# Fuse contact area



## sabahtom (Mar 1, 2011)

I've got a 160A 500v fuse. The box fits - almost. I had to cut a bit out of one tab so that one side could slide in. That means a loss of around 15% of the surface area of the tab.

The bolt shown is not the one I plan to use. I'll get two large stainless steel washers.

Can anyone tell me if this will cause overheating due to a shortage of contact surface?


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## major (Apr 4, 2008)

sabahtom said:


> I've got a 160A 500v fuse. The box fits - almost. I had to cut a bit out of one tab so that one side could slide in. That means a loss of around 15% of the surface area of the tab.
> 
> The bolt shown is not the one I plan to use. I'll get two large stainless steel washers.
> 
> ...


That does not look like a good assembly to me. I would not use it.


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## sabahtom (Mar 1, 2011)

Hi Major

Thanks for the tip. The pics only show half of the assembly. The fuse bolts into a lid that is pushed down into the prongs shown and tightened on with a taper-lock system. The setup shown in the pics is only so it wouldn't fall off while I was taking a photo. It will be firmly held in place but I'm worried about the contact area being sufficient.

Are you thinking that the fuse is too short, needs to have both holes centred in the prongs of the holder and bolted with the tab intact? 

If the tab needs to be intact then I wasn't clever to cut it....$$$. 

I like this fuse box because it's bakelite and has a spanner-free removal system. it also cost $30...

They do sell standalone bolts with plastic bases that I could use. They're normally used for the neutral bar in a home distribution board so they aren't designed for heat though.


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## major (Apr 4, 2008)

sabahtom said:


> Hi Major
> 
> Thanks for the tip. The pics only show half of the assembly. The fuse bolts into a lid that is pushed down into the prongs shown and tightened on with a taper-lock system. The setup shown in the pics is only so it wouldn't fall off while I was taking a photo. It will be firmly held in place but I'm worried about the contact area being sufficient.
> 
> ...


That makes it even more confusing. It appears you are mating parts of different sizes where the fasteners will have little chance of securing mating surfaces of the high current path flush and square with sufficient room to properly torque those fasteners. I always say to use the proper fuse with the proper fuse holder properly installed. I can't see that happening with your photos or description.


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## sabahtom (Mar 1, 2011)

major said:


> That makes it even more confusing. It appears you are mating parts of different sizes where the fasteners will have little chance of securing mating surfaces of the high current path flush and square with sufficient room to properly torque those fasteners. I always say to use the proper fuse with the proper fuse holder properly installed. I can't see that happening with your photos or description.


Hi Major

Sounds like wise advice, if I could find the matching set I would buy it. I guess if this doesn't look safe I'll have to keep looking.

Re the torque you've got a good point. I would need to put in a spacer between the taper-lock and the washer. I've got 4mm copper flatbar that will do the job. As you've guessed I don't have any experience with a high-voltage/current fuse. There is an elec engineer in town who's prepared to give my car a check once I've done everything, but I'm hoping he won't have any suggestions to make.









The lid of the fuse holder with taper-lock. The taper-lock works by twisting the black handles on the exterior.

















The fuse tab will be in this position. The space between the taper lock and the fuse tab is taken up by the double prong visible in the following photos.

























This shows the amount of flush contact surface between the double prong and the fuse tab.


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## dragonsgate (May 19, 2012)

Man that looks shaky even to my untrained eye. Exactly what is this fuse fusing and where is the placement? I intend this as constructive criticism but the cut out in the end of the fuse plate looks like it was done in a hurry thus a little sloppy. Don’t get in a hurry with your build. You have a lot of knowledge available on this forum. Ask questions first then sort out all the info given and make a decision and then think again before you drill, weld or cut. I am sure everyone one on this forum has made some slipup here or there on their builds so maybe we can help you avoid repeating them. I will finish up with my sage advice by adding it is better to spend a few extra hours on the project in the garage than spend those hours along side the road trying to figure out what you did wrong.


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## major (Apr 4, 2008)

sabahtom said:


> Hi Major
> 
> Sounds like wise advice, if I could find the matching set I would buy it. I guess if this doesn't look safe I'll have to keep looking.
> 
> ...


