Anyone know of good compact DC fuses?

[NeilP]

No idea..but i can show you my first blown fuse in over 2700 miles

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[zombiess]

No idea..but i can show you my first blown fuse in over 2700 miles

viewtopic.php?f=7&t=33321

When I ran those style holders they always got hot and melty too. I switched to some cheap car audio 60A fuses. Only rated for something like 20V, but I figure if my 100+V pack shorts the fuse should vaporize pretty well and stop the flow. Sounds like I should do some destructive testing to see how they react

[NeilP]

I know these fuses are designed to run at their rating, but I have been consistently running at 20% or more above that, and it has handled it for a long period, so yes, some destructive tests to see when your fuse does actually blow sounds like a good move

[ryan]

Any one have a better answer for this? I just got a comically huge Maxi 80A fuse and inline holder. I don't have enough room for this monster and am hoping someone else has figured out a smaller alternative.

[liveforphysics]

Any one have a better answer for this? I just got a comically huge Maxi 80A fuse and inline holder. I don't have enough room for this monster and am hoping someone else has figured out a smaller alternative.

This was the best type I've seen. Class-T fuses.

http://bluesea.com/category/81/22/produ ... erview/136

[ryan]

Wow! $40/ea! That's more than I paid for Method's HVC board! And I'd have to buy two to make sure I have a spare. I may just solder up my Maxi fuse with some heat shrink in the meantime. At least I have a half dozen of those.

[ryan]

Well soldering up my Maxi fuse is a bust...

And my inline holder is larger than a Battery Medic. I just may have to bite the bullet on some of Luke's fuses. Thankfully McMaster has them for $20ea. But still ... $20 for a fuse!

[acuteaero]

Did you consider the ANN/ANL/CNN/CNL fuse? It's not rated high enough voltage wise for the application Luke was discussing, but some versions are high enough for most ebikes (80v). They are a lower profile and lighter weight than the class T. Often used in forklifts, golf cars and other battery powered things. Search eBay for ANN fuse. There is a seller with many values of fuse for pretty reasonable cost.

As well, the smaller <70a class t fuses are cylindrical without lugs and require blocks.

I have used these maxi blade fuse holders in the past, look a bit more compact than the one you pictured. http://www.powerwerx.com/fuses-circuit-protection/maxi-inline-fuse-holder-8-gauge-translucent-red.html

-Henry

[salty9]

I was searching the web for arc quenching and found this: http://www.springerlink.com/content/g8j06g60228w7u8h/. PETN is hard to come by but I was wondering as a thought experiment what black powder could do. It made me think of Luke for some reason.

[shock]

What about a circuit breaker?

Seems like it would be better since it could be reset without tools or much fuss.

http://www.atensolar.com/m5/705-016--ou ... c-pnl.html

[ryan]

Would this one work:

http://search.digikey.com/us/en/product ... ND/1630102



It's rated 80VDC 100A (IE Series Magnetic Breaker). And it's only 1.68x2x0.75" (43x51x19mm).

[Alan B]

It should work, but I would still use a precharge circuit as the charging arc may damage the contacts of the breaker.

[amberwolf]

Just remember that a breaker can usually take an extreme overload for a fair amount of time, so you don't want to size the breaker the same as you would a fuse (which will blow realy quick pronto on extreme overload).

[ryan]

So does that mean I should look to get a lower Amp rated circuit or a higher one? Or do I not understand the comment at all.

[acuteaero]

Read the datasheet of that circuit breaker- it is a magnetic breaker and comes in versions (differentiated by a "Delay" number, from 42-69 in the datasheet) that determines how fast it trips. The one you linked to appears to be a #72- which although not present in the datasheet would assume to be even slower blowing.

A magnetic circuit breaker can trip pretty fast (or slower, based on the "hydraulic delay")- thermal circuit breakers are generally slower tripping. Fuses can be had in all sorts of different speed-to-blow. It is my general understanding that a pretty slow-blowing fuse probably won't prevent failure of sensitive devices in the circuit (that's why they have super fast blowing "semiconductor fuses") but most circuit breakers or fuses should be adequate to prevent massive meltdown in the presence of a short circuit.

