AGM vs Sealed Lead Acid Battery

[twistedtree]

Originally Posted by Captain Bill

At the boat show">Miami boat show in 2005 there was a hybrid cat. It had an electric motor in one hull, batteries in the other and a big genset on the bridge deck. It could put the motor in regen mode and he had about 1000W of solar if memory serves me. I forget the brand, but I think it was a South African cat. In any case, it was delivered to Florida on its own hull. It crossed the atlantic with a sister ship that was Diesel/Sail. The captain claimed that the two boats never got out of site of each other and most of the trip was sailing and on occasion motor sailing. If I remember the numbers he said that the hybrid completed the trip on 85 gallons of Diesel and the other boat used about 350. He said that at 8 knots in the trades he lost about .5 knots in regen mode slowing to about 7.5. While certainly an improvement in fuel consumption it was not capable of going all electric.

Interesting. With 1kw of solar, that boat probably got all it's electric power from the sun, where the other had to run it's generator daily. I wonder how much of the saved fuel that accounts for. How many days do you suppose the sail took?

[goboatingnow]

Originally Posted by twistedtree

Interesting. With 1kw of solar, that boat probably got all it's electric power from the sun, where the other had to run it's generator daily. I wonder how much of the saved fuel that accounts for. How many days do you suppose the sail took?

Id be deeply suspicious of those numbers mentioned.

Dave

[twistedtree]

Originally Posted by goboatingnow

Id be deeply suspicious of those numbers mentioned.

Dave

Maybe. It sounds like both boats sailed, so it's not about propulsion. Generation of on-board power is 100% diesel on one boat, and probably 100% solar on the other. How much that accounts for, I don't know. How much per day do you folks burn to generate electricity when cruising? A gallon a day? 2 Gallons? I just don't know.

[noelex 77]

Originally Posted by deckofficer

The solar will produce on an average sunny day around 15 Kwh, .

That figure is, unfortunately, way too optimistic

[hellosailor]

Spot on, noelex. With a 2kwt array all the standards say 8-10kwh on a glorious day would be considered high, from what I've seen.

[mbianka]

Originally Posted by twistedtree

Interesting. With 1kw of solar, that boat probably got all it's electric power from the sun, where the other had to run it's generator daily. I wonder how much of the saved fuel that accounts for. How many days do you suppose the sail took?

I would say quite a bit. Though I can move my 30 foot 8 ton sailboat using just 900 watts of power in clam conditions. I've only got 120 watts of solar panels installed. It helps but, I certainly could not run off the panels directly at this point. But, there are times while sailing where everything aligns and I reach my destination with more fuel (energy) in the battery banks than when I started:
THE BIANKA LOG BLOG: HAPPY AT THE HELM!
I suspect that's what happened with the Catamaran crossing the ocean.

[billyehh]

I have 520 watts of solar power. It takes care of my day to day elecrical needs and usually does not go below 80% of battery capacity overnight. By limiting the draw to 80% this increases the life of the battery bank. Beside having a fairly large system, I am always trying to increase the efficency of my electrical use. Almost all of my lighting is LED or flourescent. I charge all my AC items at the same time to reduce the time that the invertor is on. I went from an electric coffee maker to a French Press (no electricity and better coffee). The one thing I have not replaced is my toaster. Haven't found a reasonable alternative.

The point is unless you have a genny, electricity is a scarce resource and you must conserve it. With present day technology using battery/solar power for cooking, heating water and propulsion is a muggs game. Sure it is possible, at an incredebule cost and weight. At this point it not cost effiecent.

I'll tell you, down in the Caribbean it is hard enough to get parts and service for well known engines, just think of the blank faces you will get with an electric rig.

At this point the only system that seems to make any sense is a diesel/electric rig that does not use batteries and only for catamarans. You also better be prepared to repair it yourself.

