Check your Anderson battery connectors
 

The students are still recovering from the regional, so just in case anyone else is experiencing power lost on defenses or robot to robot impact, I know there are posts out there already to check your radio and roborio, but just to share our findings and avoid someone else figuring this out the hard way.

sadly, it took the entire regional to get to the root cause, which really frustrated the team...

Anyway, if you are experiencing power lost and reboot on impact, after checking the radio power and roborio, give your Anderson battery connect some twisting and pulling. we were able to reliably cause a reset when we did this. we are still trying to figure out exactly what is wrong with the connector (weak spring? wear and tear? too much cable movement?) but what we did find is that just within the 10 or so connectors we had with us at the regional, there were at least 3 lug designs and possibly 2 housing designs (not sure if it was a tolerance thing or a design change). we'll be contacting Anderson to get more information, but one thing that comes to mind is weather they are backwards compatible. These connectors all came the way assembled and were never taken apart till the issue was found. I'm also not sure whether andymark assembles these or if they came assembled with cable from Anderson, so will try to up date this as we figure out more details.

Re: Check your Anderson battery connectors
 

There are two terminal part numbers, a "low detent" and a "high detent" one. Last year, all the pink battery cable assemblies in the Kit of Parts came with high detent terminals. If two of those got connected together, disconnecting them was ridiculously difficult. But all terminals are compatible, and unless one is bent or otherwise damaged they should not cause problems.

The spring strip inside the connector housing is potentially an issue. If the terminal is not snapped securely in place against the spring, there can be a poor electrical connection that is susceptible to vibration or impact.


I have observed numerous cases where a team wanted to blame the Anderson connector for intermittent power but eventually discovered that the true culprit was a loose bolt on the battery terminal.

Re: Check your Anderson battery connectors
 

Thanks for the information Alan, I'll say that it was the last thing we considered checking. We even started pounding on the robot with a rubber mallet and dropping the robot from 6 inches off the ground to replicate the problem. loose battery connection was actually common with my all girls team (they don't tend to have the hand/arm strength to get it really tight. so it was the first thing we checked. but we were literally able to poke with a finger on the red wire right outside the Anderson housing on the robot side and see the robot reset. We also confirmed that the connector was fully snapped into the detent. like I said, the goal is to get the information out there, not necessarily placing blame as there could be many reasons that failed. but it was hard to troubleshoot so would like people to be aware that it is a potential thing to check.

Re: Check your Anderson battery connectors
 

we have had problems before as well when the battery cable bolts where not properly attached to the PDP (no washers or not tight enough) although this is a very easy fix it was tricky to spot without knowing where to look

Re: Check your Anderson battery connectors
 

I've been amusing myself going through some old batteries, load testing and checking resistance with a Battery Beak. Newer batteries had 0.018 ohm resistance. There were several marked "Practice Only" with 0.030 ohms resistance that dropped down to 0.018 ohm once I swapped out the battery cable and cleaned up the mating surfaces of the terminals with a wire brush.

Re: Check your Anderson battery connectors
 

548 had battery Anderson issues in one of our elims matches at Southfield. In our case, one of the battery-side pins partially slid out of the housing. This is the first time we have experienced this issue as far as I know. If you have sharp turns in your leads right next to the connector (you shouldn't) make sure the wires do not pull out of the housing.

Re: Check your Anderson battery connectors
 

This is some great advice. I was the FTAA at the NYC regional last weekend and whenever a robot would lose communication with the field, the FTAs and I would wiggle-test as much of the power pathway as we could trying to find something loose. I can recall a few situations where robots had either loose Anderson connectors or loose connections between the battery and the wires. We were able to reliably cause reboots by wiggling the cables around, which is what happened during the match when the robot hit a defense.

Re: Check your Anderson battery connectors
 

We've had similar problems at each of the bolt connections (main breaker, battery, and PDP), but never at the Andersons. About two-thirds of our connections are factory, and the other third are hand made in house, but tested after crimp and install. A properly crimped and seated Anderson connection (whether the battery or power pole style) will actually make better connection when stressed almost up to the point that it separates.

We also had a power outage after the jumping the rock wall. Upon inspection, the pink Anderson connector we had installed on the robot did not have the terminal fully captivated by the spring clip and slipped back. We have no idea if it was due to original assembly or being stressed.

