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.
Greg—
Thanks for your thoughts. What do you recommend as the best way to arrest the arcing?
Dorian
I had gliderpilot’s preload switch 3D printed for me by a local guy for a small fee.
I like it because its one handed operation. “Clear Prop!” Twist the knob a bit, wait for the ESCs to beep then turn it the full 90 degrees. The disadvantage is you need to disassemble the main switch and reassemble with the new knob and wiring.
The other way to go is to wire a resistor through a separate momentary on switch. Hold it down, wait for the ESCs to beep, turn either main switch to on, then let off the momentary. It’s two handed operation but you wouldn’t have to disassemble the switch.
if you don’t want to use a mechanical emergency switch, you can install isolating relays like in the professional eppg area that are controlled by the esc. alternatively there is for people who want a plug on play version that works independently of the esc and devices like the one in the picture. by maytech. regardless of this, it is always advisable to use antispark plug cables as standard for all battery packs.
I’m planning to get a 3D printing of the spark arrestor knob assembly and go from there. Thanks for your info.
Is this Maytech switch just for safety reason when circuit breaking is necessery or it can be used for normal “on-off” arming/powering up the system after the battery cables are plugged?
all infos you can find on the webiste from maytech: https://maytech.cn/de/products/copy-of-mts1810as-anti-spark-switch-with-on-and-off-for-electric-skateboard-mountainboard-ebike-e-scooter
Does anybody have an opinion on the safety of the design of the Maytech MTS2009AS anti spark switch? I bought it from www.elektro-skateboard.de in Germany for €113 to replace the two original red on/off switches. Advantage is that I can put the on/off button itself at a more convenient spot, and the unit has an anti-spark function.
I tested it outside my paramotor while on the ground, and it works. But I didn’t dare to fly with it, because I noticed that the cover is aluminium. The only reason that the cover doesn’t cause a huge shortcut between the plus and minus is that it has Ø12,6mm holes to let the Ø12,0mm poles through, so a gap of 0,3mm and the black anodizing is resistant. With the heavy wires on the poles, I don’t trust the poles to never touch the cover and rub off the black anodizing layer. It will be hell if that shortcuts on your back in the air.
I asked elektro-skateboard for their opinion, but they are another week on holiday.
I would feel comfortable to use the unit without the cover, and all properly packed in isolation material. Didn’t measure the heat generation yet.
Does anybody have an opinion about the safety? I think some are flying with the unit already……
PS I measured the resistance between any of two white letters on the cover (where the black is engraved away), and there you measure full conduction.
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Any further opinion on the safety of this Maytech electronic switch?? It would seem way more convenient than the 2 manual switches + pre-charge.
I have just incorporated one of these in my X4 then read the above post from Ralph. So far it is working well but I haven’t flown with it because I haven’t yet fitted the harness and props. I am really hoping I will not need to modify it.
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