Should I swap Starter and Leisure battery connections to my VSR?

[Argold57]

Hello:

I have been searching the term" VSR" in the forum but have not found anything that directly answers this question, so I thought I would post.

The setup I have on my 38' cc sailboat is the alternator feeds the starter battery (I am pretty sure) and a dual sensing VSR connects the starter battery to the leisure battery when the starter battery reaches the "on voltage". I'm pretty sure this is the original setup but I am the second owner.

Recently, before a week long trip, I upgraded my leisure battery to 2 x 220 ah of AGM (440 ah total). During the trip, I took the leisure battery bank down pretty far and when I was next motoring, the VSR kept clicking on and off. I'm pretty sure this was because the starter battery reached sufficient voltage so the VSR closed. But then it was drawing enough current from the starter battery that the voltage went down to the VSR "off" voltage and the VSR opened again. It was a calm day so we motored a long way and the VSR clicked on and off for hours until we reached our next port where we connected to mains and charged the leisure battery.

So I got to thinking, what would happen if I swapped the battery connection so that the leisure battery got the charge from the alternator first before the starter? The main risk, I think, would be if I had both a low starter and leisure battery that the leisure would get charged and the starter would not. In a pinch, I could use the battery selector to start from the leisure battery. I'm not sure how many starts I would get from my 80 ah starter without charging (my engine always starts on the first bump).

So here are my questions:
1) Are most setups that use VSR's similar to mine?
2) Is it a bad idea to make the swap I proposed?
4) Is that clicking on and off hurting anything?
3) What issues am I not considering?
4) Is there a better alternative?
a) For example, how about adding a diode so the starter battery cannot discharge through the VSR to the leisure battery yet the alternator would still charge it?

By the way, I have no solar panels on this boat. (yet) Next year we retire and I hope to take much longer trips.

Thanks folks for your advice.

 

[PaulRainbow]

Buy a better VSR, such as the Victron Cyrix.

 

[Sandy]

As @PaulRainbow says might be worth checking the VSR.

I have mine wired that when on engine it charges the starter then house, when on shore power it's the other way round.

 

[Argold57]

Buy a better VSR, such as the Victron Cyrix.

What makes one VSR better than the next? Is it not just a relay that senses voltage?

What features should I look for in a "better" VSR?

Thank you.

 

[Argold57]

As @PaulRainbow says might be worth checking the VSR.

I did check the voltages and they were just as marked on the VSR.
It seems a simple thing, there is an on and off voltage, the relay closes and opens at those voltages.

 

[Spirit (of Glenans)]

What makes one VSR better than the next? Is it not just a relay that senses voltage?

What features should I look for in a "better" VSR?

Thank you.

Probably a more expensive one
(That's the way it seems to be, with "marine" products.

 

[PaulRainbow]

What makes one VSR better than the next? Is it not just a relay that senses voltage?

What features should I look for in a "better" VSR?

Thank you.

Cheap/poor quality/some early VSRs suffer from the chatter you describe. Better quality ones don't. The Victron Cyrix i mentioned has a microprocessor and doesn't simply switch on and off at preset voltages. The voltages vary and there are delays in switching to prevent chatter. For £42 i wouldn't mess around with inferior VSRs.

 

[halcyon]

Cheap/poor quality/some early VSRs suffer from the chatter you describe. Better quality ones don't. The Victron Cyrix i mentioned has a microprocessor and doesn't simply switch on and off at preset voltages. The voltages vary and there are delays in switching to prevent chatter. For £42 i wouldn't mess around with inferior VSRs.

In this case it's probably to small an alternator now with the new bigger battery bank, output voltage callapsing. Back in 1980 we had a pulsed start up, to limit stress and allow some cooling of the alternator, rather than locking in the VSR to stop the click.

Answer is to look after the batteries and limit excesive discharge, thus holding up voltage during charge.

Brian

 

[Argold57]

In this case it's probably to small an alternator now with the new bigger battery bank, output voltage collapsing. Back in 1980 we had a pulsed start up, to limit stress and allow some cooling of the alternator, rather than locking in the VSR to stop the click.

Brian

Yes Brian, I think that this is the case. The battery bank is larger and the alternator is the same old one, likely a bit on the small side. I'm not sure what the best thing to do about that would be.

No one has yet said if my idea of swappng the leisure and starter battery connections is good or bad.

 

[Ian_Rob]

The battery bank is larger and the alternator is the same old one, likely a bit on the small side.