[deckofficer]

Originally Posted by billyehh

I have 520 watts of solar power. It takes care of my day to day elecrical needs and usually does not go below 80% of battery capacity overnight. By limiting the draw to 80% this increases the life of the battery bank. Beside having a fairly large system, I am always trying to increase the efficency of my electrical use. Almost all of my lighting is LED or flourescent. I charge all my AC items at the same time to reduce the time that the invertor is on. I went from an electric coffee maker to a French Press (no electricity and better coffee). The one thing I have not replaced is my toaster. Haven't found a reasonable alternative.

The point is unless you have a genny, electricity is a scarce resource and you must conserve it. With present day technology using battery/solar power for cooking, heating water and propulsion is a muggs game. Sure it is possible, at an incredebule cost and weight. At this point it not cost effiecent.

I'll tell you, down in the Caribbean it is hard enough to get parts and service for well known engines, just think of the blank faces you will get with an electric rig.

At this point the only system that seems to make any sense is a diesel/electric rig that does not use batteries and only for catamarans. You also better be prepared to repair it yourself.

I totally agree on your entire post, and your right on about the cost and weight issue. LiPo ThunderSky batteries and others keep dropping in cost. The 2 volt AGMs would run 4800 lbs for a 67.2 Kwh bank. The ThunderSky would be 1845 lbs for a 76.8 Kwh bank and would currently cost $30K. As the automotive industry keeps gearing up for electric cars, this price will keep coming down. I used to race 10 years ago electric vehicles, and can report first hand that LiPo has already come down in price a lot. Over the years I have designed and built many off-grid residential systems and have no reservations on this project. The dinghy will be retro-fitted first using LiPo and hopefully when I'm ready to start full time on the Cat's re-fit, the price of LiPo will have dropped even more.

[fperfect]

According to this Lead-Acid Batteries – All you need to know you should be just fine with regular flooded batteries. AGMs are safer and better withstand low temperatures, however I don't think the higher price is worth it in your case.

[James S]

Welcome to the forum fperfect.

[GordMay]

Greetings and welcome aboard the CF, fperfect.

[Capitain Mike]

Originally Posted by noelex 77

I have had a very good life from Gels. 16 years on my previous boat and 10-13 on this one (with some difficult conditions from a PO for much of their life).
This long life is their main advantage and can make them cost effective. There is also the benefit and added safety of very little gassing and no acid to spill. Low self discharge is a help if you leave the boat for long periods and no maintenance means more time to enjoy the cruising life.
With good regulators available for solar, wind and AC charges there is no excuse for poor charging practice these days.
If you do go for gel batteries get good ones, mine are Sonnenschein.

Where do sealed lead acid come into this equation.

Sterling Power Products: What is the best battery to use for an auxiliary charging system?

[btrayfors]

Captain Mike,

This thread is a year old!

ALL the batteries talked about in this thread are lead-acid types. Gelled batteries, AGMs, and flooded batteries are all lead-acid. The term, "sealed lead acid" is a generic term which is non-specific. It could mean VRLA batteries (AGMs, gels, etc.) or it could mean "maintenance-free" wet cell batteries...the worst of all types for a boat.

We know a lot more about battery types and their application on boats these days.

Flooded batteries are by far the most economical and will suit many boaters very well. They are relatively more forgiving than are gels and AGMs, and have more cycles than AGMs. But, they require periodic maintenance, sometimes give off noxious gasses, must be mounted in sealed boxes, etc., etc.

Premium flooded batteries, like those from Rolls/Surette, have very long lives, often exceeding 10 years in marine service.

AGMs are very popular these days, but not many boats have enough charging capacity to take advantage of their incredible ability to take a big charge. They also must be fully charged at least once every few weeks or they will sulfate and deteriorate badly. Still, they represent good value for some types of boaters.

Gels are the most expensive of the three types and, used properly, are the longest lasting. Many gels last 8, 10, 12 or more years. I have two in my basement now which are 15 years old and which still perform very well. However, these are the most sensitive to overcharging and the charging voltages must be set properly.

