Riding in the rain shorted out my ebike

I would dry it out the best I could. Use compressed air to blow it out, get the bike in where it is warm, or out in the sun. Some spray lubes are good at displacing water. You may want to give it a try after drying it out for a few days, but make sure you can shut it down if it goes into a run away situation. Also connections are a big cause of problems, check all you can find.

Just so you know in the future, the best thing to have done was shut the bike down as soon as you started to have a problem. Modern electronics are pretty tuff and can handle some brief shorting out, but they will burn up pretty fast if overloaded for too long.

If you fix the bike, find a way to seal it up. Silicone, tape, grease, anything to keep the water out.

Deron.

It would be interesting to note if the resistance you feel in the back wheel goes away after you unplug the controller. I'm no EE, but I believe if the controller is shorted out this could turn the motor into a generator and cause the resistance.

First unplug everything from everything else. I'll echo what deronmoped said. Get everything dried out. Throttles don't usually come apart very easily (or back together for that matter), but you can usually take the controller apart and remove any lingering water. A hairdryer or a heatgun on it's lowest setting and speed up the process. Also check for water in the batteries and in the connections. After everything is nice and dry you can start debugging.

Check the batteries with a voltmeter. (If you don't own a digital multimeter this would be a good time to get one.) If they don't have a full charge see if they'll take one. If they won't you need some new batteries. There should be several fuses in the system. At least one or two in the battery back and maybe one in the controller. If they are blown you can get replacements at your local electronics store or even Home Depot. If you have lived an exceedingly clean life this is all that is wrong. You can also check for damage while you are in there. Blown caps, resistors, and mosfets are usually pretty obvious like a smoky black mark where the component used to be. If the controller has smoked some components I would replace it.

You should be able to find out how much voltage the motor is getting by hooking up the throttle, controller, and batteries and measuring the voltage at the connector that is usually hooked to the motor. As you work the throttle the voltage should go from 0 to somewhere near 72V. This will either take a friend or leads with alligator clips so you can use the multimeter no-handed. If the motor isn't getting any juice it doesn't matter yet if it is fried or not.

Now I'm a little stuck. Brushed motors can be hooked up directly to the batteries, but brushless can't. Right? Anyone? Taking a wild stab I'd guess your controller is blown. It's less durable than the motor, and it would explain the way the bike was behaving before it stopped working.

If you do get it working you should take the opportunity before reassembly to make sure everything is properly fused. This is a step a lot of manufacturers skip. I always make sure there is a fuse on every path that carries high current. Fuses are much easier to replace than components. Fuse holders and fuses can be found at electronics stores, auto parts stores, and if you are lucky enough to have a place as cool as McGuckin's, hardware stores.

This should get you some ways down the right track. Please let us know how you make out. Trouble-shooting ebikes is something I'd like to get better at.

I'm glad the hunch played out. I didn't get much beyond Ohm's law in college, but hanging around here allows some knowledge to rub off.

I did not know that should have fuses in the system. Now it makes perfect sense. Would you put a fuse on the black (positive) lead or the red?

I always assume that current can find a way to ground so it is better to fuse the hot (black) lead. Fusing either one is enough to prevent a circuit, though. Both would be overkill. The first pack I ever owned had a fuse between the controller and the battery, but not between the switch and the battery. Guess which shorted first. :-) I learned a $300 lesson that day.

About the fuse, if I had a 40amp controller, would I use a 50amp 100V fuse? Or what?

Yes. You want to choose a fuse a bit larger than the maximum current you expect to flow through the wire. I don't know about volts, though. I have only seen fuses rated in amps.

Do you have a link to the switch you guys are talking about?

Every ebike I have ever owned has had a switch of some sort. On kit bikes there is usually a key switch inserted into the circuit between the battery and the controller. On some bikes like LashOut there is a rocker switch on battery pack. On the Bionx it's a electric switch hooked to a relay. Whatever it is there has to be some way to keep the controller from being energized when the bike is not in use. Are you sure your bike doesn't have something like this?

I would recommend two things slightly different from the above suggestions:

1 Use a circuit breaker, not a fuse, first because you can simply reset it instead of having to change it, and second because it is slower to react than a fuse, and less likely to pop due to a small current spike, but *will* do so for any sustained excess draw. You will need to calculate (or measure) the actual maximum current draw that your system needs, and is still safe to pass thru the wiring, controller, and motor, as well as being safe to pull from the batteries (because you can damage batteries by exceeding their output limits).

