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21-09-2024, 00:26
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#1
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Moderator
Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 34,989
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Blackouts and Backup Comms/Nav Power
All the thinking about emergency disconnects in other threads makes me think about blackouts. I've never (knock on wood) had a blackout on a boat in decades of cruising. That was all with lead batteries without any BMS nor any disconnects. Why should LFP power systems be any more prone to blackouts? If well design, they shouldn't, right?
Still I wonder whether it might not be worth the slight complexity to have backup power for navigation and comms gear -- as is REQUIRED on larger vessels.
It would require nothing more than a 12v drop-in LFP battery with some kind of small DC-DC charger. Inserted between the electrical panel and the bus powering this gear.
Well, in my case a bit more than that, since I have a 24v bus for that nav gear which accepts 24v, and various droppers to supply that which needs 12v. I guess if I went this route I could simplify this and get rid of the droppers. The advantages of 24v is less with LFP because less voltage sag. I guess a single 100AH battery would be ok for a few hours of navigation/communication (just no autopilot, which needs a fair amount of 24v power).
My disaster plan in case of blackout was always to connect my engine start and generator start batteries together and hot wire my nav and comm gear from there. These are completely separate from my house power system, with own alternators and chargers and zero common point of failure. For a really unlikely event, maybe that's good enough?
What do you guys think?
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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21-09-2024, 06:31
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#2
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Registered User
Join Date: Mar 2014
Location: Atlantic Ocean
Boat: Tayana 48DS 48'
Posts: 387
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Re: Blackouts and Backup Comms/Nav Power
We had a blackout with our 6 month old Victron 12V 330ah battery back in the summer of '22. Long story short, the internal BMS experienced a complete failure - it opened both the charge and discharge switches, no Bluetooth activity at all. Repeated power cycling of the board did not restore it. I did a "quick fix" by hot-wiring the charge & discharge switches and the battery worked fine (albeit without cell balancing) for several months until we obtained a new BMS board from Victron. The new one has worked fine ever since.
But this got me thinking - our "event" happened on a sunny day while at anchor, so no panic -- what if it had happened on approach to a tight entrance in the fog?
I've done two things now to reduce the chance of that scenario: First, I installed an "over-ride" switch to bypass the BMS control of the two switches. This is a high-quality toggle switch with a guard over it.
Second, I changed my electrical distribution for four critical systems to a diode combiner from both the Lithium house battery and the AGM start battery. I found some 100a Schottky diodes and constructed a combiner module with one diode from the Lithium and two in series from the start battery, so under normal service, current is drawn from the House - but the start battery will provide current if the house fails.
I'm powering my primary chartplotter, my N2K buss, the autopilot and the bilge pumps from this combiner.
Hartley
S/V Atsa
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21-09-2024, 07:31
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#3
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Registered User
Join Date: Jan 2011
Location: Cruising in SE Asia
Boat: Roberts Offshore 44 Cutter
Posts: 116
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Re: Blackouts and Backup Comms/Nav Power
Why not use the solution that worked for decades with lead acid? An "emergency parallel" switch connecting the start bank to the house bank. Close the house bank switch and run only light loads until you can resolve the situation?
Yes it may be different battery chemistries, but in an emergency it will keep you going. If your alternator regulator has adjustable output can use this setup as long as needed. Obviously not much amp hours available.
I also carry a "start pack" portable lithium designed for jump starting cars. Cheap.
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21-09-2024, 07:46
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#4
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Registered User
Join Date: Jul 2006
Location: Massachusetts
Boat: Finnsailer 38
Posts: 5,823
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Re: Blackouts and Backup Comms/Nav Power
I always have several handheld VHF radios onboard and charged up, which are all the local communication I would need for many days of no power. Same for cellphones that can run chart plotting like OpenCPN. Sure, if the entire electrical system was dead it might be hard to charge the cellphone, but you can also carry a few portable battery backups for those too. I also always have at least the basic paper charts for the areas I am going, along with compasses, plotting tools, bearing compasses, etc. All of that works perfectly well with no power. Personally, I would never go anywhere without at least the basic paper charts and guidebooks for the area that require no power.
__________________
JJKettlewell
"Go small, Go simple, Go now"
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21-09-2024, 07:47
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#5
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Registered User
Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft 381 Catalina
Posts: 6,814
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Re: Blackouts and Backup Comms/Nav Power
I don't worry too much about it. If I somehow manage to lose all house power and can't recover it, I'll jumper critical systems over to one of the engine start batteries to get them online. If things have gone wrong to the point where I can't even do that, I'm probably in a really bad situation as it's a powerboat and the engines need power to start or stay running.
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21-09-2024, 07:57
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#6
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Registered User
Join Date: Jul 2006
Location: Massachusetts
Boat: Finnsailer 38
Posts: 5,823
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Re: Blackouts and Backup Comms/Nav Power
I should add that I also carry a sextant onboard and a compact sight reduction table, though no nautical almanac. I could still do noon sights if I needed to. The GPS in my phone is very good, and the phone just sips power so if I just turned it on when absolutely necessary I could go a good long ways without any power. Pretty sure I could get 12-volt power direct from the solar panels to charge up the cell phones and laptops if I needed too, though it would be better to run it through a battery first. Maybe the best thing would be to carry a small lithium jump starter that has USB charging ports too. I have one of those for my car and it can easily jump start the car engine, though I have never tried it on the diesel on the boat.