Re: Check your Anderson battery connectors
 

The way the anderson connectors work, it was almost certainly an incorrectly installed crimp in the connector housing. I have been using the SB50 connectors for years now in situations much more stressful than FRC and I have never seen or heard of a crimp coming out of the connector housing once properly installed. The one failure mode I have seen that was not entirely user error is the wires breaking where they go into the connector from fatigue. To combat this is pretty simple. Bolt the robot side of the connector to something in the robot that doesn't move like the frame. (there are already holes for 6-32 screws in the connector housing just for this)

Re: Check your Anderson battery connectors
 

Yup that was us, luckily Mark (The FTA spotted it during our first match on practice day) after that we had 2 rio reboots which ended up being a battery cable hitting the red button on the breaker.

Pre match wiggle your alliance partners cables around JUST DO IT. If they tell you they lost comms one match do it more. If they blame it on a field fault but, there was not a replay it was not a field fault it was them. On Sunday I started doing it, and it did make a difference. There was one particular alliance partner who wouldn't let me do it saying I wasn't qualified because our alliance was seeded low and ironically enough they lost comms that match TWICE.

Re: Check your Anderson battery connectors
 

More than 9/10 times it is a loose connection at the other end of the battery cable wire...either the terminal on the battery is loose, or the terminal on the power wiring at the 120a breaker or the PDP is loose. (and in the old days, it would be one on the complicated distribution terminal blocks).

A RI caught a slightly loose breaker connection on our robot in the pre-Elims reinspection...thanks!

Re: Check your Anderson battery connectors
 

What seemed to be the problem for us (which we found out before our third last match) is that the cause for our radio to reboot was the webcam. I was told by another team WPILib's webcam support was the problem, and oddly enough turning off our webcam seemed to fix everything. We played like madmen during the last 3 matches and not a single "no robot communication" came up. Just to throw that out there is the leads weren't the problem.

Re: Check your Anderson battery connectors
 

We saw two different issues. We have one Anderson sb50 which is "loose" with one connector but not others. Not sure why yet, i need to investigate at next chance. We also had an alliance mate whose breaker bolts were less than finger tight.

I think everyone is discovering how good their wiring is this year.

Re: Check your Anderson battery connectors
 

this^^^

I've watched about 130 matches from the side of the field this year. None of them were replayed due to communications-related field faults.

Nothing is certain, but so far in 2016 robot communication problems => problem is on robot.

Things I've seen that cause "communication issues":

* loose wires at breaker
* loose wires at battery terminals
* radio barrel connector came out
* radio wire at robot came loose
* tinned wire on radio connector at robot broke off
* forgot to reconnect Ethernet cable
* something bumped the red button on the circuit breaker
* loose fuses in PDP

Things I haven't seen:

* dodgy Anderson connector (others have seen this)
* loose wires at PDP

Re: Check your Anderson battery connectors
 

So I found this... from here
http://www.powerwerx.com/anderson-po...es-50-amp.html

We have been using both pink and red ones, any chance this is a problem? or are the pink ones specific to FRC and the below does not apply?

SB Powerpoles are Color Keyed
A unique feature of the SB Series Powerpole housings are that they are keyed to only mate with the same color housing. For example, a gray color will only connect with the same gray color SB housing. The Red color will only connect to a red colored connector, etc. The exception for SB50 is the black housing which also mates with the gray housing.

This feature can be used to color code different voltages or systems and prevent accidental connection.


Read more: http://www.powerwerx.com/anderson-po...#ixzz42zCwM2yr

The pink sb50's we have been using are really red sb50's. From what I hear Anderson had too much pink plastic and donated pink versions of their red power poles to First.

Re: Check your Anderson battery connectors
 

So you are telling me that it's really lightish-red?

Re: Check your Anderson battery connectors
 

Yup. The blue box under R36 says that the pink connectors from the KOP can mate with the red connectors.

Re: Check your Anderson battery connectors
 

Shaif,
How were you using the webcam in conjunction with WPILib?
We had one, and then two webcams, but we were just streaming them through the router, not doing anything with WPILib.
Thanks,
Martin Haeberli
(de-)mentor, FRC 3045 Gear Gremlins (formerly SWAT)

Re: Check your Anderson battery connectors
 

This should be noted too: check all of your connections! For motors and pneumatics especially.

We unbagged our competition robot and were wiring up some electrical components, when we barely spotted a wire through the gap between two CIMs that had completely come out of an Anderson connector. Even worse was that it was for one of our drive CIMs. We had played through an entire district off of three motors! Good PID is both a blessing and a curse I guess...

