VSR

[PabloPicasso]

Can someone show me a typical simple circuit diagram for a two battery system connected by a vsr?

What size wire is required to connect the start and house battery to the VSR?

 

[sailorman]

try the Adverc site

 

[Len Ingalls]

Can someone show me a typical simple circuit diagram for a two battery system connected by a vsr? Thanks

http://www.ybw.com/forums/showthread.php?452757-Dual-Battery-Charging-Circuit-Is-This-Correct

 

[VicS]

Can someone show me a typical simple circuit diagram for a two battery system connected by a vsr? Thanks

Or a more detailed diag I drew not long ago

 

[PabloPicasso]

Thanks. That all looks straight forward enough.

Will the wires between vsr and batteries need to be as big as the wire from alternator to existing battery?

 

[sailorman]

Thanks. That all looks straight forward enough.

Will the wires between vsr and batteries need to be as big as the wire from alternator to existing battery?

No, suggest you check out a search engine for wire gauges :encouragement:

 

[PabloPicasso]

No, suggest you check out a search engine for wire gauges :encouragement:

How will knowing general wire sizes help with the specifics of this?

 

[pvb]

Can someone show me a typical simple circuit diagram for a two battery system connected by a vsr?

What size wire is required to connect the start and house battery to the VSR?

You should use fairly hefty wire to connect the VSR; at least as big as the charging wire from the alternator. Here's a typical diagram, which includes an optional emergency parallel switch.

 

[Len Ingalls]

You should use fairly hefty wire to connect the VSR; at least as big as the charging wire from the alternator. Here's a typical diagram, which includes an optional emergency parallel switch.

pvb-nice drawing!!
If you will show the "always on" tap from the house switch, I will steal the drawing--again
I think the connection from alt. to engine bat. should be made to the right hand terminal of engine bat. swx,instead of direct to start bat. This allows the start bat. to be removed/disconnected. by removing just the bat. cable. Also-less corrosion by avoiding conn. anything but bat. cable direct to bat.?? / Len

 

[pvb]

I think the connection from alt. to engine bat. should be made to the right hand terminal of engine bat. swx,instead of direct to start bat. This allows the start bat. to be removed/disconnected. by removing just the bat. cable. Also-less corrosion by avoiding conn. anything but bat. cable direct to bat.??

Possibly, but not quite as foolproof perhaps.

 

[Len Ingalls]

Possibly, but not quite as foolproof perhaps.

Shoot me down in flames then.

 

[William_H]

Regarding wire size for connection to VSR. Some VSR have the capability to parallel the batteries for emergency starting. Some do not. it is all a question of how robust the relay and particularly the contacts are.
So if you can use the VSR for emergency starting then wire comparable with the heaviest starter wires would be best on the VSR. However if you have a separate emergency start switch or intend to use a jump wire like with cars then the wiring need only be comparable with the wire size on the alternator. ie rated about 50 amps. olewill

 

[PabloPicasso]

Regarding wire size for connection to VSR. Some VSR have the capability to parallel the batteries for emergency starting. Some do not. it is all a question of how robust the relay and particularly the contacts are.
So if you can use the VSR for emergency starting then wire comparable with the heaviest starter wires would be best on the VSR. However if you have a separate emergency start switch or intend to use a jump wire like with cars then the wiring need only be comparable with the wire size on the alternator. ie rated about 50 amps. olewill

Ok, say 50amps, 12v less than 2meters? What size cable?

 

[halcyon]

You should use fairly hefty wire to connect the VSR; at least as big as the charging wire from the alternator. Here's a typical diagram, which includes an optional emergency parallel switch.

That is very complicated for a simple system.

The engine alternator is normally connected to starter motor battery feed, using the same cable to charge the engine battery, usually a heavy cable so little volt drop.

The VSR sits by the two isolator switches, with a short cable to the switched side of the isolator ( the one the battery is not connected to ), use 15 - 25 sq mm cable. You then need a negative 1 sq mm to common battery negative, that's it.

If you have one that can take stater motor current, the 25 sq mm cable will work fine, and only requires a push switch wiring in.

Brian

 

[pvb]

That is very complicated for a simple system.

The engine alternator is normally connected to starter motor battery feed, using the same cable to charge the engine battery, usually a heavy cable so little volt drop.

The VSR sits by the two isolator switches, with a short cable to the switched side of the isolator ( the one the battery is not connected to ), use 15 - 25 sq mm cable. You then need a negative 1 sq mm to common battery negative, that's it.

If you have one that can take stater motor current, the 25 sq mm cable will work fine, and only requires a push switch wiring in.

Brian

Is it? The only difference from your description is that the alternator output is connected directly to the starter battery, rather than to the starter itself. The reason for this is to make the system a little more foolproof - specifically to prevent alternator damage in the event that the engine isolator switch is accidentally turned off.

 

[halcyon]

If you turn the engine isolator switch off, you either stop the engine and isolate the alternator, or if the VSR is closed it will carry on running from the domestic battery.

Over the 38 years I've built VSR's the worst incident I've come across is a Westerly range with the battery isolators on the chart table seat, behind your calf muscle. Moving your legs could drop out isolators, I came across one which dropped out both with engine running, alternator supplied engine and domestic loads via VSR and the boat motored on for a few hours. When engine was turned off, all power was lost, but with isolators back in engine started and alternator worked okay.

Brian

 

[pvb]

If you turn the engine isolator switch off, you either stop the engine and isolate the alternator, or if the VSR is closed it will carry on running from the domestic battery.

Turning off the isolator switch doesn't stop the engine on most small yacht diesels, does it?

 

[Len Ingalls]

Is it? The only difference from your description is that the alternator output is connected directly to the starter battery, rather than to the starter itself. The reason for this is to make the system a little more foolproof - specifically to prevent alternator damage in the event that the engine isolator switch is accidentally turned off.

That is one reason I prefer pvb's diagram. (1) It eliminates the possibility of disconnecting alternator from start battery & consequent burn out. (2) It provides the wire necessary for an ammeter or an ammeter shunt in the alternator output. Voltmeters,as supplied in most panels,are useful,but not near as "telling" as an ammeter IMHO.

I googled two way VSRs. They don't appear to be for emergency start purposes.The largest current one found was 150 amps-questionable for starting a diesel & if used for emergency start,would require at least 1/0 cable .
My impression is that they are sold for combining charge sources,etc. A manual Emerg. Start Swx across a one way VSR would seem safer IMHO. It gives the option of opening the Engine Swx to prevent the dead start battery from sucking a large surge from house battery. Not saying it won't work,but question if it's a good idea. / Len

 

[halcyon]

I googled two way VSRs. They don't appear to be for emergency start purposes.The largest current one found was 150 amps-questionable for starting a diesel & if used for emergency start,would require at least 1/0 cable .
My impression is that they are sold for combining charge sources,etc. A manual Emerg. Start Swx across a one way VSR would seem safer IMHO. It gives the option of opening the Engine Swx to prevent the dead start battery from sucking a large surge from house battery. Not saying it won't work,but question if it's a good idea. / Len

Download this link, 400 amp start, 800 amp surge http://www.kddpowercentre.co.uk/data/11.pdf

Brian

 

[halcyon]

Turning off the isolator switch doesn't stop the engine on most small yacht diesels, does it?

Depends on engine, but as VSR is engaged it still has a battery connected.

With a alternator connected battery side, the alternator is permanently live when boat is not in use, regulator is therefore drawing power 24/7.

Brian