Backup Battery Power in Pilothouse

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Arthurc

Arthurc

Guru
Joined
Sep 24, 2016
Messages
752
Location
USA
Vessel Name
Sea Bear
Vessel Make
Kadey-Krogen 54
When I bought my boat the PO had put a battery in the pilothouse which I think ran the radio. I pulled it out as it was an odd setup but now that Ive completely redone the electronics I am starting to think about it again, specifically what are the critical systems if you have a complete power failure at sea, for instance in the event of a fire.

The setup I am thinking about is a single large 12v battery in the pilot house hooked up to charge from the main system.

That battery would then power the following:
NMEA2000 Network
Furuno GP33 GPS (through N2K)
Icom M506 w/ DSC (GPS through N2K)
Icom M806 w/ DSC (SSB) (GPS through 0183 from GP33)

Has anyone else done something like this and if so what were the critical systems you put on the secondary power source?

Thanks
AC
 
Arthurc said:
When I bought my boat the PO had put a battery in the pilothouse which I think ran the radio. I pulled it out as it was an odd setup but now that Ive completely redone the electronics I am starting to think about it again, specifically what are the critical systems if you have a complete power failure at sea, for instance in the event of a fire.

The setup I am thinking about is a single large 12v battery in the pilot house hooked up to charge from the main system.

That battery would then power the following:
NMEA2000 Network
Furuno GP33 GPS (through N2K)
Icom M506 w/ DSC (GPS through N2K)
Icom M806 w/ DSC (SSB) (GPS through 0183 from GP33)

Has anyone else done something like this and if so what were the critical systems you put on the secondary power source?

Thanks
AC
Click to expand...

AC

A dedicated 12v system for instruments is not uncommon. My instrument guy says space availability for a battery is a plus and overly complicated initial setups seems the determining factors.

After your rewiring efforts you may be fine, but try it without first especially when operating other onboard systems such as microwaves, toasters, hair dryers etc that may cause voltage surges.

Battery backup in industrial applications is not uncommon either.
 
Thanks, I also think that a separate battery system could eliminate some of the noise in my power which I think is affecting the performance of my M802.
AC
 
There are lots of things that might happen at sea and a total power failure is only one and probably pretty rare.

The real problem with your proposed setup is keeping the backup or electronics battery charged. Remember, power can flow both ways in a pair of wires so if you just connect your emergency battery to the other batteries, when they fail, power will flow from your emergency battery to the failed batteries and this will drain your emergency battery.

A simple diode would seem to be the solution because it would allow charging current but block current from your emergency battery from flowing "backwards" to the other batteries. The problem with this solution is, there would be a voltage drop across the diode and the emergency battery would never fully charge.

A "battery combiner" or "automatic charging relay" would probably solve the problem.

Again though, what you are thinking about is pretty rare so unless you have some special circumstances, I wouldn't be overly concerned about it.

Also, if you connect the batteries for charging purposes, they are no longer separate and any noise in the system will be transferred to your new battery. A better plan is to find and eliminate the electrical noise.
 
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I thought about getting one of those "jump start" portable batteries. Some of them have USB charging ports and cigarette-lighter plugs. Assuming you have a cigarette lighter outlet on the helm somewhere, it might be possible to just plug it in if the rest of the electrical system is lost, such as dead batteries or even a fire in the ER or in some of the wiring in between.

Plus, it could be used for a jump start of your own boat, or even a car shoreside.

One problem with old boats is that the electrical system usually "evolves' a lot over time. Things are added to existing circuits until a new circuit needs to be run, so there may be several circuits that feed critical equipment, and that equipment may share a circuit with other, less critical things.
 
I think a good installation, regular checks, and regular maintenance of a central main battery bank would have a very, VERY low probability of failure.

I wouldn't think the solution is to add more connections, batteries, and failure points to a vessel.

But I might not be seeing your whole picture.
 
All valid points, I have gone through the electrical system and its pretty much what you would expect out of a 30 year old boat. That said battery bank is new, charger and alternator/inverter are all high end and pretty new. Good isolation between starter batteries for Engine, Genset, House and Stern Thruster.

I just worry that all those systems are below sea level, in other words in a situation where water starts entering the boat they are in danger of failure, feels like some system to still operate the radios is a plus. Not to mention if I can isolate the noise for the M802 thats likely a heck of a lot less work than figuring out where its coming from after 30 years of upgrades, enhancements and creative solutions by the PO :)

The other easy option is a 12V battery on a selector switch to power the above electronics and simply charged by a battery tended connected to 120v.

