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12v Power Struggling - on shoreline with battery charger


Shangela

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4 minutes ago, Shangela said:

Amazing detective work from all concerned. Opened up the fuse holder and it’s a mess. Looks to be snapped and fried. No idea as to why it would burn out, but had a lot of problems on this boat from previous owner not maintaining stuff/using wrong materials!

 

 

looking like the whole thing needs to be replaced, any ideas?

 

 

The meter was new yesterday and hasn’t worked out of the pack - angry letter to Rolson ahead! 

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I expect the fuse has been overheating and/or acid fumes has got to it. This is one reason why WotEver said we need to get it outside the battery box, quiet apart from a blowing fuse in the box could cause an explosion.

 

What to replace it with is open to question APART from avoiding the ceramic pointed at both end "continental" fuses like the plague. Personally as long as my charger was rated at 30 amps or more I would use a metal strip fuse and holder and if less either a glass fuse and fuse holder or another blade fuse and holder.

 

You seem to have a yellow but crimp connector in that cable outside the battery box. This could be cu so you can make the fuse holder connection and screw the fuse holder to the outside of the box. Then a new length of cable from the fuse holder to the battery terminal but make sure the cable is thick enough.

 

The size of fuse will depend upon the cable size and that should depend upon the charger output.

 

 

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I’m West London. I’m currently waiting to hear back from a boat electrician I’ve used a couple of times, and he’s pretty fair at telling me when it’s a fix I can do myself. 

 

I never considered it could have overheated in there. Seems much more sensible to have it outside the box. Will have a search around for a decent solution.

 

Thank you all so much for all your helpful input and suggestions. It’s so easy to get frustrated with trying to work out what boat quirk has gone wrong this time, and it’s reassuring to know the community’s knowledge is on here! 

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7 minutes ago, Shangela said:

I’m West London. I’m currently waiting to hear back from a boat electrician I’ve used a couple of times, and he’s pretty fair at telling me when it’s a fix I can do myself. 

 

I never considered it could have overheated in there. Seems much more sensible to have it outside the box. Will have a search around for a decent solution.

 

Thank you all so much for all your helpful input and suggestions. It’s so easy to get frustrated with trying to work out what boat quirk has gone wrong this time, and it’s reassuring to know the community’s knowledge is on here! 

 

For clarity if it did overheat it would be caused by poor contact between the holder and fuse or running a fuse  above its rating for a long time. Acid corrosion could cause a bad fuse to holder connection.

 

Some may throw their hands up in horror but its Saturday today so you are unlikely to get any professional help until Monday at the earliest. If this were my boat I would cut the old fuse holder out of its wires, strip the wires back, twist the conductors together, tape up and try the charger. make sure the cable does not get hot. That way you should get your 12V stuff back and, more to the point, start charging the batteries. That fuse is there to protect the cable from a short circuit between battery and charger, if the charger needs protecting it should have its own fuse. The chances of a short like that over the weekend are probably infinitesimally small but this is only a very temporary measure.

 

Edited to add - I no longer drive into London.

Edited by Tony Brooks
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53 minutes ago, Tony Brooks said:

If this were my boat I would cut the old fuse holder out of its wires, strip the wires back, twist the conductors together, tape up and try the charger. make sure the cable does not get hot.

I would do (have done) exactly the same. But not everyone has the same approach to risk, particularly if they don’t understand the subject. 

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27 minutes ago, WotEver said:

I would do (have done) exactly the same. But not everyone has the same approach to risk, particularly if they don’t understand the subject. 

That's two of us who have said the same if it were our boat so hopefully the OP will be able to guess the likely risk of doing as we woul.

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Thanks for the advice on stripping back the wires for now. I’m thinking of giving it a go - anything I need to avoid so as not to mess it up completely? Just looked to see whether a new fuse would hold it until tomorrow when I’m getting a replacement holder - but it looks totally melted and think this will be riskier.

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1 minute ago, Shangela said:

Thanks for the advice on stripping back the wires for now. I’m thinking of giving it a go - anything I need to avoid so as not to mess it up completely? Just looked to see whether a new fuse would hold it until tomorrow when I’m getting a replacement holder - but it looks totally melted and think this will be riskier.

Just keep any metal tools you use to cut and strip back the wires away from any metal and negative battery connectors while you cut & strip. Do not let the cut  and stripped end of the cable flap about while you cut and strip the other side of the fuse holder. If you have a clothes pegs clip on on the end of the stripped cable to keep it away from metal or another negative connection. The weight will probably hold it still on top of the battery.

 

Make sure the battery charger is turned off before you start.

 

Insulating tape is best to wind around the twisted cables but if you don’t have any plenty of Selotape or masking tape will do as a short term fix.

 

 

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5 minutes ago, Shangela said:

Thanks for the advice on stripping back the wires for now. I’m thinking of giving it a go - anything I need to avoid so as not to mess it up completely? Just looked to see whether a new fuse would hold it until tomorrow when I’m getting a replacement holder - but it looks totally melted and think this will be riskier.

No, start off with disconnecting the battery end and switching off the charger. Then cut out the fuse, strip back about 20mm insulation on each end, twist the two ends together and neatly cover the join with insulating tape. Now reconnect the battery end and ensure the cable isn’t getting hot. Now switch on the charger and ensure the cable isn’t getting hot. 

 

Crossed with Tony B but we both said much the same thing. 

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5 minutes ago, Keith M said:

I would use a wago type connector this will give a significantly better termination. 

I would suggest the likelihood of OP having a selection of Wago connectors kicking around is zero. 

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34 minutes ago, Richard T said:

Rather than twist the cable ends together use a choc block connector if you have one on board. This will give a positive connection.

I’ve seen more poorly made chockblock connections than poorly made crimps (and I’ve seen plenty of those). Screws clamping the insulation instead of the cores, wrong size chockblock hardly touching the cores, the stripped core bent back against the insulation... a twisted together bodge is secure and low-resistance. 

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49 minutes ago, Keith M said:

A selection of wago connectors should be in every boater's onboard repair bits.

 

I took a fistful of Wago connectors and a strip of choc  blocks from home to the boat 5 years ago. Never used either. Changed several fresh water pumps and one bilge pump but these were with crimped terminals.

Edited by frahkn
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I’d suggest when you come to replace the fuse holder you avoid any blade type  and look for a heavy duty type like a midi fuse holder (google or search on eBay). 

 

My charger is only a 20A model and I was amazed how hot the blade type holder got (good quality well installed)  replaced them with midi types and no problem 

 

 

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Morning all,

 

Just to update you how it worked out. Had a look myself, but really wasn’t confident so left it. Managed to get an excellent local boat electrician to come out this morning at short notice.

 

Few things he found - the cable hadn’t been crimped with the proper tool, so that’s why it fried. There was also a loose connection that he fixed and the charger was hooked up to the middle battery in the sequence which was unbalancing the draw so he swapped that too. He changed it to a much more resilient fuse box holder too.

 

Thanks again for all your help. Have lovely Sundays all!

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OK, more "professional" bull shine then a far as the cause.

 

Those fuse holders are supplied with cables attached from the factory so no after-market crimping is required and therefore no special crimping tool is required. The only after-market crimps related to the fuse holder are the yellow but crimp some way away from the holder and  where the holder cable connects to the terminal on the battery post. Neither of those crimps would cause the holder to fail as it has but may have reduced the charging voltage.

 

I repeat the the reason the holder fried was as stated by Wotever and myself. If there was a poor crimp then it would have been done at the factory and with the correct factory tool.

 

I agree about changing the battery terminal though.

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