Connectors for altimeter, battery, switch?

[Kelly]

What is a good connection scheme to be able to connect a LiPo battery, an altimeter, and a mechanical switch, so that the three (or at least the battery and altimeter) are swappable? I've seen George Pitt's approach with a custom PCB, but of course that requires the PCB, and perhaps a bit of extra space. Are there connectors that would make this doable? I guess what I need are one-pin connectors, since I'll need one wire from alt to switch, one from switch to battery, and one from battery to alt. I've thought about using male/female jumper wire connectors, but not sure about the robustness of these nor whether they'd handle the current. I could use JST and short the wires to make it, effectively, a one-contact connector. Is there some common solution to this? Looking for something relatively compact to fit smaller bays.

 

[WillMarchant]

Take a look at https://binderdesign.com/store/page24.html and see what you think.

 

[rharshberger]

What is a good connection scheme to be able to connect a LiPo battery, an altimeter, and a mechanical switch, so that the three (or at least the battery and altimeter) are swappable? I've seen George Pitt's approach with a custom PCB, but of course that requires the PCB, and perhaps a bit of extra space. Are there connectors that would make this doable? I guess what I need are one-pin connectors, since I'll need one wire from alt to switch, one from switch to battery, and one from battery to alt. I've thought about using male/female jumper wire connectors, but not sure about the robustness of these nor whether they'd handle the current. I could use JST and short the wires to make it, effectively, a one-contact connector. Is there some common solution to this? Looking for something relatively compact to fit smaller bays.

I use two JST (RCY type, the red ones on most of my 300mah Lipo), one is female wired to the switch and the altimeter (one male one female that way the battery can only be connected one way) and one male that is on the battery (I also love the arguement that I have my Male and Female reversed as is actually the pins not the socket that determines sex). Not shown is a battery side male JST.

Two different bays one with a Eggtimer Quark and one with a Missleworks RRC2, in both cases the red wires goes to the Altimeter BAT+ to the switch and the red wire on the JST goes to the other solder pad on the switch, the Black Wire on the JST is wired direct to the Altimeter BAT- terminal. I try and keep my connections as solid and few as possible, soon as I can get them I plan to start using ferrules on my terminal blocks on the altimeters. All ematches are wired direct to the altimeter, it sometimes requires longer ematch wires but it removes at least 8 more connections (altimeter to bulkhead terminal x2). The downside is that I have to open the bay up to prep for the next flight instead of disconnecting the ematch from a terminal on the bulkhead and wiring in a new one.

 

[Nytrunner]

+1 to Rich's method. If you're doing a high-G flight, you can put a strip of electrical tape around them too

 

[warnerr]

agree! JST are robust! the only modification i make to them is marking with felt marker one edge to idiot proof against reversal- makes it easy to spot direction without refering to wire colors (and be sure to check wire color/polarity: (some jst come reversed!)

 

[Kelly]

Thanks, Rich. It's not exactly what I was wanting - the way you have it wired, you have to swap the altimeter AND the switch, as a unit. (I guess on the RRC2 you could undo the screw connectors on the alt, but all my alts have soldered-in power.)

I was looking for something where I could just take the alt out and not deal with the switch. But, maybe this is the way to go - makes it more complicated (slightly) to swap, but a lot simpler to wire up.

 

[g.pitts]

Thanks, Rich. It's not exactly what I was wanting - the way you have it wired, you have to swap the altimeter AND the switch, as a unit. (I guess on the RRC2 you could undo the screw connectors on the alt, but all my alts have soldered-in power.)

I was looking for something where I could just take the alt out and not deal with the switch. But, maybe this is the way to go - makes it more complicated (slightly) to swap, but a lot simpler to wire up.

JST (the Japanese Company, not the generic term for battery connectors) makes a wide range of connectors that will do what you want. The challenge is getting around using their crimp tools, which are typically $500+ per connector type. To do so, they sell "jumpers" that match certain families of connectors. What's a jumper? It's a wire that was terminated with the proper connector pins by JST using their pneumatic or hydraulic presses, so the connections are rock solid. On DigiKey, JST sells pretty much their entire line of in-line connectors - which I believe is what you are looking for. You would need to find a family that is robust enough for your electrical specs (specifically current level). They also sell jumpers for some of those connector families. I'd be happy to work with you via PM if you'd like to pursue that approach.

 

[Kelly]

Thanks again! I looked at the Binder design stuff, but it's not clear from the pics how it all goes together; and it looks like a lot of wiring.
One more Q - what about jumper wire connectors like these:
https://amazon.com/gp/product/B01L5UKAPNot sure about rating, but they're 26 AWG. Assuming 40 ohm/1000ft, and a 5A deployment current, that's only a tenth of a volt drop. Not sure what the other considerations are.

