AGM batteries if discharged?

I’m heading over to Green Turtle 10/17 to work on my Dorian damaged boat, and one of my big concerns is my battery bank. I have 4 expensive Lifeline AGMs as the House bank with a total of 500ah. My solar blew off in the storm so it’s been sitting for about 30 days with no charge. I don’t *think* there has been a draw because I shut off all the breakers when I left, but in the process of hauling the boat and during the storm who knows. I was not there for the emergency haulout.

So my question is, if the bank is discharged I’m wondering if I can bring them back. I have power at the yard now so can run the battery charger, and I also have 200 watts of auxiliary solar and two new Victron controllers already wired up so I will have some solar for the cruise back to FL. I will not really be lingering at anchor hopefully unless cold fronts pin me down so the solar might not be critical.

I don’t have the ability to bring new batteries with me on this flight due to weight, but if these house batteries are shot I might have to do that I suppose. I really rely on my chart plotter for navigation so I need some type of battery that will hold a charge on the cruise back.

Hopefully my start battery was isolated during all this, and if it’s good maybe I can run the plotter off that on the way home if the house bank is trashed?

Just trying to brainstorm this before I get there so I’m not surprised.

If they were discharged significantly and sat that way, their condition and ability to take a charge will be somewhat of an unknown. But I'd be surprised if you can't get at least some of the batteries (if not the whole bank) to take enough charge to manage for the trip home. In particular, being that you'll be motoring the whole time, limping along with fairly limited capacity shouldn't be too hard.

But if all of the loads were actually shut off, chances are they're not all that discharged (self discharge on AGMs is fairly low). If that's the case, they should charge right up and be pretty much fine.

I'd definitely plan to have the boat plugged in for as long as possible while you get everything sorted and ready to go. That'll get the batteries topped off and then you can see what shape they're in.

We have basic flooded golf cart batteries and don't plug the boat in during the summer. Typically, we run the boat enough to keep the batteries charged up but didn't this year because of family stuff.

I don't recall how long the longest interval was between going out on the boat but six weeks sounds about right and the batteries were fine. Never got below 80% I think, and we have a little computer type fan running all the time through the desiccating head.

I ruined a set of AGM's by leaving them fully discharged for about a month. When my buddy needed batteries, I advised against it, but he figured he would never be so stupid as to let his batteries go on charged. His boat was out of the country and someone shut off his dock power. So he needed a new set too.

Egad. I've been treating our batteries with the same disregard for 7 months a year since 2014. Difference might be that they're fully charged by the time we tie up.

"Dead " batts can almost always be brought back to service.

Usually the bank will be smaller, in terms of capacity , as if they were years older.


Starts may not come back, even once.

I have run a AGM 8D flat once by mistake and had no problem bringing it back. It was down for about a week. Even w all breakers off you may have parasitic drains... CO detector, etc that can run battys down. Most boats have some connections that bypass a shut off switch... bilge pumps, CO, smoke detectors...
My understanding is it's not a desired practice but a few and shorter ones won't kill an otherwise good AGM batty.
Do you gave a tablet?
I was very pleasantly surprised at the usefulness of Navionixs on a tablet, especially as a back up. $15 for US w a year of updates. Also free 30 day trial available.
I have had some issues w MFD run on start batty... if it's on before start they sometimes don't like the V drop at start. I have lost all my custom settings (not waypoints or rts) and had to go through set up again... always happens at the worst time of course.

Oh yes, forgot to add I have an iPad with Garmin Blue Charts on it I can use if not enough juice to run plotter. I usually use the iPad and plotter at the same time.

Autopilot also uses some juice obviously, along with the radio that’s always on.

I bought another antenna and some cable to try rig up since my vhf antenna was on top of the mast. Would like to have my AIS running.

What else should I take over to make my trip easier? I wonder how I’m going to lash the mast down but guess I’ll figure that out when I get there. I have (or had) lots of dock lines.

Do you have an installed generator?

-Chris

Yes. Have a generator.

cardude01 said:

Yes. Have a generator.

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In that case, even if you end up with very limited usable battery capacity, you should be ok, being that you can run the generator any time you're not motoring if needed (provided fuel capacity is sufficient).

Greetings,
Mr. c01. I wish you the best in your endeavors but why not get a tow back from Boat US(?) as suggested?

RT Firefly said:

Greetings,
Mr. c01. I wish you the best in your endeavors but why not get a tow back from Boat US(?) as suggested?

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I’m reserving the tow idea for an emergency. I don’t *think* I will be in a must have tow situation from what I’ve gathered so far, but maybe that changes once I get there and see with my own eyes.

My plan is to take two days to get from GTC to West End and stop at that marina (or just anchor in the basin maybe) and wait on a good window to cross. I’ve done the trip from GTC to West End a few times now and that leg doesn’t really worry me too bad as long as I don’t get caught in a front.

I am a little bit worried about crossing the GS with the boat somewhat disabled, and after I get to West End I might rethink the tow idea. I figure I can wait for a really good weather window to cross for as long as I have food and water so hopefully I won’t get antsy. However, I’ve never tried to cross during the fall (only in summer months) so I really don’t have any experience waiting like this. How long could I wait? I will have to pack lots of canned food— as much as they will let me take on the flight over. I need some lighter non-perishable food ideas however. Can stuff is heavy.

Don't think the assistance tow would be covered, thus very expensive unless hull insurance kicks in.

Although West End, Freeport, Bimini are in the FLL franchise oparea.....

It would be OK if he broke down enroute but the tow really only has to be to a suitable repair facility, not necessarily where you want to go.

I'd guess they will be OK after a charge. Lifelines can be equalized to restore lost capacity when left discharged. The Lifeline literature explains this procedure.

