Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

That just looks like a bit of toxic smoke... compared to the fiery conflagrations of LiPO I think LiFePO4 is still way safer.
Especially in the SLA "packaging" like in the OP's link, I would find it hard pressed to kill one.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

You do realize SLA will also potentially energetically vent when punctured?

Few battery chemistries will let you store significant energy and be happy when you dead short them internally (and SLA isn't one of them).

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

The types of battery OP linked has internal protections and a fuse (in this case a 25amp internal one) that keeps it pretty safe.

Like i said LiFepo4 is safer then LiPo but I still wouldn't trust high school kids with ones without a built in BMS/etc. And I don't now of any pre-made packs 12v 10-15ah that can handle the 200amp burst current FRC demands for a reasonable price.

The A123 packs I've put together/the ones you generally find in battlebots (like tombstone) are just raw cells wired together connected to whatever. Would not trust students with these.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

Wow, this thread got a lot more attention than I thought it would. Thank you all for your replies.

The biggest reason I see here that it wouldn't work is the 20A max output.

I do know that lithium batteries of all types are more hazardous due to their ability to rupture and spill out toxic fumes. However, lipo4 (supposedly) is a much safer chemistry. Combine that with good physical and circuit protections, I think these batteries would be usable for teams that know what they are.

The main reasons I wanted to use this battery was for better consistency with charges, lifetime, consistent output over the duration of the output, and it'd be a nice piece. I see now though that there is atleast one major drawback that prevents them from being used in FRC bots.

Someday I hope there are better batteries FRC can recommend, because we go through a lot of lead acid batteries every year, and it seems to be quite hit or miss if they'l keep their charge over time. One of our big things in competition is making sure the battery we put on our robot has the highest charge, because many shooting/throwing mechanisms will change depending upon the charge of a battery.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

I really appreciate the time and effort you put into that reply, it gives some very good insight into and otherwise mysterious world of batteries.

Are there any batteries you would recommend for offseason use where the Amp-hour rule doesn't apply? Just a higher Ah battery of the same type or is there anything better?

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

10 batteries isn't outlandish. We usually lose 4 or 5 a year, and I can remember a couple years ago when we did a lot worse. Some of the team were hot-cycling batteries to complete discharge at a week long fair demonstration without realizing what would happen. We lost around 10 that year.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

That would seem to imply misuse then (under the way we typically call it at work). In your opinion, would you say the brownout protection on the roborio is helping to prevent battery death? I know we're replacing once it starts to trigger.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

If one reads the data sheet linked above, the max shutdown current is 36 amps. Most motors draw more than that all on their own. Please remember that the current AGM battery is regularly sourcing more than 500 amps in our service.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

While true for that specific pack, there are many LiFePO4 cells that can safety source such currents when assembled into the AH size we would run.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

Exactly. I've worked with LiFePO4 cells all the time when I worked in the plug-in hybrid automotive industry. These cells are intrinsically safer than other lithium chemistries.

I built multiple 40AH packs using CALB, Thundersky and some large cylindrical cells for demo robots. They work fine provided you have a BMS to monitor the cells and protect them from over charging and discharging.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

Eh, just use a high- C rated RC car battery. 10AH would be fine. Make sure to use the hardshell.

My RC car pulls 200 or 300 amps on acceleration and they do fine. MaxAmps makes great ones but they are expensive. Charge them at 20amps if you want, they will do fine.

Make sure they have the hard case. Put a Lipo low voltage sensor on it, they are typically $5.

Never had a lipo explode or puff up. Just be cautious because they have the ability to.

Have fun

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

Teams regularly exceed 500 amps on the current battery.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

Not that this has anything to do with FRC bots, but I wonder what is the current draw on a Tesla car in "Ludicrous Speed" speed mode.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

According to Wired, 1,500 Amps.

Re: Use of Lithium Iron Phosphate (LiFePO4) batteries in place of Lead Acid for FRC r
 

So we can talk apples to apples, the Tesla battery is also 375 volts.