Boat wiring and charging

[portvasgo]

After many months of reading various threads and looking at advice on the Internet, and after crawling around my newly acquired boat, I think (I hope) that I am getting to grips with my boat’s wiring. I just need a little more help from the experts out there please.
I have enclosed a schematic of the current set up on the boat.
The charge, from both alternator and solar panel go directly into the leisure bank (2x70Ah). I think I am happy with this as it makes the system a little less foolproof (useful with me on board). It means that the most used batteries, the leisure batteries get priority charge. More importantly it also means that the two-isolator switches marked ‘red switch’ and ‘black switch’ control only the output from the batteries.
The engine and leisure batteries are all the same, a general-purpose type I have been informed – Varta Blue Dynamic 70Ah. I intend to use the leisure battery bank for all output, including starting. I will then keep the ‘engine’ battery as an emergency battery.
However, I have some question that I hope someone will not mind helping me with please.
1. In the schematic, the Lucas split charge relay seems to be in the wrong place, doing nothing and not necessary. Or am I missing something? There are also two thinner wires (one black, one red, not shown on the schematic) than run from the alternator to the split charge relay. What are they for?
2. As I said, the alternator is linked so as to directly charge (via the split charge relay!) the leisure bank automatically, but the way I see it, I need to close the two isolator switches, (the red and black switches just refers to the colour of the handles) to charge the start battery. I don’t like that idea as it introduces the human (me) element again, and also, the engine (emergency) battery is then linked to the instruments etc. Am I right in thinking that a VCR linked as shown to the terminal switches would create automatic charging of both batteries, whilst leaving manual operation of the switches for the ‘distribution side?
3. If so, do I need to get a particular type of VSR and are there any recommendations?
4. Would it be better to link the VSR direct to the battery terminals of each battery bank – or is that the same as linking at the switches as shown in the schematic?
In summary what I would like to do, is to be able to come onto the boat, put on the black switch, this will link the leisure battery bank for starting the engine, running the domestics, whilst the VSR will automatically sort out the battery charging. I will then also have a rarely used, but topped-up emergency battery available via the red switch. Is this logical? Is this desirable or is it flawed in some way.
Look forward to your advice, I understand there are many ways to wire up charging systems, but is what I’ve described a reasonable way of going about it? Any explanations of the doubtless flaws in my thinking will, honestly, be appreciated, just keep it basic for me please.
Thanks in anticipation of your advice and sorry for the long post.

 

[davidej]

I have just completed (this morning!) wiring up a dedicated motor battery. I have gone for the circuitry which I think is conventional wisdom.

1. the motor battery is connected to the motor starter/ alternator circuits thru its own isolator switch. This means that battery always starts the motor - not just in an emergency.

2. the house battery supplies the domestic circuits thru a second isolator

3. all blacks are linked i.e. both battery negatives

4. the two battery positives are linked via a third isolator which is normally off -ie can be used to start uing the domestic battery in an emergency

5. the VSR links the two batteries to distribute charge.

Thus the first isolator is turned on when you want to use the motor and the second when you want the domestics powered up. The third is normally left open.

I have fitted a BES VSR bought off ebay - about a £20 savings - 120 amp size

If you look on the BES website you will find the wiring diagram I have used which is only a minor modification on the existing system (Beneteau standard).

Best of luck

 

[VicS]

I can see no flaws in what you propose

But it not how I would do it. The never to be used rerve battery is not logical to me possibly not good for the battery either. I would do as, I think, davidej suggests:-

A dedicated engine battery ... always used for starting .. with isolating switch.
A dedicated house bank ... always used for all other services ... with isolating switch.
An additional switch linking the engine circuit with the domestic circuit so that if the need arises the domestics bank can be used for starting or vice versa ... or both battery banks used in parallel.

A VSR to control charging of both banks .... your choice which is the priority one to charge but for me it would be the engine battery. The alternator output would go direct to this.

When you arrive on board ... close both isolating switches .... or only the domestic services one if the engine is not to be used.

The BEP VSR from Merlin Powerstore would be one choice but there are others.
Combined with one of their isolator switch banks would be an excellent choice.

See also what our fellow forumite Halcyon has to offer from KDDPowercentre too

Anyway your relay It is not any form of split charge relay it is just a simple relay. Terminals 85 and 86 are to the coil. the heavy terminals 30 & G are the switched terminals
See http://www.autoelectricsupplies.co.uk/image_uploads/srb600_series_wiring_diagram_2_large.gif

.

 

[davidej]

Interestingly, I have just been helping a friend with a Bav - the one we all love to hate!

That does not have a separate motor and domestic isolators - just one on the common negative. No switch to connect both batteries for an emergency start - the previous owner told him to take a jump lead in case!

Incidently, I found the standards of fittings and build seemed as good, and in some cases better, than our Bene.

Sorry.......... not trying to start another Bav vs. the worlds thread!

