To fuse, or not to fuse?

[olemetry]

I recently hooked up a 48V 1kW Golden Motor and blew the in-line fuse (I think 30A) after a few runs. Do yall use an inline fuse before the controller? I just bypassed it and I'm back to smilin.

 

[LI-ghtcycle]

I wouldn't say one or another since I am not familiar with your controller, but generally, if something is fused, and you blow it, there is something wrong.

You might try using an in-line relay that you can re-set, there are a few automotive ones that would work well.

I think you might be wise to learn why it blew, because if there is a short or you're over-taxing the controller, you might now be well on your way to destroying the controller if it's getting over-loaded.

If you do try either a relay or just replacing the fuse, you might nail down when and why it blew and either fix a faulty connector or maybe you are pushing the motor/controller too hard by the way you are riding, i.e. bogging it down too much from a stop or trying to climb a hill using it too far out of it's efficiency zone, thus over-heating motor & or controller.

Are you using a internal controller like in the magic pie or external? If internal, it might just be over-heating.

 

[Hugues]

The only fuse I have is on the battery, 40 A for a 40 A controller.
I thought (still think) it's sufficient, but you got me thinking ...

 

[Geebee]

I had the same setup as the OP, mine blew 30amp fuses as well, I went up a size and it stopped, can't remeber for sure whether it was 35 or 40 amp I went to.
The 30 amp seems to be just a bit to close to its power limits.
I like the idea of fuses but have to admit to their causing most if not all of my issues with e-bikes, between their holders and blowing when to close to max. amp limit.

 

[wesnewell]

Common to blow them. I ran without one for some time. When I redid my battery cable I installed a blade fuse holder ($1.28 at Walmart) and 40A fuse. No problems since then. The glass holder sucked anyway.

 

[spudboy62]

.
I'm using a 30A blade fuse on a 9Ah, 36V battery, with a 50A controller and BMC V2S motor. I blew the fuse once and didn't have a spare at the time, so I was stuck. Now I carry spare fuses and watch my CA to keep the current under ~25A during acceleration. I'm considering moving up to a 40A fuse, but have not made the switch. It seems good practice to have a fuse or circuit breaker to avoid melting wires or damaging something else in the system.
.
.

 

[dnmun]

if you have a BMS then the fuse should be extraneous. if it is SLA or nicad then you need a fuse.

 

[neptronix]

If you're running RC Lipos, whatever is trying to short will act like a fuse.
The wonders of what multiple thousands of amps will do to anything remotely conductive... :lol:

 

[iovaykind]

Agreed. It's not necessary to run fuses, unless you're usually extremely low power setups. If you're using lipo, no fuses are needed.. there's really no chance of hurting the batteries, other stuff will get hurt (melt) a lot quicker such as 4mm bullets.

 

[liveforphysics]

If the 30amp almost was sufficient, the 40amp will likely work for you.

 

[Ypedal]

None of my own bikes have fuses at the moment, over the years i've eliminated them :lol:

However, on a customer pack ( 48v 15ah )
http://endless-sphere.com/forums/viewtopic.php?f=4&t=31480


I installed one of these :


as an absolute last resort, one shot deal, told him that it should never blow, and if for any reason it does pop, to bring the pack back to me for inspection...

Used on a 40 amp controller and 9C motor..

He reverse polarity plugged it in on the first go ,,.
result :


the fuse did not pop !!

As the tips of the andersons made contact, an arc followed that vaporized the connectors and never went over 70 amps, aaah the joys of lipo !

Now.. if he had done this with a weak, low C rate pack, the andersons would have clipped in and made full contact, slowly ( 1 or 2 seconds time ) burned the fuse... but 15ah of 30C lipo means business... fast and nasty... :lol:

 

[biohazardman]

Fuses are good so long as they are the correct amperage to protect whatever you are trying to protect with them. If your controller and wiring can take more than 30A without damage then put a bigger fuse in. Else you can just omit the fuse and burn the controller, wires, ect instead when there is a problem. Flames and smoke are pretty common around here and what's a few hundred dollars going up in flames anyway. Things last longer when they are built right. Fusses should blow when you push the limits, if you put things together right, and they are cheap to replace. I have a 30A blade type on my 45A controller and run a BMC V2 at 66V I have only blown it twice in 2K or so. Put the same back in and am careful to help and pedal some up the longer hills now so no more problems. If I had a real problem and was blowing them regularly I would go to a 40A but the need has not been seen as yet.

 

[neptronix]

:lol:

Yup.. high discharge will melt a connector in a short faster than a fuse can even react.. a fuse also introduces some resistance, does it not?

I've shorted my battery wires to controller 2x by now.. no controller damage.. did blow the solder between cell #4 and #5 on a lipo pack clean off tho.. no damage to the cell whatsoever

I agree, a wimpy 1-2C chemistry with not much AH could benefit from a fuse. Like some EU spec 200w pedelec stuff..

 

[dnmun]

did not mean to start an anti fuse campaign, i believe in protection, but the BMS is really a high tech fuse. as soon as the shunt delta voltage reaches the current limit setpoint on the comparator, the mosfets are turned off. they will shut the current flow faster than a fuse can, which continues to flow current even as the link is being vaporized by the power. the mosfets shut off so fast that little power is produced as heat. but SLA and nicad or non BMS packs need protection, imo.

 

[sn0wchyld]

lol, so I just pulled my wiring appart a few weeks ago to add in a 60A fuse to my 24s 10ah 20c lipo pack, and I shouldn't have bothered? damn. the thing is huge too... well, huge when it comes to keeping things compact. I didnt really do it to protect the cells, Ive already witnessed their power when I accidentally shorted two 20s 5ah packs, resulting in a 4mm bullet being cut in half down the middle by the arc... but I read somewhere that occasionally something in your controller can short out, and cause a high power drain, maybe not enough to melt your connectors, but enough to drain your batteries in a few minutes.

 

[MadRhino]

This means that your controller is pulling more than 30A sometimes, thus burning the fuse. Maybe a slower 30A fuse could be enough, else a 40A, but I would not recommend eliminating the fuse from the circuit. A simple, cheap, easily replaceable protection that can save you hundreds of $ or many hours of repair, is worth keeping.

 

[shock]

IMO, it's quite idiotic to run a high voltage, high amperage circuit without a fuse, especially on something like an ebike. My reasoning is that a bike is always in motion causing vibrations, g-forces, and other external factors like water or road debris can cause shorts anywhere in the system. I build well to avoid a short at all costs, but bottom line is I would rather replace a fuse, than a lipo battery bank, controller, hub, or all three!

 

[llile]

Specifically what make and model of fuseholder are you guys using, and where did you get it? Is this auto parts store stuff, or ordered from Mouser Electronics, Jameco, or another of the usual supects? I am thinking about using fuses in a series-parallel battery setup, along with the diodes. I'd like it to look somewhat professional.

 

[shock]

I'm using a standard automotive ATC weather proof fuse holder I got at O'Rielly's Auto Parts. Came with 12g copper wiring and a 30amp fuse for a couple bucks.

 

[DrkAngel]

Personally, I view fusing, as cheap insurance, very cheap insurance!
Of course, I do carry a spare fuse, or 2, maybe $1 ... 1/20th of an ounce ...