Not all gels are created equally, just as with other types of batteries. I have four UPS units in my home/workshop which are in service 24/7, and which use gelled batteries. I just replaced a gel in one of them which was less than 4 years old, and replaced one in another UPS unit last year which was only 5 years old. These batteries live in an "ideal" environment -- room temperature, always on (proper) float charge, etc., etc.

I use small motorcycle-size 7AH AGMs in my dingy, maintained with a small solar panel. These run an automatic bilge pump, a fathometer, and lights. I'm on my third AGM now; the first two lasted about 3 seasons each.

There are several other types of sealed batteries, including TPPL, spiral wound, etc., each claiming to have an advantage over other types. These tend to be the most expensive types.

Hope this helps a bit,

Bill

[Capitain Mike]

Originally Posted by btrayfors

Captain Mike,

This thread is a year old!

ALL the batteries talked about in this thread are lead-acid types. Gelled batteries, AGMs, and flooded batteries are all lead-acid. The term, "sealed lead acid" is a generic term which is non-specific. It could mean VRLA batteries (AGMs, gels, etc.) or it could mean "maintenance-free" wet cell batteries...the worst of all types for a boat.

We know a lot more about battery types and their application on boats these days.

Flooded batteries are by far the most economical and will suit many boaters very well. They are relatively more forgiving than are gels and AGMs, and have more cycles than AGMs. But, they require periodic maintenance, sometimes give off noxious gasses, must be mounted in sealed boxes, etc., etc.

Premium flooded batteries, like those from Rolls/Surette, have very long lives, often exceeding 10 years in marine service.

AGMs are very popular these days, but not many boats have enough charging capacity to take advantage of their incredible ability to take a big charge. They also must be fully charged at least once every few weeks or they will sulfate and deteriorate badly. Still, they represent good value for some types of boaters.

Gels are the most expensive of the three types and, used properly, are the longest lasting. Many gels last 8, 10, 12 or more years. I have two in my basement now which are 15 years old and which still perform very well. However, these are the most sensitive to overcharging and the charging voltages must be set properly.

Not all gels are created equally, just as with other types of batteries. I have four UPS units in my home/workshop which are in service 24/7, and which use gelled batteries. I just replaced a gel in one of them which was less than 4 years old, and replaced one in another UPS unit last year which was only 5 years old. These batteries live in an "ideal" environment -- room temperature, always on (proper) float charge, etc., etc.

I use small motorcycle-size 7AH AGMs in my dingy, maintained with a small solar panel. These run an automatic bilge pump, a fathometer, and lights. I'm on my third AGM now; the first two lasted about 3 seasons each.

There are several other types of sealed batteries, including TPPL, spiral wound, etc., each claiming to have an advantage over other types. These tend to be the most expensive types.

Hope this helps a bit,

Bill

Hi Bill thanks for your reply om this old thread.

"maintenance-free" wet cell batteries...the worst of all types for a boat.
I think I have these because there is nothing to unscrew to top up. So what do you recommend? Flooded Lead Acid that can be topped up? instead of the non top up??

[hellosailor]

billt-
I'm sure you're sure, but are you sure your UPS batteries were gel? In the typical "computer" UPS boxes the batteries quietly switched to AGM a decade ago, and while they batteries look the same--they're usually AGM these days.
Coincidentally, with a maximum 4-year life being normal for the way they are built.

As it was explained to me, UPS batteries are expected to lose 25% of their capacity per year, and another 25% per ten degrees Farenheit over room temperature, so on the typical hot summer day when they are needed...you can be down 50% before they are two years old in a hot room.

Some of the utility companies here routinely replace their larger AGM backup batteries every 2 years because of this (large "car" sized) and they've been using AGM, not gel, for whatever reasons. (The batteries often go to ham radio groups, who then stretch out whatever life is left in them.)

What this says about deep cycle AGMs versus what the battery makers say about their longevity...ahem.<G>

But unless you've got some special UPSes (as I suspect you might<G>) those sound like typical consumer units, typical battery life, apparently by design. Eveready gives away flashlights, Gillette gives away razors...those UPS companies get a sweet price for replacing batteries!