Using a VSR with a 1-both-2 off switch.

[Sneaky Pete]

I have a 1-both-2 off battery switch. Is it possible to fit into this circuit a VSR which would remove the need for me to turn the switch as and when the engine is off or running.
If it can be done is there a diagram to show the wiring connections. Would battery isolation still be the OFF position on the switch.

 

[Tranona]

If you are going to fit a VSR then why not ditch the 1,2 both as it no longer serves a useful purpose. Then create two banks with their own isolation switches plus a parallel switch if you want to retain the ability to link both banks, say for emergency engine start. The wiring diagram will come with the VSR.

 

[VicS]

I have a 1-both-2 off battery switch. Is it possible to fit into this circuit a VSR which would remove the need for me to turn the switch as and when the engine is off or running.
If it can be done is there a diagram to show the wiring connections. Would battery isolation still be the OFF position on the switch.

What Tranona says is the right answer. If you just fit a VSR it is doing half the work of the 1, 2, B switch by automatically charging both batteries but you will still have to operate the switch to select which battery will be in use . I.e. battery 1 to start the engine or battery 2 to power the domestics, or to switch both off

You can easily achieve this half way set up by connecting the VSR between the battery terminals on the switch.

A neat solution would be to separate the feed to the domestic distribution panel from the feed to the engine electrics and feed the two now separated circuits from dedicated batteries using a Blue Sea "Dual circuit Plus" switch which is basically two separate isolators and an emergency cross over switch all rolled into one

 

[KRG]

Yes I have done it, the vsr goes on the charge side and the 1,2,both,off switch on the load side. I eventually used separate switches but initially I wanted to remove the need to remember which battery was charging, the vsr was set to charge engine battery first then the domestic ones.

 

[PaulRainbow]

I have a 1-both-2 off battery switch. Is it possible to fit into this circuit a VSR which would remove the need for me to turn the switch as and when the engine is off or running.
If it can be done is there a diagram to show the wiring connections. Would battery isolation still be the OFF position on the switch.

I agree with Tranona, in that you may as well fit separate switches and circuits, but, fitting the VSR does at least remove some of the risks of using a 1-2-B switch. You can forget about charging from the alternator, it gets done automagically. If the domestic bank is suitable for engine starting all you need to do is leave the switch set to that bank and know that the "engine" battery is there should you need to start the engine in the event of a discharged domestic bank. I'm sure Calder mentions this system, as it's a common US method. I'd still favour having separate switches, but having the VSR would be better than not having it.

Installation is pretty simple, it will come with instructions, basically connect it to the two battery bank positives, either at the batteries or the switch (whichever is more convenient) and a light gauge negative wire to the negative bus or a battery. Fit a fuse in one or both positive connections.

 

[PaulRainbow]

Yes I have done it, the vsr goes on the charge side and the 1,2,both,off switch on the load side. I eventually used separate switches but initially I wanted to remove the need to remember which battery was charging, the vsr was set to charge engine battery first then the domestic ones.

Actually, (despite what many manufacturers claim) the VSR cannot do this, it will close (and charge all batteries) as soon as the alternator starts charging, or very soon after, depending on the VSR. It cannot distinguish between battery voltage and alternator output.

 

[halcyon]

I have a 1-both-2 off battery switch. Is it possible to fit into this circuit a VSR which would remove the need for me to turn the switch as and when the engine is off or running.
If it can be done is there a diagram to show the wiring connections. Would battery isolation still be the OFF position on the switch.

It is do able, either by fitting a third sense wire to the common output, select bank one or two will power VSR, which ever battery is on charge will engage relay. Only down side is a small power loss due to banks 1 & 2 being connected when 1,2 Both switch is off.

Alternate is to monitor current flow to engine battery and engage relay when charge to engine battery is above a minimum voltage and below a set charge current. It then links batteries to charge battery not in circuit, dropping out when voltage or charge current fall to preset minimums, thus no losses with switch off.

Brian

 

[Yngmar]

If you are going to fit a VSR then why not ditch the 1,2 both as it no longer serves a useful purpose. Then create two banks with their own isolation switches plus a parallel switch if you want to retain the ability to link both banks, say for emergency engine start. The wiring diagram will come with the VSR.

Two things to add to this. One, you could re-use the existing 1-2-both-off switch as a simple "connect banks" switch by rewiring it slightly.

