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XT90-S loop key short circuit

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

ahh k.
have you tried another anti spark plug for the loop?

The spark won’t damage other components, it will just wear out your loop key over time.
If all your wiring is correct then it could be a dodgy loop key.

[quote=“trbt555, post:22, topic:2383”]
If all your wiring is correct then it could be a dodgy loop key.[/quote]

I thought this wiring was a good idea. I will replace the xt90-s with a new one and retest it. Back to my questions:

  1. Do you have a better wiring i could test? (maybe i change the XT90-S with a normal XT90 and splice a new XT90-S into negative ?
  2. Faulty XT90-S??
  3. Did i plug it in too fast?

If the xt90s resistor blew, there was obviously an overcurrent.
There must be a short somewhere in your system.
You cannot have anything plugged into the charge or balance connections when you insert the loop key.
You need to re-check if your wiring corrsponds to the schematic.
Perhaps you can draw up a schematic of precisely how you’ve rigged it together.

1.) This is as far as I can see the best or only wiring for this situation. (adding more loop keys would be pointless)
2.) It is now.
3.) No.

All that complicated wiring. Why not just use the xt90s plug as a plug? Charging or turning on or of