What exactly do you want to use this overcurrent device to protect against, is the question! Then, read the datasheets!

[Alan B]

Look closely at all the ratings for the component, whether breaker or fuse. Some fuses and breakers are rated differently than others, and the time/current to open may be different than what you expect. One rating is the maximum interrupt or fault current. Especially with breakers, if the fault is too high a current they can fail to open, as the contacts weld closed instead. Plus when a high fault current interrupt occurs the breaker contacts may be damaged even if it did open, and the breaker need to be replaced after a "short" event.

I think I'd stick with a fuse.

[advancedelectricbikes]

Class T fuses are probably the smallest form factor for overcurrent protection. However, they are very fast-acting. Consequently, if you have branch or feeder loads with overcurrent protection other than Class T downstream (in series) with a Class T fuse, a downstream fault will open the Class T fuse and leave the downstream overcurrent protection closed. A short circuit and overcurrent coordination study should be done to spot potential conflicts.

[liveforphysics]

Class T fuses are probably the smallest form factor for overcurrent protection. However, they are very fast-acting. Consequently, if you have branch or feeder loads with overcurrent protection other than Class T downstream (in series) with a Class T fuse, a downstream fault will open the Class T fuse and leave the downstream overcurrent protection closed. A short circuit and overcurrent coordination study should be done to spot potential conflicts.

Just as an FYI, the 400amp 160v classT took 6 seconds of 4,000amps to blow.

They are not over-current protection at all. They are cabling/battery fire protection.

[gensem]

Luke any real sugestion (even if its bulk) of a fuse/breaker coz I really dont feel confortable running 100v without anything.

[advancedelectricbikes]

Class T fuses are probably the smallest form factor for overcurrent protection. However, they are very fast-acting. Consequently, if you have branch or feeder loads with overcurrent protection other than Class T downstream (in series) with a Class T fuse, a downstream fault will open the Class T fuse and leave the downstream overcurrent protection closed. A short circuit and overcurrent coordination study should be done to spot potential conflicts.

Just as an FYI, the 400amp 160v classT took 6 seconds of 4,000amps to blow.

They are not over-current protection at all. They are cabling/battery fire protection.

If you're only concerned about short-circuit protection and not overcurrent protection, you may consider cable limiters:

http://www.cooperindustries.com/content ... Series.pdf

They only provide short-circuit protection and they don't require a fuse block. A cable limiter on 500 mcm cu cable will clear a 4000a fault in 3s, about half the time of a class T fuse. If you paralleled 3/0 cu cables with cable limiters, it will clear the same fault in .02s.

You may also consider using cable limiters on individual feeders supplying parallel battery subpacks for two reasons: 1) It would isolate the fault to a subpack and allow for graceful degradation of performance instead of a potentially catastrophic failure 2) Because the feeder cables would presumably be smaller than the main cables, the smaller cable limiters would decrease the time required to clear the fault and greatly decrease the let-through fault current.

[bigmoose]

I have been keeping my eyes out, and found a good, practical paper on how to design a fuse. If anyone here "rolls their own" this paper might help.

[ryan]

Here's my smaller MAXI fuse holder. 8mm bullets on the ends. What do you think? Will it work for my 18S4P setup? The MAXI fuse is rated 100A.

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[Doctorbass]

Maxi fuse are rated 32Vdc just like their small version.

But.. Like i discussed in many threads here in the past, I personally found that if you parallel many of them, they blow without sustaining any arcing at up to 100VDC.

I'm using 3 x 30A fuse on all my setup...( 90A equiv) they will blow if the controller short or bad wiring, but can take 250A batt current no prob during few second of acceleration.

Doc

[Alan B]

If I remember correctly some Maxifuses are rated for higher voltage. But the average units are pretty low. Still they will probably provide protection against melting the wiring harness, but they may melt in the process and damage things near the fuse. It might be prudent to insure that the fuse isn't so close to the Lipo that it could set them on fire.

[fechter]

I wonder if you could stick a strong magnet to one of those automotive fuses to make a magnetic blow out?