Before we left Malta we changed our seven year old Lifeline AGM batteries.  They were still in good working order, but as the new Hallberg-Rassy dealer on Malta, Yachting Partner had a shipment of Lifeline batteries coming in from USA, we decided to replace them as it is not easy to find Lifeline batteries in Europe.

880 Ah Battery bank

880 Ah Battery bank in aft cabin

If you are changing to Gel or AGM from open ventilated batteries (wet batteries), try to increase the spacing in-between the batteries is as much as possible to get airflow around the battery.  Gel and AGM are sealed batteries and do not dissipate heat as good as open ventilated wet cells.  Open ventilated batteries went out water when they get hot, but water that you can replace.  AGM and Gel do not have that option, and thermal runaway is a possibility if overheated.  I´m sure you have seen AGM or Gel batteries that looks like footballs at the recycling station!

Lifeline is a premium AGM battery.  It is about twice the cost, of a good wet battery with the same footprint.  This Model GPL-4CT is a direct replacement for the “6V Golf Cart” open ventilated batteries that has been installed in Hallberg-Rassy boats for many years.

The nice things with the “Golf Cart footprint” is that it is available worldwide.  If you find a golf course, this type of batteries will be available as it is used in the golf carts.  It is also a format used in many industrial applications and it might be better to visit the local battery store, than the chandler in the marina.

We have certainly enjoyed that the AGM batteries are maintenance free, but even more important that the self-discharge is low.  During the 6-month we are not sailing, the batteries are left in the boat disconnected.  With disconnected I mean that battery cables are not connected to the batteries.  In the spring the voltage is still 12.8 V after a 6-month rest.

Leaving open vented batteries in the Mediterranean area without charge for 6 month, would certainly be asking for problems as the self discharge is high in hot climates.  Leaving them and having someone recharging them on a regular basis is the only alternative.  Unfortunately there are many examples when this did not work as planned and the batteries were sulphated after winter storage.

If you are prepared to refill your batteries and can solve the storage problem when leaving the boat,   I´m convinced that open ventilated batteries gives you the best “bang for the buck”.  Our Trojan T-125  had many years of service when we changed them for Lifeline.  If  we were cruising full-time this would have been my choice.

There are AGM batteries built for all kind of applications and prices varies a lot.  The same can be said for open ventilated and gel batteries as well.  Normally you do not find the same quality for half the price!  Batteries for industrial applications is a mature product with very little differences in price if you compare batteries of same quality.  Do not just buy an AGM.  Buy a good AGM!

Lithium ION batteries is the new technology that we will see more and more in boats in the future.     I was doing some research before making the choice to stay with AGM.  In short Lithium hold much more energy/kg  than any other batteries.  You can also use 70-80 % of  energy in the  battery instead of 35%,  which means you can manage with a “smaller” battery bank which saves weight and storage.  The recharge time is determined by the output on your charge system, rather than the resistance in the battery bank.  Lithium ION absorbs the output you can produce without any decline in the end of the charge cycle.  The other big advantage is that Lithium ION do not suffer from sulphatation.

Technically Lithium ION is a superior battery in all respects, and I´m sure it will be a technology that we will see more and more in cruising boats.

On Bella Luna we use a lot of energy for all the toys.  Our battery bank is 880 + 220 = 1100 Ah on 12 V.  With Lithium ION it could be reduced to 500 Ah!!  As our alternator capacity is 240A  we could recharge that energy in  3 hours.  Well, in the end I decided not to go to Lithium.  Perhaps next time or on the next boat…..

The reason why I did not go for the Lithium ION was following:

– On Bella Luna weight and size is not that important and the battery boxes and cabling is already done for conventional batteries.  I would not be able to use the free storage place, as I would not rebuild the battery boxes.

– I think installation of Lithium ION batteries should only be done by a reputable company, with a track record of earlier successful installations.  It is a new technology that have experienced some problems only a few years ago.  Take advantage of the knowledge they have built on,  and you might not have to hear “you should have done it like this”.

-I´m sure availability for Lithium ION will be a problem in remote cruising destinations.  If your boat is designed for Lithium ION, it will not be easy to source an alternative to Lithium as there will not be enough space.

