XT90-S loop key short circuit

Today i attached my new motor (12S) and resoldered my setup from 6S2P to 12S1P. I did it like the following wiring from @trbt555. Thanks for this. I used a XT90-S for the loop key. I plugged it in and it instantly short the circuit. My VESC is alright but the XT90-S key is burned… Now when i plug it in it will always spark…

Did anybody get the same problem? Faulty XT90-S?? Did i plug it in too fast?

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you have made a mistake in the wiring… I would guess you have the balance leads the wrong way around.

…if I had a dollar…

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The balance leads are not connected. It did not happen while charging. It happened as i wanted to power my system for a test drive.

But why should be the wiring of the balance leads wrong? That way i can discharge them in series and charge them simultaniously with my dual charger.

The loop key only needs to be spliced into either the ground wire or the positive wire. Not both. If you didn’t use an xt90 anti spark plug then you will get a spark.

What did you expect, you connected the positive straight to the negative with that loop key :open_mouth: It is supposed to connect/disconnect either the positive OR the ground, but positive is more often used, because there can be multiple grounds. Best of luck with the build!

Edit: Nevermind, the chart looks correct. What is the anti-spark connector rated for? Are the batteries in series the exact same model? Are they both charged to the same voltage?

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(red connectors = XT90-S / black connector = XT90) Do these wirings make a difference? I believe the following but i can be proofed wrong :wink:

There will be no difference → i dont create a circuit if i dont attach an esc. If i attach a esc there will be a circuit and the current will always flow through the XT90-S plug.

I want to learn something so i just wrote down my questions. I hope i get them answered :wink:

  1. So i dont have a chance to charge it seperate and discharge parallel?
  2. Only way would be to change the XT90-S with a normal XT90 and splice a new XT90-S into ground or positive?
  3. Which one is preferred? And why? positive or negative?

To be simple, consider anti spark loop key as a switch. You only instal it on the positive side / negative side. So both wires that goes in and out of the anti spark should be the same color (only red or only black).

ohh I see you use the antiloop for the series connector. Then @lowGuido is correct, you have missed something within your balance plug.

If it still shorts, my suggestion is now to swap your balance plug around. 6s and 6s into 12s. Left 6s balance plug to the right side and the right 6s balance plug to the left side. Seems weird at beginning (they are still end up as 12s anyway) but it does change the polarity of the balance plug removing your shorts.

the connection of the loop key is correct that’s not in question. something else happened to pop the resistor in the anti spark, and that’s why you are now getting a spark… I don’t know what happened to cause it, I can only assume some sort of short…

Well if it gets shorted out earlier, that resistor is dead for sure. It’s a small 100ohm’sih resistor can’t handle the heat and current that large from lipo packs.

yeah once its gone its anti spark capability is no more.

does the VESC still power up? I cant think of how you could have shorted it unless it was the balance leads?can you take photos of the actual setup? the diagram is fine, but i’d like to see the real life picture.

I prefer negative side, because thats were the electrons (the current) is flowing from. Also BMS’es seems to alternate the negative side for either charging or power switching, so I believe negative side is better.

Your diagram is correct. Your diagram shows you are discharging in series. You can charge separate and discharge parallel.

I dont quite understand the question. XT90s and XT90 have no difference at all, one provide anti spark function and the other doesnt. You can use all XT90s or XT90 or combination doesnt even matter.

nah there is nothing wrong with the way you have it set up @psychotiller and @paragon just didn’t understand what you were doing. the diagram is correct, but I want to see real world photos.

Yeah I had to stare at it for a while…it looks like a nice way way to run series and charge parallel. If the balance leads weren’t plugged into the charger why the spark then?

well thats the $500 question isnt it?

I recognised the circuit right away because it is mine.

Just get a voltmeter and test each connection before making the plug. If theres voltage reading, that means its a short! Do not plug it in.

Show us a clear picture of your wiring please.

The resistor of the xt90-s was directly shorten after i plugged it in the first time. Since that i always get a spark… Obviously. I still can Run my system with no Problem. I just always get a spark. If i still plug it in and it will spark does it make serious damage in long terms?

Here are some photos. I hope that they are not too Bad otherwise i have to take it apart.

that are the Batteries and the charging cables. that is the series Adapter with loop key. The cable to the legt upper and right upper are for the batteries and the only one going down is for the vesc

what are the balance plugs connected to in that photo?

the spark wont damage anything. its just the inrush to the caps. it tells you your caps are good. the thing I want to know is why it blew the resistors in the first place

It did not happen while charging. It happened when i Run the System.

That is the charging cables of one battery. The outside is for the charger. The right upper cable is for the battery and the right cable below is for the vesc or the series adapter