Frank,
Keep it up, we need this kind of well written professional explanations.
Information based on in-depth study, investigation and years of hands-on
experience is always welcome - and often a relief....

Maurice Marwood
aepmem@bahamas.net.bs

<snip>Just my opinion, feel free to trash it...

Frank & Claudette Weismantel
Elverta, CA
Boatless for a little while longer

Hi Bob:

Finally had a chance to catch up on TWL.  I see your comment  "There are
some high quality batteries that will last 8 or so years in heavy use.
However an active cruiser with good battery management will replace most
lead acid batteries every 4 to 5 years.  If you go back and read Nigel's
book you will see that one 50% discharge a day will lead to a 7 1/2 year
life span of a battery!"

I do not have Calder's book at hand, but this would seem to indicate
that a cruiser who did not discharge his batteries by 50% every day, but
rather discharged less or to 50% once a week for example, would have a
substantially longer expected battery lifetime?  I do not think that
most active powerboat cruisers with adequately sized battery banks would
even come close to 50% per day x 365 days per year.  Hence, assuming
that all the other things you have mentioned are managed properly, I
think 10 - 12 years is a reasonable lifetime for good GC lead-acid
batteries.  And that is my experience here.

IMO opinion, the real world is that most battery banks give limited
lifetime because of system or user errors.  Overcharging (and the
consequences of that) is probably the biggest culprit.  Accidentally
letting the batteries run below 50% especially to go completely flat is
another killer.  Failure to equalize occasionally.  So I would agree
with your surmise of 4-5 years as an average given all of the things
that can go wrong and reduce the lifetime.  But in a properly controlled
environment with good systems, I see 10-12 years at least.

That is why I am still leery of the AGM style battery.  Lifetimes have
not been established, especially under the very fast recharge conditions
that are one of the leading advantages of these types of batteries.  I
am prepared to be wrong about these AGM batteries (I hope that I am, but
I think real-world long-term experience is still not there.  I guess I
am gun-shy because of the many bad and expensive problems with the
gel-celled batteries over the past few years.  Like AGM, they promised
many advantages, but they delivered only in a carefully controlled
environment and most boats did not provide this environment.  We saw
many cases of burned up banks because of overcharging, etc.

Joe Engel
Portland, OR

Joe and others,

You overlooked failure to keep the water level up as a major cause of
premature death of flooded batteries.  This is another advantage of AGMs.  I
can't tell you how long my AGMs will last because they are still going
strong.  I've had my boat a year, and I am not sure how old they are.  I am
finished with flooded cells - that is for sure.

Todd
Portland, OR

Joe I concur with your comments on the AGM--I did try them on my last boat,
mainly because of the rapid charge--and did not keep the boat long enough to
determine the effect of the rapid charging.  I had mixed results with Gel
cells, but would not go back to them.  I had a couple of them go in less
than two years- despite controlled charging.  Another one I had six years
and it was doing very well--until I sold the motorhome (it was an 8 D
dedicated to the inverter, with an emergency cross over switch to the engine
start--and I cautioned the new owner to never charge the battery off the
alternator)  There the gel cell didn't last a week--guess what?  I don't
know of the AGM will prove to be cost effective, and I think that after 10
years experience in boats, we will have an answer--as we now have in Gel
cells, which in my opinion are not worth using on boats.

As to the longivity of lead acids--definately the Rolls and perhaps the
Surgettes will last 10 years under the circumstances you suggest.  Most of
my experience has been with sail boats/ motor sailors--and it also reflects
the experience of the 5,000 boat membershipe of SSCA.  Although there are a
few folks who get 8 or so years out of a lead acid battery, the majority of
long distance cruisers--and these are folks who are generally very careful
on battery management--replace their batteries every 4 to 5 years.  They
cannot afford to have a battery bank go bad half way across the Pacific.

As far as TWL members--frankly there are only a small percent  that are
really cruising full time.  Mark Richter is extremely careful and
conservative in his battery management and as I recollect he claims 8 years.
In fact even in SSCA the average time of cruising is only close to 4 years.
There are some who have been full time cruising for 30 years--but most make
a significant cruise and then either come back and work, or do coastal
cruising, where they can stop in Marinas farily regularly.

