Batts died .... and Bosch Relay

[Refueler]

Finally braved the strong ice-cold winds and went to the boat to have a check ....

Engine battery fine .... but the two house batts were dead ... 0V each. Despite having had maintenance charger connected.

Decided to hunt down the charge relay .... and found it up under the lip of the bunk base .... not exactly handy position as its blocked by the battery boxes.

I was expecting a typical marine VSR but what I found :

Managed to get phone in to get the photo.

Here's general setup and arrow points to the location of the relay :

Somewhere is a standing drain on that house bank ... looks like I shall be spending hours trying to find out what's cause ....

 

[B27]

It takes time to work out what 'previous owners ' have done, or allowed to happen.
It's annoying to lose two serviceable batteries, doubly annoying to realise you have more work to do, to prevent the new batteries going the same way.

Back in the 80s, I could get on most (racing) boats and understand the basics of the wiring, the dreaded 1B2 switch used to actually isolate the batteries, it's been a slippery slope of complication ever since.

 

[BabaYaga]

I was expecting a typical marine VSR but what I found :

That is a normally open relay, typically used between engine battery and house batteries, triggered by alternator D+ (charging light circuit). So on the relay should be two large wires and two smaller, D+ and negative. I have identical in my boat.
Unclear to me if the type of relay has anything to do with the flattened house batteries, probably not.

 

[William_H]

As said it is just a relay. It is difficult to see if there are any coil activating wires attached. Presumably just hard to see. Could be activated by alternator tacho output or perhaps via another normally closed relay from oil pressure light via engine power (ignition) circuit maybe simply from engine power circuit. Or possibly another VSR some where else. Just have to try to trace wiring from relay back to what drives it.
As for flat batteries. That is bad luck and hopefully you cna find a leakage or load that is flattening them. ol'will

 

[Refueler]

Like so many boats .. wires disappear into the linings / nether regions .....

I'm dreading it - but slowly coming to conclusion that I may haver to just pull everything and start again.

The two house are disconnected and I've left a couple of pulse chargers on them ... see if anything happens ...

If I could get hold of an old fashioned basic non smart charger of about 10A ... I'd be on a winner .... but all the shops / dealers now only sell smart chargers .... which are a waste of space in this situation.

 

[Refueler]

As said it is just a relay. It is difficult to see if there are any coil activating wires attached. Presumably just hard to see. Could be activated by alternator tacho output or perhaps via another normally closed relay from oil pressure light via engine power (ignition) circuit maybe simply from engine power circuit. Or possibly another VSR some where else. Just have to try to trace wiring from relay back to what drives it.
As for flat batteries. That is bad luck and hopefully you cna find a leakage or load that is flattening them. ol'will

No idea ... not what I expected to find. This afternoon will be onboard again ....

Oh - forgot to mention ... in bottom of engine battery box - found starting handle for the Yanmar ! It fits as well ...

 

[Refueler]

two smaller activator wires behind the main power ones .... but they disappear of into the realms !!
One takes a long route out ... round and back again to the -ve of the battery bank. The other cannot trace as it goes behind panelling.

Decided to lift out the two house batts and bring home ... see what my gear at home can do with them. I have 3 spare batts at home if needed. But first need to sort out that power drain ....

Can someone please explain to me why anyone would remove the lifting handles from the batts ?? All three have had the lay flat handles removed .... so had to rig light lines through to lift them out ...

If you look closely - the GREEN indicator is showing - saying battery is full charged !! Rubbish - DVM shows about 0.5v !!

Metered the solar regulator : NAPS NC5 .... shows 20.5V coming in and naff all going out ... but that may be because of my playing about with the batts. Think I will change that unit for a newer one that has display once I sort batts. I have a spare controller.

 

[wonkywinch]

Is that green thing measuring the electrolyte? What happens to it if you shake the battery?

 

[Refueler]

Is that green thing measuring the electrolyte? What happens to it if you shake the battery?

I have no idea how the little 'telltales' work ... all I know is that I don't trust them .... so often they show green and batts are definitely not full.

 

[LittleSister]

two smaller activator wires behind the main power ones .... but they disappear of into the realms !!
One takes a long route out ... round and back again to the -ve of the battery bank. The other cannot trace as it goes behind panelling.

You probably don't need to physically follow it, and certainly not in the first instance. When you next start the engine, does the relay operate, and disengage when the engine stops? If it does you can put off finding where it goes until another time. As Baba Yaga and William H imply, you'll likely find it's attached to the alternator (look for wire of same colour in the first instance).

Even without starting the engine you can put your meter across the main (big wire) terminals on the relay to check whether it is open, as it should be, with engine stopped.

More important, perhaps, for your establishing why the batteries are flat is finding out what the 'additional' wires to the batteries in the picture go to.

