what fuse?

[azreal100]

what fuse should i use between the battery pack and controller?

old bike was 36v 250watt 30amp slow blow i believe

new setup will be 48volt battery pack 1000w motor just unsure on the fuse rating.
and if anyone has a link to a specified fuse or circuit breaker that would be great.

 

[friendly1uk]

Your controller limits currant, so it dictates fuse size. Not the battery or motor. Let us know your full setup and someone might have actual readings rather than calculated values that could be way off.

A=W/V so a 1000w motor might take 20 amps with 48v. It will be nothing like that though. Chances are you will need to fit something a lot bigger. Too big for the cable size probably.

 

[azreal100]

ok well not sure on the controller it would be an ebay purchase
heres the link to the item
http://www.ebay.co.uk/itm/48V-1000W-Front-Wheel-Electric-Bicycle-Conversion-Kit-E-Bike-DIY-Cycling-Motor-/170941463949?pt=UK_SportGoods_CyclAcces_RL&hash=item27cce7bd8d

 

[Drunkskunk]

Welcome to the forum.

You want the fuse to be equil or a little higher than the amp rating of the controller. Many 1000 watt motor kits are really 1000 watt peak, which would mean they have a 20 to 22 amp controller. If your controller doesn't have it's amp limit listed, It would be safe to assume it's one of those, and therefore a 25 amp fuse would be about right, but to keep things simple, you could use a 30 amp fuse the same as your other bike.

 

[azreal100]

ok great stuff what about the volt rating?
from what i have tried to find out they come in 2 types
32 volt dc and 250 ac

 

[Drunkskunk]

The voltage rating matters very little at the voltages we use on Ebikes. Any automotive grade fuse will be fine.

 

[azreal100]

so a 12 volt 30amp car blade fuse would work?

 

[Drunkskunk]

Yep. There are some technical reasons for the voltage ratings on fuses, but for what we are using them for, just a simple DC battery fuse, that rating is essentualy irrelevent. Automotove blade fuses work great. If you ever decide to run over 100 volts, then maybe start to worry about the voltage ratings.
At 36 volts, its not an issue.

 

[dnmun]

the fuse holder will melt down anyway so why even worry about what size fuse? if you are running 30A through two tiny strands of wire crimped in a steel connector it will make more heat than the motor.

 

[azreal100]

the fuse holder will melt down anyway??

ok so what do you suggest?

 

[wesnewell]

Depends on where you live. I got my ATC blade fuse holder at Walmart for $1.28. Already had many fuses.

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[alfantastic]

the fuse holder will melt down anyway??

ok so what do you suggest?

I've been using one of these for around 1000 miles.

http://www.ebay.com/itm/Rockford-Fo...t=Car_Audio_Video&hash=item20ceb13901&vxp=mtr

Using a 30A AGU fuse, I've been drawing peaks of 32 amps and constant 18-20 amps with no problem of overheating of the fuse holder, contacts etc..

Looks good too

I would recommend soldering the bare power wires with loads of solder before tightening down the holder screws though.

 

[dnmun]

you can solder the wires to the spade legs of the fuse. use at least 40A with the big wide spade legs.

 

[migueralliart]

I've been using these
http://www.ebay.com/itm/300893414799?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

Along with a 40amp fuse. SO far so good.

On my higher power builds I use a similar MAXI holder instead. Gives me capability to do 50+ amps

 

[Drunkskunk]

Its true, there are some fuse holders that are cheaply made, with tiny contacts made out of extra thin and low quality metal. Sure, those melt fast. But then there are plenty of good ones.

If you are in doubt of the quality, its cheap enough to replace the holder all together. I often get mine from places that deal with car audio, as they are often better made than some others. But in a pinch I've used two of a better insulated version of these:

(Picture is an example. you'll want the kind that leave no metal exposed)
Just cut a battery wire someplace, put one on each side of the cut, and plug the blades of an Automotive fuse directly into them.