Are sparks normal?

[SimonMTL]

I have bought a PingPing LiFePO4 36V15Ah battery, wired everything properly (not very tough... positive to positive, and negatives to their proper charging-discharging route), and I was wondering if it was normal to have a spark when things get plugged.

When I plug to the hub-motor, there's always a spark and a "pop" sound (that's how I know it's a spark - can't see it physically, although when the wires were bare I could see it when touching them together). When I plug to the transformer, there's a pop+spark.

Everything works well, the power goes to the hub, the transformer performs its duties. Just the dang "POP" . Is that normal?

 

[bbsux]

I have no where near the setup you do but my schwinn stingray electric did this as well... I think its normal BUT that doesn't mean it couldn't be a problem. If you have a battery off switch make sure its off before connecting it.

When I put a better battery shutoff in mine, I went ahead and put a "precharge resistor" in it (300 ohm 10 watt), now I never have that spark.

 

[Dr. Shock]

It is just the capacitors in the controller sucking in some current. It is normal, and at 36v it shouldn't hurt anything, although you could put in a precharge resistor as suggested and not have to deal with it.

 

[miro13car]

Spark on power up is normal , my TForce does the same thing.
I installed SPDT switch as a MAIN swith. It has 2 contacts with common contact in the middle. Right contact is connected to + of controller through 100 Ohm resistor , left one is connected directly to + of controller. I first swing switch to right , then fast to the left contact and spark is absorbed by resistor.
Is there simpler way, anybody?
MC

 

[SimonMTL]

OK, thanks everyone for the answer.

Now, another question: can I just leave the power plugged on the motor when I charge the battery? You know, since they both use the + Positive wire... If I could, it would save me from hearing that POP every time I want to charge!

(just erring on the safe side! That battery is worth half my ebike!) :wink:

 

[Link]

You COULD, but SHOULD you?

(Hint: starts with an "n" and ends in a "o".)

If you really don't want to deal with the spark, get a breaker or a relay.

 

[SimonMTL]

... I went ahead and put a "precharge resistor" in it (300 ohm 10 watt), now I never have that spark.

Ahem. OK.... so.... how do you do that? Diagram for dummies please! There's already a fuse on the + Positive wire going for the discharge portion (hub motor).

 

[Link]

... I went ahead and put a "precharge resistor" in it (300 ohm 10 watt), now I never have that spark.

Ahem. OK.... so.... how do you do that? Diagram for dummies please! There's already a fuse on the + Positive wire going for the discharge portion (hub motor).

You just put it across whatever you're using as a switch.

 

[SimonMTL]

... I went ahead and put a "precharge resistor" in it (300 ohm 10 watt), now I never have that spark.

Ahem. OK.... so.... how do you do that? Diagram for dummies please! There's already a fuse on the + Positive wire going for the discharge portion (hub motor).

You just put it across whatever you're using as a switch.

I don't have a switch, I just got a plug. Why would I put a switch on a battery?? And where: on the + wire??

 

[Link]

I don't have a switch, I just got a plug. Why would I put a switch on a battery?? And where: on the + wire??

Some have contactors/breakers to keep the contacts in the plug from being damaged over time. I do.

Whichever wire.

 

[fechter]

Look on page 2 here:
http://endless-sphere.com/forums/viewtopic.php?f=2&t=1090&p=16852&hilit=precharging#p16852


At higher voltages and with upgraded controller caps, the spark can be pretty destructive to the connector pins. Other than that, it usually doesn't hurt anything.

It's bad practice to leave the battery always connected, but many prebuilt units do just that.
The controller will slowly drain the batteries if left stored for long periods. The other danger is that voltage spikes from the AC line can pass through the charger and zap the controller.
I heard more than one report of a scooter suddenly taking off at full throttle all by itself when charging.

 

[ngocthach1130]

Rigged up one of these. There is 2 switch with one common ground. One side have a common ground and that's connected out. The other side i wired 2.2k resistor in parallel to end end of first switch then jumped it to the end of the other switch with the wire going out. Originally i had one 2.2k resistor but i felt it was too big so it's easier to reduce resistance by paralleling it. You work the switch by first flipping the first left switch so current is drawn through the 2.2k parallel resistor. Then you flip the second switch to short the whole system. There's no spark if the cap is now charged. Then you flip off the switch one. These thing are rated for 15A 120VAC so i felt they should be good enough for my our uses. It's housed in a shallow wall outlet box. It's a bit big, but it's rugged. The black wire is straight through the box. I just like to have the swith as a stand alone part i could connect in between my battery, rather than just breaking the positive wire and deal with different length negative leads. Parts cost about 5 bucks.

 

[monster]

OMG is that a domestic light switch!!! ngocthach1130?

 

[docnjoj]

I've used a single light switch for 4+ years with no resistor. No spark and no prob. Mine is 20 amp rated on 36 volts of NiMh. Switch does not get hot with use.
Doc

 

[Link]

I use my breaker (50A) as a switch.

 

[kbarrett]

Just get a heavy duty switch. You can buy a good generic high amperage ignition switch at an auto parts store. Put it on one of the wires ... positive between the final connector and the charger lead is fine.

Leave the puppy switched off while plugging it in.