VSR Question?

[Dougal]

I'm finally coming round to the idea of upgrading our charging system. I was twice in past, let down by failing electronic charging kit and, as a result, I've been an avid supporter of old fasioned kit such as 1-2-B switches etc ever since. Having also had an altetnator fried by missuse of that switch, I have to catch up now, and understand that modern electronic kit is pretty much bomb proof.
I've slowly replaced most 12v wiring throughout the boat, and now plan on removing the 1-2-B switch, installing individual isolators and a VSR. I still expect to keep the system as simple and inexpensive as possible, utilising the least number of electronic devices possible.
While pondering this, a question sprang to mind... When the engine is running, and the VSR connects the batteries, what happens when something like the 1500w windlass wants join the party? Does this change anything?

 

[Tranona]

While pondering this, a question sprang to mind... When the engine is running, and the VSR connects the batteries, what happens when something like the 1500w windlass wants join the party? Does this change anything?

Depends on how you wire the windlass, but if to the existing batteries (one or the other) the alternator will just increase its charge to make up for the power the windlass is drawing.

Nothing magic - that is how many boats are wired.

BTW a 1500w windlass is a bit OTT for your size boat. A 1000w would be the norm.

 

[VicS]

Depends on how you wire the windlass, but if to the existing batteries (one or the other) the alternator will just increase its charge to make up for the power the windlass is drawing.

Nothing magic - that is how many boats are wired.

BTW a 1500w windlass is a bit OTT for your size boat. A 1000w would be the norm.

But is the alternator "big" enough to supply the current that a 1500 watt windlass will draw.

If not and the volts fall below the VSR cut off point it will open

 

[PaulRainbow]

I'm finally coming round to the idea of upgrading our charging system. I was twice in past, let down by failing electronic charging kit and, as a result, I've been an avid supporter of old fasioned kit such as 1-2-B switches etc ever since. Having also had an altetnator fried by missuse of that switch, I have to catch up now, and understand that modern electronic kit is pretty much bomb proof.
I've slowly replaced most 12v wiring throughout the boat, and now plan on removing the 1-2-B switch, installing individual isolators and a VSR. I still expect to keep the system as simple and inexpensive as possible, utilising the least number of electronic devices possible.
While pondering this, a question sprang to mind... When the engine is running, and the VSR connects the batteries, what happens when something like the 1500w windlass wants join the party? Does this change anything?

Connect the windlass to the engine battery, only use it with the engine running. Leave the alternator charging connected to the engine battery too, it's most likely connected to the positive battery cable on the starter, leave it there. The windlass will draw power from the engine battery and the alternator, plus some from the domestic bank via the VSR. The VSR will open, should the battery voltages fall too low for too long (the Victron Cyrix has some microprocessor control to allow this), thereby protecting the battery bank isolation. It's unlike this would happen in normal circumstances though.

 

[PaulRainbow]

But is the alternator "big" enough to supply the current that a 1500 watt windlass will draw.

No, but it will make a big contribution.

If not and the volts fall below the VSR cut off point it will open

Only if he fits a single sensing VSR. A dual sensing VSR would require both banks to fall below the VSR set point. The Victron Cyrix is smart enough to allow that to happen for a short time, as the windlass would cause a drop in surface voltage.

All irrelevant though, as the windlass will use what it uses, nothing to be done about that and that's how just about every small to mid sized cruiser works anyway.

 

[NormanS]

Connect the windlass to the engine battery, only use it with the engine running. Leave the alternator charging connected to the engine battery too, it's most likely connected to the positive battery cable on the starter, leave it there. The windlass will draw power from the engine battery and the alternator, plus some from the domestic bank via the VSR. The VSR will open, should the battery voltages fall too low for too long (the Victron Cyrix has some microprocessor control to allow this), thereby protecting the battery bank isolation. It's unlike this would happen in normal circumstances though.

I have a sailing yacht, and on occasion sail away from my anchor, so my anchor windlass is fed from my domestic bank. The "start" battery is reserved for starting.

 

[PaulRainbow]

I have a sailing yacht, and on occasion sail away from my anchor, so my anchor windlass is fed from my domestic bank. The "start" battery is reserved for starting.

If that's how you prefer it, that's fine. There is nothing wrong with either connection in most cases.

The OP has a motor sailor, fitted with a 100w solar panel and will be fitting a dual sensing VSR, so it wouldn't matter if he used a little power from the engine battery. He's also fitting an emergency start switch.

 

[pvb]

I'd be tempted to fit a low-loss splitter rather than a VSR - maybe look at the Victron ArgoFET.

