We have the 2011 charger, and when charging the batteries what setting to use, specificity the 2watt/4watt/6watt?
And how long does it take to full charge a battery?
Thanks for the help 
I’m not exactly sure on the charge times, or how long a charge will last. However, a general tip: Charge at 2Amps, when charging overnight or for long periods of time (this also generally optimizes battery life per use). 6Amps charges the battery to “Full” the quickest though.
We usually leave ours set at 6 amp, as the Schumacher chargers automatically “step down” to 2 amp to maintain the batteries instead of overcharge. It’s in the manual somewhere.
The rules say to use no more than 6 amps.
The batteries last longer if you charge them at a lower rate.
The Shumacher charger reduces current as the battery voltage approaches full, actually shuts off the current completely once the battery is fully charged, checks continually to make sure it’s still fully charged, and turns back on to top off the battery if it ever finds the voltage has dropped.
Our healthy, normally discharged batteries take about 5 hours to charge using a CTEK 3300 charger at a constant current of 3.3A.
There is no real difference in battery life up to the 6 amp setting. Charging batteries when cold (<32F) or warm (>90F) will confuse the charger in some cases. Please be aware that batteries coming from a robot (practice or match) should be allowed to cool for 15 minutes before charging.
Please be aware that the charger does change settings. Have your electrical students include checking the charge settings every time they connect a battery for charge.
I highly recommend (read that please “perform this mod”) that you purchase an additional 50 Anderson power plug and contacts to add it to the charger. The supplied alligator clips are meant for charging batteries with widely spaced terminals, not for our batteries. The Anderson connector can be purchased from AndyMark or from Powerwerx or any Anderson outlet.