Expected life of marine battery

[Mario]

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252



capedory252@aol.com

[Dave]

It sounds like you have more going on here. You shouldn't have to replace those batteries that often. I know some boaters have had the same battery in there boat for ten years, with light use. Sounds like you have something draining the batteries. Are you leaving the power on when you are not on board? Are the zinc still there on your prop shaft? What kind of batteries did you bye and how many amp hours are they? Are you running both batteries at once? This from what I have learned on this board could be a problem. If the batteries have a different voltage in them or you have a gel cell and a regular battery that the batteries will try and equal out the volatege. This in turn will drain the batteries. I guess there are alot of posible problems. I hope this gives you a starting point.

Dave

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252

ddsailor25@ureach.com

[Ken Coit]

Mario,

We have some 10-year old Rolls batteries that still are OK. We have also had some automotive grade batteries that lasted only a season or two. It depends a lot on the service they were designed for and how you treat them. They don't like to stay discharged, they don't like being discharged below 50%, and their life is measured in charging cycles, not years.

Figure out why they are being discharged, frozen, or whatever, and you will have a better time of it.

Good luck,

Ken

It sounds like you have more going on here. You shouldn't have to replace those batteries that often. I know some boaters have had the same battery in there boat for ten years, with light use. Sounds like you have something draining the batteries. Are you leaving the power on when you are not on board? Are the zinc still there on your prop shaft? What kind of batteries did you bye and how many amp hours are they? Are you running both batteries at once? This from what I have learned on this board could be a problem. If the batteries have a different voltage in them or you have a gel cell and a regular battery that the batteries will try and equal out the volatege. This in turn will drain the batteries. I guess there are alot of posible problems. I hope this gives you a starting point.

Dave

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252

parfait@nc.rr.com

[Sean Morgan]

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252

Once you established why your batteries failed, your next step is to chose the proper type of battery.
FYI - Battery life expectancy is generally measured by the number of "cycles" they are capable of before they fail to hold roughly half their charge. A 'cycle" is defined as taking a fully charged battery and discharging it down to 10.5 volts. It is then charged back up to its full capacity.

As a good rule of thumb, marine starting batteries are capable of 75-95 cycles, deep cycle batteries are capable of about 200, and some gel and AGM batteries can cycle as many as 300 or more times.

Take a look in the West Marine 2001 catalog, electrical section, pages 556 to 560. In particular read the West Advisors for some great and easy to understand info re 12V batteries.

Have fun
Sean Morgan
S/V Irie



foursailors@prodigy.net

[mike mascaros]

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252

hi Mario....
I guess we all have had different experiences with our boats electrical systems...and i have been using delco voyagers deep cycle batteries....
this year i replaced them with new ones after ten years of service...the old ones are beeing use on my son s boston whaler and they are going strong....
maybe i been lucky...i keep my electrical system as simple as it came from factory...it may not be the case in the future this cape dorians are giving me a lots of ideas lots of room for improvements.....
but batteries should last longer ...
anyway cheers and good luck
mike/compinche CD30C 119....



compinchecd30@yahoo.com

[John R.]

Mario,

We have some 10-year old Rolls batteries that still are OK. We have also had some automotive grade batteries that lasted only a season or two. It depends a lot on the service they were designed for and how you treat them. They don't like to stay discharged, they don't like being discharged below 50%, and their life is measured in charging cycles, not years.

Figure out why they are being discharged, frozen, or whatever, and you will have a better time of it.

Good luck,

Ken

It sounds like you have more going on here. You shouldn't have to replace those batteries that often. I know some boaters have had the same battery in there boat for ten years, with light use. Sounds like you have something draining the batteries. Are you leaving the power on when you are not on board? Are the zinc still there on your prop shaft? What kind of batteries did you bye and how many amp hours are they? Are you running both batteries at once? This from what I have learned on this board could be a problem. If the batteries have a different voltage in them or you have a gel cell and a regular battery that the batteries will try and equal out the volatege. This in turn will drain the batteries. I guess there are alot of posible problems. I hope this gives you a starting point.

