Batteries discharged by faulty VSR

[Redwing228]

We have a two-battery (engine start and 'house') on 'Enfys', both batteries are 110Ah and are charged by an alternator on her Beta 20. The isolators are BEP make with separate switches for each battery and an emergency paralleling switch. There is a VSR connected between the two batteries and is on the supply side of the switches.
On going to the boat last evening we found both batteries almost completely discharged (10V at the terminals) and discovered that the VSR was energised. It must have remained energised since the engine was last run, about 10-days ago. and as it held the two batteries together is has discharged both of them! Utter disaster! I've brought both batteries home to charge them but their condition has probably been harmed as they are both conventional wet cell lead-acid type.

As a quick fix I intend to remove the connecting wires to the VSR and will have to manually manage the batteries by closing the emergency switch to charge both whilst the engine is running.

My confidence in the VSR has been dented. Has anyone else experienced a failure like this? Also, is there a good reason why the relay is on the supply (battery) side of the isolators?
Thanks,
Bill

 

[Sandy]

I'd be testing the VSR before coming to that conclusion. With the VSR 'open' the voltage should just equalise over all the batteries. Was anything left on?

 

[Daverw]

Cannot answer about why vsr was still connected, never had an issue with them, my question would be why did they discharge as the vsr would not have done this.

 

[lustyd]

With the VSR on the supply side it can still connect the banks without you turning the circuits on. Often the charger is that side to allow you to charge while also isolating the load. As such, whatever discharged your batteries must be on that side too, assuming you switched all the switches off before leaving. That leaves fewer culprits to check for the discharge.

As for the VSR, yes by BEP one seems to have a very strange operating pattern. If I don't use any power it will stay on indefinitely. As soon as I use the engine start battery (e.g. for glow) the voltage drops and it disconnects after the allotted 20 seconds or so. I don't think I've seen it remain connected when voltage reduces though.

 

[Redwing228]

I'd be testing the VSR before coming to that conclusion. With the VSR 'open' the voltage should just equalise over all the batteries. Was anything left on?

When I disconnected the engine start battery I heard the VSR click open and then just dabbing the lug onto the battery post it could be heard closing and opening. The voltage sensing circuit seems to have failed. The spec for the VSR says it should close when start battery gets to 13.7V. The terminal voltage was a little over 10V last night as it and the other battery had been discharged by the VSR's permanent current draw.
Both isolators were left open, as they always are when the boat is left unattended; only the VSR is in the circuit.

 

[Redwing228]

With the VSR on the supply side it can still connect the banks without you turning the circuits on. Often the charger is that side to allow you to charge while also isolating the load. As such, whatever discharged your batteries must be on that side too, assuming you switched all the switches off before leaving. That leaves fewer culprits to check for the discharge.

As for the VSR, yes by BEP one seems to have a very strange operating pattern. If I don't use any power it will stay on indefinitely. As soon as I use the engine start battery (e.g. for glow) the voltage drops and it disconnects after the allotted 20 seconds or so. I don't think I've seen it remain connected when voltage reduces though.

I see now the reason for having the VSR on battery side of the switch; to enable external charging of both batteries from one source. On 'Enfys' there is no external charger connected and nothing is connected directly to the batteries, i.e. upstream of the isolators. The VSR was fitted about 10-years ago and has always operated as expected till now; dropping out as soon as the batteries fall to 'resting' voltage plus 20-second time delay or so, after stopping the engine.

 

[lustyd]

Hmmm that being the case it's even more perplexing where those 2kWh of juice went! doesn't look like the switches or VSR got hot so I'd keep a close eye on the batteries as they charge. It could just be a failed cell in a battery causing a drop of a couple of volts, my old car had a battery that did that intermittently it was a bugger to troubleshoot!

 

[geem]

When I disconnected the engine start battery I heard the VSR click open and then just dabbing the lug onto the battery post it could be heard closing and opening. The voltage sensing circuit seems to have failed. The spec for the VSR says it should close when start battery gets to 13.7V. The terminal voltage was a little over 10V last night as it and the other battery had been discharged by the VSR's permanent current draw.
Both isolators were left open, as they always are when the boat is left unattended; only the VSR is in the circuit.

