Jump to content

Electrical questions (from a plumber, please be gentle...)


Featured Posts

Although pretty much everything on our (ten year old) boat has worked fine since we bought it, I have had a few electrical niggles which have been 'entertaining' me recently.

 

I've just had to swap both the engine and domestic battery master switches as they weren't making a decent contact all the time. While doing this, I've realised that even with the domestic 12V circuit battery master switch turned off, when the engine is running, the interior lights still work, albeit with flickering (I've not checked the other stuff such as the shower pump, etc).

 

Would I be right to assume this is normal, and they're running from the alternator or should it be the case that when the switch is off, nothing domestic 12V should work regardless of whether the engine is running or not?

 

And if the switch is off but the engine running, would the domestic batteries still be being charged?

 

I've not tried (and won't) turning the engine battery master switch off with the engine running as I gather that's bad things, man!

 

Loads of questions, and probably gormless ones, but I'd appreciate any thoughts.

 

Thanks very much, as always.

Link to comment
Share on other sites

Wiring strictly to the BSS is likely to have the main charging lead to the domestic bank connected to the switched side of the maser switch so it is likely that your supposition is correct.

 

If the switch is off the domestic bank will not be being charged if my reading of the situation is correct.

 

I assume that you have a single alternator boat otherwise turning the domestic master switch off would be a bad thing in that it could wreck the domestic alternator. It would also tend to be a bad thing if you have a split charge relay boat if the main alternator output ran to the domestic bank but perhaps any charge splitting plus the domestic loads that were on was enough to keep the alternator on load.

 

NEVER turn either master switch off when the engine is running to be on the safe side.

Link to comment
Share on other sites

It is very difficult to determine answers without the actual circuit diagram of your boat.

 

The first thing I would do is try to follow the wires and try to draw one.

 

If the electrics work different to when you bought the boat something is amiss. Flickering lights definitely sound wrong.

Link to comment
Share on other sites

It is very difficult to determine answers without the actual circuit diagram of your boat.

 

The first thing I would do is try to follow the wires and try to draw one.

 

If the electrics work different to when you bought the boat something is amiss. Flickering lights definitely sound wrong.

 

 

Probably not if its just the alternator output with no battery to damp any voltage fluctuations, especially if the engine is running at idle.

Link to comment
Share on other sites

 

NEVER turn either master switch off when the engine is running to be on the safe side.

 

 

If the battery becomes disconnected from the alternator whilst it's running the alternator will produce significantly more than the nominal 12 - 14V possibly up to 60V. This is called load dump and can destroy electronics connected to the alternator. TYpically this is a problem caused by loose battery terminals not battery switches. Automotive grade electronics is designed to survive it, domestic 12V devices aren't and it could destroy them.

Link to comment
Share on other sites

Thanks folks. The boat has two alternators (standard Beta B43 set-up), one each for the (four) domestic and (one) engine batteries.

 

When I think back, we've had the lights flickering with the engine running before, even when the domestic master switch was turned on. That's partly why I changed the switch today as realised it clearly wasn't always making a connection, and conversely I now think it also sometimes didn't properly switch off, even with the key removed (and the engine not running).

 

I don't think we've fried anything, thank goodness, but I'll take the good advice and make sure never to have the engine running without both master switches 'on'. I was vaguely aware of that for the engine one, but not the domestic side.

 

I'll have to look into a wiring diagram Tiggs. There may be one in the boat's documentation (however I don't think so) but I might struggle to draw one up myself. My dad was the electrician...!

 

Thanks again folks. What a splendid lot you all are.

  • Greenie 1
Link to comment
Share on other sites

Check things like the engine earth connection at both ends and the alternator connections at both ends. These are connected to the engine which will vibrate and could work loose / break. We had flickering lights and traced it to a damaged engine earth making intermittent contact. I re-crimped it and the flickering stopped.

Link to comment
Share on other sites

Check things like the engine earth connection at both ends and the alternator connections at both ends. These are connected to the engine which will vibrate and could work loose / break. We had flickering lights and traced it to a damaged engine earth making intermittent contact. I re-crimped it and the flickering stopped.

Yes, so often with electrics it's the earth side of things that goes wrong and is the last thing that people look at.

  • Greenie 1
Link to comment
Share on other sites

  • 10 months later...

Dragging my old topic back up, I've just had to buy two more battery master switches as the ones I replaced last April (which solved all the

problems I initially asked about, incidentally) have started playing up again.

 

Where they're located, they will get damp from condensation (as indeed do the batteries and all the "heavy" wiring to them)

so I can understand it if the terminals inside the switches get tarnished and start to become less conductive.

 

The chap at the chandlery said that most of this type of switch are okay if you switch them on and leave them on, but they're

not so happy being switched on and off frequently. They're these ones:

 

http://www.midlandchandlers.co.uk/store/category/1939/product/vs-033.aspx

 

I'm considering drilling the rivets out so I can bolt them together and then take them apart to clean the terminals up as required, but

can anyone recommend some different ones that will be more reliable in a damp(ish) environment please?

 

Thanks as always folks.

Link to comment
Share on other sites

Unfortunately those switches you linked are absolute rubbish. Tony B will I am sure confirm that they're more a cause of electrical problems than any other piece of equipment.

