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battery replacement tips


pquinn

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But shouldn't everything (other than perhaps a battery monitor such as SG) have its neg connection to the main neg stud on the hull?

 

Tony

 

 

:cheers: I still isolate EVERYTHING through the negative. EVERYTHING!.

 

I know its not the norm. commence condamnation

 

befoer you start... isolator does 600amp continuous (to get the 'continuous' rating only 90 minutes is needed.)

 

It does 900 amps for hours in reality. peaks at a little under 2000.

Edited by Pretty Funked Up
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And that makes two of us (at least)

 

sorry spent my green thing, you can have tomorrows :)

 

ONE switch does ALL!!

 

If i was to leave my boat for some time (doesnt happen) I would turn all fuse breakers off. This leaves only the bilge pump on (which has its own inline fuse). If I wanted everything off, yes everything!, I just use the isolator.

M12 fittings required.

Edited by Pretty Funked Up
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  • 4 weeks later...

Right time for an even bigger thicko question. For many years I tinkered with cars as a hobby and even completely rewired one after writing it off racing it. I then went and lived on a plastic yacht and soon realised that Fibre Glass does not conduct and so everything had to have an earth wire run back to a central earth bank. Er what about canal boats - do they use the hull as a common earth or do I need to run additional earths especially to remote devices?

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Right time for an even bigger thicko question. For many years I tinkered with cars as a hobby and even completely rewired one after writing it off racing it. I then went and lived on a plastic yacht and soon realised that Fibre Glass does not conduct and so everything had to have an earth wire run back to a central earth bank. Er what about canal boats - do they use the hull as a common earth or do I need to run additional earths especially to remote devices?

Every thing should have its own return, no returns via the hull.

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Every thing should have its own return, no returns via the hull.

 

Thanks - Just out of interest - why is that? There can't be that much difference between a car body and narrow boat hull. Er and if the hull is not earthed - why worry about 'sparking spanners' if you undo the positive first???

Edited by larryjc
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Thanks - Just out of interest - why is that? There can't be that much difference between a car body and narrow boat hull. Er and if the hull is not earthed - why worry about 'sparking spanners' if you undo the positive first???

The hull is earth bonded to both 12 volts and if available 240 volts but is not used as a return path for the circuits.

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  • 6 months later...

On this point I have just replaced all my domestic batteries. I now have a bank of 4 110ah and before I had 100ah. I did not look at this discussion board beforehand (unfortunately) and just removed each battery one at a time. When I used the Webasto heater again it made some weird noises, then didn't work, then did work on a couple of occasions and now seems not to be working again. Any ideas?

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I'd check the voltage at the heater terminals before and while it's firing up, or trying to. If it drops excessively there's a wiring or connection problem somewhere, or possibly the batts are flat as a pancake or even shot.

 

To avoid problems with changing the batts it's best to isolate EVERYTHING on the positive side FIRST. Even those wires strung directly to the terminals which probably shouldn't really be there. unsure.png

 

cheers, Pete.

~smpt~

Edited by smileypete
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On this point I have just replaced all my domestic batteries. I now have a bank of 4 110ah and before I had 100ah. I did not look at this discussion board beforehand (unfortunately) and just removed each battery one at a time. When I used the Webasto heater again it made some weird noises, then didn't work, then did work on a couple of occasions and now seems not to be working again. Any ideas?

Co incidence possibly or a bad re~connection. They don't like low voltage on start up.

 

Check your connections.

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  • 2 years later...

I think Gibbos point is that where there's interconnected equipment, removing negatives one at a time can cause a mischief.

 

For example you remove a negative that goes to the diesel heater, then it tries to fire up and destroys the timer! ohmy.gif

 

cheers,

Pete.

 

I think this is where all negatives on that battery bank need to go to a single terminal that can be isolated by removing/loosening one nut.

 

Also surely anything on the domestic bank should go via an Isolation switch and fusing else it fails BSS.

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I think this is where all negatives on that battery bank need to go to a single terminal that can be isolated by removing/loosening one nut.

 

Also surely anything on the domestic bank should go via an Isolation switch and fusing else it fails BSS.

Not everything, things that need to run 24/7 don't like battery charges, bilge pumps, etc. They still need to be fused tho.

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  • 1 month later...
  • 3 months later...

Just to say,, just replaced my domestic batteries, 8 x 6 volt USS 2200,, last lot lasted 8years,, boat used for 6 months every summer only,, on mains in winter 3 stage Stirling,

 

New batteries arrived on Tuesday, great service from Tanya batteries, fitted, oh yes, they did come with the nuts and spares, but could not say what the thread was,, real odd ball that. and a carry handle..

