A local battery supplier does not offer the right batteries for us.
The only legal source of electrical energy for the Robot during the competition is one MK ES17-12 12VDC non-spillable lead acid battery, or one EnerSys NP 18-12 battery, as provided in the 2012 KOP. This is the only battery allowed on the Robot.
It leads me to wonder several things:
what if any are the differences between these two batteries?
Is one or the other preferable for competition use?
Do you have a preferred source of supply for either one?
What speculation will you offer about why only these specific batteries are allowed for FRC competition use?
My opinion on question 4: The GDC wants to allow enough energy that we can do interesting and educational things with our robot, but not so much that it becomes unsafe. Allowing only one battery (or one of two nearly identical batteries) makes it much easier to accomplish that goal.
Well I take that back then…
In running though our batteries about half and half of each we have not been able to notice a difference so far.
But thanks for the info, sorry for the mis informed response.
There is a type of lithium battery something with iron phosphate maybe. Anyways you can drive a nail through it and it will not produce any fire or smoke. The lithium batteries have a more favorable voltage cure, they are lighter, plus they last considerably longer cycle wise, enough to make up for the cost. I am in favor of them except that special chargers and battery management systems are required to use them. I think it would be nice to have them as an option but leave the current lead ones for anyone who wants to use them. Rookie team might have a problem with lithium.
Here’s a cost comparison from my senior design project, LiFePO4 compared to sealed lead-acid (SLA). Note that in this particular application, weight is a HUGE disadvantage, to the tune of -10 points per kilogram (and any GDC members reading this: don’t get any ideas, please!). I want to say that it’s a total of 24V available, but for competition we’re running 12V.
The main problem with Li batteries is like you say, cost. The other is that only some are safe considering the beating our bots take. I think the good one is a LiFeP. Probably more expensive too.
Mostly I’d just as soon stick with what we have because of the investment we have in both batteries and chargers. I could see stocking up on batteries and chargers the first year being a kilobuck expense.
Also, even though we are only 4 years old, we’ve yet to build a bot that even comes close to running out of juice in one match…