I see better. It appears you are forcing an unintended part into that assembly. I recommend against it. Get the right parts and be safe. I post often about fuses and mentioned just recently that only EV I have ever seen burn to the ground was due to an improper fuse installation. 

http://www.diyelectriccar.com/forums/showpost.php?p=332938&postcount=8


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## dragonsgate (May 19, 2012)

major said:


> http://www.diyelectriccar.com/forums/showpost.php?p=332938&postcount=8[/QUOTE
> _I am serious when I say this should be posted on a brass placket for everyone to see._


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## poprock (Apr 29, 2010)

Or maybe mounted on a placard, but seriously,I have realized through this forum that the tradesmanship required for something such as an EV is far greater than my skills with lawnmowers. I would recommend that you take on board the safety advice given by these experienced mentors.


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## dragonsgate (May 19, 2012)

(Plaque) I guess I have lived in Arkansas to long. That among other handicaps.


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## poprock (Apr 29, 2010)

Or why Kansas is just that yet Arkansas is Arkansaw?? Re safety; One of the things I learned by lurking on the edge of the forum was that as a general rule below 50v was generally accepted as non-fatal?(please correct if wrong). I started with 36v, lifted the tops off two batteries, but survived. I was surprised then to receive a panning from a senior member for only having 36v in a road going car.Now, two years on, I feel confident to advance to 72v. It is foolhardy to go against expert advice. In this issue the reduction of fuse contact area does not seem to be a good move.


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## dragonsgate (May 19, 2012)

I think the point about proper connections has been made. Sabahtom did ask for advice so that says to me he intentions of doing a safe build. I would still like to see a diagram showing where this fuse is to be located and exactly what it is for. It might give some idea of how to use the fuse on hand or if it is a total wash.


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## sabahtom (Mar 1, 2011)

dragonsgate said:


> I think the point about proper connections has been made. Sabahtom did ask for advice so that says to me he intentions of doing a safe build. I would still like to see a diagram showing where this fuse is to be located and exactly what it is for. It might give some idea of how to use the fuse on hand or if it is a total wash.


The last time I got a hiding was in school. Probably overdue...

I'll try and do a diagram tonight. The fuse is going right next to the traction pack, with about two feet of 20mm cable. 

If anyone knows where I can get a proper fuse box for this kind of fuse, please let me know


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## sabahtom (Mar 1, 2011)

Thanks for the advice everyone. 

This fuse is going next to the traction pack. Looks like I don't need a contactor for this setup, Azure Dynamics recommends that the DMOC controller is connected to the HV all the time unless in storage.

I only have one battery pack now, so there'll only be one fuse in the traction circuit. The pack is 312v 100A. The cable is 20mm diameter.

View attachment 15006


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## dragonsgate (May 19, 2012)

I have gotten some fuses through these guys. www.intermtnfuse.com phone 1 800 246 8336 If you sent them info and a picture of the fuse they might be able to help with a holder.


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## TEV (Nov 25, 2011)

I think he is from UK.


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## sabahtom (Mar 1, 2011)

Thanks dragonsgate I've contacted them.


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## sabahtom (Mar 1, 2011)

Finally got the right parts, I hope, thanks for the help everyone.

Looking at how to mount it in a confined space. I need to bend the HV cable through 90 degrees over a length of approx 540mm. It's 20mm diameter cable, doesn't feel like it's under too much stress being bent like that.

The insulation tape is only to hold it in place for the photo. It'll be inside a bakelite enclosure (the enclosure is meant for another fuse but there's enough space in it). 

The base of this fuseholder is phenolic. Can I drill into it to fix it to the battery box, provided there's >15mm clearance between the screwhead and the studs of the fuseholder to prevent arcing in case of a fault?









I need to cut out the edges of the battery box to allow a straight exit for the lugs. I'll need to get a grommet to cover the edge and insulate the lug. 

What's the easiest way to do that? Sprag tubing? How much clearance should I leave around the lug where it goes through the box?

















The wall of the box warped. My welder should have seen that coming and told me to have all four edges folded!


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## dragonsgate (May 19, 2012)

sabahtom said:


> View attachment 15371
> 
> 
> I need to cut out the edges of the battery box to allow a straight exit for the lugs. I'll need to get a grommet to cover the edge and insulate the lug.
> ...


Personally I would not have as much metal as you do sticking up around the top of the batteries. I do not know what the battery box looks like and its placement but I would have tried to use something less conductive.


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## sabahtom (Mar 1, 2011)

Hi Dragonsgate

The plan is to make the lid out of polycarbonate and have a lip coming down around the inside of the box.

The box is sitting on top of the van's floor behind the last row of seats.


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