Keep blowing fuses in my battery all of a sudden

[some.bloke]

Hi Guys, nice forum, Gday from Oz!

So I have a weird one: I have a 6 month old 48V 800Watt brushless front hub, a 2 year old heavy duty ESC, and a 6 month old 48volt 11.6AH Lipo battery, equipped with a 20Amp fuse.

I have been riding hassle free for 6 months, and given the rig a decent work out over this time (Im a 100kg guy, and its pulled me up hills for 5 mins constantly at peak power on my watt meter reaching almost 1000Watts. So thats pretty much 20amps@48Volt~1000Watts.

Then all of a sudden just last on level ground, after 10 mins into my ride at probably 70% utility, the motor cuts out. THe fuse had blown. I sourced another 20amp, and it tested ok, but under a little load, POP goes the fuse again. I rang my supplier and he said just "try" a bigger fuse, he suggested 30amp. So i did, and low and behold no more blown fuse!

So its left me wondering, why all of a sudden a rig that had for 6 months never exceeded 20amps, all of a sudden is consuming more?

Anyone have experiences similar? My thoughts are degraded FETs in my ESC, or my motor is showing signs of "wear and tare" and is a bit more sluggish in its teen years?

My other thought is maybe one of the coils in the hub has overheated and the enamel has melted away, such that it is shorting that coil. Maybe its confirmational bias, but I do feel my motor is 'whining' more than usual and isnt as snappy off the mark as it used to be. But I cant confirm this 100%

Ideas? Similar experiences? Cheers

 

[d8veh]

A 20A fuse was always too low. You need a reasonable margin to stop the fuse from running hot. Maybe the small variation in manufacturing tolerances put it just above working level, but the constant hot running would cause it to degrade and eventually blow.

 

[wesnewell]

Assuming it's a brushless motor controller, that's what draws current from the battery, not the motor, so don't waste your time with the motor unless it's not running right. If it was a glass fuse, most of those fuse holders suck, Over time they develope bad connections which cause the fuse to heat up and blow. Put more tension in the clips or better yet, replace the fuse holder with a better model. Maxi blade fuses are better, but an ANL fuse would be spec'd for higher voltages.

 

[dogman dan]

Spin your motor by hand. feel the resistance? Back spin if it's a geared motor. Now unplug your motor from the controller. did the resistance change, get less? No? Then you don't have shorted coils.

My bet is that your fuse holder is causing some resistance, as explained above. This means your controller could be drawing 15 amps, and your fuse holder is adding another 5. Then it blows. Especially if that area looks a bit toasty. I've had similar issues with old cyclanalyst shunts that were old and toasty.

I'd try replacing that fuse holder. After all, that's a cheap fix if that is what it is.

A watt meter would allow you to tell what your controller really draws, and know if 20 amps fuse is enough. And tell if your battery is sagging, causing reduced performance.

Your sluggish performance could be from not enough power making it through that fuse holder, if it's acting like a resistor. Or you could have similar issues with any wire on the bike. Particularly check for cut wires to the motor, or even just a poor connection on the throttle dropping your throttle voltage signal back to the controller. Might be you just need a new throttle. Lots of possibilities for your recent low performance. One we can rule out is winter chilling your battery, it's summer in Australia now.

 

[Ykick]

You've been at this how long and still no Watt (power) meter? Get in line brother, you need a simple power meter, wires and connectors or just bite the bullet and install a CA (cycle analyst)?

Hard top beat any of these for the money although you'll need wiring and connectors to complete an install:

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR11.TRC1.A0.H0.Xgt+power+meter&_nkw=gt+power+meter&_sacat=0

30A fuse minimum, IMO.

 

[some.bloke]

Jeez you guys are GOOD!. Thanks for all your input, I'm in agreeance. I just didnt want it to be my motor, i've had some shitty chinese\ebay motors in my time, but this one was sourced locally from a reputable australian source who says he has hardly ever had problems with them.

It may be a leak on the motor cabling, i had to re-terminate my controller to the new motor plug, and ended up having to use electrical tape as insulator.

For now I'll ride on and assume its an introduced resistance somewhere, either worn components or fuse wiring (auto blade). And yes, watt meter has just been installed. Just the inline hobbyking one for now, but next bonus pay I'll invest in a 'cycle analyser' so i can monitor it on the go!

Anyway thanks all, nice to know i'm in good company 'round these parts!