As for the depth of discharge--think of the amount of gear on a modern ocean
crossing sailboat-or motorsailer has that runs 24 hours a day--auto pilot,
GPS, Radar, plus SSB/Ham radio for E mail and commmunications, W fax,
inverter,  refigeration, running and cabin lights and many have 12 volt
water makers--so the battery loads and energy effeciency are extremely
improtant.  The trawlers also have the same managment problems-to wit;
Nordhavn ended up running the genset the entire trip--even before the Air
conditioning was installed.  Sailors are more energy conscious than Nordhavn
was.. You may argue that even ocean crossing boats did go without occasional
marina hookups--and that is true.  My experience was averaging 10,000 miles
a year.  I have friends who average as much as 20,000 miles a year--not a
lot of time to stop doing that.

As for Calder's book--(and it is not a Bible) he points out that a "top of
the line"--so I assume a Rolls, would have a expectancy of 2600 life cycles
of 50%--or about 7 years.  In reality most boaters do not use "top of the
line" batteries, they discharge more than 50% and abuse batteries in many
other ways--see my references to rate of charge, rate of discharge,
temperature, vibration etc.

If you get more than 5 years out of a battery--great--but what is the actual
residual capacity of that battery?  Will using pulse wave technology
increase this longvity?  My expererence is that I replace batteries before a
major passage after four years--Although I did not measure residual
capacity, it definately seemed to be decreasing.

Regards.

Bob Austin
----- Original Message -----
From: "Joe Engel" joe@jre.com
To: "Bob Austin" thataway4@cox.net
Cc: "1trawler world" trawler-world-list@samurai.com
Sent: Thursday, December 26, 2002 1:13 PM
Subject: RE: Batteries

Hi Bob:

Finally had a chance to catch up on TWL.  I see your comment  "There are
some high quality batteries that will last 8 or so years in heavy use.
However an active cruiser with good battery management will replace most
lead acid batteries every 4 to 5 years.  If you go back and read Nigel's
book you will see that one 50% discharge a day will lead to a 7 1/2 year
life span of a battery!"

I do not have Calder's book at hand, but this would seem to indicate
that a cruiser who did not discharge his batteries by 50% every day, but
rather discharged less or to 50% once a week for example, would have a
substantially longer expected battery lifetime?  I do not think that
most active powerboat cruisers with adequately sized battery banks would
even come close to 50% per day x 365 days per year.  Hence, assuming
that all the other things you have mentioned are managed properly, I
think 10 - 12 years is a reasonable lifetime for good GC lead-acid
batteries.  And that is my experience here.

IMO opinion, the real world is that most battery banks give limited
lifetime because of system or user errors.  Overcharging (and the
consequences of that) is probably the biggest culprit.  Accidentally
letting the batteries run below 50% especially to go completely flat is
another killer.  Failure to equalize occasionally.  So I would agree
with your surmise of 4-5 years as an average given all of the things
that can go wrong and reduce the lifetime.  But in a properly controlled
environment with good systems, I see 10-12 years at least.

That is why I am still leery of the AGM style battery.  Lifetimes have
not been established, especially under the very fast recharge conditions
that are one of the leading advantages of these types of batteries.  I
am prepared to be wrong about these AGM batteries (I hope that I am, but
I think real-world long-term experience is still not there.  I guess I
am gun-shy because of the many bad and expensive problems with the
gel-celled batteries over the past few years.  Like AGM, they promised
many advantages, but they delivered only in a carefully controlled
environment and most boats did not provide this environment.  We saw
many cases of burned up banks because of overcharging, etc.

Joe Engel
Portland, OR

Bob Austin wrote:
As far as TWL members--frankly there are only a small percent  that are
really cruising full time.
In fact even in SSCA the average time of cruising is only close to 4 years.

If you get more than 5 years out of a battery--great--but what is the actual
residual capacity of that battery?  Will using pulse wave technology
increase this longvity?  My expererence is that I replace batteries before a
major passage after four years--Although I did not measure residual
capacity, it definately seemed to be decreasing.

Regards.

Bob Austin

Joe wrote
IMO opinion, the real world is that most battery banks give limited
lifetime because of system or user errors.
Lifetimes have not been established,

Like AGM, they ( gel ) promised many advantages, but they delivered only in
a carefully controlled
environment and most boats did not provide this environment.