AC
 
The need for emergency power, separate from the engine starting battery and the house battery system would be a very rare event. Something would have to fail like a sulfate shorted battery taking down the other house batteries. Even in that case you just start your propulsion engine, switch the house systems over to the start battery and keep going.

Or your propulsion engine's alternator can fail, but then that should immediately trigger a warning light and power adjustments can be made to keep going.

We can postulate all sorts of scenarios, but it will be extremely rare if it disables your boat, navigation or communications for long.

FWIW offshore sailboat racing rules do require an entirely separate battery system, nav lights, and nav radio, but because it applies to sailboats there is nothing about an emergency engine starting battery.

David
 
Depending on how isolated your cruising area is.....keeping a charged handheld, with the ability to plug it into your main antennae might be a much simpler goal, that would provide emergency comms if your batteries were underwater. It wouldn't give you all the capability of the system you describe, but it is uncomplicated enough to be reliable and easy to set up.
 
Large commercial fishing vessels (>20m) in Canada are required to have an emergency battery supplying power to a vhf , GPS and wheelhouse light. Can't remember if one of the SSB's was also required to be connected. I had a 4d battery for this purpose. For emergency lights we had to have kerosene lamps with colored lenses (or clear for white light). I'm sure there were other alternatives for portable emergency nav lights too.
 
wow....I can't imagine trying to ( or wanting to!!) light a kerosene lamp when the **** is hitting the fan !!! I don't even like lighting candles in my house !!
 
Passed along to me, but I used to tend to quite a few backup systems on commercial fishing boats when working for a marine electronics firm....even put one on my sportfish to eliminate flybridge voltage drop on engine starts....

"All inspected towing vessels, and GMDSS equipped vessels are required to have a battery backup system.

https://www.law.cornell.edu/cfr/text/46/143.555

https://www.navcen.uscg.gov/?pageName=gmdssReservePower

This does not apply to recreational vessels, it is not required for (smaller recreational) boats but it shows that such systems are far from rare or exotic. The systems are simple and effective and easily fitted to a recreational trawler if that makes the owner feel better. "
 
Arthurc said:
Has anyone else done something like this and if so what were the critical systems you put on the secondary power source?
AC
Click to expand...

I have a separate above deck battery bank for the HF SSB & Vhf radios only.

The cranking batteries are also separate, and while I don't see other assorted electronics as necessarily "critical" I do have extra hand held units.

My boat was once in commercial survey, so the above deck batteries were mandated, along with high capacity firefighting pumps and bilge pump manifolds.

While I mightn't install any of this stuff myself, it certainly doesn't hurt to have them.
 
My boat has an 8d in the pilot house that runs a few emergency lights, radios, nav appliances and can be used to power the bilge pumps. There's a relay that turns on the emergency lights with a power failure. The boat used to carry eco-tourists in 5 double cabins along the NW inland passage and emergency lighting was required.
 
Some times the PH battery is to keep the electronic items from dropping out from low voltage during engine start.
 
FF said:
Some times the PH battery is to keep the electronic items from dropping out from low voltage during engine start.
Click to expand...

Powering the electronics from the house bank eliminates that problem but if the boat doesn't have a house bank, that is one solution.

Of course, the additional battery pretty much becomes a "house bank".
 
Like EAGLE419 said , I didn't install the equipment but it is nice to have.
Our bridge helm has a separate 12V battery that powers the bridge electronics. The battery has its own 20amp charger that is powered by an inverter. The inverter is supplied with power from the engine batteries. The bridge 12v system has a separate volt meter and battery monitor.
The reasoning here is that if the boat is going down you would still have communications until the bridge was awash.
 
aboatman said:
Powering the electronics from the house bank eliminates that problem QUOTE]

I can tell you first hand that the house bank does not necessarily eliminate voltage surges that instruments may see. That is why I suggested to AC to run all his 110 appliances with instruments and inverter on and no shore power to insure no issues.

Each vessel's wiring setup, grounding system, inverter, battery and instrument layout is different. That is the purpose of the instrument only battery, to isolate the instruments from the sporadic other loads, voltage or frequency spikes that may (or may not) weasel their way through.
Click to expand...
 
Adding a separate battery for critical electronics is not a bad idea.

From your house battery bank run a ACR to the “nav battery”.

This setup does present risks though. Big risk is that you then have a single point of failure in your “nav battery”. It also presents a risk when on the hook as nav loads represent a significant power drain even at anchor. This would require sizing the nav battery accordingly, and it would have replacement lifecycle to consider as well.

