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Hi All,

I have (2) group 27 lead/acid (maintenance type) batteries on the ship now, they're 3+ years old and after doing the "battery health" checks, they're both at about 70-75%. This winter I was going to swap them both out. Question is: with what. There are 3 types of batteries I could install; maintenance, sealed and gel. Is this correct? I've seen some brands that are sealed, but are $450. :eek: Is your everyday "no maintenance" battery that expensive? I just don't want to deal with checking and adding water anymore (batteries are a pain to get to). Thoughts, recommendations? Thanks.

Dave
 

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Sams Club sells Group 31 AGM batteries for about $180 each. But if you are only getting 3 years out of flooded batteries it sounds like there's an inadequacy with your charging setup. Undercharging an AGM will shorten its life even more than undercharging flooded.

You may be best off sticking with flooded, getting a battery watering system, and improving your charging.
 

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Discussion Starter · #3 ·
Sams Club sells Group 31 AGM batteries for about $180 each. But if you are only getting 3 years out of flooded batteries it sounds like there's an inadequacy with your charging setup. Undercharging an AGM will shorten its life even more than undercharging flooded.

You may be best off sticking with flooded, getting a battery watering system, and improving your charging.
I have a West Marine charger that seems to work just fine. I turn the charger on when I'm at the boat only. When the charger is on the batteries show 14.5 VDC (there about). But the minute I take them off the charger and remove the surface charge, they go right to 12.25 - 12.32. If I look at the charts correctly this is somewhere between 60-75%.

The PO said he got 7 years out the last pair doing this. Basically never used the batteries on their own, i.e. always had shore power plugged in with the charger on or running the engine.

See anything out of the ordinary here?
 

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I have a West Marine charger that seems to work just fine. I turn the charger on when I'm at the boat only. When the charger is on the batteries show 14.5 VDC (there about). But the minute I take them off the charger and remove the surface charge, they go right to 12.25 - 12.32. If I look at the charts correctly this is somewhere between 60-75%.

The PO said he got 7 years out the last pair doing this. Basically never used the batteries on their own, i.e. always had shore power plugged in with the charger on or running the engine.

See anything out of the ordinary here?
I think if you are going to stick to a West Marine charger, then I would stick with wet cell batteries. If you have room I would put in golf cart batteries. They seem to be able to take quite a bit of abuse and the plates are thicker and last longer than most of the 12 volt "deep cycle" that are mostly just relabeled starter batteries. Unless you go with a big name battery. If you go either jell or AGM then I would recommend going with a more sophisticated charging system as both seem more sensitive to correct charging. Do you have any solar or other means to charge when not plugged in.

If it were me, I would get golf cart batteries at Sams Club, and be done with it. Even if you just get one pair to replace the 2 batteries you have. If you really want to up your bank capacity then get 4 golf cart (they are 6 volts and are wired in pairs to equal 12 volts)
 

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I wonder if you have some sort of parasatic load. Maybe try disconnecting the batteries entirely for several hours and then try testing the voltage. You could also take them to an auto supply store for a true load test. It may be worth investing in a small solar panel to trickle charge the batteries when you're away from the boat. If you go AGM you will need to make sure your charger is three stage with a setting for AGM charging. I would still stick with flooded and golf cart batteries are a good recommendation.
 

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I agree with the golf cart suggestion. They are actually a bit smaller than group 27 in length but are taller. The best value in batteries and very long lived - true deep cycle as opposed to any affordable 12 volt battery.

I would also stick with flooded batteries. You will very likely get less life with Agm batteries and gels are very rare now but very expensive as well if you can find them. I would also look at a new charger - the Promariner Pronautic P or the Blue Seas are probably the best choices available - both come with temp sensors as well, a must I believe.
 

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I had somewhat similar problems until I got a 20W solar panel and controller to keep everything topped off. I have two 6V flooded "golf cart" batteries (225Ah) for the main bank, and a 12V AGM (50Ah) reserve bank, with a Yandina combiner between the banks. All the charging (via solar, alternator, or shore; I almost never use the shore-powered charger anymore) goes into the main bank and the combiner steps the voltage down a bit for the AGM reserve. Works great. No more half-charged batteries after not having been on the boat for a while.

Note: I am in Southern California, and 20W of panel seems more than adequate. However, you may need a bit more solar panel in Washington State.
 

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I have golf cart type batteries and only check the water every couple of months, but if you really don't want to check the water the AGMs are the way to go.

But before you do anything you should fully charge the batteries you have as based on your description you have not been fully charging them.
 

