Confused about alternator/duel battery selector switch. - Jeanneau Sundream 28(1988)

UK-WOOZY

UK-WOOZY

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I got the boat a year ago and have been doing work on it non stop and plan to launch soon. The last of the work is pretty much the wiring. Myself and a friend are unfamiliar with how the inboard and alternator charge the batteries. We have replaced all the wiring for the lighting and redone the mast wiring and added deck lights and power sockets for usbs on a separate new fuse panel and utilised the original panel again for the deck light and bilge etc so we are happy all the house electrics are working great now and with LED used throughout. When redoing the bundle of wires behind the panel we saw a black cable from the negatibe bar that goes to the earthing bar in the bilge then anodes and keel bolts then to the side of the engine chassis. My friend has the fuse panel negative now coming off both battery negatives. The battery selecter switch does 1/2/both/off. Engine is a yanmar 2gm20. We cannot work out how everthing should be linked with regard to the alternator/starter motor and both batteries and boat panels. thanks.

EDIT: i have added a 50w panel via a duel battery regulator to the system too.
 
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UK-WOOZY said:
I got the boat a year ago and have been doing work on it non stop and plan to launch soon. The last of the work is pretty much the wiring. Myself and a freind (whos is an electrician) are unfamiliar with how the inboard and alternator charge the batteries. We have replaced all the wiring for the lighting and redone the mast wiring and added deck lights and power sockets for usbs on a separate new fusepanel and utilised the original panel again for the deck light and bilge etc so we are happy all the house electrics are working great now. When redoing the bundle of wires behind the panel we saw a black cable that goes to the earthing bar then anodes and keel bolts then to the side of the engine chassis. My friend has the fuse panel negative now coming off both battery negatives. The battery selecter switch does 1/2/both/off. Engine is a yanmar 2gm20. We cannot work out how everthing should be linked with regard to the alternator/starter motor and both batteries and boat panels. thanks
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Very probably all your electrics, that is supply to house electrics and engine electrics, including the alternator output, are fed from the common terminal of the selector switch. The switch merely selects which battery, house or engine, or both, is connected to supply everything and ( unless there is any split charging system) be charged.

Care is need to be sure never to switch to "off" while the engine is running while switching from one to the other.

i'd suggest: select engine battery to start engine, start engine and allow the engine battery to recharge.

Then switch briefly to both and then to house batter only. This will then supply all power and recharge while the engine is running. Leave the house battery selected until you next need to start the engine. You can select the engine battery by passing through off or both while it is not running.

Golden rule: Only the skipper is allowed to operate the battery selection switch!


IT would have been a good idea to have Thrown out the 1,2 both switch, separated engine and domestic circuits, feeding each via an isolator from the receptive battery bank. An emergency linking switch would be needed for times when one battery fails and a split charging or VSR system so that both batteries are charged.

Both battery negatives should be connected together and to the engine. The anodes should also be connected to the engine but should not use current carrying wiring to make the connection.

I am assuming that your engine uses the engine block as the negative and does not have an isolated negative system. ( Looking at the wiring diagram it appears to do so)

Take note of any advice from Paul Rainbow but bear in mind he is heavily biased against 1,2 both switches

Tell us more about your anode system. What's it protecting. Is your flexible shaft coupling bridged to complete the circuit to the prop.


tillergirl said:
If you send me an email via a PM, I can send you a copy of the GM series workshop manual. It helps some of that.
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You can down load both Owners manual and Service manual from the Barrus website:- https://www.barrus.co.uk/divisions/marine/diesel/yanmar-marine/manual-downloads/ The 1GM manual covers the 2GM and 3 GM engines.
 
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EDIT: i have added a 50w panel via a duel battery regulator to the system too.
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Presumably directly to the batteries, or the battery terminals of the selector switch, via fuses rated below the safe working current of the wiring.
 
Excellent reply, thank you. Appreciated.

