranking amps to start that engine.

-Chris