Maybe upgrade to a 1, 2 both switch ?

 

[pandos]

Maybe upgrade to a 1, 2 both switch ?

I did this after my VSR did something similar...I highly recommend it....

 

[Stemar]

deleted - different system

 

[Redwing228]

I did this after my VSR did something similar...I highly recommend it....

I've still got the 1,2 both switch that I removed when installing the BEP cluster

 

[dolabriform]

I've still got the 1,2 both switch that I removed when installing the BEP cluster

Sell it on ebay, you'd be surprised how much they go for

 

[Sandy]

When I disconnected the engine start battery I heard the VSR click open and then just dabbing the lug onto the battery post it could be heard closing and opening. The voltage sensing circuit seems to have failed. The spec for the VSR says it should close when start battery gets to 13.7V. The terminal voltage was a little over 10V last night as it and the other battery had been discharged by the VSR's permanent current draw.
Both isolators were left open, as they always are when the boat is left unattended; only the VSR is in the circuit.

Not my idea of testing, but hey ho.

My VSR opens at 13.7 volts allowing the charging current to both the engine and house battery banks. At 13.0 volts it closes; no current is delivered to the house batteries. This is usually when the engine is switched off or shore power removed.

I still can't get my head round why your isolators are 'open' I switch my master switch to off when I leave the boat, that isolates the batteries and I lose about 0.10 volts of charge in a month (AGMs). As I stated before it sounds like something has been left on with your isolator 'open'.

 

[Alan S]

Not my idea of testing, but hey ho.

My VSR opens at 13.7 volts allowing the charging current to both the engine and house battery banks. At 13.0 volts it closes; no current is delivered to the house batteries. This is usually when the engine is switched off or shore power removed.

I still can't get my head round why your isolators are 'open' I switch my master switch to off when I leave the boat, that isolates the batteries and I lose about 0.10 volts of charge in a month (AGMs). As I stated before it sounds like something has been left on with your isolator 'open'.

Wrong terminology can cause confusion. The VSR CLOSES at 13.7 Volts.
Just sayin.....

 

[Sandy]

My wrong. Apologies all.

 

[r_h]

Maybe upgrade to a 1, 2 both switch ?

I have done the same, but I only recommend it as an option to those with a very healthy paranoia that leads them to immediately switch to the correct banks when appropriate and, just in case, to keep a near continuous eye on battery state

 

[LittleSister]

Normally VSR systems are extremely reliable.

Certainly vastly more reliable than my memory (and, I suspect, most other people's) for remembering to switch a 1-2-Both switch to the appropriate setting at the appropriate times. In years of use I've never had a BEP VSR fail, but I have been on boats with one flat battery because the skipper has forgotten to change over the 1-2-Both switch. So it would seem perverse to me to abandon using VSR use on the basis of a single failure (if that's what it is).

As others have suggested above, it seems unlikely that the VSR itself, if operating normally, has drained the batteries, though you don't state how long the boat had stood since the last visit. (My previous boat with a BEP VSR stood for weeks, probably sometimes months, without flattening the batteries). The spec for the current BEP VSR states it consumes 1.8mA in 'standby' mode, and though it doesn't state the current draw when activated, I doubt this is very high, and it would fall as the batteries' voltage dropped below 12v. (Note that the current model BEP VSR has an optional 'storage' mode, which (by addition of an external sensing wire) consumes no current at all when the engine ignition (or other external switch) is off, but I wasn't aware of that option being available on my older BEP VSR.)

