Battery required by rule

[Joe Ross]

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.

Not until all teams learn what robust bumper mounting means.

[AdamHeard]

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.

I use liPo and LiFe batteries all the time in my personal projects and toys and love them.

I hope FRC doesn't switch anytime soon; they simple aren't safe and robost enough for the average FRC team.

The "average" "big" battery is a 2s 5 AH and that's enough energy to cause serious fire and injury, a 3s 18 AH would be a bomb.

[the man]

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.

[EricH]

Originally Posted by the man

There is a type of lithium battery something with iron phosphate maybe. [...] 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.

The LiFePO4 type batteries are pretty expensive.

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.

Cost (for 2 12V cells)
SLA: $72
LiFePO4: $358 (plus $50 for charger)

Weight (for 2 12V cells)
SLA: 12.7kg
LiFePO4: 6.5kg

[Mike9966]

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.......

Here's to a great year!

Mike

[Jack Jones]

Originally Posted by EricVanWyk

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.

And doesn't catch fire!

[jvriezen]

Last year we bought 4 batteries from AndyMark for free shipping to CMP in St. Louis. A couple of mentors from our team were going to volunteer, so we picked them up and drove them back. Don't know if AM is offering the same deal this year. I think they were bringing an otherwise empty truck to CMP so that they could bring a field back with them.