REPLY
Bob and Joe's comments point out the difficulty of establishing reliable
data over a long timeline.
Recreational boaters seldom  provide the sort of detailed documentation and
data collection needed for a reliable and accurate picture of AGM or even
gel batteries compared to flooded cells which have been arounf for a
century.
Fleet operators, the military and other large volume users  with a permanent
maintenancce staff and detailed recors do not represent  the typical
recreational boater.

I would  say that even establishing a 10 year life history of a set og AGM
batteries is  difficult.
During the past ten years, charging technology has changed dramatically.
Micro processor controlled chargers was virtually unheard of as a consumer
product ten years ago.
Yet this is the only way to  properly  charrge and maintain gel and AGM
batteries.
Those manufacturers who did make them also experienced a steep learning
curve in the past ten yearrs.

Misuse, benign neglect and outright abuse from ignorance or other reasons
all contributed their share of premature failures.
Human nature did the rest.

As Bob points out, the prudent mariner especially a well educated and
technically  conversant one would rather spend a bit more now to avoid a
future potential failure in some remote place.

Gel cells were created to fulfil a need to make spill proof lead acid
battteries.
The gel is created by adding fine sillica particles to the liquid
electrolyte.
As we all know silica ( or glass to use its common name)  is not a
conductor. Therefore, the silica  displaces  a certain volume of active
electrolyte. This is bound to affect battery performance and operating
characteristics.

AGM  batteries were developed in response to the need to retain the spill
proof benefits of the gel battery while eliminating the drawbacks.

The AGM electrolyte is contained in a special absorbent mat which is placed
between the lead plates.
There is just enough electrolyte soaked into these "blotter" mats to provide
suffficient free electrons for the electro-chemical process to  take place.
Sometimes AGM batteries are also called starved electrolyte cells.

Flooded wet cells will continue to enjoy popularity for the reason they are
more tolerant of abuse and misuse.
Every technical advance carries a penalty of increased complexicity and
tighter operating parameters.
Those people who are unable or unwilling to live with the restrictions
dictated by advanced technology will have to stick with the more basic
forms.

For that reason, the basic flooded cell is likely to remain the  battery of
choice for the majority of recreational boaters.

regards

Arild

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Joe Engel wrote, "IMO opinion, the real world is that most battery banks
give limited lifetime because of system or user errors."

I agree, although I would condense it down to neglect and abuse,
probably in that order. For military customers and charter operations
they reverse. This is the main reason that we have gone to the Hawker
Genesis batteries. Since it doesn't hurt them to go to 100% depth of
discharge (DOD) and they require no maintenance, about the only way to
hurt then is the leave them discharged for a long time or severely over
charge them. Since we use microprocessor controlled chargers, which I
have never heard of over charging a battery unless they didn't have
temperature compensation installed correctly, that only leaved neglect.
To reduce warranty claims we are considering incorporating a computer
monitoring and data logs system data which will periodically transmit
operational data to our customer's logistics group and then forward it
to us. We could actually call our customer up and tell then that they
need to recharge their batteries. We would also be able to collect real
world data on the system performance and life cycle.

"That is why I am still leery of the AGM style battery.  Lifetimes have
not been established, especially under the very fast recharge conditions
that are one of the leading advantages of these types of batteries.  I
am prepared to be wrong about these AGM batteries (I hope that I am, but
I think real-world long-term experience is still not there.  I guess I
am gun-shy because of the many bad and expensive problems with the
gel-celled batteries over the past few years.  Like AGM, they promised
many advantages, but they delivered only in a carefully controlled
environment and most boats did not provide this environment.  We saw
many cases of burned up banks because of overcharging, etc."

There are some valid arguments against AGM batteries, for example they
cost more and if you think you might neglect them to death, you would be
better off going cheep (this is what I assume when ever a see someone
prefers flooded lead acid batteries), but this certainly isn't one of
them. AGM batteries were developed in the 70's and have been in service
in aircraft since the early 80's. They have demonstrated superior
performance to flooded lead acid and gel cell batteries and my
understanding is they totally dominate the aircraft market. To the best
of my knowledge all the US military services have switched almost
exclusively to AGM batteries with the final convert being NAVSEA.

AGM batteries are also dominant in the Telecommunications industry. The
TelComms started replacing their large flooded lead acid float batteries
with AGM batteries in the early 1990's (I know because we experienced 42
week lead times due to TelComm demand.) because their higher current
capacities allowed them to use 1/4th as many batteries to carry a load
until a back-up generator could be brought online. Their cost trades
showed that AGM made economical sense provided they got 3 to 5 years of
float service. Real world experience is that they have exceeded the 10
year float life of flooded lead acid batteries that they are still going
strong.