The fact, though, that (if I understand correctly) your VSR is cutting in (closing) with a voltage below 12v indicates something severely amiss with it. I think you can consider it failed and requiring replacement. Apart from some random component failure within it, things that spring to mind that might perhaps have caused a failure are -
(a) an excess current draw - i.e. over 125 amps continuous (though you'd expect visible damage, I think from that) or 140 amps instantaneous (could a failed battery cell result in either of those?); or
(b) an excess voltage applied to it (could it have been shorted to a mains supply or other high, or your alternator regulator failed, perhaps?); or heat (perhaps from a poor connection or other source, though you'd think you'd see charring); or
(d) water ingress..

If I were you, I would simply buy a replacement BEP VSR, and consider connecting the optional 'storage mode' wire to your ignition. I would also want to check, before fitting it, neither of the batteries have failed (e.g shorted cells), the alternator output voltage is correct, and any potential source of a stray high voltage or water ingress.

Link to manual for current model BEP VSR -
https://www.bepmarine.com/-/media/inriver/710-140A_INSTR_BEP.pdf?modified=20211027183358

 

[geem]

I did this after my VSR did something similar...I highly recommend it....

Normally VSR systems are extremely reliable.

Certainly vastly more reliable than my memory (and, I suspect, most other people's) for remembering to switch a 1-2-Both switch to the appropriate setting at the appropriate times. In years of use I've never had a BEP VSR fail, but I have been on boats with one flat battery because the skipper has forgotten to change over the 1-2-Both switch. So it would seem perverse to me to abandon using VSR use on the basis of a single failure (if that's what it is).

As others have suggested above, it seems unlikely that the VSR itself, if operating normally, has drained the batteries, though you don't state how long the boat had stood since the last visit. (My previous boat with a BEP VSR stood for weeks, probably sometimes months, without flattening the batteries). The spec for the current BEP VSR states it consumes 1.8mA in 'standby' mode, and though it doesn't state the current draw when activated, I doubt this is very high, and it would fall as the batteries' voltage dropped below 12v. (Note that the current model BEP VSR has an optional 'storage' mode, which (by addition of an external sensing wire) consumes no current at all when the engine ignition (or other external switch) is off, but I wasn't aware of that option being available on my older BEP VSR.)

The fact, though, that (if I understand correctly) your VSR is cutting in (closing) with a voltage below 12v indicates something severely amiss with it. I think you can consider it failed and requiring replacement. Apart from some random component failure within it, things that spring to mind that might perhaps have caused a failure are -
(a) an excess current draw - i.e. over 125 amps continuous (though you'd expect visible damage, I think from that) or 140 amps instantaneous (could a failed battery cell result in either of those?); or
(b) an excess voltage applied to it (could it have been shorted to a mains supply or other high, or your alternator regulator failed, perhaps?); or heat (perhaps from a poor connection or other source, though you'd think you'd see charring); or
(d) water ingress..

If I were you, I would simply buy a replacement BEP VSR, and consider connecting the optional 'storage mode' wire to your ignition. I would also want to check, before fitting it, neither of the batteries have failed (e.g shorted cells), the alternator output voltage is correct, and any potential source of a stray high voltage or water ingress.

Link to manual for current model BEP VSR -
https://www.bepmarine.com/-/media/inriver/710-140A_INSTR_BEP.pdf?modified=20211027183358

With large display LCD voltmeters for each bank of batteries and analogue Ammeters it's pretty easy at a glance to see what's going on. No VSR here and never flattened a battery

 

[Yngmar]

VSR current overload can weld the relay contactor shut. If so, the VSR is permanently bridging the battery banks even though the measurement side is probably still working correctly. You can cut it open to confirm, the welded contacts should be obvious.

Can happen for a number of reasons, most common: engine starter was drawing cranking current through it. Make sure it's sized appropriately for the way it is wired.

Another is undersized cables or insufficient contact area (from corrosion). Then the current flowing through is handled fine by the relay but it heats up the contacts, causing the plastic to deform and the relay to jam mechanically. I see no signs of corrosion on your picture, but the cables look definitely too small for the 145A the relay is rated for.

 

[Tranona]

Those cables are the standard fitted to the switch cluster - I have a new one in front of me and exactly the same. Like others I have had a BEP Marine cluster for years without any problems.