What we do is to provide separate circuits to our crtical nav equipment (which is 100% redundant). These come from a dedicated house battery that we monitor all the time, and have more than one charging source for.

We also have the house circuits on a switch that can choose between the house battery and one of the dedicated engine batteries, providing throw of the switch redundancy.

We do have a risk of fire or flooding though as all the batteries are in the same general vicinty in the lazarette.

In the case of fire we protect using an auto fire system, with networked smoke detectors.

In the case of flooding we have a high bilge water alarm and a real 60 gpm dewatering pump (not some 12V unit that claims high volumes and does not deliver in real life).

The key to mitigating flooding and fire in my opinion is early detection.

I have carefully considered a dedicated nav battery (or in our case two of them) and have not seen a convincing case that with our setup that we have any real gains in system reliability to be realized.

We boat in one of the remotest areas of North America, and because of this I am a huge fan of redundancy. People in our situation should carefully plan their systems taking into account and mitigating single points of failure.

Do you have fully redundant navigation systems?
Redundant propulsion?
Redundant dewatering?
Redundancy against inverter failure?
Redundant battery charging?

Look at your boat and imagine if a particular piece of equipment was to malfunction. Would you be safe to continue your voyage? Woud you be so inconvinced that you need to cut your trip short?

Those are the things that people that boat in remote areas need to think about. It’s not just life health safety. It’s ruining a long planned trip because a piece of gear malfunctions.
 
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sunchaser said:
aboatman said:
Powering the electronics from the house bank eliminates that problem QUOTE]

I can tell you first hand that the house bank does not necessarily eliminate voltage surges that instruments may see. That is why I suggested to AC to run all his 110 appliances with instruments and inverter on and no shore power to insure no issues.

Each vessel's wiring setup, grounding system, inverter, battery and instrument layout is different. That is the purpose of the instrument only battery, to isolate the instruments from the sporadic other loads, voltage or frequency spikes that may (or may not) weasel their way through.
Click to expand...

Then that is a poor installation. Wiring to the loads is likely undersized. A good sized house bank is essentially a BFC (Big F*&#ing Capacitor). If the wiring is of adequate size, you can do no better than to use the house bank for smoothing the voltage droops.

RF riding on top of that is an entirely different matter, and requires other solutions.
Click to expand...
 
boathealer said:
sunchaser said:
RF riding on top of that is an entirely different matter, and requires other solutions.
Click to expand...

Then throw in a microwave oven, induction cooktop and MSW inverter. Not to mention marine age and klutz fingered marine electricians. Few of us with boats live in a perfect marine electrical world.

So not to miss my point though, AC will hopefully find out real quick if he needs the PO's installed setup. That pilothouse battery may have been placed there for a reason only known to him and said issues altered or removed with AC's new re-wire and equipment.
Click to expand...
 
When starting, or restarting, engines it is not unusual for electronics to reboot because of low voltage. Having a battery and isolation diode for them eliminates that problem.
 
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boathealer said:
sunchaser said:
Then that is a poor installation. Wiring to the loads is likely undersized. A good sized house bank is essentially a BFC (Big F*&#ing Capacitor). If the wiring is of adequate size, you can do no better than to use the house bank for smoothing the voltage droops.

RF riding on top of that is an entirely different matter, and requires other solutions.
Click to expand...

I did not post what you quoted, only the first paragraph so I'm not sure what you are trying to say.
Click to expand...
 
FF said:
Some times the PH battery is to keep the electronic items from dropping out from low voltage during engine start.
Click to expand...

I experienced drop outs during engine starts so after a bit of research, installed a Newmar DC UPS Nav-Pac which in addition to a UPS, provides clean, spike free, noise free power to navigation equipment. It won't power the equipment for long, but perhaps long enough to get alternate power online. I'm completely satisfied with the results.

Nav_Pac.jpg
 
For a toy boat? Covering for a two-second start on one's engine?
 
I join those with a separate battery at the helm. This battery powers my vhf radio and my ssb radio. It has a separate tiny charger that charges whenever on shore power or the generator is running. Everything else in the boat, including engine starting is powered by a large house bank.

The thought was that I should have a battery separate from the house bank in the event the house bank goes dead. The helm battery serves that purpose. The helm battery also avoids noise on my ssb radio. Further since the helm battery powers the radios and is six feet higher than the house bank it would provide radio communication for a longer period of time if we were taking on water.

The helm battery, being a size 24 12 volt battery, is portable and over the years has been used several times to start dead engines/generators on other boats. Have picked up a number of bottles of wine / six packs from that.
 
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