2 Use a relay *controlled by* a switch, not a switch directly. This will save your switch's contacts, and also keep you from having to deal with a huge clunky switch somewhere (since a switch would otherwise have to be able to easily sustain the current draw for the *entire system* just like the fuse or circuit breaker would). You can then use any switch that will handle the coil-current for the relay.

I have used a reed switch buried in silicone alongside a small steel bar or plate, and a magnetic "key" that sticks to that plate during the ride, holding the relay closed. No one will even know you *have* a switch to turn it on, and may assume it's not working, if they start messing with it while it's unattended in a lockup. Any magnet will be able to turn it on, so if you somehow lose your "key", it's easy to go make or get another one, almost anywhere. If you have to, you can always borrow someone's nametag at a retail store--they tend to use those highstrength thru-shirt magnetic namebadges everywhere now. (that's what I used as the *original* key for a long time).

Just don't accidentally wire the relay so it keeps itself turned on (latches) after you turn off the switch. :-) I've seen this done before by another experimenter in a different area a few years back.

Put the relay as close to the controller as you can, to keep everything together and shorten wires to their minimum. Use a relay that can handle a lot more than what you expect your system to use (unlike the circuit breaker which should be as close to the max safe current as possible). Otherwise, if there *is* an overcurrent, it's possible to weld the relay contacts together, defeating the whole switch thing in the process--but the circuit breaker should at least prevent worse damage and fire, etc.

Even the cheap little Electra controller I found on a burned out Scoot'n'Go uses a relay method, where the relay is enabled by the keylock switch.

FWIW, the black GE and DAP silicone II types of "caulking" are more flexible than other colors, if you still need to seal everything up when done. You can make gaskets from it, too, instead of a permanent seal you'd have to cut.

First, apply a 1mm thick layer of water-soluble lubricant (available at some dollar stores by the brand name Sheffield--it makes a great "peelable masking tape"!) to one edge of the device case you're sealing up, for instance the controller lid. Let this dry completely. It's ok if you get it on areas other than just the edge-seam, since extra masking won't hurt--you're going to peel or wash it off later anyway. If you want to be able to see where you are masking off as you do it, just add some food coloring to the lubricant/masking before you apply it, and mix it in well. Also makes it easier to see what thicknesses you're applying in, as the color will be darker in areas with more masking.

Next, once the masking is dry, put a thin bead (your discretion) of silicone caulk around the same edge on the opposite part (for instance, the controller's case), and let it dry for a few minutes, just long enough to "skin over" a bit, but still be a little tacky.

Next, gently set the first part (lid) onto this bead just so that it makes complete contact with the silicone at all points, but does *not* squish the silicone out of the bead or flatten it out against the opposite part face. You want to be making a gasket that will fill up the space between parts, pretty thin, but still thick enough so that when you later screw the casing together, it compresses and seals water- and dust-tight.

Let that sit overnight in a warm room (at least 72F, preferably 80F, as it will cure better. If it's too cold, say below 60F, it may not cure properly for a really long time, perhaps days).

Now separate the parts, carefully peel off the dried "masking" but do NOT peel away the silicone. If it won't peel, take a damp sponge and a bowl of hot water, and wipe gently at it, rinsing the sponge and squeezing it out in the bowl as needed, until the masking is all gone (you'll be able to feel it not being slippery anymore).

You can now reassemble the casing, and tighten the screws down just enough to ensure the seal is complete, then a 1/4 turn more, perhaps (depending on the coarseness of screw thread). Don't crush the seal, or it'll break, and leak later. Now you'll be able to take it apart for repairs or modifications later on without having to redo the seals over and over.

(BTW, this technique can also be used to isolate vibrating components in your PC case to make it much quieter, depending on how it and they are constructed).

Sealing a motor can be a lot more complicated, if it has cooling vents; if not then it may already be well-sealed. IF there are vents you will either need to alter the casing so it does not need vents but instead uses heatsinking fins, or else make a casing that keeps out water splashes or drips, but still allows air inside. It's not impossible, but it depends so heavily on the arrangment and size/shape of your system components that you'd have to figure it out based on those.

One of the best in the world NKK made in Japan, i have 3 of them on my TF .
They have easy to navigate , very informative website, lot`s of tech info.
You can get some toggle for free, but not above 30 bucks ones.
Digy-Key stocks them.
Miroslaw