Pre Charge Resistor Very Hot When Hooked Up

D

drew12345

10 kW
Joined
Oct 16, 2013
Messages
895
Location
MD, USA
Hi ES. I need your help. I bought a couple precharge dongles from IceCube (http://lipoconnectionsolutions.com/Standalone-Precharge-Dongle-PrechargeDongle.htm). Been working great for my 12s bike and 18s bike. My 18s bike uses Infineon controller (37v - 72v). It started acting up when switched to 18s so I got a new 18 fet Lyen controller (http://endless-sphere.com/forums/viewtopic.php?f=31&t=16605). Well, when I hooked up the dongle between battery and controller, the dongle started smoking after a minute. Luckily, it was just the heat shrink around the resistor that was melting. Can someone tell me why?

I already contact Lyen and IceCube and didn't a get a response why this happens?

Please don't ask me to make another precharge because I'm not good at electronics. If you can point me to something that I can buy that would work, I would really appreciate it. Could switch work instead?

precharge.jpg
 
Possible that the resistor wattage is too small. What size is it? I use 150 ohm 10 watt resistors. Wattage overkill, but even if I hit the throttle without connecting the main wires, it won't get hot before lvc cuts in after the motor engages for less than 1 second.
 
The resistor is getting hot because there is current flowing. Normally, the current should only flow for a few seconds until the main capacitors charge up. The Lyen controller must be "always on" and drawing some current on standby.

Possible solutions:
Don't wait so long before making the last connection. The resistor takes a little time to overheat. Precharge should be done in a few seconds. Since the controller is drawing some power, the caps won't completely charge and you will get some spark when you make the last connection.

Use a higher wattage resistor.

Find the "key" switch line on the Lyen controller and separate it from the positive power input wire. Use a switch on this line and turn it on after the precharge is done. I'm not exactly sure how Lyen has this arranged.
 
In general I know IceCube makes products that work.
I think it is either user error or there is a bad connection caused from wear and tear of the Pre Charge Resistor dongle.
How long have you had the Pre Charge Resistor dongle?
Can you describe the process you take to connect your battery to your controller using the Pre Charge Resistor dongle?
 
Thanks to all that replied. I've had them for couple months and have been using them.

I tried following his video. I disconnect the loop. I connect the neg/pos pair to battery then controller. Wait about 5 - 10 seconds and then connect loop again.

I'll try to find resistor size.
 
Yes, you guys are right. I let it stay disconnected too long. I connected after 5 seconds and was fine. So user error. Thanks.
 
drew12345 said:
Yes, you guys are right. I let it stay disconnected too long. I connected after 5 seconds and was fine. So user error. Thanks.
Click to expand...
The plus side is that even a small resistor is incredibly resilient against damage, even if you smoked it pretty good if you check it with an ohm meter it should still report the correct resistance.
But yeah just don't leave it pre-charging too long and it should be fine.
 
drew12345 said:
Yes, you guys are right. I let it stay disconnected too long. I connected after 5 seconds and was fine. So user error. Thanks.
Click to expand...
I wouldn't call it user error. It should be of a high enough wattage that it won't get hot no matter how long you wait to connect the main leads. I'd call it a design error and the resistor should be replaced.
 
1K 5W may work with some controllers and battery packs, but I can assure you it won't work with many. The 5W is plenty, but 1K ohm is way too high to let some controllers get to high enough voltage to eliminate the spark when connecting the main power lead to the battery. Anything between 100-200 ohm should work fine, Use 150 ohm 10W and it will work well with any controller and battery pack up to 100V and probably a lot higher. I don't have any above 100.8V.
 
Don't know what the forum rules are for posting product links so I won't but if you check the popular Chinese hobby distributors at least one offers bullet connectors with good isolation shrouds and resistors built into the tips of the male ends so that you just touch the tip for a few seconds then slide them together. They work great for me everywhere I've tried them and they're rated for very high current.
 
did you mean that ones?

http://www.hobbyking.com/hobbyking/store/__42825__7mm_ax150_anti_spark_self_insulating_gold_bullet_connector_2_pairs_.html

i use them too, but it looks like you have really wait some SECONDS, because when you put it together instantly (just waiting 1 second)
you can hear a "spark-pitch" and ive seen allready some smoke too.
The Inside looks after 10 uses like 1 or 2 big sparks without resistor.
so i will try next ride to wait some MORE seconds.
 
Wheels_78 said:
Don't know what the forum rules are for posting product links so I won't but if you check the popular Chinese hobby distributors at least one offers bullet connectors with good isolation shrouds and resistors built into the tips of the male ends so that you just touch the tip for a few seconds then slide them together. They work great for me everywhere I've tried them and they're rated for very high current.
Click to expand...

This is a laid-back mod team and links posted in the spirit of helping discussion and problem solving - I've never known the mods to get involved. The problem is mindless "I got a product" link posted by retailers in practically any and every thread. Just not cool.

However, links which follow discussion of connectors, tools, supplies, etc., never seem to be prohibited and often encouraged since it helps grow the understanding and improvement of what we do.
 
Merlin said:
did you mean that ones?

http://www.hobbyking.com/hobbyking/store/__42825__7mm_ax150_anti_spark_self_insulating_gold_bullet_connector_2_pairs_.html

i use them too, but it looks like you have really wait some SECONDS, because when you put it together instantly (just waiting 1 second)
you can hear a "spark-pitch" and ive seen allready some smoke too.
The Inside looks after 10 uses like 1 or 2 big sparks without resistor.
so i will try next ride to wait some MORE seconds.
Click to expand...

Yes, those are the ones, I've used them on 14s rc planes and now my bike at the same voltage no problems so far.
 
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