Think twice before ripping all the existing wiring out, tempting though that may be (as I know from experience). You know hard it is to trace wires that disappear behind panels? It's even harder to put new wires in there!

 

[rogerthebodger]

I have no idea how the little 'telltales' work ... all I know is that I don't trust them .... so often they show green and batts are definitely not full.

They work by measuring the SG of the battery electrolyte in a crude way not very accurate

Yo may be able to remove the green indicator and use a battery hydrometer through the hole

 

[VicS]

They work by measuring the SG of the battery electrolyte in a crude way not very accurate

Yo may be able to remove the green indicator and use a battery hydrometer through the hole

No need to remove the magic eye indicator. The batteries in the pictures have removeable filler caps/plugs!

 

[B27]

I would try charging the batteries with a simple dumb source, like a higher voltage wall wart with a resistance in series if there's no basic charger available. You can use a light bulb in series perhaps?
Put some volts across the battery, see if it takes a current. If it does let it get up to a point where a smart charger works..

I would guess that the relay is not part of the problem, had it been energised, the start battery would have probably been in parallel and killed too!

It's worth having the cell plugs out and looking at electrolyte levels.

Looking ahead, the main thing is to be sure the same doesn't happen to the next pair of batteries.

 

[Boater Sam]

A bit slight for a split charge relay @75A . How big is the alternator?

 

[VicS]

I have no idea how the little 'telltales' work ... all I know is that I don't trust them .... so often they show green and batts are definitely not full.

An internet search engine will find an an explanation ( eg G--g--) if you really want to know . Search for "battery magic eye"

As far as the total loss of charge of the domestic bank is concerned I don't think it will be caused by the relay sticking on, or being energised, because the starter battery is still OK. If the battery banks are paralleled it will not result in one bank being discharged while the other remains fully charged, both would go down together if there is some leak or parasitic load.
It might not be a charge relay though.

.

 

[Supertramp]

That is bad luck.

As an early step I would establish if there is a current drain, even small, when they are at rest (you need another battery or recharge if possible). Check again with the isolator off. And I would trace those reds and blacks connected directly to the battery - I added a buss bar and a battery monitor to my domestic batteries which is great for helping diagnosis. If you had a maintenance charger connected it seems unlikely it couldn't keep on top of a small drain.

I have had old batteries that gave up the ghost when harsh cold weather arrived, despite charger or solar panel support. What year were they made (usually embossed on the case)?

 

[Refueler]

An internet search engine will find an an explanation ( eg G--g--) if you really want to know . Search for "battery magic eye"

As far as the total loss of charge of the domestic bank is concerned I don't think it will be caused by the relay sticking on, or being energised, because the starter battery is still OK. If the battery banks are paralleled it will not result in one bank being discharged while the other remains fully charged, both would go down together if there is some leak or parasitic load.

Looks like I'm guilty of the limited info first post !!

Yes the two domestics are parallel (2 x 75 A/hr) .. the start battery is a single 75 A/hr ...

The -ve cable connects all 3 ... but the +ve is divided so that they are not common ...

The wiring as I see it so far ... but as I say earlier - cables go off behind panels etc so difficult to be sure have ID'd same cable ... but I have idea that the start battery is charged and isolated - has literally nothing to do with the relay .... the domestic is only charged when engine starts and that relay closes.

 

[VicS]

Looks like I'm guilty of the limited info first post !!


The wiring as I see it so far ... but as I say earlier - cables go off behind panels etc so difficult to be sure have ID'd same cable ... but I have idea that the start battery is charged and isolated - has literally nothing to do with the relay .... the domestic is only charged when engine starts and that relay closes.

At which point the battery banks will be connected in parallel surely ? Similar to the way in which a VSR works except that it is closed by some connection to the engine's electrics rather than being voltage sensitive

.

 

[Refueler]

Year of the batterys ??? I looked today when bringing them home ... but couldn't find anything ... will look again tomorrow.

I had one episode before when the domestic bank dropped low .. I put that down to the fridge on all night .. and lack of charger. it may be that the batts are past their useful life ...

They both have had boost charge to get them to register on my pulse mode chargers ... so they can sit overnight on Pulse mode ... maybe I can salvage them for less strenuous use ...

Another aspect I want to check ... and the present controller tells me nothing as it has no display ... once I have a reasonable battery back in - what is the solar doing ... I have a controller with display ... so once I know I can connect without damaging the controller - that will tell me a lot on that side.

 

[Refueler]

At which point the battery banks will be connected in parallel surely ? Similar to the way in which a VSR works except that it is closed by some connection to the engine's electrics rather than being voltage sensitive

.

That's my belief ... but until I can put a battery in that is in good condition to at least check - its only guess at present.

And as 'supertramp' says - I need to trace that power drain. Not possible while no battery ...