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Old 07-01-2016, 17:19   #31
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Re: Are The AGM Worth 2X The price Of PB?

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The problem isn't the battery, its the magnetic field from current flow in the battery leads. Not normally a problem especially if the pos and neg leads are close together AND not near the compass or fluxvalve etc..
Quite so. However, if you do have six 2 volt cells linked together to produce 12 volts, then you will set up a field current that, if near a compass, will potentially affect the compass. Interestingly, the effect may vary by heading. Most professional compasses will have adjustments to offset this effect. Usually money worth spent to have a pro come aboard and do the compass adjustments as you swing the compass.

For those who have a 24 volt system, the field may be quite strong. Just an issue to check off on your list of things to do when preparing your boat for a long trip. Weekend sailors can ignore all this stuff.
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Old 07-01-2016, 17:36   #32
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Re: Are The AGM Worth 2X The price Of PB?

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What it's involved with "rebuilding"a battery? We certainly haven't been in those parts of the world where thousands of shops exist doing this. I have never seen a single place doing this, nor heard of one. And we have spent a lot of time in places where nothing gets thrown out unless it is truly worthless and can't be turned into something else - and batteries are always piled up in trash heaps in these places. Our batteries don't have any way to even open the cases, and I can't imagine that it would be cheaper to add new plates to them than buying new batteries, even if it was possible to get the cases open.

I'm calling B.S.

I don't think there is anything paramagnetic in a battery that would effect your compass.

Mark
Battery rebuilding is/was real! I haven't seen it for 35+ years. A good percentage of battery failures are/were due to sentiment building up on the bottom and shorting out the plates. A rebuild would consist of cleaning out the case and putting it back together.

Today they just recover the lead.

But, rebuilding anything is a dying practice.
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Old 07-01-2016, 19:48   #33
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Re: Are The AGM Worth 2X The price Of PB?

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Didn't you just install 750 watts of solar? If so, then you won't be running your genset that often or that long, unless your usage is way out of normal.

You get submarine batteries from submarines. Those are common and for sale in thousands of shops on the planet that guy lives on. For the rest of us on planet earth, they just aren't a viable option.

Mark

I've had a few people that would know, like Mainsail advise me that it isn't the size of the Solar array that is the issue, you could have an unlimited one, it's the charge acceptance rate of the batteries and the number of hours it takes to fully get you to 100% charge are more hours than there are useable Solar hours in a day.
If that is true, then the only way to get to 100% is to run your generator early in the morning and get at least through the bulk phase and deep Into absorption, then as the sun comes up enough to where the panel output is decent, then the panels can finish the batteries off.
For me it's all theory until I get out there and see for myself, but it does sound logical to me. The last 5% of charge seem to take longer than the first 30% did.

I plan on running the thing twice weekly anyway, to make water, wash clothes, maybe make ice, who knows?


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Old 07-01-2016, 19:53   #34
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Re: Are The AGM Worth 2X The price Of PB?

BTW , as a kid I was for some reason interested in WWII Fleet subs, I don't know why, but I seem to remember that the individual cells on a Sub were massive, I mean huge. I think a single cell weighed over a half a ton, and there were a couple of hundred of them?


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Old 07-01-2016, 20:49   #35
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Re: Are The AGM Worth 2X The price Of PB?

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BTW , as a kid I was for some reason interested in WWII Fleet subs, I don't know why, but I seem to remember that the individual cells on a Sub were massive, I mean huge. I think a single cell weighed over a half a ton, and there were a couple of hundred of them?

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After serving (and qualifying) on both diesels and nukes for more than 10 years, I'll confirm A64's comment regarding submarine batteries, at least those on U.S. boats. Some have more than 100 cells. I have no idea what the previous poster was referring to.
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Old 07-01-2016, 20:50   #36
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Re: Are The AGM Worth 2X The price Of PB?

We bought LIFELINE AGM factory direct and delivered to our industrial loading dock. Buying through the business, the price was about 1/2 retail. We build energy testing machinery so there was a break. Do you have any contacts? You might also get a good deal at a boat show.
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Old 07-01-2016, 21:07   #37
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Re: Are The AGM Worth 2X The price Of PB?

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....

For those who have a 24 volt system, the field may be quite strong. Just an issue to check off on your list of things to do when preparing your boat for a long trip. Weekend sailors can ignore all this stuff.
Hmm... the magnetic field is not really voltage dependent; it is directly proportional to the current flow.
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Old 07-01-2016, 21:07   #38
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Re: Are The AGM Worth 2X The price Of PB?

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What it's involved with "rebuilding"a battery? We certainly haven't been in those parts of the world where thousands of shops exist doing this. I have never seen a single place doing this, nor heard of one. And we have spent a lot of time in places where nothing gets thrown out unless it is truly worthless and can't be turned into something else - and batteries are always piled up in trash heaps in these places. Our batteries don't have any way to even open the cases, and I can't imagine that it would be cheaper to add new plates to them than buying new batteries, even if it was possible to get the cases open.