Although Gel cell and AGM batteries are both valve regulated, the
similarities end there. AGM batteries are very different than Gel cell
batteries and they do not share many of their vulnerabilities. AGM
batteries actually thrive on high charge and discharge rates. Laboratory
work performed at Hawker Genesis shows that with high charging rates
they shed sulfates and are able to tolerate high depth of discharge
(i.e. 100% DOD) provided the charging rate in amps is >25% on the banks
amp hour capacity. This has been demonstrated in electric cars which
typically use very high DOD.

On our "Phantom" boat we have used a pair of 42 AH batteries for 6 years
now. These batteries see 550 amp current spikes 180 times in a day and
then they are recharged with a 25 amp "Battery Tender" from Deltran.
Then they are neglected for weeks or months (although the Battery Tender
is plugged in and automatically maintaining them). Literally the only
attention they ever get is when we (usually I) give tours and the
customer wants to see the batteries. We have tested a pair of Hawker
Genesis Batteries in the lab and simulated 400 charge/discharge cycles
to 100% DOD at a 20 minute discharge rate with a three hour recharge
time (bulk charge only). I wanted to test to depletion but after 400
cycles the charge capacity had only been reduced to 90% of rated
capacity, projecting a life of 800 cycles. Since our goal was only to
demonstrate the batteries would survive our 2 year warranty period (25
to 50 cycles max) we could not justify expending additional engineering
effort.

I hope this helps. Sorry for ranting about batteries again.

Regards;
Mike Schooley
Designing "Portager" a 36' trailerable trawler with AGM batteries

<<Mark Richter is extremely careful and
conservative in his battery management and as I recollect he
claims 8 years.>>

Bob,
Actually, I replaced my bank of 4 Trojan L-16 batteries after 4
years when I noticed appreciably diminished capacity.  But my
useage of the house bank is unusual, in that typically I
discharge for 3-4 days before recharging.  This practice is hard
on the batteries in that there is a longer time for sulphation of
the plates to harden.

This time, I went with 6 golf carts for the house bank, and added
a pulsing desulphation device.  We'll see how it goes.

Mark Richter, Winnie the Pooh
Stuart, FL

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Hello All,

I am NOT trashing Mike Schooley here.

Mike states that the telecom industry moved to AGM batteries from flooded
cells due to their higher current capacities.  This is not entirely correct.
In the early 1990's we started building cellular systems in earnest.  The
first round of cell sites called for an unprecedented increase in the number
of building permits applied for.  Prior to the cellular industry, most
communication facilities were not permitted.  Once all the various municipal
agencies saw the 8 foot wide by 4 foot high racks of lead acid battery
plants they began demanding sophisticated (Rube Goldberg) venting systems
for battery gases or separate vented rooms for battery plants.  We were
trying to drive the per site costs down, not up, so the industry moved
wholesale to gel cell batteries.  Unfortunately, at first we simply replaced
lead acid batteries with gel cells and didn't do a thing with our old style
ferroresonant rectifiers.  Big mistake.  Lots of gel battery plants were
frequently equalized and ultimately destroyed.  Eventually, we figured out
reading the documentation that came with the batteries might be a good
thing.

Today we rely on flooded lead acid cells for really enormous battery plants
(thousands of AH) and most sub 1000 AH plants rely almost exclusively on AGM
batteries and high frequency switcher type rectifiers.  Our plants are set
up so the batteries mainly provide filtering of the rectifier output and
offer the cell site equipment very smooth DC power. We think of a battery as
a giant smoothing capacitor. Telecom battery plants are placed in parallel
across rectifier output. Thus the rectifiers actually power the site
equipment.  The batteries only take the load when the rectifiers fail.  On
boats, batteries directly feed a DC buss that feeds all shipboard systems,
are on the input side of inverters and are the main supply of operating
power for shipboard systems.  Telecom systems are hoped to rarely even
partially discharge.  Thus batteries perform very different jobs for telecom
sites than for marine systems.  The real benefits to telecom operators of
AGM batteries are no monthly maintenance, reduced size, no equalization
requirement and no out gassing.  As usual it all came down to capital and
operating cost reduction.

