What fuse to use?

[rich43]

60A anl should be good. I use a 40A fuse with a 40A controller and it hasn't blown in 2 years use.

The fuse holders sell for £4.50 each (about $7.50 usd), some cost much more. Seems like a rip off to me. I might have to DIY my own holder using said bolt and washer arrangement.

Do you use Mini ANL? If so what holder do you have?

 

[wesnewell]

I use an ATC blade fuse. A short would blow it up, but it only cost $1.28 ay Walmart. Easy to make an anl fuse holder with a couple of bolts and a block of plastic, or any non conductive material.

 

[Trick]

Hi Liam. From what you tell us the motor is brushed and rated 250 watt, at 24 volts. That's a 10 amp draw.
This means that the motor can handle a 10 amp draw, continuously.It could probably hold 20-30 amps for short times, but no more than 10-20 seconds.
If fact it does that every time the current is applied and it starts spinning. The length of time at those levels is determined by the load.

Anyway, when it comes to current draw, your weakest link should be the fuse. In your case running without a fuse, the next weakest link is the motor brush shunt wires. Remove a brush and look how small that wire is. It can handle 10 amps continuous. Now look at the brush spring. It's even thinner wire. If you pass up to 20 amps thru that for any more than half a minute the shunt wire begins to heat up and loose performance. The current has no choice now, but to travel thru the spring. Guess what happens next. Once that spring is toasted, forget saving it. And the shunt wire is probably toast at this time as well.

You should have 2 spare brushes at all times, even if you have a well fused system.
I would suggest no more than a twenty amp fuse to start(non fast-blow, it will take 200% load for 3 seconds). If you don't blow it and you don't cook the motor, under normal load conditions, then its working fine. If you blow a 20 amp fuse (hopefully under more severe than normal conditions), replace the fuse, count your blessings and carry on.

I'm going to assume that a fuse will be your only current limiting device. Does the speed controller you use have current limiting capability?
Most brushed controllers don't. You could use a CycleAnalyst to limit the current flow in your system.

Good luck.

 

[wheelbender6]

The manual for my 24v 450w Currie kit says the fuse should be rated no more than 40 amps. it doesn't mention any particular style of fuse (regular or slo-blow)

 

[rich43]

Here's how my ANL fuse is laid out with nuts, washers and bolts:

So it's like this:
M5 Bolt --> small M5 washer --> fuse --> small M5 washer --> normal M5 nut --> M5 penny washer --> output wire (10/12awg?) --> M5 penny washer --> M5 nyloc nut

Feels very sturdy and reliable , no fuse holders to melt here!

 

[Modbikemax]

First you need to think what a fuse is for.
A fuse is normally used to prevent a fire in the event of a short circuit.
It is designed to prevent the wire in the circuit heating up and starting a fire. That is all it supposed to do.
If your wiring can handle 20 amps use a 20 amp fuse.
If your wiring can handle 100 amps use a 100 amp fuse.
You also can get fast blow and slow blow fuses because some appliances have a high startup current which will not start a fire so a slow blow is the go. If your wiring won't handle the high surge then fast blow is the go.
A fuse is not designed to protect equipment as is commonly supposed.
If fire is not a concern you can forego the fuse.

 

[dnmun]

use a 40A fuse minimum if you are using a 22A controller. 12AWG will handle 40A. solder the fuse to the wire so there is no contact resistance. you can solder the wire directly to the tab on the fuse if it is one of those big ATC type fuses. or even the smaller ones. i have a buncha 40A fuses if you need some. in the US.

 

[flyingbeekeeper]

This thread is not giving a good rule of thumb on fuse sizes. THere is discussion on why certain fuse sizes are no good, and what a fuse is for. But can someone put forth a guideline and let the forum narrative converge on the 'best practice' answer?

I expect different correct answers for brushless vs brushed motors.

My vote would be a fuse = amp rating of controller x 25% for brushed motor, which is what I have. So my BD-36 WE controller is 35A thus, 1.25x35 = 43.75amp, which rounds to a 45amp fuse.

 

[Modbikemax]

This thread is not giving a good rule of thumb on fuse sizes. THere is discussion on why certain fuse sizes are no good, and what a fuse is for. But can someone put forth a guideline and let the forum narrative converge on the 'best practice' answer?

I expect different correct answers for brushless vs brushed motors.

My vote would be a fuse = amp rating of controller x 25% for brushed motor, which is what I have. So my BD-36 WE controller is 35A thus, 1.25x35 = 43.75amp, which rounds to a 45amp fuse.

Unfortunately votes don't count. It has zero to do with motor or controller.
The correct approach is select the wire gauge to suit your application then use the appropriate fuse for that gauge of wire.
It's pretty simple really.

 

[Burntspot]

T-Spec available from 100-200amp

http://www.ebay.com/itm/T-Spec-V12-...ash=item1eab8d14d8:g:E3cAAOSwzgRWv3lU&vxp=mtr

 

[ddk]

Selection of a fuse for an e-bike should probably be based protecting not just the wiring, it should include wire connectors, which are usually the weak link in the equation.
wut i do:
Using LiPo pouch batteries capable of safely discharging hundreds of amps I use connectors rated @ 60A, wiring rated for safely handling +120A, controllers rated 25A and the whole mess is fused for 30A (normal blow) at the battery.
I've never blown a 30A fuse. Also I've never experienced major wiring failures other than anderson connector/crimps (I usually use andersons for phase connections to the motor, never the battery)

Since I run 16-30-50-60V battery voltages it's safe for me to use blade-type automotive fuses
-over 60V I would use glass fuses rated for 125V. There are other choices but blade and glass fuses are usually available at most stores.
Not interested in using motors/controllers higher than these power levels, especially on a bicycle.
... so choose w/care if you do.

If you chose to use a slightly odd fuse or even an easy-to-source fuse carry a spare somewhere because stuff sometimes happens.

 

[Modbikemax]

Selection of a fuse for an e-bike should probably be based protecting not just the wiring, it should include wire connectors, which are usually the weak link in the equation.
wut i do:
Using LiPo pouch batteries capable of safely discharging hundreds of amps I use connectors rated @ 60A, wiring rated for safely handling +120A, controllers rated 25A and the whole mess is fused for 30A (normal blow) at the battery.
I've never blown a 30A fuse. Also I've never experienced major wiring failures other than anderson connector/crimps (I usually use andersons for phase connections to the motor, never the battery)

Since I run 16-30-50-60V battery voltages it's safe for me to use blade-type automotive fuses
-over 60V I would use glass fuses rated for 125V. There are other choices but blade and glass fuses are usually available at most stores.
Not interested in using motors/controllers higher than these power levels, especially on a bicycle.
... so choose w/care if you do.

If you chose to use a slightly odd fuse or even an easy-to-source fuse carry a spare somewhere because stuff sometimes happens.

If your connectors are getting hot you have a high resistance connection. A fuse will not protect against this. You need better connectors. This includes the resistance at the fuse connection. Bolt down fuses are better than push in fuses and gold plated connectors are better than zinc plated ones.

 

[Punx0r]

I've given up on fuse holders. Many are unreliable - the best ones are just bulky. I now just solder a mini-ANL type fuse directly inline and cover the ends with heatshrink. It takes up barely any room and provides some chance of protection against a short in the wiring, hopefully preventing a fire. There's no requirement for a fuse to be quick and easy to change - if you plan on changing one at the roadside your system is designed incorrectly IMHO...