Dave

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252

A few additional points:

They don't like heat

They like slow gradual charging

Over charging is the end

Correct Service type and matching is critical

Absolutely no voltage leaks

Ample wire gauge size for the *entire circuit*

Long periods in dicharged state detrimental

Proper acid levels at all times if wet cell (distilled water only)

Clean terminals, clean battery tops at all times

Stored properly during cold months

Excess vibration must be eliminated (wet cells)

Low quality batteries have high failure rates under even the best of conditions. No question gels or AGM's will provide best service life in a situation like yours.

[Scott Ritchey]

There are two main factors that determine battery life: quality if the battery and how it is charged. With a good marine charger that's usually plugged into shore power, even low-cost batteries will last a long time. But overcharging (e.g. using an aotomotive-type charger) will kill a battery, especially if the fluid gets low (below tops of the plates). Chronic undercharging will probably kill it even faster. Depending on how you used the batteries (e.g. were they often discharged more than 50%) and how you charged them, a decent battery should last more than two years. Gell and AGM batteries can take more abuse, but there's nothing wrong with well-maintained wet (flooded) batteries.

If you find you need to add water to a flooded type battery often, there is something wrong. Either it is being overcharged (check with volt meter) of it is near the end.

I have a pair of low cost (about $50 at SAMs) flooded "deep cycle" batteries and they are over 3 years old, andboth are still going strong. But then I also keep them fully charged.

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252

ritcheyvs@aol.com

[Will W.]

You could also not have enough power, amoung many other potential problems. The trick, I think is tracking down the problem. Fixing it should be easy once the problem is isolated.
I recently purchased a copy of "Boatowner's Mechanical and Electrical Manual" by Nigel Calder. It explains boat electrical systems in detail. I am currently trying to learn how to rebuild my electrical system and everything I need to know seems to be in it. It is a bit expensive ;$50 at West Marine, but it is extremely informative. I'm sure that it or some similar manual would help you.
Best of Luck

Will Wheatley
Suzi Q
CD25

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252

willwheatley@starpower.net

[Murray Glue]

I use two Trojan six volt batteries in a single bank on my Cd30. They have lasted 3 years so far, but every 3 months I change them with two others which are kept at home and cycled whenever I can ( every month or so ) to keep them alive. The ones on the boat have a solar panel and regulator to keep them in good shape. I think that split battery systems and split charging systems are just too complicated for my little ship...I am happy to be the battery monitor, and checking them is one of the ships regular jobs.

Murray Glue
CD30 Dayspring
Nelson
New Zealand



murray@offshoretechnical.com

[D. Stump, Hanalei]

Mario,

Try this web site for everything you ever wanted to know about 12 volt systems and batteries. WWW.amplepower.com then click on "Ample Power Primer". Batteries DO NOT need to be connected to a charger ALL the time, as someone suggested earlier. I charge Hanalei's three times a year: before launch, when she is hauled for the winter, and once in January or February. I am on the third year of two Group 24 Exide batts from boatUS and they are just fine. Proper maintenance and feeding are the clue.

Dave Stump
Captain Commanding
s/v Hanalei CD-30C
CDSOA #1

[Larry DeMers]

Mario,

You have gotten quite a few opinions about what could be ailing your batteries, and most of it is good info. Here is my $.02 worth, based on actual experiences and too many years in engineering experimental batteries for Gould National Batteries/Marine Corp division.

I have personally gotten 10 years from the cheapest Wet-cell Deep Discharge batteries. The Group 31 I replaced this spring was 10+ years old and had been used as a power source for a trolling motor prior to being pressed into service on our boat. It also would take a full charge acording to the Specific Gravity of the electrolyte and voltage of the bank. The charger I was using at the time was a ferro-resonant charger, left connected all week long, and the electrolyte levels checked monthly (was needed as the ferro charger will not stop charging completely, so boils away the electroyte faster than a 3 stage charger). It failed when there was little capacity left, but the cells indicated that they were fully charged. It is still being used to start a diesel powered tractor at our marina.

What kind of charger do you use? Is it connected all week long? How deep a discharge do you pull from the bank before recharging?