I'm calling B.S.

I don't think there is anything paramagnetic in a battery that would effect your compass.

Mark
Many years ago my dad had what was commonly called a taxi battery. This was a tar coated 12V dismantlable flooded lead acid battery.

Every 5 years or so dad would drain it, scrape the tar off, bend the tabs apart and dismantle the battery. He would then replace any broken seperators or lead plates, reassemble, retar, refill and he was good for another 5 years.

After 35 years he reluctantly sold the beast for scrap. The outer case wouldn't seal and the tabs were all broken.

Havent seen one since the 1980s. They werent that common then.

The big 2V traction batteries are still repairable. They're also called submarine batteries. Not easy to find these days. They are very efficient. They arent really suited to low draw environments.

6 of them in a sailboat isn't a great option as they would take too much current to keep them healthy. Solar and wind wont recharge them adequately. They are true deep cycle batteries.

Their tall form factor wouldnt fit in most sailboats and they need dedicated venting and pressure water replenishment.

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Old 08-01-2016, 05:15   #39
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Re: Are The AGM Worth 2X The price Of PB?

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For those who have never sailed or cruised beyond their docks, most places like Turkey, India, Malaysia, and even in Chile will have shops that cut open the batteries, change plates, and reseal the cases. Not pretty but works.

Oh, please describe your vast experience cruising India. And Turkey is an uncharted end of the world you will find only the most intrepid and knowledgeable sailors...

Mark
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Old 08-01-2016, 11:33   #40
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Re: Are The AGM Worth 2X The price Of PB?

Our boat came with Lifeline AGM batteries, and we are still using the same batteries, 9 years later. Our usage, they are usually maintained by the charger while at the marina; we sail/motor the San Juans, and that keeps them up.

One benefit is that they can handle below freezing temperatures even when discharged. When I was working at McMurdo Station, Antarctica, we were switching over the batteries that were at the remote field stations from Lead/Acid to AGM. The lead acid were very problematic in that one deep discharge, the electrolyte freezing temperature rises, the electrolyte freezes, and then the battery is destroyed. With the AGM the batteries can be left at the field station for the 8 month winter, and revived the following research season.
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Old 08-01-2016, 12:12   #41
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Re: Are The AGM Worth 2X The price Of PB?

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The last 5% of charge seem to take longer than the first 30% did.
Correct. It's got a name: battery acceptance.
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Old 09-01-2016, 08:40   #42
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Re: Are The AGM Worth 2X The price Of PB?

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The big 2V traction batteries are still repairable. They're also called submarine batteries. Not easy to find these days. They are very efficient. They arent really suited to low draw environments.

6 of them in a sailboat isn't a great option as they would take too much current to keep them healthy. Solar and wind wont recharge them adequately. They are true deep cycle batteries.

Their tall form factor wouldnt fit in most sailboats and they need dedicated venting and pressure water replenishment.

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Not sure I agree. I ran into a pro-captain on a 78 foot sloop a couple years ago. He said they ran 2-volt batteries and that they were 15 years old, still tested well, never replaced one. The advantage was that a failed unit can be replaced easily or repaired. Condition of individual batteries can be easily checked and handled. I see this as a plan on very large boats and as very difficult on smaller boats.
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Old 09-01-2016, 13:22   #43
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Re: Are The AGM Worth 2X The price Of PB?

Even the 6v or 2v wet cell are looks nice, the acid relase in case of excessive rolling and gas exhaust stop me to get it...

I just saw tha lithium titanium battery are getting on sale

50 dollars for a 2,3 v nominal 40 ah cell...i know new tecnology but states, LOOOONG lasting..2500 for 4,6kwh, or let's make a big investment 5000 euro for 9,2 kwh, of wich usable about six...very light, no need to be putted into the bilge...

I really need helpI just need a 24 volt 100 a (or even more) alternator with lithium charger curve an especially customizable voltage (max 3.0v 2,3 nominal 1,5 cut out) for the DIY generator

For solar panels no problem, easy to find, for wind generator, i'm still looking for it


Much thanks all!
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Old 09-01-2016, 21:46   #44
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Re: Are The AGM Worth 2X The price Of PB?

After several years of using LiFePO4, I would absolutely not buy any other kind of battery for any purpose on any boat.
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Old 10-01-2016, 04:51   #45
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Re: Are The AGM Worth 2X The price Of PB?

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After several years of using LiFePO4, I would absolutely not buy any other kind of battery for any purpose on any boat.

Thanks, wich brand?

How did you regoulate the alternator battery charger? wich brand?4 cells and 15, 2 v max charging voltage? (3.8v x 4cells, 90% max recharge for long lasting)
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