Similarly in 2014 we learned that pneumatic tubes should be checked for a complete fit into ther fittings/connectors. Our pneumatic catapult experienced some issues in the semifinal matches of our second district event, which caused us to lose both matches. We didn't figure out it was a pneumatic connection that was loose until it blew completely out of the fitting during our second semifinal match. If you take a sharpie and draw a line around the hose right by the connector to display where it should sit in the connector you can easily check for this issue by simply looking.

Re: Check your Anderson battery connectors
 

Great idea. Our hoses are all black which makes this a bit more difficult to spot but now we have a great reason to use a different color next time.

(If only they sold purple air hoses, to go with our team branding...)

Re: Check your Anderson battery connectors
 

Just use a silver or gold sharpie! That'll actually be easier to see than clear tubing (we have clear blue tubing) with a black sharpie.

Re: Check your Anderson battery connectors
 

Had a good one at L.A. last weekend. Team comes to the field for their match, tries turning it on in queue... NOTHING. Reset the breaker. Same result. Match almost ready to start. They plug in a battery from their partners, and the lights go on--at which point, the field staff proceeded to help them get the new battery secured and get the robot onto the field.

I never did hear what the root cause was...

Re: Check your Anderson battery connectors
 

We had an entirely different problem. Two matches in a row, our battery connector actually separated from the connector on the robot. Both times, it happened after going over the rock wall the second time.
The part that bugs me the most is that we had hours and hours of practice, and this never happened. Also, the connectors on those batteries and the one on the robot were properly constructed, and they are just as hard to pull (wiggle) apart as those on any of our other robots.

The first match, when we pulled the robot off the field, we wiggled the connector and the robot turned back on.
The second match, everyone on the drive team checked to make sure the connectors were properly seated. When we pulled the dead bot off the field, the battery connectors were at least 3/8" away from being fully seated.

Being dead for two of nine matches really sucks. Fixed by zip tying the connectors together.

Re: Check your Anderson battery connectors
 

Crooked cuts from wire cutters can exacerbate this problem, because they make it hard to fully seat the tube. Using a $7 tubing cutter from McMaster helps immensely.

Re: Check your Anderson battery connectors
 

This is a problem I first saw at TRR last August. It turns out that the issue was a broken connection at the battery terminal that was covered and being hidden by heat shrink. The #6 wires provided on the cables can work harden as they move back and forth and become brittle over time, leading to snapping the connection. Here's an example of a failing connection.

http://i.imgur.com/JRINTHW.jpg?1

I recommend inspecting these on a pretty regular basis.

Re: Check your Anderson battery connectors
 

I have been told for years that the SB50 connectors should be zip-tied together, but still don't quite agree.

If you find the connector pulling apart, SOMETHING is doing it. It won't happen spontaneously.

Your wires may be too short and/or your battery may be moving around within the robot. Both are problems that should be corrected by something other than adding a zip tie.

Someone always says "I've seen matches where the battery fell out and was dragged by the power cables across the field." If that happened, I'd rather have the connector come apart and disable the robot. You're going to get an E-stop anyway.

If zip-tying the connector makes a problem go away, you are really masking the problem. You have something wrong with the connection. The SB-50 connectors are very reliable and are designed for exactly this purpose.

That doesn't mean they can't fail, but failure is usually due to wear, mis-assembly, or abuse. You can't take them for granted. You need to check them and spot any potential problem. It all comes down to attention to detail.

The fact that they come pre-assembled doesn't mean that one can't be mis-assembled. The mating surfaces inside can be scratched and pitted by connecting things with clip leads, etc. (This is why the rules now state that battery chargers must be fitted with a matching SB-50 connector.)

Re: Check your Anderson battery connectors
 

I myself, along with the other drive team member when we put the robot on the field. Checked the connection, tugged on it, wiggled it. It was seated in there for good. We made sure it was not going to pop out like our previous match.

But then we go over a rock wall (not even at full speed if i remember correctly!) and boom, out for the whole match.

Back in the pits, we tug on it, wiggle it around, bend it, do everything possible. Drop the robot from 5 inches multiple times. Nothing! D:

Nothing like this has happened during any practice where we basically bashed the robot into defenses every which way.

Like you say, there maybe an underlying cause, but I guess we have to wait till our next regional to do further inspection. But even if we do fix the issue, definitely still going to use zip ties, can't risk it.