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I second the recommendations for flooded batteries and a solar panel.

You can buy a nice deep cycle at Costco for around $100. I use two in a bank with the switch on both.

My batteries stay fully charged with a 40 watt panel and a simple charge controller with an inline fuse. It also allows me to use an autopilot full time when cruising. Occasionally, I add distilled water in the summer when the batteries lose some fluid.

Keep it simple and inexpensive.

My batteries are on their third season and doing fine. If one will no longer hold a charge, I will replace it with another $100 battery. Big deal - it is a fraction of the set up costs for many other house battery set ups.
 

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I am on my 7th year with Lifeline 6v AGM with no drop off noted at all. The trick with agm is to make sure they get charged back up. AGM are not for everyone and its imp[ortant to match your sailing, usage, charging capabilities ( engine and shore), passsoive ( solar). all together. Buying expensive agms is not worth it if you cant keep them charged and topped off

We are able to so they have been cost effective amd this year have paid for themselves vs similar wet cells. The next few years should they continue to last will be the cost savinings over wet cells for us. Also note Lifelines are able to be equalized which we do regularly to desulfate them

Your applicaion sounds like wet cells and a better charger
 

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I get seven or eight years out of wet cell batteries. $/Ah/year-of-life wet cells are the best. If you are going to pay the premium for AGMs part of the deal should be upgrading charging to take advantage of the faster available charging rate. My 80A shore power charger and 120A alternator don't justify AGMs for my 900 Ah house bank.
 

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Never an easy choice, really. Wets seem to be the best value, AGMs can be charged quickly, but are seriously needy and must have high end charging and temp control systems included.

Our house bank is 400+ amps of gels. The primary reason is the OEM charging system was designed for them and it was too much trouble to change, when the time came. However, they do have a few other advantages. They self discharge very slowly, which is helpful for us over the winter. I can't leave the boat plugged in and it's impractical to remove all 13! batteries aboard (four of which are house). Also, gels can withstand a few accidental deep discharges and live, which sounds good for house batts.
 

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Never an easy choice, really. Wets seem to be the best value, AGMs can be charged quickly, but are seriously needy and must have high end charging and temp control systems included.

Our house bank is 400+ amps of gels. The primary reason is the OEM charging system was designed for them and it was too much trouble to change, when the time came. However, they do have a few other advantages. They self discharge very slowly, which is helpful for us over the winter. I can't leave the boat plugged in and it's impractical to remove all 13! batteries aboard (four of which are house). Also, gels can withstand a few accidental deep discharges and live, which sounds good for house batts.
GEL's are hands down the longest lasting VRLA battery, when charged properly...I have multiple customers who are well beyond 10 years...
 

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To echo what most others are saying if you can fit golf cart batteries do that and be done. They're good and cheap. 2 golf carts and a group 24 or group 27 backup battery is a good set-up.

If you can't fit golf cart, regular costco (etc.) deep cycles are fine too, not quite as long lasting but decent.

As an aside there I find it frustrating that you have to skip the batteries labeled "marine" and choose "golf cart" to get the best marine batteries. But such is life. Golf cart batteries (and a few other more obscure types) really do have the thickest plates, and therefore last the longest under deep cycle use (with a relatively small penalty in starting power).

Solar is always a good thing to have. Smallish solar systems are pretty cheap these days. 1-$200 will keep you topped off if you're a weekend sailor.
 

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Hi All,

I have (2) group 27 lead/acid (maintenance type) batteries on the ship now, they're 3+ years old and after doing the "battery health" checks, they're both at about 70-75%. This winter I was going to swap them both out. Question is: with what. There are 3 types of batteries I could install; maintenance, sealed and gel. Is this correct? I've seen some brands that are sealed, but are $450. :eek: Is your everyday "no maintenance" battery that expensive? I just don't want to deal with checking and adding water anymore (batteries are a pain to get to). Thoughts, recommendations? Thanks.

Dave
and

I have a West Marine charger that seems to work just fine. I turn the charger on when I'm at the boat only. When the charger is on the batteries show 14.5 VDC (there about). But the minute I take them off the charger and remove the surface charge, they go right to 12.25 - 12.32. If I look at the charts correctly this is somewhere between 60-75%.

The PO said he got 7 years out the last pair doing this. Basically never used the batteries on their own, i.e. always had shore power plugged in with the charger on or running the engine.

See anything out of the ordinary here?
Basic battery types;
  • Lead Acid or FLA or "Wet Cell"
  • Sealed or Maintence Free (proof!)
  • Gel Cell
  • AGM
  • and then there are exotics like Lithium Iron Phosphate (new) and I have even heard that someone used Nickle Cadmium(!)... but let's try to keep this simple.

