Factory fit battery charger Bav 42 2001

[Notaclue]

Hi all, new to the forum, hope you can help me with some electrical issues. First question; does anyone know why the battery charger only charges the domestic batteries? Also, has anybody had any problems with current leakage/ electrolysis? I have a current leak somewhere, I've checked voltages between keel and -ve on battery, it looks like it is either the bilge pump or the equipment on deck. I cannot understand why Bavaria have put the isolating switch on the negative - from my point of view this is just asking for trouble. Ideally I would like to put in a positive isolation switch on both the engine and domestic supplies so sorting the problem once and for all. The issue is though the charger, it currently connects directly on the large positive post on the panel behind the switch board, I will need to connect it directly to the battery. At the same time I think it makes sense to connect the engine battery as well to the charger - I know there are loads of potential issues with this, do I put in another switch to charge either domestic, engine or both. I could go on, it could be a very long note,  but for now I'll see what feedback I get. Thanks in advance for any help I may get!

[symphony2]

The isolator in the negative is very common at the time your boat was built. Beneteau, Jeanneau (and no doubt others) did the same. Really does not cause any problems, neither should it be the source of any current leaks. I had a 37 of similar vintage and replaced the isolator with a BEP Marine switch cluster that not only separates the 2 banks with their own isolator but also has a VSR which replaced the inefficient diode splitter. You need to check that your battery charger actually has more than one outlet. not sure what the factory fitted then as I fitted my own with 3 outlets. My later 33 had a Cristec 3 output 40A which did all 3 banks. If you do fit a cluster or any switching arrangements that allow the house bank to connect to the engine circuit the need for mains charging of the engine battery is less important. Generally start batteries have an easy life and hold their charge well when not in use.

[Notaclue]

Thanks fo the quick response. As I see it, the problem with the negative isolation switch, is if the switches on the cct board are left closed, then 12v will be found on all the circuits in the boat including shower pump, bilge, pilot etc, where there is the potential to find a route to ground - in my case it seems to be the keel. As a bit of background, I have been putting on a large zinc anode on the keel for the past 10 years during the annual lift for antifouling, the following year it has disappeared and there are plenty of rust soars breaking thorugh the antifouling.

The alternator has a splitter between it and the 2 battery banks, so both can be charge simultaneously. As detailed before, the charger just charges the domestic batteries; no splitter, any idea why not?.

What I would like to do is completely isolate the batteries when in port but at the same time keep them charged. At the moment I dont seem to have a problem with the engine battery, it holds its charge well over the winter period - surprising considering the boat is not used between October and May. I still think it is a good idea to keep it charged, although the counter argument is that constant charge may 'cook' it.

The charger has a second port on it marked Bat II. Cant find any manual in my documentation for it. Also cant find anything on the internet. I dont know enough about chargers to understand how this interacts with the other port BattI. I will try and attach a photo of the charger. Doesn't help that all labelling is in german - for that matter so are the cct diagrams.

I will look up the equipment you have used. How is yours configured?  Appreciate your help.

[symphony2]

You may find this helpful https://bavariayacht.org/forum/index.php?topic=1993.0 as it covers exactly this issue. The posts by Jeff Jones describes in more detail the system I suggested. It vastly improves battery control and alternator charging compared with the original and is somewhat similar to the newer Bavaria systems except they now use a different low loss splitter rather than a VSR and individual isolators for each bank.

As I suggested mains battery charging for both or all banks is really not necessary, although most modern chargers do have 3 independent outputs direct to each bank. Modern chargers also have much more sophisticated charging profiles and are quite safe leaving on all the time keeping the batteries on "float" You may consider fitting one of this type such as a Victron IP22. For obvious reasons chargers should not be wired through the splitter.

If the isolator is off even if it is in the neutral there are no flows through the panel and I don't see now anything can "escape" to the keel. There is no electrical connection between the DC system and the keel.

Have difficulty in understanding why you have an anode on the keel. The keel is solid cast iron (with a few impurities) and what you are getting is straightforward rust. An anode (of zinc) is only useful to protect one metal that is in contact with another of a different potential underwater such as a bronze propeller and a stainless shaft or an aluminium housing and stainless fastenings. Your boat does not have the former, but the saildrive has the latter so has an anode. The anode on your keel is disappearing because of the impurities in the casting reacting with the surrounding iron and has no effect on rust which is formed by the action of seawater on exposed cast iron. The only way to deal with rust is to clean it off and paint the iron. You can either do this by patching or long term have the keel blasted and immediately apply 5 or 6 coats of an epoxy such as Hempadur.

[Notaclue]

Thanks for the info - I have learnt more from your posts than through weeks of talking to electricians. I do not know exactly why I have an anode on the keel, not even sure which electrician put it there. Very interesting article, will do some more research. I still think though that it cannot be a good idea to have a 12v active connection into the bilge (or deck for that matter) where there is a chance of leakage.

Any idea what the Bat I terminal is used for on the charger? Its not used - I will try again to find some documentation on the unit.

Thanks again for your help