Anyone know of good compact DC fuses?

[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?

[DrkAngel]

Couple possibilities.
Bussmann ACK-200 Fuse. 200 Amp, 72 VDC, Dual Element.

ANL!
Typically used in, up to, 48VDC applications.(Golf Carts etc.)
Cheap enough to experiment with, individual fuses are about $2!

ANL FUSE HOLDER 0 2 4 GAUGE WITH 100A - 300A Gold Plate - US $9.95

[DrkAngel]

Couple possibilities.
Bussmann ACK-200 Fuse. 200 Amp, 72 VDC, Dual Element.

ANL!
Typically used in, up to, 48VDC applications.(Golf Carts etc.)
Cheap enough to experiment with, individual fuses are about $2!

ANL FUSE HOLDER 0 2 4 GAUGE WITH 100A - 300A Gold Plate - US $9.95

Buss (Bussmann) makes a 80VDC - 125VAC, 200amp model, w/fuse function.
Buss 200 Amp ANN Fuse Limiter ANN-200 ANN200 - $11.99
$4.99 shipping - $1 each additional

[ryan]

This isn't a compact dc fuse, and stretches the limits of this thread, but...

Would this breaker work for an 18S setup?
http://bluesea.com/productline/specs/21#td

I'm looking at the 7248 model, rated 80vdc, 80A.

[ryan]

By the way, DrkAngel, I bought that Bussman off eBay too. Thanks.

[DrkAngel]

Buss (Bussmann) makes a 80VDC - 125VAC, 200amp model, w/fuse function.
Buss 200 Amp ANN Fuse Limiter ANN-200 ANN200 - $11.99
$4.99 shipping - $1 each additional

Warning! This is not a "standard" fuse, but a current limiting device, with "eventual" fuse function.
But, might actually be a better "fit" for eVehicles.
Bussmann ANN series

[DrkAngel]

While searching for DC fuses, I was dismayed at the limited selection of DC fuses.
Most fuses seem to be rated for AC current while most ebikes, use DC current.

So, I decided to investigate the mathematical relation of AC to DC voltages, as pertaining to fuse ratings.
Most basic fuse types are usable, for AC or DC, but the voltage is rated differently.
Fuses with dual ratings, were very rare but ...
Determined from Buss, (Bussmann), fuse ratings, DC volts, is approximately 2/3 the AC volts.
For example, the same fuse is rated as 80V DC 200a and 125V AC 200a.
Amperage is listed, as same, but DC voltage is about 65% of the AC voltage.

From AC, multiply the voltage by .65, to determine the DC voltage.
A 220VAC 100a fuse would be nearly "spot on" for a 144VDC 100a build! (220V x .65 - 143V)
A 110VAC 100a fuse would be nearly "spot on" for a 72VDC 100a build! (110V x .65 - 71V)

From DC, multiply the voltage by 1.55, to determine the AC voltage.
If you want a 100VDC 200a fuse, a 155VAC 200a fuse would be perfect, 150VAC fuse, should do.

Please note!
Basic fuse function: While Amperage is reasonably critical, matching voltage is much less so!
But, the rated voltage should be higher than the working voltage!
110VAC fuse, (110V x .65 = 71.5V), should not be used for an 80VDC build!
(Inadequate voltage protection!)

[Doctorbass]

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

This is a great idea!.. just like some contactor and relay have!

This have to be tested!!

I will test that this week!

I recall that i often blown these 32Vdc ( 12V car) little fuse with my controller blowing up and i never had any fire... the worst that happened was that the plastic of the fuse vaporized and left a black coated stuff inside the fuse protector...

I saw more bad fuse connections making fuse to melt than fuse catching fire!.. the fuse terminal that connect to it MUST be able to sink the heat otherwise the plastic just melt... The only location that can heat is the little filament right onthe center of it. I already saw one fuse that was so melted than the two terminal was touching together and the fuse was no more a fuse... but a conductor!

So the terminal that connect to the maxi and normal fuse ( the one up to 40A with the orange color) must have proper connection with minimal resistive loss and must have the proper wire size to sink the heat... just like the anderson connector spec data are specifying!.. fuse also have ingineering !

Take a look of the 100A+ blade fuse terminal block!.. they are heavy and can sink the heat and share the current with the proper uniformity to only allow the melt or heating spot to happen on he right spot.

If the fuse have too much heat on his terminal, the spec current become derated and it will probably blow at lower current than the specified one. This also change alot the delay.

Doc

[Njay]

The problem with DC and fuses apparently is arcing/plasma. With AC, the voltage will pass through 0 and extinguish any arc. With DC, the arc can form and stay, current still flows through the fuse if it's not properly designed. I wouldn't thrust any extrapolation of DC voltage from an AC-only rated fuse, it's more than that.

[DrkAngel]

I would guess, that is why the DC voltage is de-rated.
Voltage ratings are factored, partially, by the possible arc length.
Reducing the rated voltage, should reduce, possible DC arcing, to comparable with the higher AC rated voltage.

[gensem]

Maybe this ll be a good option.

http://www.discountfuse.com/A3T100_p/a3t100.htm

By the specs they would take a little while to blow, what you guys think?