Need help with oddball fuse selection

I was replacing the lead-acid cells in the battery pack for an electric tricycle, for someone who needs it badly. Pretty straightforward job. Put it all back together and got the proper 36v across the pack connector terminals, great! Hmm these highly exposed terminals are always live, that's odd and dangerous. Anyway, now to test the switch for the 3rd pin. Just move my probes here and BANG! Whoops accidentally bridged those terminals. Fuse blown, fuse holder melted (naturally), 24 hours wasted.

Now if a 36V fuse exists, I sure as hell won't be able to find one here. I can find 12V/24V (automotive) and 110V/220V (household) fuses. Can I make any of these work? Fuse holder needs to be small to fit inside the pack BTW, even a regular automotive blade fuse w/ holder will be a tight fit.

Try a forklift parts company. Someone like emc or tvh if you have them? There's quite a bit of 36V stuff when it comes to mobile plant.

A picture of said fuse will help.

The voltage rating of a fuse has to do with things like insulation, heat resistance, and it not starting an arc when it blows, it has no effect on how many amps it takes to blow it. I think automotive blade fuses are actually rated at 30 something, and you can use a higher voltage rated fuse no problem.

All the low voltage fuses I use for work are rated at 250V. Most of my stuff is 24V.

The fuse came apart so I can't really get a pic of it, it was a tiny glass cylinder type about 17x4mm.

I also want to keep my solution "3rd-world-friendly" so if a common 110v fuse can do the job instead of a special forklift fuse, that would be ideal.

A pro says that a 12v or 24v fuse is fine for up to 48v:

http://support.electricscooterparts.com/support/discussions/topics/1000036780

I guess I'll see what I can find tomorrow, 40A automotive fuses are hard to find in anything smallish.

17x4... isn't that a standard automotive fuse?

Well what I think of as a standard automotive fuse. You know, back when the three fuse types you had were "Long Glass" (22lr), "Short Glass" (dangit Ford why you do this to me?), and "Frickin' Weird-Ass German Ceramic" (anybody got a nail I can cut to fit?)

17X4 is an odd size. 5X20 is a GMA fuse, but that's as close as I could find.

It's hard to figure out the exact size of the fuse from the bits left over, I didn't look at it before it went supernova. 5x20 is a possibility, but since I have to put in a new fuse holder anyway, a standard (modern-ish) automotive fuse would be a great option. As long as nobody else sticks anything unusual in the battery pack connector, the fuse should never blow without good reason.

This thing is a cheapo Chinese piece of junk and it shows. The connector on the pack is the same as the AC input connector on the back of a computer PSU, and two of those pins are live at all times once the pack is assembled, all 3 are live if you switch the pack power on. It would've been vastly safer to have the connector with pins sticking out on the vehicle side instead.

In reply to GameboyRMH:

IEC 60320 type C13/C14? If so, that's scary. You might want something like this covered connector if you have a chance.

Exactly that and it is indeed scary. I'll mention the covered connector to the owner.

What about going to a circuit breaker: http://www.amazon.com/DZ47-63-12V-48V-Circuit-Electric-Scooters/dp/B00WILQEP4/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1453297244&sr=1-1-catcorr&keywords=48v+circuit+breaker

I've thought about a manual reset circuit breaker (auto-reset could be bad in the case of a real problem), but it would have to be small to fit inside the pack, like one of these, but I need 40A:

http://www.amazon.com/Manual-Reset-Low-Profile-Blade-Style-Circuit-Breakers/dp/B00NVJ2G5Y

Again ordering stuff is not an option, I've already taken too long to fix this thing and nobody stocks those locally, sadly.

Got some 40A standard blade fuses and a holder, I'll take pics when I install it tonight.

You're welcome!

Was in a big rush and forgot to take pics but at least the fuse worked. Turned out there were other problems with the tricycle however.

Bummer. Did you get it 'back on the sidewalk'?

Plugged in the battery and turned it on, lights lit up, but twisting the throttle did nothing, so either the motor or controller is dead.

OK so the owner had an electrician look at it, I had a chat with him on the phone, the problem is the controller - it has two signal wires and closing the circuit gives it full power. The electronics inside are melted and he can't be sure whether it was a variable-voltage or PWM controller, but I figure either should work and a PWM controller is better.

I'm thinking that replacing it with a momentary switch (maybe with a relay?) might not even be a bad idea for such a low-powered vehicle.

LSx swap?

GameboyRMH wrote: OK so the owner had an electrician look at it, I had a chat with him on the phone, the problem is the controller - it has two signal wires and closing the circuit gives it full power. The electronics inside are melted and he can't be sure whether it was a variable-voltage or PWM controller, but I figure either should work and a PWM controller is better. I'm thinking that replacing it with a momentary switch (maybe with a relay?) might not even be a bad idea for such a low-powered vehicle.

how many wires to the motor? IIRC PWM is 3, voltage is two.

java230 wrote:

GameboyRMH wrote: OK so the owner had an electrician look at it, I had a chat with him on the phone, the problem is the controller - it has two signal wires and closing the circuit gives it full power. The electronics inside are melted and he can't be sure whether it was a variable-voltage or PWM controller, but I figure either should work and a PWM controller is better. I'm thinking that replacing it with a momentary switch (maybe with a relay?) might not even be a bad idea for such a low-powered vehicle.

how many wires to the motor? IIRC PWM is 3, voltage is two.

Good point. I think I'll check it out today. May hook up a momentary switch as a temporary quick fix.

Thought I'd update, I got the tricycle working this weekend. Needed not only a new battery, but a new throttle and controller. I think the PO overcharged the battery and fried everything short of the motor itself.

The throttle was PWM type and also has wires for a charge indicator.

LSx is over kill.

Think Hyabusa

Or McCullouch (love the smell of bean oil)

I seriously told the owner that when these batteries wear out, li-ions are an option (10 li-ion cells for 36.5v instead of 3 lead-acids for 36v). All battery charging is handled by an external unit anyway, the battery is disconnected from the trike for charging. Just changing the batteries wouldn't improve power, but it would lighten the trike significantly and increase range.