– When I contacted  suppliers,  I was told that Lithium ION will last 7000 cycles and because of that it is  more economical alternative than my AGM.  We sail 6 month/year and cycle the batteries perhaps every third day. (Before we installed 440W solar panels)  That means 60 cycles/year.   If cycles would be the only problem, Lithium ION would last 116 years!

When I asked what the design life was, I got no answers.  cycle life is bla, bla, bla……..              Design life is how long the batteries will last in float. (Fully charged on the shelf)  At last one manufacturer came back and disclosed that design life is approximate 10 years.  I´m sure all Lithium batteries are about the same.  With this information it might be more prudent to base your decision on 10 years pay back time, than 7000 cycles!  (7000 cycles over 10 years is 2 cycles/day!) What is harder to put a numbers on, is the savings on less recharge time with engine or generator.  Fewer hours does not only save diesel, it also means less wear on the generator and engine.

When choosing new batteries there are many things to think about:

  • Changing cables, connectors and rebuilding battery boxes is expensive.  Sometimes as expensive as the batteries. Choose a footprint that is available world-wide.
  • If you end up in a remote part of the world you want to avoid expensive shipping of new batteries with odd sizes. Owners to older HR and Tudor truck batteries know what I´m talking about. The Tudor truck batteries were difficult to source outside Sweden.  Choose a battery that is used in an industrial application and the chances increases that you find it next time you change your batteries.  Prices on batteries used in industrial applications are normally lower if you can avoid the marine store.
  • Gel, AGM, Lithium have low self discharge that is an advantage if left without charge in hot climates. They also requires regulated charge to avoid damage due to overcharge. A good regulator to the alternator is important.  The regulator that comes with the standard engine is not a good option as the float voltage is above 14V and will not be regulated down. This is a problem if you motor many hours and the batteries are getting fully charged.  Recommended float voltage AGM/Gel is in the region 13.2-13.4 V.  Check with your supplier.
  • How much battery do I need?  With a AGM, Gel or open ventilated battery you can only use the capacity between 50-85 %.  (35%)  You do not want to discharge under 50% and it is not economical to try to charge to more than 85% with your engine or generator. (Do not panic if you once in a while have to discharge the battery to only 25 %. A good battery is normally designed for cycling down to only 25 % left.   The sweet spot for maximum cycle life is normally 50%.)
  • Life expectancy. Get the rated cycle life when discharged to 50% as this is the sweet spot for most batteries.  (With Lithium, forget about cycles and calculate with 10 years or what they say is the design life or shelf life)   Compare this figure with the purchasing price and how you use your batteries.  The more expensive battery might have better cycle life.  Question is, if it is the most economic alternative?  It might be more economical to buy a cheaper battery and change more often.  I talked to one technician on a large battery manufacturer.  He said, it is very seldom they come across a boat battery that died because it was cycled too much.  Much more common is that the battery is damaged because of sulphatation.  Sulphatation happens when we are not able to fully recharge the batteries on a regular basis.  Lifeline recommendation is that the  battery is fully charged to 100% every 10 cycle. Lithium batteries does not suffer from sulphatation.

And finally even the best battery must be replaced one day.  If you live on the boat and use it every day this will happen sooner than later.

Our earlier Lifeline were good after seven years cruising.  That might sound like a fantastic battery, but the truth is that it was sitting on float with the battery charger in float mode most of the time.  Our cruising was weekend sailing and a four week summer cruise for five years out of the seven.

It is unrealistic to expect the same life expectancy when doing  long-term cruising.  Here in Greece it is a long distance between the marinas that offer electricity.  We cruised eight weeks whiteout plugging in to shore power!  We have installed 440 W Solar panels that helps  topping up the batteries when off grid.  More about that in another article.





  1. Steve Ricci

    Good note, Roland. Nigel Calder lives in my old Marina in Boston and does a lot of research in this area. You probably have come across some of his articles. – Steve

  2. Roland Post author

    Hi Steve, Hope you have had time to enjoy the boat this year. Have met Nigel several times and also have his books on the boat. Excellent books! Best Roland

  3. Yves George

    Dear Roland ,

    Excellent summary , well balanced on the pro and cons of the different types of batteries .
    With a life long engineering career in power generation and power transmission and distribution , I can bring some industrial know-how : the preferred solution when weight is not an issue (NOT cars e;g; ) is still classical open cell batteries with a professional maintenance procedure .

