How to make an XT90 Loop Key

Thanks @yelnats8j @Flasher!

I’d never heard of liquid electrical tape, going for some of that then cast some resin in there.

More compact if you ditch all the XT60 connectors and solder everything, unless you take apart your board all the time

cool, yeh i would do if it was more permanent, at this point though i am taking it apart a lot, the idea is to have an easily swappable battery between 2 set ups,
at least until the bank balance levels out and i can buy another battery :wink:

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JB Weld does have actual steel in it. It is definitely very magnetically conductive. It doesn’t seem to conduct electricity at low voltages, but I would not count on that. I just tested it (JB Weld 8265-S Original Steel) with the multimeter and no conduction. It’s not steel – but it has steel powder in it.

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Thanks!
yeh i’m gonna not use it if there’s even a slim chance of conduction at higher voltages,
plus it doesn’t look as pretty as resin, and with resin i can patch up a few old decks at the same time

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Being snug is really good, and it will get looser with use. Also sometimes I slightly bevel the edges of the plug as seen in this photo on the bottom-left edges

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I’m afraid to tear the cables from the connector with an lanyard :frowning:

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Shouldn’t happen. If it’s a good solder joint, you’re saying that the tensile strength of metal wire isn’t comparable to wool/plastic lanyard. As long as it’s not razor thin, I think the most you’ll risk is cutting the silicone sheathing

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I’ve used the same loopkey for 3 years, 10awg wire loop

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Can you help me figure out why I fried 2 times in a row my XT90S loop key ?

My battery is a 14s3p Samsung 30Q, the loop key is on the positive terminal of the battery.
I fried my loop key (big spark when connecting it, black residue, and now I measure a resistance way higher than 5.6Ω). I made another one, after 1 or 2 connections, it fried again.

Any idea why ?

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I burnt one by not having the loop key all the way in during a quick test. Smelled it and pulled it out. Next time installed it went pop.

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Not pushing the key all the way in.

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Check the polarity of the XT90 connectors on the battery

@b264 well it wasn’t pushed all the way in, but it sparked before letting me a chance to do so :frowning:

@Linny I checked with a multimeter, the polarity is ok

It’s permanently broken because it was operated without being pushed in all the way.

Make a new key. You used the female side for the key, right? (male side on board)

The female side is the one that’s broken.

In the future, make sure you fully insert it, don’t just plug it partially in.

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Yes I use the female connector for the key.

I’m pretty sure I pushed it all the way in since I knew it could damage the connector if I didn’t.
I’ve made a new loop key which fried too, so I’m trying to figure out what’s going on before killing more connectors :smile:

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It would be interesting if you could make a loop key with a tiny buzzer that would go off until it was fully inserted.

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The only thing that will kill them is being operated while not plugged in all the way.

and using them for 20S voltages (84V)

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AS150 is another option. I used one for quite a while on a board until I popped in an Antispark.

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Is it possible that the black residue on the male connector because of the first spark, prevent the connection with the resistor on the female connector ?

How long does it take to kill while partially connected ? Maybe I plugged it too slow, I really don’t know :sweat_smile: