What battery charger have teams found the best to use ?
We use a pair of these:
They work pretty well… and 2 will charge 6 batteries at the same time.
This is the charger we use at CTRE.
Its a bit pricey but it charges eight batteries at a time.
So far, no complaints - works well.
http://www.boatandrvaccessories.com/schumacher-inc-812a-2-12-amp-charging-station.html
For single-battery chargers I’ve used regular $80 automotive chargers from the closest hardware store, with a wide range of success (some terrible and some great).
We use one of these http://www.amazon.com/HiTec-44169-4-Port-Multi-Chemistry-Charger/dp/B0075DB89C/ref=sr_1_2?ie=UTF8&qid=1417892162&sr=8-2&keywords=hitec+charger as our primary charger/maintainer with a couple of the KOP ones as backups.
It has four really nice displays (one for each battery) that tells you the current voltage and charging amperage. It also has some “PC link” features that allow you to access charging data on a computer but we have not taken advantage of that feature as of now.
That particular model requires you purchase an external PSU but there is a more expensive one that comes with one built in. We chose to get our own cheap power supply but I would recommend against it because its became a pretty big hassle (we needed to add fans to cool the PSU, etc…).
We got this one locally for a little less than amazon had it. Price worked out to be a little more than two of the ones linked above at Andymark, but it charges and maintains 10 batteries. We’ve had it for a few years and have noticed very little change in battery health (max voltage, sustainable amps delivered under load, etc) since. We are still able to use batteries several years old for heavy practice bouts or for a competition if necessary. At competition, by the time you use battery five or six, battery one is charged and maintaining.
This would be illegal as it is capable of charging in excess of 6amps.
We use Auto Meters BUSPRO-660. It charges 6 batteries independently of each other at the same time and has indication lights for charge levels as well as if the charger detects problems with any of the batteries. The charger will adjust voltage/current once batteries are charged and will maintain a full charge on all of the batteries.
Here is a link to the product page. http://www.autometer.com/6-station-automated-battery-charger-5-amps-per-station-115v-agm.html
We also created a battery cart designed specifically for this charger with the charger mounted vertically. The cart hold 10 batteries (6 charging and 4 storage) and has wheels for easy transportation to events
Any pictures of the cart?
+1 to bobs reply. We like ours. And I can get cart pics for you
I don’t have any pictures on this computer but I do have a solidworks rendering on a flyer. We also posted the cad files on our Google drive as well as grabcad so if you are interested in looking at our cart you can. We also included assembly instructions. Ill try to get a picture next time I am at the shop.
Battery Cart Flyer.pdf (115 KB)
Battery Cart Flyer.pdf (115 KB)
Big discussion on that last year. I think we came to the conclusion (after someone asked HQ) that it’s legal to HAVE the charger, but not to USE the >6A charging option. And if the inspectors see it, you can expect random spot inspections of your charging.
Cool, thanks. You’ll have to stop by our pit area at Long Beach. 
Not last year, but 2 years ago, I was part of that big discussion and asked the GDC. We have some stanley 15A chargers which we use to top off/float charge our batteries during competiton. We were getting horribly inconsistent performance from what we had which is what we still use to do the bulk charging but using these allowed us to solve the problems we were having. It’s legal as long as at no point more than the manufacturer’s recommendation(6A) is being charged to the battery.
Of course, there’s one big problem with this statement…
I have the 2016 Game Manual on my desktop, but no password (yet–give it less than 36 hours and we’ll take care of that). 
We’ll find out whether this is still the case for this year when we can open the rules.
FRC 4607 does have a couple of Dual Pro SR3 chargers from AndyMark. They are great and we have had no problems with them charging our batteries…
BUT,
if I could go back and redo our purchase, I would go for the Battery Tender as it offers more charging stations and is more compact than our two Dual Pro SR3’s. When space is a commodity in a PIT, every inch counts.
Just my two cents.
the safety manual is already out and accessible and they have a specific section for charging batteries which has been the same as previous years from what I can tell so the ruling in that regard should be the same.
Have you found that having 6 chargers available is enough? We have been running 6 of the KOP chargers for a few years with 3 batteries in backup and there have been times when the oldest battery on the charger was not fully charged when needed.
We have 4-5 batteries charging and 4-5 in storage at all times. If we pre charge all the batteries a night before we have no problem getting through all of our matches putting batteries on at 100%. It helps that our robots are generally simpler requiring less power in general.
the battery tender is a max 2amp charger. Is that enough to ket them fuly charged at a competition? We have been running 6 of the KOP chargers at 6 amps and that is not always enough.
Is the issue the charger drawing 6A from the outlet or charging the battery with more than 6A?
Either way: why not simply insert a fuse at the limited current such that no one can accuse you of exceeding it because the fuse would open?