    On Cayuga , I use commercial lead batteries and get easily a life time of 6-7 years : the discharge problem in the winter is not an issue as we have average temperatures of +/-5°C . As you rightly pointed out the batteries must be FULLY disconnected (all wires detached ) : after 5 months winter storage , the batteries are still 75-80% charged , measured by my NASA battery monitor ; water level is checked only once a year .


  4. Roland Post author

    Dear Yves, Thank you very much for sharing your professional knowledge and experience.

    Over the years I have been talking to many people in the battery trade. The technicians always recommend open cell, and the sales people recommends AGM or Gel. The most important reason for me to go with AGM is that it solves the storage problem we have when we do not use the boat!

    The lower resistance of AGM technically means I should be able to recharge faster. I used a 14.8 V bulk voltage on the open cells. With the AGM it is 14.4 V. The difference 0.4 V might not sound a lot, but when charging batteries it makes a diffrence. The charge of the AGM is only marginally faster.

  5. Jeff

    When cruising, most Lifeline Battery banks last about two years. This is because 1) they are organized as parallel strings and 2) they rarely get fully charges. It is very clear that every additional parallel string (you have 4 of them) reduces total battery life by a significant amount, up to 30% or more. Golf cart batteries are convenient, but are not going to last long. We also have Lifeline AGM batteries but they are organized into a bank of six 2-volt cells (AGM 900AH GPL-6CT-2V) to give a total of 900AH. I.e. we have ONE BIG BATTERY which still needs proper full charging every third day or more, but avoids the degradation associated with parallel strings.

    1. Roland Post author

      Dear Jeff,

      Thanks for your input. Very much appreciated.
      Techniqally it is better if paralell strings can be avoided. But the question is if it really is as damaging as you say? When I was in the marine business we delivered 1000 of boats with Golf Carts in parallel. We never did see any higher failure rate because of that. Many customers reported 7-8 years use before replacing. That was open 6V like Trojan. My first set of Lifelines was in good condition after many years in service when replaced. The first set of Lifelines did however get much more time on shore power. But on the other hand I cyckled much deeper (50%) as I had no solar panels.

      I´m not yet 100% convinced sure that AGM will be as long lived? Time will tell. But there are other factors that are important. AGM are maintenance free. I can charge them full and disconnect them for 6 month. When I get back they are more or less same voltage as when I disconnected them. That would not been the case with open ventilated batteries.

      I actually did a capacity test on my Life Lines batteries, 3 days ago. They have been used 2 seasons for 12 month of cruising. Most of the cruising was done in Greece. That means only shore power every 4-5 weeks.

      The batteries are still perfoming as new. Our bank cycles between 70-90 %. It never goes under 70 % as we have solar panels.

      The 2 V cells you are referring to is excellent batteries. I´m sure you will be satisfied. The only concern I have with them is that they are difficult to source in remote cruising destinations.

  6. peter cs bae

    Dear Roland,

    Thank you for valuable knowledge and info. listed on this SY Bella Luna.

    I like to know how people handle height of battery issue, I just installed 8 of 4PL Lifeline benchmarking your installation and could not close the battery box cover since bettery height of Lifeline is higher than wet batteries. (HR seems like designed battery box based on wet batteries.)


    1. Roland Post author

      Dear Peter,

      In the very beginning HR used Heavy Duty Truckbatteries from Tudor for many years. It is hard to find a matching battery if that is the case. Sonnenshein gel batteries is one option. Many owners have had to rebuild the battery boxes in order to install new batteries from another brand.

      In the early 2000 the yard started to install “wet golf cart” instead of the Tudor. One of the many advantages is that they are available wordwide. The Lifeline AGM are actually 10 mm lower than the original golfcart batteries.