 

[fireball]

That (the Bav) does not have a separate motor and domestic isolators - just one on the common negative. No switch to connect both batteries for an emergency start - the previous owner told him to take a jump lead in case!

yes - a bit odd really - ours is the same - single negative switch and no manufacturer built way of joining the banks - although if the engine battery goes shot then I can fairly easily remove the +ve lead and attach it to one of the leisure batteries - 1/2ing the leisure bank, but giving me an engine battery!!

We changed the wiring on our last boat to give us a leisure bank & engine bank and put in split diode (it was free!) to charge the two banks. I'm glad we did do this as I managed to flatten the leisure battery when I forgot the coolbox was left on - I could still easily start the engine and leave it charging!

 

[Tranona]

I have just rewired my Bavaria to use a BEP Marine switch cluster rather than just the negative isolator. Quite straightforward except that you need to put terminals on the existing main cables - no easy task unless you have the right crimping kit - and take them to a termiinal stud for linking into the cluster. I have used the 3 in line through bulkhead type so the switches are on the outside just to the left of the chart table.

 

[VicS]

I have just been helping a friend with a Bav - That does not have a separate motor and domestic isolators - just one on the common negative.

I think I probably knew that some boats are wired like that. The OP could use his black switch as the isolator in the common negative and his red switch as the emergency "paralleling" switch.
It limits the options a bit though

 

[mitiempo]

Portvasgo
I see nothing wrong with your wiring. The position of the proposed VSR is the same as wiring it direct between the 2 battery banks as it is wired into the hot leads from the battery banks. It will charge the emergency battery regardless of switch position as shown. I would make sure the 2 always on loads (fridge and Eberspacher) are properly fused. I would also fuse the batteries as close as possible to the positive post. And also make sure the negative wires from the 2 banks go to the same place. As for the red and black from the alternator to the VSR best to look at the manual for your specific VSR. Any of the split charge relays I have dealt with such as the Blue Seas ACR are wired to each bank and ground only.
I do agree with VicS that the emergency battery should be used once in a while as it is better for the battery. Because the output from the 2 switches is connected this is easy to accomplish as by turning the red switch on (and leaving the black switch off) you can draw from the emergency battery once in a while to give it some exercise.

 

[portvasgo]

Thanks for the answers, they are all really helpful. May I ask a couple more questions please?

The first one really shows my ignorance. Vic stated about the relay.
‘It is not any form of split charge relay it is just a simple relay. Terminals 85 and 86 are to the coil. the heavy terminals 30 & G are the switched terminals.’
On looking this up on T B Training it seems that relays are used to turn the glow plugs on and off via the ignition switch. So is this what you reckon this relay is there for Vic?
Also you recommend
‘A dedicated engine battery ... always used for starting .. with isolating switch.
A dedicated house bank ... always used for all other services ... with isolating switch.
An additional switch linking the engine circuit with the domestic circuit so that if the need arises the domestics bank can be used for starting or vice versa ... or both battery banks used in parallel'.

I take on board and understand the logic of the above and about using the emergency battery sometimes. Could I therefore not adopt the following procedure.
First put the red switch on to start the engine, then switch it off and put on the black switch to run the domestics? The engine battery is then isolated from the rest of the system. I can also if required close both switches in order to be able to start the engine with the leisure batteries. To me this seems very similar to what is being suggested. Does that make sense or is there a flaw with my thinking? If this is a reasonable system then all I need do is connect the VSR across the isolator switch terminals as shown on my schematic?

 

[mitiempo]

Portvasgo
If your schematic is correct you do not have to close both switches to start the engine from the leisure batteries. Your schematic shows a connection between the output of both switches and the feed to the starter from this point. Closing the black switch by itself will allow you to start the engine from the leisure bank. Because the house loads are also coming from this connection point you can use the emergency battery for these loads as well by simply closing the black switch and leaving the red switch open. In other words you can select either the emergency battery or the leisure batteries for all loads by operating the switches separately. There is no reason to use the 2 switches at the same time. The proposed VSR looks ok where it is shown. The Lucas split charge relay makes no sense as shown as it is only connected to the leisure bank and was probably disconnected by a previous owner or installed incorrectly to start with. It should be removed.

 

[portvasgo]

Mitiempo thanks for your reply.
You are of course right about the switches regarding the battery start. And thanks for your advice regarding the system as a whole. Just one thing though. At the beginning of the thread I did get it wrong (again) regarding the relay, I called it a split charge relay. As Vic has pointed out, it isnt. He said
'It is not any form of split charge relay it is just a simple relay. Terminals 85 and 86 are to the coil. The heavy terminals 30 & G are the switched terminals'
I gather form this that it should be left in as it is involved in turning the glow plugs on and off via the ignition switch for starting the engine, or have I got hold of the wrong end of the stick?
Thanks for your time and knowledge.

 

[VicS]

The first one really shows my ignorance. Vic stated about the relay.
‘It is not any form of split charge relay it is just a simple relay. Terminals 85 and 86 are to the coil. the heavy terminals 30 & G are the switched terminals.’
On looking this up on T B Training it seems that relays are used to turn the glow plugs on and off via the ignition switch. So is this what you reckon this relay is there for Vic?

