this is my plan now… to use AS150 connectors in place of any switch… they have a built in anti spark using a resistor (you can see this on the male connector) so this protects the ESCs and there is no switch to be damaged. The amps rating is the same or higher than the current design without the additional limitation of the switch contacts. As per earlier posts I propose to mount 1 connector securely to the hub allowing the other to be pulled (in flight emergency if needed to kill all power). Any comments or advice appreciated…
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I am thinking also that pulling a connection in an emergency might be quicker and easier than turning 2 switches.
Still planning the design… I am thinking I would need 2 of these AS150 connectors to get the 300amp rating and they would both need to be pulled in a kill power situation. I am thinking of a simple loop of the cable which would be situated by the side of the batteries. Not sure if this would be reasonably accessible in flight. The loop would be close to where the switch is in the normal configuration but a bit further back. Alternatively, maybe a paracord line. Also, I am wondering if it is considered reasonably safe to connect power BEFORE getting into the harness? (the controller being unarmed of course). Otherwise my connector plan might be a bit awkward to power up. Any thoughts??
Gotta consider the possibility it snags or vibrates open-- how will you reconnect midflight?
KISS. Use a switch, consider it sacrificial, and replace as necessary.
I don’t mind the dual switches. I still haven’t set up the anti spark resistor and I hardly ever hear an arc. I have very short wiring
Just wanted to say thank you … I had not quite understood the picture, but I am much closer with this explanation.
The anti spark feature on those connectors only protect the connectors from arcing. They don’t protect the ESC from anything. Using a precharge resistor only protects the switch from arching. Arching only happens at the point where the circuit is closed. Each arc will pit the contacts and eventually cause a bad connection which can’t handle the amps. In my case it melted my switch a few minutes into my flight. I was only using one switch though… but with two switches they each take half the current.
The arc inside the switch is really hard to hear. The switch makes more noise than the arc does. If you take apart the switch you will see pitting and black residue from the arcs.
Also, wire length doesn’t impact the arcing. The caps inside the ESC are what cause the arcing because they charge up so fast. The caps are there to protect the ESC from voltage spikes and short wires will help reduce that.
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Great. Thanks for that advice Gliderpilot. I think I am going with your 2 switch + pre charger design now. As someone building the kit for the 1st time, this switch controversy has been a bit of a headache. Perhaps a brief list of “best practice” from the forum could be made available to all new kits sent out. Especially anything safety critical. Regarding the switch issue: it seems to me gliderpilots design should be the “best practice” currently and maybe a circuit diagram for this could be posted. I have a scribble currently & plan to post a neater version. That switch does seem to be way overloaded in full throttle but as jbernal says it could be regarded as sacrificial. additional: I see this switch on eBay but the amp ratings vary considerably from each seller. Is anyone aware of this switch being available in different ratings? Or is it likely exactly the same switch? Thanks again everyone.
Found this.
Might work nicely as a solution to all the woes.
Not cheap but better than becoming a fireworks display.
Really didn’t have much luck with your electronics, eh?
When my switches need replacing, I’m thinking of going with these:
I’ll change the XT150 connectors to anti-spark and only use the switch as a breaker/emergency stop.
I’ve a few dozen flights on my X4 now and I’m really glad I went with the dual switch with spark arrest in one of them. When I’m running my pre-flight and post flight I ensure those switches are off before I stick my hands between the props to plugin or unplug the batteries. Without them I’m relying on the controller alone to prevent a prop strike that would be the envy of the 2 stroke crowd. Perhaps that controller is infallible. I KNOW that if it’s not, the switches are. In fact I now only turn the switches on after I’ve strapped on the motor and announced ‘Clear Prop’. I switch off before unstrapping.
Do you have a source for the resistor? I haven’t been able to find one locally and the online stores are always out of stock.
Really didn’t have much luck with your electronics, eh?
I’ve had it working great without switches but the sparks hooking up the battery cables always give me palpitations.
I know it won’t just start up and saw off my fingers until the safety is off, but there’s still that fear as well. Probably healthy to have that fear.
Regarding the rest of it, it’s one of those frustrating projects that you have to distance yourself from after frustrations, yet it’s always nagging at the back of your head because there is a better solution than the crap which you’ve been dealt.
I installed some of those anti-spark connectors on my rig and wow they are awesome. So much better engineered than standard xt150 plugs too, in terms of the solder connection and the threaded casing. Put them on each positive lead on one battery per pair, now it not only prevents the spark but prevents accidental shorting when hooking it all up because the connections can only go together one way.
So to solve this once and for all, so long as we have anti-spark caps for the batteries, could we not just put in a small spdt switch, say, on the throttle, and a relay after the low-draw power supply, so we can cut off power to the Hub, and all woes go away for ever and ever? Then you could also reboot it from the throttle if you need to.
It’s not as SAFE as having switches, but then again how safe is it flying with switches that melt?
Allow me to clarify some things. We use caps on the ESC to protect only the ESCs from high voltage spikes. We use a resistor on the switch to reduce the spark that occurs inside the switch as it’s turned on. That spark degrades the switch over time because of repetition and then it can’t handle 300 amps anymore. Two switches cut the amps to 150 per switch so even if the contacts are slightly degraded the switch shouldn’t melt.
Those sparks you see are damaging your connectors. It’s that same spark which would damage the switch and cause the switch to not handle the amps and melt. Instead you risk having your connectors melt. If you don’t use switches you should get some anti spark connectors.
I did install antispark connectors and they are wonderful. I’m just wondering if there is any downside to using a low power switch to kill the hub instead of several high power switches.
Question for Paul Butler—
I’m in the process of wiring my new batch 6 X4. If I install two standard switches and a crossover wire between them and don’t install a 22 ohm resistor or spark inhibiting knob, am I still likely to have a problem with arcing?
Seawind Pilot - Dorian Olson
TLDR: yes
The switch shipped with the X4 is designed as an emergency cut-off for high current applications. It’s engineered to be normally on and switched off in emergencies or as a safety. We are using it as an ‘on-off’ switch for the power electronics. It’s probably seeing a lot more on-off cycles than it’s really designed for. In high current applications a big 'ole cartoon knife switch is more typical. You know the type Hollywood used to love to show c/w the sparks flying? yeah.
Turning on the power electronics (ESCs) is not a really high current application but it is, apparently, high enough to create a nice healthy spark. Anyone measure that draw? I’d say the spark arrestor knob is more important than dual switches. Dual switches brings the current each switch is handling to under half their rating. That’s good but the spark created when you turn on the first switch will not be affected by the second switch. You’ll reduce the damage created on each switch by 50% if you alternate between two switches every time you turn the system on. Ultimately that damage will accumulate and the switch will start showing resistance. Resistance=heat instead of thrust. Heat = switch melting. The heating will be halved between two switches as well but still that damage has to be building up.
Alternately you could switch on first then connect your battery. You could use spark arresting plugs and forgo the switch entirely or have it as a cut-off only. Personally I would feel more than a tad uncomfortable reaching through those four wooden hand choppers to plug in batteries and hear the system activate. You’d be relying on the controller and hub to be working properly and not shorted in any horrible way. I’m sure it’s designed so that any part failure will prevent the system from powering up the motors/ESCs at all rather than have one power up on it’s own. But still… reaching through those props tho.