Hello, our teams have recently had problems with faulty battery connections between the battery and the cortex. We found that jiggling or bumping the cortex/battery can interrupt the VEXnet connection. The only way we’ve found to correct this problem has been to attempt to correct the connection manually so that the connection is more secure. However, this is only a temporary solution as we’ve found that, over time, the connection will be misaligned again.
Is this the only solution to this kind of problem, or is there any mechanical hack that we can implement that would help?
We have the same exact problems. First we had team 677 show us a way to fix it, which is to use a precision screwdriver to bend it back to be secure. Now we just use a rubber band to pull down the battery a connection a little bit. We found out that you should never jiggle the battery as your pulling it out of the brain, just pull it straight out.
Right, that’s how we corrected it the first time (with a precision screwdriver), but we’d rather find a way to make it a bit more permanent if possible. If there isn’t a way then of course we will just bend it back again. I will have to test later if the battery works if pulled a certain direction, but I’m pretty sure that our connection is the same as yours, in that applying downwards force keeps it on.
Yes that is exactly like ours. We haven’t found a way to fix it sadly. But it works, whenever we work on it/drive it, the battery connection never goes lose.
Are you sure it’s the cortex side of the connection that is damaged? If it’s the battery then replacing the connector is fairly easy, parts are available here but also from places like digikey. If it is the battery and you change the connector out then be VERY careful and only remove one pin at a time from the old housing to avoid shorting the battery otherwise damage may happen to either the battery or you.
Replacing the connector on the cortex is possible but will be hard, I have not done it and would recommend that you ask if VEX can do this. Internally it’s covered with hot glue or some type of plastic resin, not sure what exactly, anyway it is technically possible but not for the inexperienced.
I should add that the 9v backup battery is also there so you don’t loose connection but only power to the motors (which I guess is just as annoying).
Yes, however, the rules do allow for repair. The battery should be covered by this rule as it is a VEX electrical component with external wires.
Now whether repairing the cortex is covered by this I don’t know, however, having a $250 bricked cortex is not very useful so what is a team supposed to do. If I have a damaged cortex and VEX will not offer to repair it, then if I have the ability to repair it whilst retaining it’s original functionality that’s what I will do.
Thanks for the replies. Yes we’re pretty sure it’s the cortex-side as we have 10+ batteries that we share between our 3 teams and we’ve had this problem come up twice now. We’ve tested it on two batteries during both occurrences (probably could have done more), but I’m fairly sure it’s the cortex. Anyways, as it seems that there isn’t much to do more than we have already done, we will just have to continue with manually correcting the connection. Will have a look into the replacements though, thanks again!
The team had this come up at Worlds last year, and Vex tech support looked at it. They assured us that it was the cortex, not the batteries, and that they had seen the problem before. Their suggestion was to purchase a battery expander, get a snug fit, and never remove it.
We ended up not taking their advice a) because this year’s budget didn’t allow for it and b) because it would force us to use 2 batteries at every competition, because the rules require that both battery docks be used if an expander is used.
After a couple months of carefully plugging and unplugging batteries straight in/out, the problem seems to have worked itself out – we haven’t had any problems for about 3 months now, and the problem never showed during a competition.
We have had the same problem and it usually occurs at the most inopportune time. These power connectors are manufactured by Molex and aren’t really designed for high cycle usage. I doubt VEX is going to depart from this design so you need to look at all the options. Using the precision screwdriver to modify the pins/receptacle can help but it’s not a great long term solution.
The problem may not be totally attributed to the connector on the Cortex side. The connector on the battery side can be equally at fault. As stated by jpearman the battery connector can be replaced. Radio Shack offers this type of connector which might be an easy repair if you don’t mind cutting the wires and soldering it in. Here is the link: http://www.radioshack.com/product/index.jsp?productId=2062132.
A possible solution to prevent this situation is to make a connector cable that goes between the Cortex and the battery connectors. This intermediate connector (selected for high cycle usage) would take all the connection cycles during practicing and keep your Cortex and battery connectors from wearing out. This solution would not be an approved part so it would have to be disconnected on competition day. I have to admit we haven’t implemented this but have been tempted to do so every time this issue crops up.
I agree, they should have a power expander style connection. I’ve never had a problem with the power expander connector, and it would be easier to repair if it was to happen. As of now, I have to pretty much pull off the cortex to fix it…
If you get an RMA number and return your Cortex I can probably replace the power connector in your unit.
For further information please contact the VEX Technical Support Department: http://www.vexrobotics.com/contact/contact
That would be great! Would it be possible to get an estimate on how long it would take to have the Cortex returned from the time we send it to the time we get it back? This would help us plan when to send it in, thanks again.
Yes, you can return it at the end of the season.
However, before returning the unit you will have to call VEX for some basic over-the-phone troubleshooting.
Just to make sure there is actually something wrong with your power connector.
Thanks.