That relay as it is shown in your diagram is a bit of mystery. If the coil is energised from the alternator it will close when the alternator is generating, and open again when it is not, functioning as an automatic means of connecting/ disconnecting the alternator from the battery.
I'd want to see a bit more of the engine and alternator wiring before I would be happy about it.

You are quite right in that a relay of that type could be used to switch the glowplugs. The coil would be energised via switch on the panel (or a position on the key switch) and the switched contacts would then connect the glowplugs to the battery.
It could be used to switch the supply on and off to any high load item.

 

[mitiempo]

Portvasgo
If the Lucas relay is wired as shown in the schematic and has 2 wires going to the alternator I don't see what it has to do with glow plugs as it isn't wired to them as far as I understand. Are you sure the 2 wires not on the schematic are going to the alternator?

 

[VicS]

If the coil is energised from the alternator it will close when the alternator is generating, and open again when it is not, functioning as an automatic means of connecting/ disconnecting the alternator from the battery.

Thats rubbish .... ignore.

Do not know what the relay is supposed to be doing as you have shown it!

 

[William_H]

Relay

I agree with Vic. a normal alternator has diodes to rectify the AC but in doing so they also provide reverse current blocking so an alternator can be connected to batt +ve all the time with no need to switch it off. (unless for total isolation when leaving the boat)
I agree also that it far more normal to use the engine battery for starting always. It means you can when replacing the battery buy one designed for engine stating not the more expensive deep cycle type used for services.
A simple normal electrical system will be intuitive if ever you or someone else needs to work on the system. as described by davidej. ie an engine start battery wired as the engine manufacturer intended.
Connect all batt negatives with heavy wire. Use a VSR as the link for charging to the doemestic battery and also as an option for emergency start. olewill

 

[portvasgo]

Thanks to everyone for taking the time to give such good advice. After taking on board your comments I have decided to
1. Move the alternator output to the starter battery.
2. Put an isolator switch between the existing two switches to completely isolate the two systems but allow for emergency combining.
3. Put a dual-sensing VSR across the black and red switches
4. In the future I may add an AC charger, which I will feed into the leisure batteries.
Bearing in mind comments made, I would point out that negatives from the batteries all go to the same place (although not made obvious on my basic schematic).
On boarding the boat I will then be able to simply switch on the red and black switches for the two separate circuits whilst the dual sensing VSR will sort out the charging.
I would very much welcome anyone who has the time to run their eyes over the enclosed schematic for potential errors. The changes seem quite simple to make - even for me.
You are all helping me get to the bottom of the electrics, and by answering my questions, slowly deepening my basic knowledge so that I can ask more questions! The relay worries me, but I need to find out more. The two small wires head back to the engine, to the vicinity of the alternator. However it is all very tight around there and therefore I must hold up my hands Mitiempo and say that I do not know exactly where the wires go, they are certainly close to the alternator. I need to investigate this when I go back to the boat. Once I’ve done that I’ll comeback to the forum if I may. I suppose I should not worry too much about the relay, the engine starts ok, battery charging seem to work, but not knowing what it does is an irritation.

 

[VicS]

Yes sort out what that relay is all about.

As it is the alternator is not connected to anything unless the relay coil is energised.
Why it should be there at all is a puzzle but it might become clearer when you find out where the wires on the two small terminals are connected.
I'd guess one is connected to ground/ battery negative but where does the supply on the other come from? (It may be switched via the key switch so that until the "igntion" is turned on the alternator is disconnected from the battery.)

Move the fuse for the fridge as close as possible to the connection with the battery in order to protect the wiring

Fit a fuse in the solar panel connection, again as close as possible to the battery

The fuse for the Eber should likewise be as close to the connection point as possible but why not also make the connection directly to the battery busbar like the fridge.

A bit pedantic at this stage but the earth connection for the house bank should be taken from the opposite battery to the one to which the load connection is made.

Question for someone else to answer Does the VSR draw a current continuously .... if so should it be wired to the other (ie swtiched) side of the isolator switches to avoid a constant drain on the battery(ies)

 

[halcyon]

Yes sort out what that relay is all about.
As it is the alternator is not connected to anything unless the relay coil is energised.

Sounds like an old alternator, the relay feeds the rotor and voltage to the regulator, only energised with the ignition switch on.

Apart from that, may I say the diagram is a very complicated way to solve a simple problem, but I will leave you to it.

Brian

 

[NormanS]

I'm no expert, but one of the disadvantages of using the domestic batteries for starting the engine is that when feeding the starter, there will be a noticeable voltage drop, and it may be enough to cause sensitive electronics, like plotters, to switch off. Better, in my opinion, to use a dedicated engine starter battery.

 

[halcyon]

I'm no expert, but one of the disadvantages of using the domestic batteries for starting the engine is that when feeding the starter, there will be a noticeable voltage drop, and it may be enough to cause sensitive electronics, like plotters, to switch off. Better, in my opinion, to use a dedicated engine starter battery.

Very true.

Which is why in 1980 we introduced a VSR system, to allow a seperate service and engine battery for clean supply, avoid drain on engine battery, maintan maximum security to charging the engine battery, that is to say the alternator perminently connected to the battery, and so on.


Brian