- If you use a ferroresonant charger, you will have to add water much more frequently and a deep discharge could take 4-5 days to be completely replaced do to the very slow charge at the tail end of the ferro resonant chargers cycle, necessitating that the charger be left connected all week long while gone. To do otherwise results in a partially recharged battery, which has fewer amp-hours available to use, and will accumulate damage to the plates due to the partial recharging over time. The battery will have a few years life max, and will have a far diminished capacity..or ampacity.

- Discharging the bank beyond the 50% dischage floor will result in damage to the plates and diminish the life expectancy of the bank remarkably. (*The number of recharge cycles spoken by someone else earlier seems to be off by a factor of 10, at least according to my experiences). Typical values I have encountered are; Discharge floor (where you stop discharging the battery and begin recharging)at 35% of amp-hour rating (ie; for a group 27, use 100amp hours = 100% discharged and 50 amp-hours to the 50% discharge floor etc.), you should get 500 to 750 recharge cycles before any loss in capacity is noted. The loss in performance (capacity) is very gradual, dependant on your own cycling habits). If you use the 50% discharge floor as the cutoff point for discharging, then your max number of cycles before loss of capacity may be encountered is reduced to perhaps 200 to 500 cycles. If you use 100% as the cutoff point for recharging, then your expected life on that bank will be short..at 30-75 cycles perhaps. These numbers are of course rough estimates, that depend on several factors outside your direct control, such as plate thickness and separation, construction of the plate to dissipate heat quickly, but allow access of the electrolyte to the plates spongy surface entirely, and temp of the electrolyte/battery.

To Dave, who charges his cells, well...infrequently. This is the worst way to treat deep discharge cells that you can come up with. Your long life experienced with your bank is due to the apparently lite loads that you place on the bank itself, such that the bank is not really getting much discharge in total. Your total cycles in a summer are so few, that given your situation, you may be getting only 20-30 cycles before failure. That is not very efficient me thinks.


In our situation, where we are aboard every weekend, from mid-March thru November, we usually draw about 30-50 amp hours out per day (with lights, radio, reefer as loads). On the Group 31, with a 125 AmpHour rating, that is a lite discharge of around 24-40%. This allows the battery to be used as it was designed..litely. We recharge using a 3 stage intelligent charger and charge combiner that disconnects a bank when it reaches it's 100% recharged point. For the other house bank, we have a 225 AH Golf Cart battery bank of 2 -6v cells in series. With this bank, we do go 3-4 days without recharging..say 100AH worth. At that rate we are still above the 50% discharge point when we recharge. That bank should last a very long time also.

So you should be getting 3-4x better performance from that battery bank/charger setup. It is time to take a look at what is installed for a charger, the connections from the charger to the battery banks and to ground, what size the conductors are, and whether you have an unknown load still attached to the bank when the battery switch is turned off. Also electroylte levels need to **never** ever go below the top of the plates in the cells. Once they do for any sustained period of time, the plates will begin to grow crystals, which will eventually reach the neighboring plate and short it out (sulphation causes this).

This topic is complicated, but it can be made much simpler by paying attention to the few do's and don'ts mentioned in these posts.
If you have additional questions, feel free to write me offline anytime.

Cheers,

Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~Sailing Lake Superior~~~

This weekend one of Rhapsody's 12V batteries died. We replaced the other one in May. Both were only about 2 years old, according to the punched tapes on the batteries, and both came with the boat which we bought 6/00. Replacing them isn't expensive or difficult, but I was surprised to get only 2 seasons' worth of use out of them. We don't use them much except to start the engine so they are fully charged all the time. We noticed that as the batteries failed they would apparently charge fully on engine power or shore power, but even minimal use would completely discharge it. Water levels were fine and maintained all summer.

So--can we expect to replace these batteries every other year?

Mario
s/v Rhapsody
CD 30 #252

demers@sgi.com

[D. Stump, Hanalei]

Captain DeMers,

So, what to do? We do NOT use the 12v system for much else than the VHF, minor lighting, AM/FM radio, and domestic water pump. I believe what you are saying is that my lake appears full, but the water is very shallow.