 

These look quite good at a sensible price although I have no personal experience with them: http://www.12voltplanet.co.uk/marine-battery-isolator-switch-2-positions.html

 

Hopefully someone will come along shortly with personal experience of a decent make.

Link to comment
Share on other sites

Unfortunately those switches you linked are absolute rubbish. Tony B will I am sure confirm that they're more a cause of electrical problems than any other piece of equipment.

 

These look quite good at a sensible price although I have no personal experience with them: http://www.12voltplanet.co.uk/marine-battery-isolator-switch-2-positions.html

 

 

Ah now I bought one of those a few weeks ago and it is nice and stout yet compactly built. It works fine but then it's installed in a nice dry back cabin with no condensation so I suspect even the cheapy nasty one would still work.

 

I chose it because it is 'face mounting'. The cables connections are on the back of the switch, then you screw the whole lot to the wall or wiring panel. With the OP's switch the cables have to go through the back of the mounting panel to the connections. A flippin' awkward format in my experience.

Link to comment
Share on other sites

Unfortunately those switches you linked are absolute rubbish. Tony B will I am sure confirm that they're more a cause of electrical problems than any other piece of equipment.

 

These look quite good at a sensible price although I have no personal experience with them: http://www.12voltplanet.co.uk/marine-battery-isolator-switch-2-positions.html

 

Hopefully someone will come along shortly with personal experience of a decent make.

Those switches you linked to are not quite the real deal

Fitted a single action (on/off) one to a friends Boat ,it is O.K.

 

Fitted a 3 Position one to my Boat and it was erratic,took it apart to discover the Terminals were smeared with Grease which appeared to be unwilling to conduct Elecktrickery !

 

Have kept it to play with as and when,it may not be beyond redemption?

 

CT

Link to comment
Share on other sites

I would suggest you go to Beal.org and look for isolator switch SH24. I have changed loads of the plastic switchs you are using, they don't like to take as much current as they state, especially find a lot of melted ones on the domestic side of the electrics. I have replaced all the faulty ones I've found with the SH24 switch and never had any problems. Please note I have no connection to beal, just a satisfied customer who has brought from them for many years.

Hope this helps. Andy B

Link to comment
Share on other sites

I agree - absolute rubbish. Never trust and master switch that uses a plastic key.

 

I have a pair of Lucas branded master switches mounted vertically under the cruiser stern deck and so far in 17 years or more the only problem is they need a squirt of WD40 followed by light oil around the spindle every few years so they operate freely.

 

The original switches had a metal case terminals mounted in a ceramic type material while the new ones still have a metal case but the terminal seem to be in a hard thermosetting plastic so heat can not soften it. In many cases the switches like the one the OP has carry a current rating that is optimistic to put it kindly so they overheat, the internal and sometimes the external plastic softens allowing the contacts to move apart so they hardly make contact.

 

 

Edited to add: - http://www.flyingspares.com/shop/rolls-royce-spirit-spur-bentley-turbo-mulsanne/electrical/silver-spirit-turbo-battery/battery-cut-off-master-switch-ud22765p.html

 

to show type but a quick google shows no suppliers who will give proper specifications. Ebay has an visually similar switch for £14 but it all depends upon the material used and the current rating.

 

 

Here you go http://www.demon-tweeks.co.uk/motorsport/switches/lucas-battery-master-cut-off-switch-isolator-classic-race-rally-12v-or-24v

 

Note the current rating.

Edited by Tony Brooks
Link to comment
Share on other sites

I would suggest you go to Beal.org and look for isolator switch SH24. I have changed loads of the plastic switchs you are using, they don't like to take as much current as they state, especially find a lot of melted ones on the domestic side of the electrics. I have replaced all the faulty ones I've found with the SH24 switch and never had any problems. Please note I have no connection to beal, just a satisfied customer who has brought from them for many years.

Hope this helps. Andy B

 

 

This one?

 

sh24.138.jpg

 

https://www.beal.org.uk/automotive/switches-flasher-units/battery-isolator-switch-250a.html

  • Greenie 1
Link to comment
Share on other sites

Do we suppose this is a misprint? "2000a for 10 seconds. 25a continiuos @ 24v."

 

I like the look (and spec) of the Lucas one Tony B linked.

 

Seeing as Beal can't even spell continuous I get all scared with them ;)

Link to comment
Share on other sites

Do we suppose this is a misprint? "2000a for 10 seconds. 25a continiuos @ 24v."

 

I like the look (and spec) of the Lucas one Tony B linked.

 

Seeing as Beal can't even spell continuous I get all scared with them wink.png

I just found the missing zero, here it is '0' Shall I send it to them to fit on their web site?

Link to comment
Share on other sites

Look for isolators made by Blue Sea Systems. All their kit is well made imho.

 

This is good, and often repeated advice.

 

"Flamingo" didn't come to us with much good quality equipment suitable for reuse, but it does have 3 isolator switches by Blue Sea, and all seem bullet-proof, and far superior to most others I have seen.

 

They will cost you more initially, but ultimately you are unlikely to need to replace them every few years.

Link to comment
Share on other sites

Blue Sea stuff is very good albeit somewhat expensive. Having said that, £28 for a 300A isolator that is likely to actually be capable of handling 300A isn't as bad as I thought.

http://www.piratescave.co.uk/blue-sea-mseries-battery-isolator-switch-single-circuit-onoff-300a.ir

 

Edited to correct the link

Edited by WotEver
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.