__________________
JJKettlewell
"Go small, Go simple, Go now"
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21-09-2024, 10:55
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#7
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Registered User
Join Date: Mar 2007
Location: Santa Cruz
Boat: SAnta Cruz 27
Posts: 7,068
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Re: Blackouts and Backup Comms/Nav Power
I had a blackout on a Mastervolt LFP system at the dock on a race boat I was contracted to deliver up the coast of California. Rather than miss my tight weather window, I bought jumper cables and jumped from the starter battery to the 12v distribution panel. The boat had a separate alternator for the start battery, and I was planning to motor most of the way. It worked out well, and the boat was repaired in time for the race. The cause was they let the boat sit unplugged at the dock for a year and discharged the LFP batteries. It took a Mastervolt tech to bypass the BMS for two of the batteries but the third was too far gone to recover. I now have a 200 amp BMS that I throw in my delivery bag for ocean crossings on LFP boats.
I also had a near blackout on my own boat at 0300 at anchor in the Greek Isles. One of 3 gel batteries shorted a cell and I woke to a low voltage alarm. I isolated the bad battery with existing switches and got the engine started. However, I then burned out the battery isolator when I began to charge, as it was putting full alternator output into the shorted battery. Had to rewire to bypass the isolator, and it was dawn before I got back to bed.
In your case, why not have a 24v drop in battery? Do you have two alternators, both 24v?
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21-09-2024, 12:14
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#8
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Moderator
Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 34,989
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Re: Blackouts and Backup Comms/Nav Power
Quote:
Originally Posted by svloki
Why not use the solution that worked for decades with lead acid? An "emergency parallel" switch connecting the start bank to the house bank. Close the house bank switch and run only light loads until you can resolve the situation?
Yes it may be different battery chemistries, but in an emergency it will keep you going. If your alternator regulator has adjustable output can use this setup as long as needed. Obviously not much amp hours available.
I also carry a "start pack" portable lithium designed for jump starting cars. Cheap.
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That has been my system for decades. Only instead of a hard-wired switch, I carry jumper cables. And never needed them so far (knocking furiously on wood).
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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21-09-2024, 22:09
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#9
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Registered User
Join Date: Jan 2011
Location: Cruising in SE Asia
Boat: Roberts Offshore 44 Cutter
Posts: 116
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Re: Blackouts and Backup Comms/Nav Power
Quote:
Originally Posted by Dockhead
That has been my system for decades. Only instead of a hard-wired switch, I carry jumper cables. And never needed them so far (knocking furiously on wood).
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Unless someone has a sound reason to not have the emergency parallel switch on a lithium system, why not have it? *No idea if your start and and house banks are both 24v* As long as all the crew understands it is an emergency switch, it seems safe. There will be interruption while switching, but given the odds I can accept that.
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21-09-2024, 23:03
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#10
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Registered User
Join Date: Jan 2018
Boat: 50ft Custom Fast Catamaran
Posts: 12,131
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Re: Blackouts and Backup Comms/Nav Power
Quote:
Originally Posted by Dockhead
That has been my system for decades. Only instead of a hard-wired switch, I carry jumper cables. And never needed them so far (knocking furiously on wood).
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I do the same and carry jumper cables.
I guess a single point of failure is the real issue in a blackout though.
I have
*2x 12v LiFePO4 batteries in case one goes down
*2x solar charge controllers charging those batteries or supplying power to the DC system in general
*1x battery charger that connects to...
*2x generators
*2x starting batteries
Hard to imagine a scenario where I'd be unable to keep up with power due to the redundant systems and lack of a single point of failure.
Personally, that's the approach I like. Multiple backup systems and manually configurable things like jumper cables and extension cords handy.
Comms and nav are important to survive, but so is food and water, so to me, the best defense is to have no blackouts possible
In addition to all that (and a complete Raymarine primary nav system) I have everything Kettlewell talks about too.
*Handheld vhf
*Phone with chart plotter
*Additional phone with gps location
(no sextant)
A lightning strike might put me out of business but that's about all that would
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22-09-2024, 01:54
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#11
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Moderator
Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 34,989
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Re: Blackouts and Backup Comms/Nav Power
Quote:
Originally Posted by rslifkin
I don't worry too much about it. If I somehow manage to lose all house power and can't recover it, I'll jumper critical systems over to one of the engine start batteries to get them online.. . .
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That's always been my plan. I carry jumper cables (and flashlights ) in the compartment where the engine/gen start battery box is located, which is conveniently next to the bus bars for my electronics.
Never needed them in 15 years using this boat. Knocking furiously on wood.