Re: Check your Anderson battery connectors
 

When you drop and bash your robot, you can only determine that you may have some loose connections. You will have a hard time determining which connections are bad by doing this. To find the bad connections, you really need to methodically check each and every connection point, starting from the terminals of the battery, to look for loose connections. Do not stop if you have found one loose connection. It is quite possible that you have two or more. You also have to treat the crimp of the contact in the connectors as a separate connection point to be checked apart from checking that the contacts are actually connecting. You seem to be focusing only on the battery connectors.

Re: Check your Anderson battery connectors
 

Because that's what our problem was 2 of our matches.

After each of those matches, when going to take the robot off the field, you could see that the battery connector was not seated in right. Even though before, like I had said. We made sure it was in there properly.

Rest of our matches we used zip ties so there was no chance of it getting unseated and we had no issues.

We just can't seem to figure out how that connector could have come loose going over rock wall those two matches.

Re: Check your Anderson battery connectors
 

How is your battery secured??

Re: Check your Anderson battery connectors
 

Here's a bad picture, but it's the best I could find.

There is velcro strapping holding the battery down into a "box" of sorts. In neither of the two matches where the connector separated did the velcro become undone. It's pretty hard to get the battery in and out, you could even say that it's a "press fit."
All of our battery leads are that long, so the battery would have to be launched up 6 inches to pull the connectors apart.


The best theory that I came up with is that it has something to do with the robot-side connector being bolted solidly to the frame (the "attacking side" that hits the defenses before anything else.)

Re: Check your Anderson battery connectors
 

Thank you, but... please use JPG for photos, not PNG.

Re: Check your Anderson battery connectors
 

Any reason why? I don't see anything wrong with using PNG

Re: Check your Anderson battery connectors
 

Here's the reason:

Re: Check your Anderson battery connectors
 

The only difference is file size, and the difference between them is ~600 KB, which is negligible.

I'm still failing to see what's wrong.

Re: Check your Anderson battery connectors
 

We've been getting tons of these free with our Automation Direct orders as well. Super useful.

Re: Check your Anderson battery connectors
 

The pictures really help people understand your situation.

The loops in your battery cables are long enough that the movement that is possible should not cause a good pair of connectors to come apart. How much force is needed to pull them apart? Try pulling at different angles. I don't see where your bumpers end up. Is it possible that another robot is hitting the battery wires? It seems that the constant in this is the connector on the robot side. Have you tried replacing it? Try putting painters tape so part of it is on the battery and part of it is on the bracket. Put other pieces so they are on one of the battery wires and the frame next to it. If anything is moving more than a few millimeters, the tape on it should tear and give you some clues.

Re: Check your Anderson battery connectors
 

We tried tugging on it pretty hard, and at all different angles. It is not at all easy to just pop that connector out.

The inside of the bumper comes right up against the outside face of the aluminum on the other side of the connector. Sorry if I'm not explaining it properly, we don't really have good pictures.

And both times the connector did dislodge, it happened during the second (this really baffles us) crossing of the rock wall. So no robot was hitting the connector at the time.

Re: Check your Anderson battery connectors
 

I'm not sure that this will alleviate the problems that some teams are experiencing regarding connections and Anderson connectors, however, for the past 10 years or so we require all new connectors to be back-filled from the wire side with hot glue. This helps with stability issues sometimes related to those who continue to lift the battery by the cables (WRONG) or separate the connectors by pulling on just the cables.

Re: Check your Anderson battery connectors
 

Have you tried installing the battery and putting the Velcro strap on then try lifting the robot by lifting the battery? Perhaps the battery is "jumping up" and stretching the Velcro strap then popping back into position during the violent manoeuvre.

At Bayou yesterday, we popped our PDP panel off and separated all the Anderson connectors to our motor controllers when we hit the Portcullis too hard. It was stuck on with two long strips of Duo Lock which holds more strongly than Velcro. We (and others) have broken things that have never broken before.

Re: Check your Anderson battery connectors
 

We've had a few issues with the contacts separating slightly woke the connector was mated. One of these was supposedly from the contacts having come off the retaining clips (not sure how, but I've seen this before on our battery charger ). On the other, if I rotated the wire, then the contact also rotated in the connector. We've instituted an inspection since they on order to catch these and I've had some spare cables made up on case we see more. I think we're starting to see aging issues with the wiring. These connectors are mated and unmated frequently and may be wearing out the housings and contacts.