I added to my post that i have added a 50w panel with a duel battery regulator. I had the same setup on my previous intro 22 without inboard engine though, and both house batteries were topped up fully all the time with that setup, so this is my first boat with alternator and inboard. Im happy to isolate both batteries with 2 separate switches, i will mention that to my sparky friend. "should" be a simple rewire, but we will connect the negatives of both batteries. And yes i believe you are right about the earth strip whatever it is, it goes over the prop shaft area under the stern cabin bed. then goes to the single anode then to the keel stub/bolts i think, there is also earth cable going to the seacocks and the valve for shoving a pole though should the lift keel needing freeing. For emergency to use the house battery to start the engine i could just get some crocodile clips, will that do for linking the house to the engine cables. Hoping the panel keeps then both topped up however and the alternator keeps the engine battery topped up. But is there a way the alternator can recharge the house battery as well as the engine battery? many thanks. all complicated to me.
 
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I'd agree with much of post #3, expecially the part about my dislike for 1-2-B switches :)

Rather than croc' clips, i'd fit the 3rd switch, they don't cost much and if the engine doesn't start when you need it in a hurry you'll be pleased you have it.

For dual battery charging from the alternator, you can fit a VSR or a FET based spliter (amongst other things). Have a look at the Victron Cyrix 120a for a VSR or the Victron ArgoFET. Yes, i like Victron kit :)

As you have a dual output solar controller, you don't need to split the solar charge, so in your case i'd fit the ArgoFET, there is also no issue with switch power off with an ArgoFET, if you connect it to the batteries or to the battery connections of the isolator switches.
 
Ref anode bonding, modern thinking is to not bond the seacocks and anything else that would otherwise be not part of a circuit or made from dissimilar metals. I would remove any wiring from the seacocks. Not familiar with the lift keel gubbins, so cannot comment on that one.
 
UK-WOOZY said:
Excellent reply, thank you. Appreciated.

I added to my post that i have added a 50w panel with a duel battery regulator. I had the same setup on my previous intro 22 without inboard engine though, and both house batteries were topped up fully all the time with that setup, so this is my first boat with alternator and inboard. Im happy to isolate both batteries with 2 separate switches, i will mention that to my sparky friend. "should" be a simple rewire, but we will connect the negatives of both batteries. And yes i believe you are right about the earth strip whatever it is, it goes over the prop shaft area under the stern cabin bed. then goes to the single anode then to the keel stub/bolts i think, there is also earth cable going to the seacocks and the valve for shoving a pole though should the lift keel needing freeing. For emergency to use the house battery to start the engine i could just get some crocodile clips, will that do for linking the house to the engine cables. Hoping the panel keeps then both topped up however and the alternator keeps the engine battery topped up. But is there a way the alternator can recharge the house battery as well as the engine battery? many thanks. all complicated to me.
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I hope your "sparky friend" is familiar with 12 volt boat wiring, not just mains voltage domestic wiring. There are some important differences particularly regarding cross-sectional area to avoid unacceptable volts drop.

Take care if using jump leads. Batteries can give of hydrogen and oxygen gases in just the right proportions for maximum bang if ignited by a spark ( thats why when using jump leads on cars and other vehicles the last connection made and the first to be broken should always be away from the battery). An explosion is not highly likely but it can happen and does happen. A face full of bits of battery case and battery acid will spoil your day and possibly the rest of your life!

At one time it was fashionable to bond all underwater metal bits and pieces to the anodes. That is not not considered t be correct. All sea-cocks and skin fittings should be made of corrosion resistant materials and therefore not require the protection of anodes. Bonding of skin fittings to the anode system was considered, by the MAIB, to be one of the contributing factors to the near sinking of the F.V. Random Harvest a few years back.

A VSR ( voltage sensitive relay) or the modern low loss equivalent of a diode splitter ( eg Victron ArgoFET) is the way to simultaneously charge both batteries from the same alternator.
 
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thank you all for the replies. looking at relays / getting batteries separated too.

i took some photos of the electrics today.-

original boat panel does- mast lights, VHF, water pump for sink, autohelm
new panel (ASAP) does- usb sockets, lights, instruments
the house battery is connected to an MCB near the selector before going to the panels.
bilge pump is on a separate fused circuit (with fuse and switch straight to battery).

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the black cable going to the strip on the bilge was coming from the original negative busbar, then to the battery. Does it need to go to the strip, then the rest of the negatives as the negative from the battery is already going to the other negatives


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UK-WOOZY said:
yes, a lot of ties were cut when redong things.
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Your question is not clear to me, can you knock a sketch up ?

The wiring on battery in front of the engine would be better if you ditch the clamps, put the battery cables on the studs, connect the two small wires to the busbar (or the studs as a last resort).
 
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