Or better, you can just remove it entirely and choose the Victron Cyrix-ct battery combiner, which doesn't cost more than a similarly rated conventional VSR, is dual sensing (so either bank being charged will link them together, and break the link when charging stops), and most importantly to you has a "start assist" feature, which means you can wire a tiny low-power push-button to it from anywhere on the boat which will cause it to link the banks for 30 seconds after pushing, so you can start the engine from the house bank if the starter battery is low. Saves a bunch of thick cables and simplifies the whole wiring diagram greatly.

 

[PaulRainbow]

Two things to add to this. One, you could re-use the existing 1-2-both-off switch as a simple "connect banks" switch by rewiring it slightly.

Or better, you can just remove it entirely and choose the Victron Cyrix-ct battery combiner, which doesn't cost more than a similarly rated conventional VSR, is dual sensing (so either bank being charged will link them together, and break the link when charging stops), and most importantly to you has a "start assist" feature, which means you can wire a tiny low-power push-button to it from anywhere on the boat which will cause it to link the banks for 30 seconds after pushing, so you can start the engine from the house bank if the starter battery is low. Saves a bunch of thick cables and simplifies the whole wiring diagram greatly.

The Cyrix is good, i use them a lot. But, the start assist feature is pretty much pointless, IMO. It does work as you describe, but is limited to 30 seconds and only rated for the VSR (obviously). To use it with just the 120a Cyrix you would need to use 16mm cable, a bit chunky on 6mm terminals.

Fitting the 3rd switch Tranona refers to requires two cables, rated the same as the battery cables, about 3 inches long, not exactly a bunch of cables making the wiring complicated

The 3rd switch allows options that the start assist function does not have. For instance, if the engine battery has totally failed you can isolate it and use the 3rd switch to allow the engine to use the domestic bank, ditto if the domestics fail. Also, if the engine battery is heavily depleted, the start assist will likely not work, once again the engine battery could be isolated and by using the 3rd switch the engine could be started, turning the engine battery back on and the 3rd switch off once it's running.

 

[JumbleDuck]

I have a 1-both-2 off battery switch. Is it possible to fit into this circuit a VSR which would remove the need for me to turn the switch as and when the engine is off or running.

Yes, and you would then have something matching standard American practice, which is to use one main battery for everything but have another charged one kept in reserve for emergencies. It works very well on thousands of yachts there.

 

[PaulRainbow]

Yes, and you would then have something matching standard American practice, which is to use one main battery for everything but have another charged one kept in reserve for emergencies. It works very well on thousands of yachts there.

As i explained in post #5

 

[JumbleDuck]

As i explained in post #5

Pah. I barely have time to read the reposts I reply to, let alone the others.

PS. Oops.

 

[JumbleDuck]

As i explained in post #5

Pah. I barely have time to read the reposts I reply to, let alone the others.

PS. Oops.

 

[JumbleDuck]

As i explained in post #5

Pah. I barely have time to read the reposts I reply to, let alone the others.

PS. Oops.

 

[Sneaky Pete]

My previous boat had on/off switches for house and engine and here I fitted a VSR to that system it was simple to fit and worked well with peace of mind. This 1-2-B I still can’t get my head around but fitting a VSR into the existing switch is a good starting point which I could do now. I will leave the alternative of removing the 1-2-B until winter lay-up to much swearing involved here.
Thanks for the replies.

 

[RichardS]

Pah. I barely have time to read the reposts I reply to, let alone the others.

PS. Oops.

I barely have time to read all these identical posts.

Richard

 

[PaulRainbow]

Pah. I barely have time to read the reposts I reply to, let alone the others.

PS. Oops.

Know the feeling.

 

[halcyon]

Know the feeling.

Not sure what you youngster's are moaning about, been designing charging systems for over 45 years.

Brian

 

[PaulRainbow]

Not sure what you youngster's are moaning about, been designing charging systems for over 45 years.

Brian

Should be getting good at it by now

 

[halcyon]

Should be getting good at it by now

Not much sign of people catching up :encouragement:

In 1983 this was our literature http://www.kddpowercentre.co.uk/data/P4000_82_lit.pdf

In 85 we added a multi-stage mains charger that interfaced with the VSR display control module, now it's just interesting how far we can push charge systems.

Brian