Battery required by rule

[Bill_B]

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:
1. what if any are the differences between these two batteries?
2. Is one or the other preferable for competition use?
3. Do you have a preferred source of supply for either one?
4. What speculation will you offer about why only these specific batteries are allowed for FRC competition use?

[Cal578]

To answer question 3, AndyMark is an obvious source.
http://www.andymark.com/product-p/am-0844.htm
I haven't shopped around to see if there's a better deal, but $89 for two doesn't seem too bad.

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.

[Jim Wilks]

Originally Posted by Cal578

To answer question 3, AndyMark is an obvious source.
http://www.andymark.com/product-p/am-0844.htm
I haven't shopped around to see if there's a better deal, but $89 for two doesn't seem too bad.

But watch the shipping cost -- sometimes more than the batteries.

[Cal578]

Originally Posted by jgw

But watch the shipping cost -- sometimes more than the batteries.

Good point. Regular shipping is $19.10 (for me, in New York, I just checked). But overnight is $167 - ouch!

They are heavy (13.8 pounds each), so be sure to check shipping before you buy from anyone online.

[Mk.32]

Both types of batteries are exactly the same in terms of specs and output. And I have seen teams use both interchangeably during competition.
Just remember to take care of your batteries!

[cgmv123]

I like the look of the Enersys batteries better than the MK ones, but that's purely a personal aesthetically-based decision.

[Cory]

Originally Posted by Mk.32

Both types of batteries are exactly the same in terms of specs and output. And I have seen teams use both interchangeably during competition.
Just remember to take care of your batteries!

Multiple teams have found the Enersys battery to be inferior to the MK battery in terms of performance.

[Ether]

Originally Posted by Mk.32

Both types of batteries are exactly the same in terms of specs and output.

The specs are similar in many ways, but they are not identical.

The spec'd max discharge current of the MK ES17-12 is far higher than that spec'd for the Yuasa NP18-12. Whether or not that corresponds to reality is a separate question.

[seg9585]

I wonder when FRC will decide to switch to 3-cell LiPo batteries instead?
They are much lighter, smaller, and have a more favorable voltage curve compared to lead-acid.

[Mk.32]

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.

LiPo would be nice....

[rsisk]

I prefer the MK battery since they are manufactured in nearby Anaheim and I can pick them up at will call for $40 each, no shipping.

Call MK and see if they have a distributor that is local to you and save the shipping.

[Cory]

Originally Posted by rsisk

I prefer the MK battery since they are manufactured in nearby Anaheim and I can pick them up at will call for $40 each, no shipping.

Call MK and see if they have a distributor that is local to you and save the shipping.

MK ships everywhere in CA via UPS ground for free as well. I don't know if that extends to neighboring states also.

[sanddrag]

The MK may perform better when they're good, but I've had many MK batteries fail. Probably due to abuse, but still, I have many dead MKs.

The old old dark gray Exides are still going strong.

[Bill_B]

Originally Posted by sanddrag

The MK may perform better when they're good, but I've had many MK batteries fail. Probably due to abuse, but still, I have many dead MKs.

The old old dark gray Exides are still going strong.

Good to know about the differences, thanks. The exides may be going strong, but doesn't the rule preclude their use this year?

[EricVanWyk]

Originally Posted by seg9585

I wonder when FRC will decide to switch to 3-cell LiPo batteries instead?
They are much lighter, smaller, and have a more favorable voltage curve compared to lead-acid.

As soon as someone suggests a specific part number for a LiPo or LiFePO4 pack that meets the energy/power requirements AND is cost-comparable and readily available.