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#1
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Re: Battery required by rule
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. |
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#2
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Re: Battery required by rule
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.... |
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#3
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Re: Battery required by rule
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. |
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#4
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Re: Battery required by rule
MK ships everywhere in CA via UPS ground for free as well. I don't know if that extends to neighboring states also.
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#5
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Re: Battery required by rule
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. |
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#6
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Re: Battery required by rule
Good to know about the differences, thanks. The exides may be going strong, but doesn't the rule preclude their use this year?
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#7
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Re: Battery required by rule
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.
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#8
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Re: Battery required by rule
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 |
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#9
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Re: Battery required by rule
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.
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#10
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Re: Battery required by rule
And doesn't catch fire!
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#11
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Re: Battery required by rule
Not until all teams learn what robust bumper mounting means.
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#12
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Re: Battery required by rule
Quote:
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. |
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#13
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Re: Battery required by rule
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.
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#14
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Re: Battery required by rule
Quote:
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 |
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