The best bang for the buck at this time is in Lead Acid batteries. Unfortunately, they require periodic maintenance, which INCLUDES charging to 98+%, AND adding distilled water (about once every month or three). Simply connecting the battery to a charger, and measuring the voltage while charging, or shortly thereafter, is NOT checking the health of the battery.

The proper way to check the "health" of the battery with only a volt meter is; disconnect all loads from the battery, charge the battery, and then let it rest for 24hrs to see what the voltage is. (you could pick nits with this, but I am assuming that your test equipment consists only of a DVM)

Per Nigel Calder, at 70°F
  • 100% - 12.6-12.7V (wet) 12.85-12.9V (gel) 12.8-12.9V (AGM)
  • 75% - 12.4V (wet) 12.65V (gel) 12.6V (AGM)
  • 50% - 12.2V (wet) 12.35V (gel) 12.3V (AGM)

Your reading of 14+ volts is simply a reading of the charger's output...
 

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Basic battery types;
  • Lead Acid or FLA or "Wet Cell"
  • Sealed or Maintence Free (proof!)
  • Gel Cell
  • AGM
  • and then there are exotics like Lithium Iron Phosphate (new) and I have even heard that someone used Nickle Cadmium(!)... but let's try to keep this simple.

The best bang for the buck at this time is in Lead Acid batteries.
Ummmm which "lead acid" batteries...?;) Arghhhhh the semantics kill me some days....:D

ALL BATTERIES WHETHER GEL, AGM or FLOODED ARE LEAD ACID....:)

The proper way to check the "health" of the battery with only a volt meter is; disconnect all loads from the battery, charge the battery, and then let it rest for 24hrs to see what the voltage is. (you could pick nits with this, but I am assuming that your test equipment consists only of a DVM)
There is no way to test the "health" of a battery with a volt meter. All you can test is SOC. Open circuit voltage readings do not represent the health of the battery, nowhere even close.

Battery health can only be determined by a physical capacity test (reserve minutes @25A or 20 hour test) or a capacitance test. Even expensive capacitance testers only test for short duration "impulse" or cranking capacity and are not accurately representative of the actual Ah capacity left in the battery.

Per Nigel Calder, at 70°F
  • 100% - 12.6-12.7V (wet) 12.85-12.9V (gel) 12.8-12.9V (AGM)
  • 75% - 12.4V (wet) 12.65V (gel) 12.6V (AGM)
  • 50% - 12.2V (wet) 12.35V (gel) 12.3V (AGM)
While Nigels chart is one of the better ones, open circuit voltage for SOC ideally needs to be determined from each manufactures product or spec sheets. Better yet physically testing your own batteries.. Because of the way batteries are "formed" today the old on-line voltage points for batteries are no longer very accurate when applied across the board..

I am pretty sure Nigel would agree that the latest technology AGM batteries we are currently field testing do not fall into any of the voltage windows above. I have one of them on my bench today that has been at over 13.0V now for the last 7 days in a shop that has been above 70F for 7 days....

The group 31 prototype battery that is currently undergoing a full 20 hour test is at 12.716V with 7.614 Ah's removed and was loaded at the 20 hour load when that voltage reading was taken.... I paused the capacity test when writing this post and the voltage rebounded to over 12.97V (and was still rising) yet this battery has had a solid 7% of its capacity removed. A resting 12.97V OCV is not full on this battery....

7.614 Ah's removed over 1:23 minutes at 5.5A and the battery voltage still climbed past 12.974V when the test was paused, and voltage was not yet stable and still climbing. (NOTE: This is a calibrated lab grade tool I use for capacity testing and constant load applications so the accuracy shown here would be very difficult to reproduce on your own boat.)


Back under 20 hour capacity test:


Different batteries support different voltages and each owner really needs to determine what full is for their bank in order to get an accurate reading..

Another huge factor is battery temp. With cool batteries, like the bilges of boats in the North East, batteries will take many days to attain a resting voltage and 24 hours simply may not be enough..

Your reading of 14+ volts is simply a reading of the charger's output...
Bingo, even LiFePO4 don't rest at 14+V and any of the lead acids will drop below 14V pretty quickly, though they may slow the voltage decay at 13.6V or so. Some AGM's in cooler bilge areas will sit at over 13V for a number of days but not 14........
 