 

[halcyon]

No, but it will make a big contribution.



Only if he fits a single sensing VSR. A dual sensing VSR would require both banks to fall below the VSR set point. The Victron Cyrix is smart enough to allow that to happen for a short time, as the windlass would cause a drop in surface voltage.

All irrelevant though, as the windlass will use what it uses, nothing to be done about that and that's how just about every small to mid sized cruiser works anyway.

These days we monitor both amps and volts to control VSR, in older units we monitored winch or bowthuster relay operation to isolate domestic battery before load came on.

Brian

 

[Dougal]

The alternator is either 75 or 85amp, although I've only ever seen it 'bend the needle' on the 60amp a meter once

 

[BabaYaga]

If you feel reluctant to use electronics for charge splitting, one other option worth considering is to use a simple, heavy duty relay controlled by alternator D+ output to combine the battery banks.
This means that the banks will always be paralleled when the engine is running and always be separated when it is not.
I have used such a system for over a decade and it has worked well. Some people say there are drawbacks in certain scenarios (rather far-fetched in my view), but there are potential drawbacks to VSRs too.

 

[PaulRainbow]

I'd be tempted to fit a low-loss splitter rather than a VSR - maybe look at the Victron ArgoFET.

I was tempted to suggest just that, but the OP wants the solar panel to charge the engine batteries too.

I think with the simpler installations, couple of batteries, alternator, odd solar panel etc, the VSR still has its place. It's inexpensive and does the job. More complex installations would not be best suited to VSRs.

I've got to sort some issues on on a large boat, twin diesels, bow and stern thrusters, mains charger, large solar array, generator and inverter. Total of six battery banks. The current "professionally" installed system consists of a 3 way diode and 4 VSRs, with just one emergency switch between the engine banks, the switch doesn't allow emergency starting with the dead bank isolated, due to the way the BEP cluster comes wired.

Some ArgoFETS will make a really neat job here, i might just add a single VSR to keep the generator battery topped up.

 

[PaulRainbow]

If you feel reluctant to use electronics for charge splitting, one other option worth considering is to use a simple, heavy duty relay controlled by alternator D+ output to combine the battery banks.
This means that the banks will always be paralleled when the engine is running and always be separated when it is not.
I have used such a system for over a decade and it has worked well. Some people say there are drawbacks in certain scenarios (rather far-fetched in my view), but there are potential drawbacks to VSRs too.

There are drawbacks, no question. The failure of a single battery could discharge every battery on the boat, depending on the failure mode of the battery. You would be unaware of the problem until you turn the engine off, because the electrics would all be running from the alternator. I can assure you this is not far fetched, as i have personally had it happen, although i was saved by not having a basic relay, i had solid state split charging. 50 miles into a 150 passage we stopped for fuel, when the engine was turned off all of the onboard electrics went off. Investigations found that one of the domestic batteries had failed whilst underway, discharging the whole bank, the electronics had been running from the alternator. If we had a relay that permanently paralleled the banks the engine battery would also have been flat and we'd have been screwed. As it was, the faulty battery was isolated and we carried on our way.

Had we have had a VSR, the entire domestic bank would still have discharged, as the batteries were obviously connected together. But, the VSR would not have allowed the faulty domestic battery to discharge the engine battery, the drop in voltage at the batteries would have caused the VSR to open.

On a day to day basis, with no faults, your relay will do as good a job as a VSR. It will not protect you from faults any more than having one single battery bank for the engine and domestics combined, whilst the engine is running.

A modern VSR is no less reliable than a simple relay and i doubt the cost difference would be significant.

 

[BabaYaga]

There are drawbacks, no question. The failure of a single battery could discharge every battery on the boat, depending on the failure mode of the battery. You would be unaware of the problem until you turn the engine off, because the electrics would all be running from the alternator. I can assure you this is not far fetched, as i have personally had it happen,

Not claiming this could not happen, still in my view such a sudden and catastrophic failure mode, likely because of some kind of internal short, is rather unusual.
Also, it seems to me that the fault could have been spotted, if someone had glanced at the battery monitor or V/A meters at some time during the 50 mile trip?
My own set up is such that the alternator connects to the house bank first and then via the relay to the start battery. Not everyone's preference, I know, but it allows me, during long engine passages, to manually disconnect the start battery after an hour or so.

 

[PaulRainbow]

Not claiming this could not happen, still in my view such a sudden and catastrophic failure mode, likely because of some kind of internal short, is rather unusual.

Sorry, but it isn't at all unusual, i've dealt with sudden and catastrophic battery failures more times than i can count.

If you're happy with what you have, that's fine by me.