Bavaria 37

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William_H

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Have just been looking at a friend's 4 year old Bavaria 37. All very nice but I had some questions about the electrics. the owner had no idea and the manual didn't seem to help.
Perhaps some forumite can guess at the answers.
It seems to have the 240v ring main earth taken directly to battery negative hence the prop etc. It really needs to have a galvanic isolator and my continuity measurement indicates there is not one fitted. I was doing an inspection for Fire and safety for our club marina. Must have GI for 24/7 connection to mains.
It has a box described as a dual battery isolator system. It is not clear if it is diodes or VSR. I can not see any built in provision for emergency start of the engine off the house battery. Has any one got any experience or clues thanks olewill
 
A GI can be fitted. The prop is not electrically connected to the rest of the boat. It is isolated from the shaft by a rubber bush in the prop. The saildrive is almost certainly isolated from the engine by an insulator between the engine block and the gearbox and a damper on the drive plate. The saildrive is protected by its own anode and the prop may be depending on type.

Pretty sure the split charge/isolator is a diode - it was on my earlier 37, now replaced with a VSR. Normal Bavaria wiring does not have a means of using the domestic for engine start - just an isolator in the negative, usually under the chart table. I have replaced mine with BEP isolators and parallel switching.
 
Quite deliberate on most modern production boat not to provide a means of starting the engine from the services batteries - too easy for muppets to flatten the whole lot, and you can't start many engines these days without battery power.
 
jwilson said:
Quite deliberate on most modern production boat not to provide a means of starting the engine from the services batteries - too easy for muppets to flatten the whole lot, and you can't start many engines these days without battery power.
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Doesn't that mean ' no way to start the engine anyway with domestic batteries which may as well be flat then if the start battery is flat ' ?!

I'd much prefer to have the ability to start with either battery, not one set unable of even being given the chance.
 
nigelmercier said:
I agree, but it is possible that a meter would show continuity through a GI.

Perhaps your friend would like to try the forum in my signature.
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Thanks Nigel. I will pas on the Bavaria Forum details to him. I used a multimeter on low ohms (200) showed about .5 ohm and on diode test showed no volts drop in either direction. However the test was from 240v socket earth pin to (house) battery negative. (Which was I think on.) I did wonder later if the engine might have had an insulated negative or perhaps a negative battery insulated from the water as suggested. Which might make GI not necessary. He is going to get an auto electrician (good with boats) to look at it. I hope I have got the advice given correct.
Interesting one club member had built a GI tester but it was away being repaired at the time. I believe it has a power plug male, with connection to earth pin, a battery and current limiter and a volt meter to measure volt drop. Presumably 1.4 volts or so. regards olewill
 
Seajet said:
Doesn't that mean ' no way to start the engine anyway with domestic batteries which may as well be flat then if the start battery is flat ' ?!

I'd much prefer to have the ability to start with either battery, not one set unable of even being given the chance.
Click to expand...

If you are not a muppet it is fairly easy to fit a bridging switch with a removable key that links the starting and services batteries positives: then hide the key away somewhere for emergency use only. Or you could just carry one jump lead. If builders fitted an easy built-in way of starting engine from services batteries I am sure many more muppets would flatten the lot and be immobilised than would find the starting battery would not start the engine. Boat starting batteries on modern production boats have a really easy life and rarely drop more than a few percent of charge before being topped up. Conversely the services batteries do get a really hard life - lots of lights, electronics, fridge, pumps, and often pulled down to a low voltage. Charter boats - which all AWBs are more or less designed as - typically get new services batteries every couple of years but the starter batteries are rarely changed.

The UK charter coding requires a way to start batteries from services if needed: a bridging switch with hidden key is a good way to do this. I don't think Med charter boats need this.
 
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Its not a good idea to just link the batteries when one is flat since the good one will just try and charge it up so you end up with two flattish batteries and not enough to start the engine.
You need a changeover switch with the common going to the engine starter
 
jwilson said:
If you are not a muppet it is fairly easy to fit a bridging switch with a removable key that links the starting and services batteries positives: then hide the key away somewhere for emergency use only. Or you could just carry one jump lead. If builders fitted an easy built-in way of starting engine from services batteries I am sure many more muppets would flatten the lot and be immobilised than would find the starting battery would not start the engine. Boat starting batteries on modern production boats have a really easy life and rarely drop more than a few percent of charge before being topped up. Conversely the services batteries do get a really hard life - lots of lights, electronics, fridge, pumps, and often pulled down to a low voltage. Charter boats - which all AWBs are more or less designed as - typically get new services batteries every couple of years but the starter batteries are rarely changed.

The UK charter coding requires a way to start batteries from services if needed: a bridging switch with hidden key is a good way to do this. I don't think Med charter boats need this.
Click to expand...

The KISS principle is valid for charter boats which get a new user each week and only a few hours between them to fix things. The more choice you give the more things to go wrong. When I took my boat off charter I converted switching to the BEP Marine cluster and VSR so can isolate either bank independently or parallel. Not ideal because you are connecting a potentially duff battery to a good one, but it is an emergency. Never used it as the start battery is still fine after 6 years and the engine starts instantly.
 
jwilson said:
The UK charter coding requires a way to start batteries from services if needed: a bridging switch with hidden key is a good way to do this. I don't think Med charter boats need this.
Click to expand...
No need for hidden key. I have emergency bridging switch but without a key. The engine and service battery keys are on cords. The service key cord won't reach the emergency switch, the engine key will. That way the engine battery (duff) must be isolated before the emergency switch is on.
 
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