 

[rharshberger]

Thanks, Rich. It's not exactly what I was wanting - the way you have it wired, you have to swap the altimeter AND the switch, as a unit. (I guess on the RRC2 you could undo the screw connectors on the alt, but all my alts have soldered-in power.)

I was looking for something where I could just take the alt out and not deal with the switch. But, maybe this is the way to go - makes it more complicated (slightly) to swap, but a lot simpler to wire up.

It would be easy enough to solder a JST to the alt (both wires) and use a JST on each side of the switch, say both red wires soldered to the pads on the switch, with the black wires soldered together, then you leave the switch in the bay and the battery and alt is still removeable. Its more connections than I like for reliability reasons though.

 

[sl98]

JST (the Japanese Company, not the generic term for battery connectors) makes a wide range of connectors that will do what you want. The challenge is getting around using their crimp tools, which are typically $500+ per connector type.

I make my own JST-RCY connectors using an IWISS ratcheting handheld crimp tool and silicone wire. Paid about $25 for the crimper. I can use it on a variety of connector pins. During our continued stay at home time, I've been making quite a few connectors. I don't think this pin is coming off.

 

[g.pitts]

I make my own JST-RCY connectors using an IWISS ratcheting handheld crimp tool and silicone wire. Paid about $25 for the crimper. I can use it on a variety of connector pins. During our continued stay at home time, I've been making quite a few connectors. I don't think this pin is coming off.


View attachment 414579

Nice. Kinda hard to see, but the crimp around the wire insulation looks nicely centered.

I am jaded by my experience having spent too many days doing dye / shear testing only to find out the "genuine" tooling that I paid for was not, in fact, genuine tooling. I've had way too many cable issues in my professional life using Chinese cable vendors on products over the past few years, which results in a lot of pull testing and dye / shear testing, so connectors are just an area I'm unwilling to compromise on. I have enough problems in life.

 

[caveduck]

I use hand-built JST connectors as well, like sl98 I assemble mine from known genuine JST parts and silicone wire from Digi-Key, though I use Engineer Inc crimpers. Too many of the ones on Hobby King etc. are poorly built, may have counterfeit parts, and occasionally have colors reversed. I actually solder *and* crimp the connectors...takes a bit of care but they are not gonna come apart on me like some of the pre-made ones.

For switches I now use the FingerTech Robotics screw switches: https://www.fingertechrobotics.com/proddetail.php?prod=ft-mini-switch . They are fantastically rugged, having been designed for combat robots. My current strategy is to mount one on each side of the sled board and drill matching holes in the switch band.

 

[Reinhard]

What is a good connection scheme to be able to connect a LiPo battery, an altimeter, and a mechanical switch, so that the three (or at least the battery and altimeter) are swappable? I've seen George Pitt's approach with a custom PCB, but of course that requires the PCB, and perhaps a bit of extra space. Are there connectors that would make this doable? I guess what I need are one-pin connectors, since I'll need one wire from alt to switch, one from switch to battery, and one from battery to alt. I've thought about using male/female jumper wire connectors, but not sure about the robustness of these nor whether they'd handle the current. I could use JST and short the wires to make it, effectively, a one-contact connector. Is there some common solution to this? Looking for something relatively compact to fit smaller bays.

What you describe is a custom wiring harness. As mentioned above, you can get pre-crimped leads from various manufacturers, but if you need a crimp terminal on both ends than you are limited to the available lengths. Most pre-crimped leads come with female crimp terminals and are not enough to complete a wire-to-wire connection, but if you look carefully you can also find male ones.

A better approach in my opinion is to crimp the terminals yourself. Here is a short video explaining the crimping process:

Here, an affordable generic tool (Engineer PA-09) was used. Compared to the official tools, this is a bit slower and you need to pay a bit more attention, but it is very doable and you save hundreds of dollars.

For a wiring harness you need you need crimp terminals and housings, both male and female. Most of the time, when people talk about JST connectors they talk about JST-PH, JST-XH or JST-RCY. The PH and XH connectors are strictly wire-to-board connectors. If you want to use them in a wire-to-wire application, you need to solder a board header to a cable - which is a widely used, but a hack. The RCY on the other hand is a wire-to-wire connector family. Others are for example the JST-SM, Molex SL or Molex Microfit 3.0 etc., all of which I'd personally prefer over the JST-RCY (which are non-locking and not exactly immune to connecting them in reverse).

If you want to avoid crimping, you can use an IDC connector like the 3M Mini-Clamp 371 series. Those are nice connectors, but rather expensive with only two options (3 or 4positions).

Reinhard