I'm a new 320 Hanse owner and have limited experience with the electrical system onboard. My question is how do you charge the batteries (especially the small battery for starting the engine) when you are connected with shore cable? I have noticed from the instrument panel that the capacity on the start battery is getting lower. Tried to run the engine for an hour with no readable effect on the instrument panel. There is a charger installed onboard and would think that when you are connected to shore, the batteries will automatically be recharged. I would like to avoid removing the battery for recharging. Comments appreciated.

The boat is a newbuilding from this summer, so you might say that the batteries are brand new. I have a small "car battery" for starting the engine and a large gel battery for domestics. I will measure using a voltmeter.

Shaukaas,

I'm not an official expert, but working as a service engineer in a company for automation technology for offshore equipment, I have some of the basic knowledge. The rest is from forums like these, manuals and technical handbooks/datasheets  - and, of course, off my keen interest...

If your charger is a Sterling Power; check the manual to verify that the jumper is set to sealed lead/acid batteries. I think this will give you a maximum charging voltage at 14.4V, and 13.8V float - whilst the open lead/acid will charge (boost) at 14.8V. As the sealed lead/acid batteries does not allow any water to be refilled - these are not suitable for "quick charging". The same rule is for AGM and Gel batteries.

The way your charger behaves is different from my Sterling Power CED1250 - which gives a steady 13.8V power supply at all times in float mode; and functions as a very stable powerpack being able to supply up to 50 Amps.

Please take into account that we have to different charging circuits here: A) Shore power and B) generator off the engine.

A) The Shore power battery charger (in my case) have three independent outputs. When this is turned on, the starter and the domestic bank will not be equalized. The outputs are separated by diodes, internally in the charger. A drawback with this charger, it that it is not able to independently control the three different battery banks - and can not charger different types of batteries at the same time. But in practical terms, I guess, this is not a common problem anyway...

B) Engine generator - charging voltage is controlled by a "blind" regulator at 14.4V on the original 60A Hitachi generator. The problem with this solution is that it is not very efficient; and it will take a lot of time/almost be impossible to charge your batteries all the way up to 100%. (The Ah-meter shows this clearly!)

To be able to isolate the starter battery from the domestic bank, a charging relay is normally fitted in between the generator and the batteries. In some cases they use manual switches, some a relay, others a transistor based system; maybe in some cases preventing the different battery banks from equalizing (discharging each other.) These transistor based devices will normally have up to a 0,6V voltage-drop across, so the maximum charging voltage on your batteries is 14,4V - 0,6V = 13,8V. This gives a horrible charging if it is the case.

One way to get around this, is to install a "smart" voltage regulator on the generator, with a voltage sensing on for an example the domestic bank. You will then charge your battery with 14,4V, as the voltage regulator always have control of your battery. Most of these also have a temperature sensor for your batteries, to avoid "cooking" the battery - but also to compensate the charging voltage according to the temperature.

The problem then, however, is with two or more battery banks... 
If the charge current to the domestic bank is fairly high and you have a voltage drop across the battery cables; you run the risk of overcharging your start battery. If the start battery is a open lead/acid, this can normally be dealt with by checking the water level occasionally - and refilling when needed.

What I did to be on the "absolute sure-safe" side; is to install a smart voltage regulator sensing the voltage on a intelligent battery separator. This is software controlled, and have a only a neglectable voltage drop. It also assures that the different battery banks get the sufficient charging - avoids overcharging and equalizing/discharging.

And also, of course, the Ah-meter which gives me the full picture of the battery and charging condition! (Generator voltage, generator amps, start battery voltage, domestic battery voltage and Ah-meter.)

The cost of installing this is certainly moderate; but taking into account the total of money and effort being spent on the boat - I find it satisfactory to have a perfectly working charging system; and not have to worry about charging problems in the near future. My only concern is to refill water on my batteries...

The main reason for me to install this, was a "lack of juice" when using the original installation. Just by using the electrical anchor-winch to set the anchor for the weekend; my batteries where almost totally drained... This can be explained by a generator not charging much at idle speed - and me using the anchor winch when idling. Combined with a lot of sailing, a fridge full of beer, stereo and navigation electronics the 6-7 hours before anchoring - showed the weak sides of the original charging system.

If you're able to hook up to the grid every evening, the need for this is not existing. But I preffer to be at anchor, away from the crowded places - being capable of a long distance cruise without running the engine.

When the red light is on , the charger is in float mode. When the red and green lights are on , the charger is charging. The manual for the charger should be available online.
Incidentally, I have also always struggled to understand the led lights for the battery charge state. After 3 seasons of worrying about the battery charge I have left have stopped worrying . So far ( touch wood) I have no problems with the batteries. I checked te electrolyte levels for the first time last week and they were fine.

However my theory on the battery lights is as follows: there are 5 bars for each of the 2 banks. You only get five bars when the batteries are full and have zero drain, or are charging. This is the only tme I ever get five bars.
The other 4 bars represent 25% increments in charge state. I base this on the fact that my invertor has similar led lights. When I have 4 bars on my switch panel, the invertor shows 100% charge, 3 bars on the panel; 75% charge on the invertor and so on.

On a final note, when I had the boat delivered, the charger had a loose connection and would not charge. Hanse tightened everything and it worked fine. Also apparently occasionally the Stirling chargers break. Their customer service is meant to be amazing , but if you have a red float light on I guess it's all working .
Hope this helps