Tag Archives: Batteries


After installing the new Life Line batteries, I installed new Solar Panels.  The new generation panels produce more energy per sqm, compared with the earlier generation.  They are also more efficient and convert 21.5 % of the solar energy to electricity instead of 17-18%.  But best of all, weight is only 1.8 kg /100W which makes it possible to install them on the Bimini.

After installation we now have five solar panels, (total 444 W).  A sunny day in the Mediterranean they produce 25 A/h.  Morning and evenings we get less, as the sun is at an angle and less intense.  After the installation our batteries have never been under 75 %.  Keeping in mind we did not plug-in to shore power for 8 weeks in Greece, that is pretty good.

24 A on a Sunny day

23.9 A on a Sunny day!

If you read my article about batteries, you might remember that battery manufacturers recommend that you charge the batteries full every 10 days to avoid sulphatation.  Without Solar panels it would not have been possible to charge the batteries to 100%  just by motoring.  With the panels it was not unusual that the batteries were fully charged already after 4-5 engine hours, as we started at 85-90 %.


So how do you install that many solar panels on a boat whiteout making it look terrible?  I was not allowed by Vickie to install a tower across the stern.  Last year in Malta I did see some boats with solar panels on the Bimini.  I contacted the supplier, and got a price that was crazy expensive.

Back in Sweden I did find a company that sold panels with the same specification to a lower price.  I contacted Viktor on Teknikhamstern.  It was a delight to correspond with Viktor as he did know his product.  All the questions I had, were answered.  When he did not have an answer, he got back after some reserch.  It did not take long until I had signed up for four panels.

Two panels are installed on top of the Hardtop, and two more on top of the Bimini.  We also  had an existing 44 W panel in front of the Hardtop.  The two panels on the Bimini was the challenge as they had to be installed on top.

2 x 100W on Hardtop

2 x 100W on Hardtop

2 x 100 W on Bimini

2 x 100 W on Bimini

The solar panels on the Bimini were installed with velcro and Tenax buttons.  I glued 50 mm velcro to the edges of the panel and had velcro stitched to the Bimini.  Under each panel there are two long battens in the same length as the panels. This was necessarily as the standard model did not have a reinforced backside and could be damaged by vibrations.

The new Sunzip models have a reinforced backside to stabilize the panel.  The Sunzip model has  velcro attached to the backside as standard.

It takes in total about 3-5 minutes to take down the bimini including the panels and battens.  The panels have quick MC4 contacts.  We had 40 knots whirlwinds in Monemvasi and did not experienced  any problems.  Some boats took down their sun protections as the wind was gusting so hard.

So far we are really happy with the amount of energy the panels are producing.  It is better than expected.  With this setup I would consider to reduce the battery bank next time we have to buy new batteries.  Off course we are in a very good area for Solar Panels!!  Take a look at this weather forecast for the Athens area.  This is the weather we have had most of the summer.

Sunshine in Athens

Sunshine in Athens

Sun hours in Athens

Sun hours in Athens i August


Avoid any shadows if possible!  Building a tower over the stern with antennas on one side, and a wind generator on the other is not a good solution as there will be shadows covering parts of the panels.  Even the smallest shadow reduces the charge a lot!!!  In fact a cloudy day with indirect lightning, can be better than a sunny day with a small shadow.  If you install a tower make sure that antennas etc, are under the solar panels.

When we are at anchor we pull out the main boom to one side.  As the sun in the Med is almost straight up, it is unusual with shadows from the mast itself.

Position of regulator

The voltage out from the solar panels are around 19 V.  Higher voltage means less voltage drop.  The “out” voltage from the regulator is 14.4 V.  On this side a voltage drop will be more significant as the voltage is lower.   I installed the regulator in the locker behind the electrical panel.  Our  batteries are in the aft cabin, and you might think that is not so close to the batteries.  The distance is about 3 m, but the cabling  is massive (350 mm2 ) as it is made to support the charger, inverter and alternators. Take advantage of the existing cabling!



I improved the ventilation in the locker with ventilation holes in the bottom and a ventilation louver above the panel.

New holes for air circulation

New holes in the bottom for improved  air circulation

Extra ventilation louver

Extra ventilation louver above the electrical panel



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.