So, why did I write all this?  Simple.  Our marine battery systems must be
designed to survive hundreds of charging cycles and a pretty adverse
environment.  Regardless of what battery type we choose, our single biggest
contribution to battery life appears to be properly sizing the amp hours of
the plant to address the expected load and appropriate discharge percentage.
Once that mission is accomplished, choosing the appropriate charger type and
applying an appropriate charging schedule or charger program seems to be the
next logical step.  Finally, maintenance of the plant, including corrosion
control (not mentioned in this thread but critical), becomes the last piece
of the puzzle needed to insure long life.  The problem with shipboard
battery plants is that you must do lots of things correctly to insure they
live a long life, regardless of which type you choose.  Throw in a dozen
accidental 100% discharges and all your planning and maintenance work can go
for naught with replacement looming as the only alternative.

If I were going world cruising I'd probably choose wet cells just in case I
needed to add a replacement in some far away land.  There would definitely
be an AGM with separate charging system up on the flybridge or somewhere
above the bilge for powering my ssb and other safety critical communications
gear.  If I were coastal cruising and never left the US, Canada, Australia,
NZ or other developed country I'd surely go all AGM (please don't flame me
for terming New Zealand "developed". They're big boaters, OK?).  We make
choices for our own reasons and, if we do our homework, stand a good chance
of being satisfied with the result regardless of which technology we choose
(Murphy notwithstanding).

Just my opinion, feel free to trash it...

Frank & Claudette Weismantel
Elverta, CA
Boatless for a little while longer

-----Original Message-----
From: trawler-world-list-admin@lists.samurai.com
[mailto:trawler-world-list-admin@lists.samurai.com]On Behalf Of Michael
Schooley
Sent: Friday, December 27, 2002 8:34 AM
To: '1trawler world'
Subject: TWL: RE: RE: Batteries
SNIP

Dear Mike,
You seem to be intimately familiar with AGM batteries, so maybe
you can answer a question I have.  Is there anything in the
design of AGM batteries that makes them inherently 2-3 times as
expensive as flooded cells?  I know that many manufacturers
charge a premium price for new products, to help recoup the
development cost in a short time, and to help promote the
product's premium image in the consumer's mind.  Can we expect
the price premium to come down as volume goes up?

I have waited for years for the price of 406 mhz Epirbs to
descend, but they never have.  While the price of GPS dropped
from $1000 to $100, the price of Epirbs inched down from $1000 to
$700.  What gives?

Mark Richter, Winnie the Pooh

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Mark Richter wrote;

"Dear Mike, You seem to be intimately familiar with AGM batteries, so
maybe
you can answer a question I have.  Is there anything in the design of
AGM batteries that makes them inherently 2-3 times as expensive as
flooded cells?  I know that many manufacturers charge a premium price
for new products, to help recoup the development cost in a short time,
and to help promote the product's premium image in the consumer's mind.
Can we expect
the price premium to come down as volume goes up?"

Basically AGM batteries are always going to be more expensive than
flooded lead acid batteries. There is no simpler or cheaper way to make
a battery that flooded. They don't need pressure regulated valves or
glass mats and the plate alloys are cheaper. OTOH if production rate
were equal, the cost difference should be about 10% as opposed to 100%
to 200%. I believe that the main reason for the cost difference is that
AGM batteries haven't broken into the high volume market yet (car
batteries). This is because car manufacturers don't see any value in
installing a battery that outlasts the warranty and once the first
battery dies few people understand the cost benefits of AGM batteries or
plan to keep the car long enough to recover their investment.

"I have waited for years for the price of 406 mhz Epirbs to
descend, but they never have.  While the price of GPS dropped
from $1000 to $100, the price of Epirbs inched down from $1000 to
$700.  What gives?"

"I don't know about EPIRBS, but I do know that the cost of GPS have come
down because of higher levels of integration which are only economically
feasible with very high volume. GPS used to require several hundred
components with a bill of materials cost of about $250. When you add
assemble, test, overhead, profit, marketing, ... the results was $1,000
unit cost. Today Motorola has developed a single integrated chip GPS
which cost $24. The kicker is the development cost was in the hundreds
of millions. Motorola will need to sell a billion to break even. There
aren't a billion boaters, but GPS is going into many cell phones to
provide the FCC mandated emergency location service. The problem with
ERIRBS is the market is too small.

Regards;
Mike Schooley
Designing "Portager" a 36' trailerable trawler