battery circuit

[ghostlymoron]

Does any one have a circuit diagramme showing batteries, alternator, selector switch, diodes etc. I have just moved up from a boat with just a battery charged by solar panel and am rather confused by all this!
/forums/images/graemlins/confused.gif

 

[mikehibb]

There was an interesting (and informative) thread on here a few weeks ago that explained how the one/both/two/off selctor switch worked.( it saved me asking just the same question)

Try a search for battery selector switch or similar it might find it.

 

[VicS]

You will find a lot of helpful info in the electrical notes on The TB Training website

 

[sailinglegend420]

[ QUOTE ]
.....am rather confused by all this!
/forums/images/graemlins/confused.gif

[/ QUOTE ]

How confused? - Electrics, especially on a boat, can be daunting. A circuit will help you - but following your existing wiring and making changes could be disastrous.

The TB training site posted by VicS is a great resource which I have bookmarked for future perusal, even though I am a retired electronics and electrical engineer. This does show the breadth of knowledge needed to safely tackle electrics.

My suggestion would be to find someone in your area to help you who has the knowledge - and then you do most of the hard manual work yourself.

 

[VicS]

Another source of info much liked by some forum members is THE 12 VOLT DOCTOR'S PRACTICAL HANDBOOK

It was at one time available as a download from http://motoren.ath.cx/ but it does not now seem to be.

The book is readily available though for purchase.

 

[William_H]

I am guessing that you have acquired a new boat with 1,2,both switch and are wondering what the circuit is like.
There are variations but usually the circuit is what you might expect from a single battery arrangement much like a car. Except that the positive connection to the battery has a provision for disconnecting the battery or to connect to another or both batteries.
A such the most common way to manage this is to start and run on both position. This means that when the alternator starts charging it charges both batteries at once. (getting the quickest charge)
There is a problem here in that if one battery is old (dead) you may not know because the other battery will provide the start current. It is like a permanent jump start. So you should periodically start the engine on just one battery then later the other. So any battery failure will be obvious. If you don't you may get to the point where both are dud before you find out.
Obviously you should when camping or sailing just use 1 battery or the other so if it is discharged too much you have the other battery to start the engine.
There is a concern with the 1,2,both switch that you can have a in between position when changing batteries that there is no battery which may damage the alternator. Some switches have a make before break to avert this but you can still go through off inadvertently.

if you want to rewire or change from thois system. I think the better arrangement is to have a dedicated specialised start battery and a dedicated deep cycle domestic battery. The engine battery is wired to the engine via an isolation switch and "ignition" switch in a normal manner.
The domestic battery is wired with the negative connected to the engine battery with heavy cable. The domestic battery has an isolation switch that feeds to you services just like your old boat.
A high current switch is then connected between the positive of the engine battery and the positive of the domestic battery.
So you start the engine then engage this last switch to provide charge from engine to domestic battery. This switch must be opened when you stop the engine. It can however be closed to provide a jump start for the engine if you have an engine battery problem.
From there you can substitute a Voltage Sensing Relay in place of this linking switch, which will automatically connect the two batteries when charging but disconnect when not charging. Some types have an emergency function to jump start the engine battery or you can provide a jumper lead or another high current switch.

Diodes can be used in place of the relay in either dedicated battery or 1,2,both set ups. One goes between the alternator and engine battery the other goes between the alternator and domestic battery.So current can only flow from the alternator to each battery but not between batteries. However diodes lose about .7 volt in transmission so you need to increase the voltage of the alternator regulator or have a regulator that senses at one of the batteries. That usually means having another regulator and making connections in the alternator such that you may as well get a smart regulator. (money)
So while I am waffling on you should make an attempt to understand what you new boat does electrically then draw a diagram your self then consider if you are happy with it. A diagram can only give in principal arrangements and will not help you that much with your new boat. regards good luck olewill

 

[colvic987]

Is this what you are looking for:

 

[oldsaltoz]

If you must use word or some other program to set out your question or reply, please "create new mail" it will spell check and not result in a posting that is too wide to display without scrolling.

Many thanks.

Avagoodweekend

 

[ghostlymoron]

Spot on Colvic, that's EXACTLY what I was after - thanks very much. GM

 

[VicS]

[ QUOTE ]
If you must use word or some other program to set out your question

[/ QUOTE ] The "problem" was caused by Colvic's diagram not Ghostlymoron's question.

It quite often happens with pictures but can be avoided by reducing the size before uploading to Photobucket or by simply setting the maximum size in P'bucket's uploading options to "message board". P'bucket is a bit slow with its resizing but for the odd one or two images it is OK and less of a fiddle anyway.