 

No problems, in and working , on float charge now, seem great.

 

Trouble is now got a lot of spare ballast with the old batteries, 8 x6 volts a lot of weight, anybody like them,,, free.

Edited by fretman
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Just to say,, just replaced my domestic batteries, 8 x 6 volt USS 2200,, last lot lasted 8years,, boat used for 6 months every summer only,, on mains in winter 3 stage Stirling,

 

New batteries arrived on Tuesday, great service from Tanya batteries, fitted, oh yes, they did come with the nuts and spares, but could not say what the thread was,, real odd ball that. and a carry handle..

 

No problems, in and working , on float charge now, seem great.

 

Trouble is now got a lot of spare ballast with the old batteries, 8 x6 volts a lot of weight, anybody like them,,, free.

Lots of scrap dealers in your area, It will buy a few pints.

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  • 2 weeks later...

After all that, I am still no wiser. I am about to replace my 4 leisure's have a diesel heater and an inverter with monitor.....and I am now totally confused. In addition the new batteries have terminals on the opposite side so will need at least 1 new lead.

Can someone out there who is technically qualified give us the definitive answer....disconnect the positives or negatives first ?

thanks

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I have a new set of cabin batteries to go in this weekend as they have just arrived from Tayna, so I am in the same position.

 

My view from this thread is switch off isolators, take all positives off, then take all negatives, remove and physically replace all batteries and then reverse all of the rest.

 

What I will do though is to tape up my spanner well to insulate it as there is a lot of metal around the battery housing in the engine room.

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Since none of the boat electric experts has answered this, and I think you guys above need help pdq, I'll chip in.

 

It's usual to remove negative first on vehicles with negative chassis return. This means that should your spanner touch the body when disconnecting the negative there's no problem as they're at the same potential. Should your spanner touch the body when in contact with the positive terminal, there will be no problem either if the negative is already disconnected, but there would be if you did positive first - and a taped up spanner might let you down.

 

Although Narrowboat domestic electrics don't use negative chassis return, the engine and domestic battery negatives will usually be connected and the engine battery negative will go to earth on the engine via the starter motor. For that reason, I treat my boat batteries like I do my car battery and do negative terminal off first, negative terminal on last, having isolated at the battery isolation switches first.

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What I will do though is to tape up my spanner well to insulate it as there is a lot of metal around the battery housing in the engine room.

Good idea, its probably one of your biggest dangers followed by a metal strap on your watch and a medallion hanging round your neck on a gold chain. I am still very cautious on working on batteries and that is after many years looking after them.

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Isolate all the positives feeds first. If your isolation switch isolates everything you can use this, then remove other positives like bilge pumps if they bypass the switch. Then remove the main negative on the battery post so you don't get spanner hull sparks when doing the positives posts.

 

Here's why you should isolate all positive feeds first - http://www.smartgauge.co.uk/whereiso.html

Edited by Robbo
  • Greenie 1
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Isolate all the positives feeds first. If your isolation switch isolates everything you can use this, then remove other positives like bilge pumps if they bypass the switch. Then remove the main negative on the battery post so you don't get spanner hull sparks when doing the positives posts.

Here's why you should isolate all positive feeds first - http://www.smartgauge.co.uk/whereiso.html

Hold on a minute there, musky! That very nicely explains why you need the battery isolation switches in the positive lines. Those switches will have been opened before you take a spanner to the battery terminals, so the reasoning no longer applies.

 

Edited to add:

 

Oh, hang on, I've just re-read your post and we're agreeing! Isolate the positives, disconnect the negatives first, then disconnect the positives.

 

I'll leave my post as it may be useful to the point in question. :)

Edited by Sea Dog
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Good idea, its probably one of your biggest dangers followed by a metal strap on your watch and a medallion hanging round your neck on a gold chain. I am still very cautious on working on batteries and that is after many years looking after them.

In my experience, rings are the biggest danger. I once saw a guy burn a finger on each hand to the bone when he used an uninsulated socket and ratchet to undo a nut holding a 50 volt cable on.

 

Always remove metal objects, rings, watches, chains etc before working on batteries. If you can't get rings off, then put 2 layers of insulating tape over them.

 

Edited to add the last paragraph.

Edited by cuthound
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Oh, hang on, I've just re-read your post and we're agreeing! Isolate the positives, disconnect the negatives first, then disconnect the positives.

 

 

You do realise this is a forum and agreeing with each other is against forum etiquette :)

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