Do you you know what output your alternator is actually producing…?

 

[ghostlymoron]

It's common UK practice to give priority to the starter battery so that you can always start your engine. I understand that in the US they do the opposite but can't see the logic.
My first vsr was a BEP which chattered a bit.

 

[Iliade]

A quick fix would be to set your 0-1-2-both switch to 'both' if you are planning to motor for an extended period. Don't forget to disconnect them when you stop motoring lest you flatten the engine battery.

 

[ghostlymoron]

This kind of defeats the object of a VSR.

A quick fix would be to set your 0-1-2-both switch to 'both' if you are planning to motor for an extended period. Don't forget to disconnect them when you stop motoring lest you flatten the engine battery.

 

[Boater Sam]

I would try it connected to the cabin batteries first, its a subject like boat toilets though, two schools of thought. With a small alternator charging the cabin batteries first would be a good ide as if they are quite well discharged the alternator will produce maximum output for longer than it will charging one almost fully charged engine battery.
You will get many many starts from an 80Ah battery before you notice any fall off in cranking speed.

 

[halcyon]

Yes Brian, I think that this is the case. The battery bank is larger and the alternator is the same old one, likely a bit on the small side. I'm not sure what the best thing to do about that would be.

No one has yet said if my idea of swappng the leisure and starter battery connections is good or bad.

It will not make any difference, alternator feeds the engine battery direct, the relay only links the service battery in circuit and then uses battery internal physics to direct charge to the service battery.

Brian

 

[johnsilver2]

Bring your boat up to date by getting rid of the 1-2-both switch, completely separating the domestic and engine start circuits and fit a good quality efficient (no voltage drop) split charge system. Alternatively use a battery to battery charger from start to domestic. The alternator could be upgraded and a modern multistage regulator fitted to make the most of engine hours. There are several suppliers out there who will guide you and I have found Sterling to be very good.

 

[PaulRainbow]

If you fit a decent VSR the problem goes away. My own boat has a single battery for the engine and 4 Trojan T105s for the domestic bank, that's 450AH. The Victron Cyrix does not chatter. I have fitted dozens of these VSRs to similar systems and never had a problem with chatter.

 

[halcyon]

If you fit a decent VSR the problem goes away. My own boat has a single battery for the engine and 4 Trojan T105s for the domestic bank, that's 450AH. The Victron Cyrix does not chatter. I have fitted dozens of these VSRs to similar systems and never had a problem with chatter.

First question is does the OP have a problem during normal use, batteries around 50% discharge?,
Next question will the OP be heavely discharging his batties on a regular basis ?
Next question what is the alternator size ?
If the alternator can cope with load, either bolt both charge cables on same bolt if low batteries or buy new VSR that does the same internally, check charge circuit cable rating.
If the alternator is to small, then first change it for a larger one, check charge circuit cable rating. either see if that sorts the problem, if not fit a new suitably rated VSR.

The problem stopping chatter is avoiding creating a new problem else where, i.e. in the alternator, that's why we started using both volts and amps to calculate VSR operation.

Brian

 

[VicS]

Yes Brian, I think that this is the case. The battery bank is larger and the alternator is the same old one, likely a bit on the small side. I'm not sure what the best thing to do about that would be.

No one has yet said if my idea of swappng the leisure and starter battery connections is good or bad.

You have identified the possible snag with this yoruself

You have a number of options including :

Replace the VSR with a modern electronically controlled one ( eg Victron Cyrix ) which will not chatter on and off ( although it may cycle on and off will with a period of several seconds for a short while ).

Replace the VSR with a low loss splitter ( eg Victron Argofet)

Replace the VSR with a Sterling alternator to battery charger, which will give you enhanced charging of the house bank and bog standard charging of the engine start battery simultaneously.
Not everyone is all that keen on Sterling equipment though.

Use your main battery for all purposes, including normal engine starting, and charge a smaller reserve/ emergency start battery via a VSR

 

[PaulRainbow]

You have identified the possible snag with this yoruself

You have a number of options including :

Replace the VSR with a modern electronically controlled one ( eg Victron Cyrix ) which will not chatter on and off ( although it may cycle on and off will with a period of several seconds for a short while ).

Replace the VSR with a low loss splitter ( eg Victron Argofet)

The Argofet is another good solution, although as the OP has suggested he'll be fitting solar, the VSR seems like a better option for him.