How should I go about discharging the batteries and how often should I do so? For the minor load we place on them, they are probably at "full charge" after we motor back into the slip. Any suggestions appreciated. Oh, when I do charge them, I do so until they off gas freely and show "charged" with the spg. tester. Usually for about 12 hours.

D. Stump

[Don Carr]

I completely agree with you Larry. Although I use gel technology now, my experience with wet cell coincides with your dissertation. One additional technique is to 'equalize' the battery once a season or as many manufacturers recommend about every 4th cycle of deep discharge.

Having obtained a True Charge 20 (smart charger)I found dramatically better results on charging. I recommend a good quality non-ferro resonant smart charger..the charge quality has much to do with battery longevity.



carrds@us.ibm.com

[Larry DeMers]

Hi Capt,

Your charging routine is not a problem per se, as I see it. It is that you don't charge between uses except for a couple times a year that may be causing the bottom of the charge graph to rise, decreasing your deep discharge amount..As you say, it appears to be full, but may be a shallow charge.

What can happen, and indeed may be happening in your case, is that the lite and very occasional charging allows the electrolyte to stratify in the cells..because there is no charging going on (which tends to mix the electrolyte throughout the column) except for a lite alternator kick for the small drain that the house uses cause. You see, if the cells are used often and within the limits of 30-50% discharged, there is a good amount of 'stirring' going on in the cells when they recharge, which disperses the electrolyte evenly throughout the electrolyte column. This then keeps the whole plate active and ready for use.

When the plate is only litely discharged as your case seems to be, there is a definite loss of capacity over a short time, due to the stratification of the charge within the electrolyte column. Here is where an equalization charge really pays off.

This may be all you need to do Dave. Once every 6 weeks, run an equalization charge (**with all loads turned OFF** since the operating voltages will be 16v or so, higher than most electronics are made to take without problems). Unfortunately, there is a catch... you gotta have a 3 stage charger to do this..either on the alternator if it is externally controlled and/or on the shore charger. The cells will gas profusely, so follow the directions from the charger manufacture explicitly..especially the time limit for this operation.

The return to you will be batteries that tend to last nearly forever without problems at inopportune times.

For those that do use their batteries more heavily..anchor lights, electronics like radar, and reefer's etc., understanding this whole concept is an ironclad must. Heavier uses will show the low battery capacity problem much faster, requiring a replacement more often than desired. Usually at a bad time too...giving a bow towards Mr. Murphy and his laws.

So I hope you did not take offense at my differing opinion here. Your use is quite different than most folks, and that means that your case is non-typical.

Sincerely,

Larry DeMers
s/v DeLaMer
Cape Dory 30 ~~~Season is over on Superior..we pull out this weekend~~

Captain DeMers,

So, what to do? We do NOT use the 12v system for much else than the VHF, minor lighting, AM/FM radio, and domestic water pump. I believe what you are saying is that my lake appears full, but the water is very shallow.

How should I go about discharging the batteries and how often should I do so? For the minor load we place on them, they are probably at "full charge" after we motor back into the slip. Any suggestions appreciated. Oh, when I do charge them, I do so until they off gas freely and show "charged" with the spg. tester. Usually for about 12 hours.

D. Stump

demers@sgi.com

[D. Stump, Hanalei]

Captain,

Do you mean to say that I don't need to discharge the batteries to about 50% and then recharge them to maintain the full "depth" of charge. All I need to do is to hit them with an "equalization" charge to restore the full "depth" of charge or shall we rightly call that "capacity"? So, flooded batteries are not like ni-cads, that will take a set if only discharged a little and then recharged. This then would make a ni-cad show full charge when in fact the charge is very "shallow".

When I recently pulled the batteries and took them home to charge them, I noted that the electrolyte level was down a little in each cell. Plates weren't exposed, but level was definately down. Did it just evaporate, or is this an indication that in fact the batts. had been brought to an "off gassing" state and boiled off some electrolyte when charged by the alternator?

I don't remember what top voltage is when the alternator is charging, but I seem to remember about 13.5 to 13.8 volts. Wouldn't that cause the electrolyte to "boil" and remove the stratification problem?

Thanks for your help Larry........

Dave Stump