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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22-09-2024, 02:05
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#12
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Moderator
Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 34,989
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Re: Blackouts and Backup Comms/Nav Power
Quote:
Originally Posted by svloki
Unless someone has a sound reason to not have the emergency parallel switch on a lithium system, why not have it? *No idea if your start and and house banks are both 24v* As long as all the crew understands it is an emergency switch, it seems safe. There will be interruption while switching, but given the odds I can accept that.
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I don't have a start bank -- I have individual 12v start batteries, 1 each for main and gen. These are in completely separated systems with their own alternators and battery chargers.
My plan in case of disaster would be to connect these two batteries (large truck start batteries) in series, then jumper them to my electronics bus bars. So a switch wouldn't work by itself -- I still need to series connect the batteries together.
This would not work for long because I couldn't charge these batteries like that.
Single point of failure for certain aspects of my electrical system is my Victron Multiplus charger/inverter, which if it goes down (and it did once), takes out all 230v power since shore/gen power runs through it to get to the panels. This can be solved with jumpering.
A failure here also takes out battery charging from AC power, but I do carry a spare 24v 40A charger.
A separate battery feeding the nav/comms electronics would elegantly simplify all these disaster plans, as hardly anything happening in the rest of the electrical systems could take down nav and comms systems, which would make a blackout vastly less dramatic. This is required by GMDSS.
An interesting story about how this requirement came to be here: https://navcen.uscg.gov/gmdss-reserve-source-power
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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22-09-2024, 02:15
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#13
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Registered User
Join Date: Jan 2011
Location: Cruising in SE Asia
Boat: Roberts Offshore 44 Cutter
Posts: 116
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Re: Blackouts and Backup Comms/Nav Power
Quote:
Originally Posted by Dockhead
I don't have a start bank -- I have individual 12v start batteries, 1 each for main and gen. These are in completely separated systems with their own alternators and battery chargers.
My plan in case of disaster would be to connect these two batteries (large truck start batteries) in series, then jumper them to my electronics bus bars.
This would not work for long because I couldn't charge these batteries like that.
Single point of failure for certain aspects of my electrical system is my Victron Multiplus charger/inverter, which if it goes down (and it did once), takes out all 230v power since shore/gen power runs through it to get to the panels. This can be solved with jumpering.
A failure here also takes out battery charging from AC power, but I do carry a spare 24v 40A charger.
A separate battery feeding the nav/comms electronics would elegantly simplify all these disaster plans, as hardly anything happening in the rest of the electrical systems could take down nav and comms systems, which would make a blackout vastly less dramatic. This is required by GMDSS.
An interesting story about how this requirement came to be here: https://navcen.uscg.gov/gmdss-reserve-source-power
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Makes sense. Quite difficult to reconfigure batteries, especially because these things always happen at night in foul weather, in a difficult place.
On some commercial boats they sometimes use a selector switch for the wheelhouse panel feed. A small car battery with it's own charger is connected to that. Quite easy to roll the switch over if things go dark.
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22-09-2024, 02:24
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#14
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Moderator
Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 34,989
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Re: Blackouts and Backup Comms/Nav Power
Quote:
Originally Posted by svloki
Makes sense. Quite difficult to reconfigure batteries, especially because these things always happen at night in foul weather, in a difficult place.
On some commercial boats they sometimes use a selector switch for the wheelhouse panel feed. A small car battery with it's own charger is connected to that. Quite easy to roll the switch over if things go dark.
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Even simpler than small car battery/switch/charger would be small lifepo4 battery/DCDC charger continuously feeding the nav/comms gear.
If the main power fails, you've got that battery still, which even acts as a UPS, so no interruption of power.
I try to avoid complexity in my already very complex boat, but the advantages of this, particularly in terms of safety, are so profound. That story on the Coast Guard site was pretty hair raising.
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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22-09-2024, 05:54
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#15
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Registered User
Join Date: Sep 2019
Location: Lifeaboard
Boat: FP Lavezzi 40
Posts: 3,894
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Re: Blackouts and Backup Comms/Nav Power
Simple I have all nav electronics plus NMEA and autopilot are isolated from rest of DC by an Victron Orion TR isolated converter 12-12/30A that charges a 20AH LTO buffer battery with 14.9V which then power the electronics.
Like this no spike etc can reach them, the LTO running at 14.9V delivers clean 14.9V to all devices connected and the power supply has to work less due to 14.9V. All nav electronics can do 15V.
Means if the lifepo4 gets blackout the 20AH buffer still powers all I need for sailing/motoring.
Then I switch over to the BB hull 60AH LTO starter as hybrid starter/house.
This gives me about 45min in worst case (on passage at night running all navgear, autopilot and lights) to sort out the lifepo4 issue and get it back online.
If that doesn't happen I pull the main NH-fuse which is also disconnect switch for the LFP house and switch on solar via Victron BT connect or at night start the engine to get charge by engine for the LTO.
ElectrodacusBMS switches all on/off via remote which I can also manually switch via BT connect. My cutoff is either a smart victron device with remote or where hot side is cut are all smart battery protects. If BT doesn't work I can still bridge the remote port, the solar and alternator has a switch in the BMS case to override/manually switch that on/off.
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