Wiring diagram - circuits added for new stuff to my 1-2 both boat electrics - opinion/advice appreciated

[Minerva]

Your wish is my command.

Skip the shunt if you don't have a battery monitor and obviously ignore one domestic battery.

can I ask a daft school laddie question about the VSR?

Am I correct in assuming that the alternator sends 100% of the charging load to the engine start battery. Once this is full and only when it is full; it continues to send the charge to the engine start battery only it is now linked to the house bank via the VSR which has been activated so the charge can flow through to charge them too?

 

[VicS]

can I ask a daft school laddie question about the VSR?

Am I correct in assuming that the alternator sends 100% of the charging load to the engine start battery. Once this is full and only when it is full; it continues to send the charge to the engine start battery only it is now linked to the house bank via the VSR which has been activated so the charge can flow through to charge them too?

The VSR closes when the volts reach the closing voltage ( Typically 13.8 but there are intelligent VSRs, out there, eg the Victron Cyrix . . . . . see the technical data.) Unless the "priority" battery is deeply discharged this will be almost immediately .

Most VSRs are dual sensing so you can connect a single output solar controller or a battery charger to the domestic battery and that will charge first, and again the VSR will close when that reaches the closing voltage to continue charging both batteries.

 

[Alex_Blackwood]

View attachment 150731

Your VHF and Masthead lights are shown as being on with the 1-2- Both - Off switch being in the off position? nothing else is shown going through this switch so what does it do?

 

[FairweatherDave]

Your VHF and Masthead lights are shown as being on with the 1-2- Both - Off switch being in the off position? nothing else is shown going through this switch so what does it do?

 

[FairweatherDave]

You have it correct in terms of the VHF and mast head lights all function irrespective of how the 1 2 Both is set. It is a while ago since I set that up so not sure how I did it, but the 1 2 Both functions as a normal 12 Both for the engine and house circuits, I just did not include them in the diagram for simplicity. I just wanted to illustrate the wiring I have ADDED to the standard set up on my 1979 Konsort.

 

[Alex_Blackwood]

You have it correct in terms of the VHF and mast head lights all function irrespective of how the 1 2 Both is set. It is a while ago since I set that up so not sure how I did it, but the 1 2 Both functions as a normal 12 Both for the engine and house circuits, I just did not include them in the diagram for simplicity. I just wanted to illustrate the wiring I have ADDED to the standard set up on my 1979 Konsort.

So which battery are they connected to? Maybe the one that shows a slight discharge? I don't really know what your present arrangement achieves. I think that you maybe over complicating things. Perhaps do as others have suggested with VSR etc. and possibly a Positive busbar as well.

 

[FairweatherDave]

So which battery are they connected to? Maybe the one that shows a slight discharge? I don't really know what your present arrangement achieves. I think that you maybe over complicating things. Perhaps do as others have suggested with VSR etc. and possibly a Positive busbar as well.

Thanks Alex. I will have to look at what work I did about 5 years ago around the 1 2 Both. And simplify things as has been suggested - and maybe even go for the VSR job. The whole exercise has been very useful here - thanks people -I'll be back!

 

[Poey50]

But behind my questions about my wiring is a bit of a mystery. Both batteries were bought at the same time (March 22) and are same specification/identical. But battery two always seems to drop its voltage level a bit more than battery one. I monitored voltage closely through the summer and alternated which battery got decent charge when motoring. It never got too low but sometimes 12.2 while the other 12.5 volts. The solar had an issue and I ended up getting a new dual battery controller, but only at the end of the season. So I suspect a little voltage draw somewhere but not surewhere to look or how - nothing was ever left switched "on".

You are having to do a lot of monitoring and manual switching. Sometimes people support this with the KISS* principle but nothing could be simpler than a fit-and-forget VSR which will manage things automatically as per the set-up that Tranona and PaulRainbow recommended.

* While KISS is often a worthwhile aim, it is not difficult to illustrate the limitations. The simplest way to climb one of the big wall routes in Yosemite is with a pair of rock shoes and a chalk bag. You can then dispense with all that other annoying complex gear and you can do the routes in hours rather than days. What could be simpler?

 

[PaulRainbow]

You are having to do a lot of monitoring and manual switching. Sometimes people support this with the KISS* principle but nothing could be simpler than a fit-and-forget VSR which will manage things automatically as per the set-up that Tranona and PaulRainbow recommended.

<snip>

That one always makes me smile. What could be more KISS than turning two switches on and off as required and all charging being automatic ?

 

[awol]

One possible advantage of a 0-1-2-Both switch is that the charging circuit and domestic loads are all connected to the Common. Even if the switch is turned off while the engine is running there is still (probably) a load for the alternator, lights will stay on, etc. I admit to not being entirely convinced that alternator diodes will spontaneously fail if the load is removed while the engine is running but I'll let someone else carry out that experiment.

 

[Poey50]

One possible advantage of a 0-1-2-Both switch is that the charging circuit and domestic loads are all connected to the Common. Even if the switch is turned off while the engine is running there is still (probably) a load for the alternator, lights will stay on, etc. I admit to not being entirely convinced that alternator diodes will spontaneously fail if the load is removed while the engine is running but I'll let someone else carry out that experiment.

Have a look at the diagram below which shows a voltage surge of 100 volts on sudden alternator disconnect. With the battery removed from the system imagine what that spike would do to sensitive marine electronics. I have, by the way, done the experiment and can confirm that the alternator diodes were killed. This was on a Balmar alternator which has avalanche diodes resistant to voltage spikes.

[ATTACH type="full" alt="Chart, line chart

Description automatically generated"]150762[/ATTACH]

 

[awol]

Have a look at the diagram below which shows a voltage surge of 100 volts on sudden alternator disconnect. With the battery removed from the system imagine what that spike would do to sensitive marine electronics. I have, by the way, done the experiment and can confirm that the alternator diodes were killed. This was on a Balmar alternator which has avalanche diodes resistant to voltage spikes.

[ATTACH type="full" alt="Chart, line chart

Description automatically generated"]150762[/ATTACH]

Ooh, nasty. When it says the battery was removed does that mean field current was also cut?

 

[PaulRainbow]

Ooh, nasty. When it says the battery was removed does that mean field current was also cut?

It would mean the isolator was turned off.

With separate switches the electrics/electronics are isolated from that surge.

 

[Alex_Blackwood]

It would mean the isolator was turned off.

With separate switches the electrics/electronics are isolated from that surge.

That seems to be a deliberate action for test purposes. Not saying it is not possible in practice. However it will also depend on where the 1/2/B switch is in the circuit and where the alternator sense connection is taken from.

 

[awol]

It would mean the isolator was turned off.

With separate switches the electrics/electronics are isolated from that surge.

... and good-bye diodes? With the load remaining connected (and the field) at the common of a 0-1-2-Both would the disconnection of the battery not be like turning off part of the load and within the regulator's control? I am happy to let others

 

[PaulRainbow]

... and good-bye diodes? With the load remaining connected (and the field) at the common of a 0-1-2-Both would the disconnection of the battery not be like turning off part of the load and within the regulator's control? I am happy to let others

The trick is, NOT to switch the isolator off while the engine is running, irrespective of whether using a 1-2-B switch or an on/off switch.