  7. Ernest Vogelsinger

    Hi Roland,
    as I found on the excellent MarineHowTo site ( LiFePO4 batteries don’t need to rest at full charge, their expected storage should be done at approx. 50% of their capacity. So a constant float charge would not be necessary to get them over the resting period – when you are winterizing your boat, simply turn off the electrics and leave them unattended. They should feel more comfortable this way.
    Best regards, Ernest

    1. Roland Post author

      Great article,

      I have no doubt that LiFePO4 batteries is the future. Next time perhaps!
      Perhaps we then have seen a substantial price reduction.
      So far my Lifelines are doing just great!


  8. Lasse Berg

    Hej Roland !

    Jag har köpt Lifeline GPL-4CT och instalerat det i min HR342-271.

    Du nämner ovan att när man kör för motor så laddar den med ca.14,25 V och det är för mycket för AGM batterierna, de ska ha 13.2- 13.4 V skriver du ovan.
    Det verkar inte vara så många som vet om detta, eller vad man gör åt det.
    Det verkar som de flesta bara kör på med den laddning som generatorn och laddningsregulatorn ger ?
    Hur gjorde du för att få ner spänningen till 13.2-13.4 V ?

    Jag har ställt om min Mastervolt/Kombi Inverter på AGM batterier, så det ska ladda rätt när man kör på landström.

    Lasse Berg

    1. Roland Post author

      Hej Lasse,
      Det var ett tag sedan. Det finns två laddspänningar som Du bör hålla reda på. (Absorption (en del kallar det bulk) och float.

      Lifeline rekommenderar:
      Bulk/Absorbtion skall vara ca: 14.6V vid 20C.
      Float skall vara ca: 13.6 vid 20C.

      Det betyder att 14.25 V är O.K. om inte perfekt. 14.5 -14.6 V är bättre. Högre spänning ger snabbare laddning!

      Din Mastervolt laddare har fasta inställningar för olika batteri typer. Det finns många AGM tillverkare. De har olika rekommendationer. Vilka spänningar Mastervolt har för AGM vet jag inte. En del laddare kan programmeras. Jag har programmerat min laddare så att den ger den spänningen som tillverkaren (Lifeline) rekommenderar.

    2. Roland Post author

      Hej igen Lasse, Jag tror jag missuppfattade Din fråga. Du har en inbyggd (dum regulator) Den levererar 14.25 V så länge som motorn går. Den går aldrig i float. Det kan vara ett problem för AGM om Du går motor många timmar. Risken finns att Du överladdar batteriet. Torkar ur batteriet. Eftersom det är ett slutet batteri kan Du inte fylla på vatten. Det vore bättre att Du byggde om Generatorn för en extern regulator där Du kan ställa spänningen till 14.6 resp 13.6. Ett annat alternativ är att köpa en Sterling Power alternator to batterycharger. Det är en laddare som Du sätter mellan befintlig generator och batterier. Den kommer göra laddningen bättre/snabbare utan att riskera att torka ut Dina nya Lifeline.

      1. Lasse Berg

        Tack Roland för snabbt svar !

        Ja, det var ett tag sedan, vi köpte ju båten av dig och fick den levererad 4-5 Maj 2011.
        Vi trivs bra med båten, men en lite större vore bättre !
        Jag har följt eran blogg och speciellt dina Hands-On-Tips, intressant !
        Sjösatte i Fredags och Mastade på och bytte batterierna nu i helgen.
        Så nu bär det av upp till Bohuslän över våren.

        Jag köpte en Battery Mate 1603-IG igår, som jag ej installerat ännu, tvekar lite nu ?!.
        Den tar ju bort förlusterna och levererar 14,6 V men sedan går det ju inte att ställa in den på någon lägre spänning, utan det blir ju så att resistansen ökar när batterierna börjar bli fulladdade och då går spänningen ner lite men till vad ?
        Men det är frågan om det kommer förstöra batterierna om vi kör motor i 10 timmar i sträck exempelvis.
        Det här känns som en djungel, verkar som jag skrev innan att man inte tar hänsyn till detta när man har AGM batterier utan bara kör på, med förkortad livslängd med hur mycket ?
        Hur mycket är det värt att kosta på att bygga om med bättre grejer och vad skulle det kosta ?

        Mycket Tankar !

        Ha det bra !



Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.