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Ummmm which "lead acid" batteries...? Arghhhhh the semantics kill me some days....:D

ALL BATTERIES WHETHER GEL, AGM or FLOODED ARE LEAD ACID....
Yup, I agree that these are ALL three types listed are variants of lead acid, but for the OP's benefit, I was trying to simply differentiate between FLA, AGM and Gel, the three most common types of batteries in use today... And I should have said "FLOODED Lead Acid."
There is no way to test the "health" of a battery with a volt meter. All you can test is SOC. Open circuit voltage readings do not represent the health of the battery, nowhere even close.

Battery health can only be determined by a physical capacity test (reserve minutes @25A or 20 hour test) or a capacitance test. Even expensive capacitance testers only test for short duration "impulse" or cranking capacity and are not accurately representative of the actual Ah capacity left in the battery.

...

While Nigels chart is one of the better ones, open circuit voltage for SOC ideally needs to be determined from each manufactures product or spec sheets. Better yet physically testing your own batteries.. Because of the way batteries are "formed" today the old on-line voltage points for batteries are no longer very accurate when applied across the board..

I am pretty sure Nigel would agree that the latest technology AGM batteries we are currently field testing do not fall into any of the voltage windows above. I have one of them on my bench today that has been at over 13.0V now for the last 7 days in a shop that has been above 70F for 7 days....

The group 31 prototype battery that is currently undergoing a full 20 hour test is at 12.716V with 7.614 Ah's removed and was loaded at the 20 hour load when that voltage reading was taken.... I paused the capacity test when writing this post and the voltage rebounded to over 12.96V (and was still rising) yet this battery has had a solid 7% of its capacity removed. A resting 12.9V OCV is not full on this battery....

Different batteries support different voltages and each owner really needs to determine what full is for their bank in order to get an accurate reading..

Another huge factor is battery temp. With cool batteries, like the bilges of boats in the North East, batteries will take many days to attain a resting voltage and 24 hours simply won't be enough..
I knew that this would come up... Again, I was trying to keep this simple, perhaps overly so. However, most boaters don't have access to the test equipment that you do. For most of us, testing is using a volt meter (PLEASE, at least use a good DVM, and not the analog meter on the breaker panel!)
 

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Yup, I agree that these are ALL three types listed are variants of lead acid, but for the OP's benefit, I was trying to simply differentiate between FLA, AGM and Gel, the three most common types of batteries in use today... And I should have said "FLOODED Lead Acid."

I knew that this would come up... Again, I was trying to keep this simple, perhaps overly so. However, most boaters don't have access to the test equipment that you do. For most of us, testing is using a volt meter (PLEASE, at least use a good DVM, and not the analog meter on the breaker panel!)
I agree simple is always best!

Unfortunately simple can get you into trouble at times.. I tested a bank a few weeks ago that put up just 56% of its rated capacity. The owner was using open circuit voltage and basing that off the when new Ah capacity rating of the batteries.

The reality was as the health of the battery slid he was drawing is bank to about 10-15% SOC (actual) and devices began shutting down on low voltage. He assumed he had more capacity then he really did and because his OCV readings were still reading okay (above 12.6+ when rested) he assumed he still had the capacity he always had... In his case using simple, eg:voltage only, failed him because he had no way to track overall health and his voltage performance observations were clearly lacking..

This is not an uncommon conundrum and not a problem that is relatively easy to solve.

As for the OP:

Hi All,

I have (2) group 27 lead/acid (maintenance type) batteries on the ship now, they're 3+ years old and after doing the "battery health" checks, they're both at about 70-75%. This winter I was going to swap them both out. Question is: with what. There are 3 types of batteries I could install; maintenance, sealed and gel. Is this correct? I've seen some brands that are sealed, but are $450. :eek: Is your everyday "no maintenance" battery that expensive? I just don't want to deal with checking and adding water anymore (batteries are a pain to get to). Thoughts, recommendations? Thanks.

Dave
If you can't tolerate the 10 minutes once per month or every other month to check electrolyte, Water miser caps can help. Unfortunately these are usually only available for 6V or true deep cycle batteries but some could be made to fit cheaper batteries...

If you don't want to go that route then buy the cheapest valve regulated batteries you can find and ignore the price. Don't be too surprised when they are dead in a few years despite the higher cost.. Or just by the cheapest flooded batteries you can find and toss them every few years and replace.... There are some maintenance free flooded "dual purpose" batteries but their cycle life generally sucks...

It seems like opening the cells would be faster and easier than replacing the batteries every few years...

There really is no free lunch. All batteries, sealed or maintenance, like proper charging and proper care.
 
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