Very simple question, we ordered a bunch of stuff and the Rev Robotics parts got here first, when they got here I realized I forgot to get stuff to connect the batteries to anything (I thought they would come with it but I should have looked into it more, but it isn’t a big deal because we haven’t gotten anything else anyways)
Soooo basically my only question is what connectors do we use to connect to the batteries on the batteries themselves?
You will then need lockwashers (NORDLOCK if at all possible), bolts, and electrical tape to insulate the connection.
WPILIB has a battery guide posted here:
Easy-mode for this is to buy the pre-made ones from Andymark that Eric mentioned and then get some grasshopper nuts from Thriftybot.
There is a rabbit hole you can fall down with battery optimizing but you don’t need to worry about it as rookies.
Nordlock washers are the only type of lock washers that are effective. Nylon lock nuts are sufficient in most cases, but I’d strongly recommend nordlocks for batteries. I’d also recommend throwing away the fasteners that come with the batteries and replacing them with high quality nuts and bolts (grade 8 for imperial or class 10.9 for metric)
Just out of curiosity, do you have an opinion on the PVC vs EPDM insulation material that they offer? We have used both and never seen a difference, the EPDM is nice because of how flexible it is, but would there be any drawback of significance using one over the other?
EPDM is a better choice. Tougher, higher service temperature. Much more cut resistant than silicone.
OMG, grasshopper nuts with Nord locks are the Bomb!! Go get yours!!!
Don’t be afraid to take your lugs and put a 90 degree bend in them to make the wires dress better. The pre-bent lugs are excessively expensive and hard to get. No real difference, no issues at all on any of our batteries built up this way.
I forgot about this. Looks like the 900 website is under maintenance, but here’s a re-up of the document.
I don’t like telling people to bend their own lugs because I’m nervous about too tight a radius resulting in tearing the copper instead of bending it - particularly using a bare steel vise, which is what most teams would have access to.
I use a radius from a piece of wood to support the copper, so that the wood mushes before the copper tears. I still get a tighter radius than I really like but haven’t invested in hard tooling yet.
Second that! Nicer on batteries and much easier to route as the main power feed in the robot. It’s commonly sold as “welding cable”.
For those making their own from scratch, we’ve often sourced it from Temco Industrial - 6AWG red and black in 50’ lengths are just over $1/ft each and free shipping. They have shorter lengths at incrementally higher prices, and also larger gauges if you go that direction.
Of course you must have a proper (true AWG sized) crimper to make your own cables. If you don’t, and don’t have a team near you that has one and can give you a hand, you’re much better off with the commercially made ones. These are the most important connections on your robot.
We just bought some 90-degree lugs from Ferrules Direct for $1.10/ea (4AWG) to try the right-angle dressing approach. They appear to be nice and sturdy but we haven’t actually assembled a battery with them yet.
I always shied away from DIY lug-bending for fear of inducing metal fatigue, so we never actually tried it. @Weldingrod1 you’ve never had one crack, either initially or after a season of hard use?
Not rod, but I remember I cracked at least one during manufacturing… haven’t seen any come off damaged at the end of a season. (Total of 50+, so only losing one isn’t bad, but definitely wouldn’t tell a novice on Chief to go do it.)
The FerrulesDirect 90° lug at around $1 is a godsend, I don’t want to spend my time bending lugs. It was worth it when I could only find $5 Panduit stuff.
Slightly off topic, but could you explain how you strain relief your batteries with those metal tie in clips that hold the wires to the battery? And where did you get that part?
Thanks!
Most common clip I’ve see is these Panduit clips that Zondag shared a few years ago.
Thank you!
My team has been buying these kits from AndyMark and it’s been completely fine for us.
It’s also makes it easy for us since everything is in 1 packaging and AndyMark is a approved vendor for our district.
All of y’all are mentioned nordlock washers, maybe we could reach out to AndyMark to update these kits with those washers.
EDIT: Also, ThriftyBot had a missed opportunity for their SKU for the Grasshopper nuts. The SKUs are TTB-0071 when it would be cool if they were TTB-0095.
I highly recommend the Thriftybot kit (also just getting all of the mainstream FRC vendors onto the district approved list). If McMaster is on your approved list, the MMC pn is 91812A427.
Lugs should come to you pretty close to fully annealed to accomodate the crimp. If they crack, I’ve gotta wonder what the crimp would look like!
Anyway, clearly your mileage WILL vary 
Fyi, ThriftyBot’s grasshopper nuts come with Nordlocks 
Yep, used them last year, very solid results. We plan to use them with the 90 degree terminals this time around.
@CyberClone that’s the correct part number
I set up an alert and got a couple hundred on eBay a few years ago for 1/10th of list price. We reuse them when we cycle out old batteries.