DDW said:

I'd guess they will be OK after a charge. Lifelines can be equalized to restore lost capacity when left discharged. The Lifeline literature explains this procedure.

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Ahh excellent. Will check that out. Thanks.

Found it. The recovery from deep discharge seems a bit risky and needs to be done in 86 degrees or less if I’m reading it right. Hopefully I’m not deep discharged!


http://lifelinebatteries.com/wp-content/uploads/2015/12/6-0101-Rev-E-Lifeline-Technical-Manual.pdf

I normally store my boat from October to May with no charger (or charging) on the house bank or start battery and my batteries are still in good shape in the spring. I do get them completely topped off before going into storage, usually by running for a couple of hours before puling out for the winter.

Unless there is a draw, they should still be in very good condition after only a month. Check the voltage before turning the system back on to see if they have been run flat. I have 400 AH in my bank, and they top off in under an hour running with a 100A Balmar alternator unless I have been on the hook for several days. The smart charging system tells me where I am in the recharge cycle.

My batteries are also Lifeline...

Greetings,
Mr. ps. Not trying to be argumentative but from the Boat US site:


Is my BoatUS Towing Service valid wherever I boat? Yes. BoatUS Towing Service follows you and your boat. No matter where your homeport is or where you keep your boat. If you're within a TowBoatUS service area, BoatUS will provide for towing service up to your selected service level. Your local TowBoatUS Unlimited Service Area can be found here.




and...


TowBoatUS Boynton Beach

2301 Broadway
Riviera Beach, FL, 33404
(561) 842-1525
Services:

• 
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Unlimited Service Area:

130 Miles Offshore



Might be worth a call to find out what's what.

Not sure if it might help, but contrary to what I understood at that time, it is practical to equalize AGM batteries. We were advised of this after our batteries had been through many cycles over a 5 year period. It helped bring them back substantially. Prior to then I had always thought only lead acid batteries should be given an equalizing charge.

cardude01 said:

Yes. Have a generator.

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Good to go, probably. If necessary, turn it on when you start out, turn it off when you get the mainland dock. Charger on, all should be good.

If you didn't have any parasitic loads at play, you could find your batteries are still amost topped up. We've been on the hard for about 5 months before (Odyssey AGMs) with no appreciable self-discharge. I'd expect the Lifelines to be the same.

DDW said:

I'd guess they will be OK after a charge. Lifelines can be equalized to restore lost capacity when left discharged. The Lifeline literature explains this procedure.

Click to expand...

Chrisjs said:

Not sure if it might help, but contrary to what I understood at that time, it is practical to equalize AGM batteries. We were advised of this after our batteries had been through many cycles over a 5 year period. It helped bring them back substantially. Prior to then I had always thought only lead acid batteries should be given an equalizing charge.

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FWIW, Lifeline is the only AGM maker -- that I know of -- that recommends equalizing.

-Chris

Thanks everyone. I’m feeling better now.

I equalized FullRiver 8D AGMs following the advice of East Coast battery (Ft Lauderdale) and, as previous, it worked out just fine, contrary to what I had thought previously. So, would guess it is not just Lifelines - after all the chemistries are the same - just packaged differently.

cardude01 said:

I don’t *think* there has been a draw because I shut off all the breakers when I left, but in the process of hauling the boat and during the storm who knows.

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If there was no draw, then AGM batteries lose an insignificant amount of amperage per month. (1~3 I think). I regularly turn my boat off (no trickle or periodic charging of any kind), then 6 months later, turn on battery switches, LED lights and the stereo. I've done it for 9 years on a set of Lifeline AGM batteries with no apparent issues.

AGMs can be equalized, the challenge is doing it without popping the vents and losing electrolyte. That's why many recommend against it.

Personally, I've seen AGMs in land vehicles show significantly higher resting voltage and somewhat better performance after sitting on a desulfating battery tender for a while. Mind you, I'm not talking a day or 2, I'm talking about being plugged in whenever it's not in use for a few months. I've got a few Battery Minder 1510 units (temp compensated and desulfating) around my house for vehicles that aren't driven a lot and they seem to do the trick.

My Victron multi went bad and I ended up discharging my 1200 ah lifelines to zero twice and sat for at least a week that way. They are maybe 4 years old. They charged right back up. The lifeline instructions are not easy to follow, it would take days and depending on your charger size, you might have to do it in batches a few batts at a time, it requires some real amperage.

My guess is if they charge back up, you would put off the equalization for a later date. Mine act as if nothing happened, so I never did it. Hope yours fare the same. They are good batts. Good chance it will be a non issue, especially in the short term.

I might be ready to take a pair out of the circuit, but if bad probably not all of them.

For light weight food options you might try camping supply
stores for freeze dried products

Good idea on the freeze dried. I guess. Never had them.

I was thinking jerky, canned sardines/kippers etc (I like that stuff and it doesn’t weigh much), some canned veggies. Maybe some Spam. I have pasta onboard.

cardude01 said:

Good idea on the freeze dried. I guess. Never had them.

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They aren't bad at all. Expensive, but easy.

Rip the top off the bag...pour in 2 cups of boiling water...stir...wait a few minutes, and you're done. Pretty filling as well, as they're meant to fuel an adult carrying a big pack through the mountains.

Best of luck!

"I wonder how I’m going to lash the mast down"

Use care as masts may be repaired by splicing, even the old 12 meter boats had spliced masts with big !!! loads.

No Fear crossing , without the mast the side to side motion will be quicker , but you have a basic single engine cruiser , like most cruisers..

I had a bilge pump hose come off while the boat was on the hard and accumulated rain water leaking through a hatch coaming due to the boat not being blocked level recirculated until the two AGM batteries went dead flat. I recharged them and they are still working about 5 years later for the new owner. Technically, this should not be possible but you might luck out.