I designed some battery locks to prevent the battery from unplugging. I wanted to eliminate the hassle of using and removing wire ties. We tested these locks at Lehigh and in Detroit and they worked very well. The team seemed to prefer them over the wire ties. There are 2 designs included, a design for connectors using the T-handle, and a design without… Only the T-handle version has been tested because that’s what we install on the robot. The design for the non T-handle connectors works but is not field tested. We leave our wires floating, but I may add some mounting holes to mount the clips.
Looks great! We may have to mess around with these this summer. In 2018 we used a small strip of velcro to retain the connector and worked great, but this season we never added it, resulting in a disconnected battery on the practice field. We just used zip ties for the rest of season, this definetly looks like a better option.
There are holes on the Anderson Connectors designed for specifically this purpose you can interface with - I would use those instead of clamping around the outside.
Our team had issues with the powerpole locks coming our during matches, so we switched to a zip tie around the whole thing, which then evolved into this part.
We used a small piece of 3mm aluminum, an M4 bolt nut and thumbscrew, and an M3 bolt and nut to do the same thing. We were worried because the robot side of the Anderson was attached securel to the robot, but the battery side wasn’t; that can make the Anderson connection vibrate and come loose. Our solution worked like this:
It worked well; we didn’t have a battery disconnect all season. We threw it together with parts we had around the shop and it was plenty strong. I don’t know that I would trust a standard (ABS/PLA) 3D printed part to do the job.
I’ve had SB50s come apart… when the contacts were inserted upside down
If the battery is close to the outside of the robot and the main cables can get snagged by another robot or the corner of the field, I can see how this might be wanted, but in FIRST I’d rather pull the connector open and take my L with a relatively safe failure mode than lock the connector closed and get much higher forces on the connector/wire insulation/battery terminals/etc…
They don’t pop out on their own that much, but sometimes the cables get snagged on things, or your battery pops out of your robot, or whatever craziness happens in a match. And you really, really don’t want that battery coming undone! Once it happens to you once you’ll be ziptying the Andersons for the rest of your days in paranoia.
I have seen where vibration from the robot driving around has caused an otherwise untouched SB50 to come undone. If one side is attached solidly to the robot and the other isn’t, the battery cables will move the battery side connector relative to the robot side connector. Enough wiggling, and you’re dead for the rest of the match. This effect is especially pronounced if you’re using two red connectors.
The pink connectors are tighter than the red ones. If you have two pink connectors mated together, it can be very hard to get them undone. If you have two red, it can be too easy. I always recommend teams use one red and one pink for a medium fit.
Agree, we have seen them vibrate loose as well. It’s incredibly rare mind you, we discovered over March break when practicing getting free of defense with another couple of teams, only the connector on one particular battery. Also, the field looked like a wood chipper had gone through and gnawed off about 20% of the field After that, we began zip-tying for competition matches so this little gem looks like it would be very useful!
In this case, coming apart is a blessing, as otherwise the housings would likely melt into each other.
And the solution here is to secure the battery and cables, not the connectors to each other. Secure the robot side connector to the robot chassis, robustly secure the battery to the robot chassis, and route the battery cable away from exposed locations.
I haven’t worked with the pink ones much - the team always seemed to lose them. Maybe that’s why!
What?
My understanding is the housing is the same mold and product specification, dyed pink instead of red so that donated connectors can’t get resold.
(It makes literally no sense for APP to roll a custom mold or spring specification for our application from a business perspective)
I assume you’ve tested them. You might be seeing batch variation? What you’re more likely seeing is “low force” and “high force” contacts?
From years of batteries, chargers, etc, we have 40+ of these connectors in our shop. Some of the older ones are definitely easier to unmate, a lot of time I find stamped contacts, but once I rebuild the housings into new assemblies they’re right back up to normal range (“very difficult”).
Related: Some of our 9th graders didn’t have the grip strength to undo our SB50s until we added t-handles to the comp batteries, and removing sharp edges on the robot directly above the battery connector is a high priority due to a busted knuckle incident… maybe I should invest in some low-force contacts
Their battery pops out during auto, but they still put up at least three game pieces before getting disabled.
We can fix a busted crimp or replace a broken breaker in the event of a catastrophic failure. But it’s hard to recover lost points due to a small mistake or hiccup.
Anecdote: This year our team experienced a complete power off due to the connector getting snagged on the field. However we powered back up and were playing again ~35 seconds later because we had a zip-tie around the Andersons.
I haven’t seen anything official saying this, just my own experience and a lot of anecdotal evidence. See a bunch of other people saying the same thing from an old(ish) thread here:
Whether this is due to a difference in the plastic itself, the mold used, or different tolerances for different batches, I don’t know. In theory it is possible that the different color connectors use different strength contacts, though that seems less likely.
At least for me the worry is a battery falling out at an inopportune time. Having a battery disconnect in a qualification match looks bad on scouting and likely results in a loss. Having a battery disconnect in elims is a loss that may cost the team a blue banner- not to mention robot damage depending on the state of the robot at the time of the disconnection. Even the best teams have had batteries fall out at inopportune times- only to be saved by a ziptied powerpole conector:
No, but if the robot side terminal is secured to the chassis, I’m certain that the battery is secure, and the cable is not particularly vulnerable to snagging, any scenario likely to disconnect the SB50 is way outside what I consider likely, and quite likely to break the battery’s internal connections if there is not a tension release somewhere. In my mind, safety is on the side of letting the connection go for this contingency as regards FRC. If the game were battlebots, I would probably think otherwise.
I’ve never had or even seen a problem with the SB50’s coming apart, excepting that sometimes they are difficult to get apart.
After that, we began zip-tying for competition matches so this little gem looks like it would be very useful!
