Anyone know of good compact DC fuses?

[bigmoose]

We ought to see what fuses the big Sevcons use that are rated up around 115 V. Might pick up some cost effective ideas.

[amberwolf]

Try an iPhone.

Ok, that *is* big.

Largest one I have held in-hand is an old (unfortunately blown) JKS-250, and though it is bigger than yours it is not by all that much:

DSC06127.JPG (41.89 KiB) Viewed 524 times

I'd guess at 2-3lbs or more for weight, without trying the scale. 600VAC 250A, can interrupt up to 100,000A.

But this isn't helpful to the discussion at hand...sorry.


I only bring it up because I have considered opening it up and rewiring it using thin solder or the like, since in a dead short at least I know that would melt before the rest of the system caught fire or something, if I had a really huge battery setup on a bike or whatever. I believe it uses sand or similar inside, so that during an extreme event it melts the sand into glass to close the current path.

We ought to see what fuses the big Sevcons use that are rated up around 115 V. Might pick up some cost effective ideas.

I found a number of "Sevcon fuses" in a search, but am not sure which ones would be useful to us. Very few have pictures or useful information. Prices vary a lot, too.

Sevcons like this one:
http://www.electricmotordepot.com/sevco ... 0v-350amp/
are using a fuse I don't know the type name for, but it is visible on the controller as the white "bar" with end tabs below:

G2445__67435_zoom.jpg (13.92 KiB) Viewed 524 times

I assume it would be rated over 100VDC / 350A as the Sevcon itself is.

I have smaller versions of these fuses, labelled as "mega fuse", from huge APC UPS's external battery packs and from powerchairs (both of which also used SB50 Andersons, oddly enough). Mine are rated at 100A, and probably 24-48V at a guess, but I can't remember just now, and don't have them handy to check. Been considering digging them out for installation into my packs on the bike, but all the tuits I have here are non-circular.

[DrkAngel]

Pictured Sevcon is a 72-80V.
Wrong - It appears to use a Shawmut CNN Series fuse, which is rated as 130VAC - 80VDC. - Wrong
The Shawmut CNN cross references as the Bussmann ANN Series.

Tis a "Littlefuse" 80 amp DC rated.

MEGA vs ANL
"MEGA" and standard "ANL" are both rated as "48VDC max"

[Alan B]

I believe that fuse has been pictured in this thread earlier. I bought mine from Digikey or Mouser.

[DrkAngel]

littlefuse 80VDC - click on picture

Littlefuse.jpg (75.34 KiB) Viewed 506 times

[Doctorbass]

The problem remain... fiding a fuse OVER 80VDC , that is cheap, small enough and accessible!

Doc

[nicobie]

The problem remain... fiding a fuse OVER 80VDC , that is cheap, small enough and accessible!

Doc

How about this circuit breaker...

125 VDC, 90A, $17, aprox 2" x 3" x 3/4" mounts almost anywhere and can be used as a main battery disconnect too.

http://www.affordable-solar.com/store/d ... nt-breaker

[bigmoose]

The problem remain... fiding a fuse OVER 80VDC , that is cheap, small enough and accessible!Doc

Doc, that is why I was interested in what Sevcon did for their controllers that are rated over 100V. When I look at the spec's they talk about like rated 80V but then say:
Conventional working voltage 50.4 to 96V
Working Voltage 39.1 to 116V
Non Operating over voltage limits 132V

Now they may be playing a bit of requirements chess with respect to controller/fuse ratings. However, it appears if there was "really a problem" with an 80V rated fuse at say 96 and 116V, Sevcon would change the design, assuming they use that 80V rated fuse. I wouldn't use a 48V fuse at 116V, but what about an 80V DC rated fuse at around 100 and change?

[DrkAngel]

Oops!

Frankin.gif (3.83 KiB) Viewed 485 times

[liveforphysics]

They simply call it an 80v controller to get around the 80v fuse limitation.

Even at 66v, testing various ANN type 80vdc fuses, the normal method of blowing involves exploding the quartz window out and melting with plasma through any plastic materials around it. It's also interesting that the 425amp ANN fuse actually peaked over 6,800amps before it popped.

It is the very wrong assumption to make that these high current DC fuses will offer anything in the way of protecting your electronics from over-current related failures. They are to avoid cabling/battery fires, and nothing more.

In the case of a Sevcon, the fuse is there to protect the battery and cabling from fire if the controller somehow faults into a shorted input condition. The fuse offers no protection for the controller itself.

[DrkAngel]

Littlefuse JLLN T Series
"200 Amp Fuse, High Speed, North American Style, Brand or Series: Class T, Power T, Type: Bolt Mount, Voltage Rating: 300 VAC/125 VDC, Interrupting Rating: 200000 Amp VAC RMS Symmetrical, Dimensions: 1 1/16 Diameter x 2 7/16 Length Inch, Features: Fast Acting."

$25.67

JLLN pdf

JLLN's Various amps - 200a $16 etc.

[gensem]

As far as I understand the fuse was supposed to protect and save the controller... if its not able to do it, why bother?
the wire leads that happen to short ll just vanish and stop the short.

[Alan B]

The fuse is to protect the batteries and wiring harness and prevent fires. Not to protect the electronics.

[Doctorbass]

To protect the electronic, a good shunt monitoring the current with a circuit that disconnect a contactor might be a good solution ( not cheap.. but..)

It will react in the ms reaction time

The only problem is that you still have the capacitor bank of the controller thathave enough joules to keep current high to blow the fets... maybe including the contactor right between the mosfet rail and the shunt?

It's like the overcurrent detection of our controller that desactivate the power output.... but in our case the contactor would break the current path directly and fact... or maybe just the hysterisis of the contactor ....

Was it discussed before?

Doc

[mdd0127]

I'm using a pair of paralleled 4mm castle bullets as a fuse/cable fire/battery protection and it works pretty well for a dead short. I accidentally shorted my 15ah 44v pack for a split second and the bullets vaporized pretty much instantly. I didn't even burn my fingers.

I think castle's pretty accurate with their 75 amp rating.

I had so many conventional breakers and fuses fail....for no apparent reason.....at amp loads 1/10th of their rating that I gave up on them and went straight to bullets on the bike. My solar array was burning 12v 120A breakers up too and it's only 12v at 35A coming out of the charge controller. I replaced the breaker there with an 80A automotive fuse and it seems to be doing fine.

Anyway, I'm glad that you posted this thread. I'm glad there are some options to look at.

[jonescg]

I have a Bussman 600 A fuse on Voltron. It is prominently visible on the top of the bike:


I have dragged 800 amps through the system and it still didn't pop .

My next bike will be interesting - 700 V and 300 A max fuse... Probably the size of a VW Beetle!

[Doctorbass]

I have a Bussman 600 A fuse on Voltron. It is prominently visible on the top of the bike:


I have dragged 800 amps through the system and it still didn't pop .

My next bike will be interesting - 700 V and 300 A max fuse... Probably the size of a VW Beetle!

700V ???

Wich controller?

Doc

[jonescg]

No secret, Doc. I've been working on the designs for a while. I'm planning on using a Rhineheart PM150 DZ inverter - they are good for 720 V maximum DC Bus. The alternative is to go for a PM150 DX inverter with a maximum 360 V DC bus, but the issues is the Evo motors have a sweet spot somewhere around 400 volts.