30C Continuous(ish) Lipo Discharge

[Arct1k]

http://www.bigsquidrc.com/dischargin...c-lipo-at-30c/

[magman]

interesting...especially the last paragraph.

if the testing equipment he is using is right...then sweet. proves a point....


as for the last paragraph...hes saying bashers pull 3c?
thats like saying " you bought a 500hp car, but its about the about 200 your typically gonna use" and dropping a 250hp motor in it instead

[magman]

Originally Posted by Andrew32

if the testing equipment he is using is right...then sweet. proves a point....


as for the last paragraph...hes saying bashers pull 3c?

I think that he means that us bashers are harder on our batts. than racers. That's what I took out of it any way.

[scarletboa]

i bet it was maxamps or smc.

that battery did not like 30c at all.

[sikeston34m]

I think he's referring to the average amp draw that we pull. Bashers and Racers alike.

If you've ever really looked at an Eagletree graph, they turn out to be alot of spikes.

Average amp draw is surprizingly low. Although, Amp Spikes for 1/8 scale can easily hit 150 amps.

These spikes only last for maybe 1/4th of a second.

Originally Posted by sikeston34m

I think he's referring to the average amp draw that we pull. Bashers and Racers alike.

If you've ever really looked at an Eagletree graph, they turn out to be alot of spikes.

Average amp draw is surprizingly low. Although, Amp Spikes for 1/8 scale can easily hit 150 amps.

These spikes only last for maybe 1/4th of a second.

ahh that makes sense. i really need to get myself a eagle tree...it sounds fun

as for the brand, i think it may be maxamps, my packs had the same yellow tape holding it together...but again i dont know if any other brands use that tape

[BrianG]

Yeah, average amp draw is around 6 -7 times lower than the spikes, and "running" amperage is ~2X lower than the average. Of course, this depends on how it is used, gearing, etc, but pretty typical.

[sikeston34m]

Originally Posted by BrianG

Yeah, average amp draw is around 6 -7 times lower than the spikes, and "running" amperage is ~2X lower than the average. Of course, this depends on how it is used, gearing, etc, but pretty typical.

Hi Brian. I'm glad you stopped into this thread.

Remember the home brew battery discharger? That would have been turning alot of lipos into goo. LOL (Testing of this nature isn't something you would want to do in your home.)

Although, if what I suspect is correct, it wouldn't be fair to judge all Lipos by the one in the video.

I also suspect that a 30C continuous discharge (even to 3.0 volts per cell) would substantially shorten the life of just about ANY Lipo pack on the market.

[BrianG]

Oh I know. That's why I had said any donated packs may not survive the testing. It would just be nice to define a set of criteria (like v under load, duration, temp, duty cycle, etc) and then see what kind of C rates the pack can really deliver under those criteria.

I think we can all agree that constant discharging at anything approaching 30C is not representative of 99% of car users. At best, we can usually assume that higher C rate batteries will maintain a higher voltage under a given load, which is better for cell longevity.

[hoober]

Looking at the numbers they tested a good 5-8C pack , it never really made 30C. The pack should've been done at around 10C or so. It is customary to progressively go higher until one reaches the point of "max C" so that the other tests aren't lost.

[JThiessen]

Originally Posted by BrianG

Oh I know. That's why I had said any donated packs may not survive the testing. It would just be nice to define a set of criteria (like v under load, duration, temp, duty cycle, etc) and then see what kind of C rates the pack can really deliver under those criteria.

I think we can all agree that constant discharging at anything approaching 30C is not representative of 99% of car users. At best, we can usually assume that higher C rate batteries will maintain a higher voltage under a given load, which is better for cell longevity.

Brian, do you think there might be a way to develop a theoretical amp draw calculation, and thereby use that data to select battery requirements? I know there are a lot of variables, but we already input most of them into the calculator already...

[JThiessen]

Originally Posted by Andrew32

if the testing equipment he is using is right...then sweet. proves a point....


as for the last paragraph...hes saying bashers pull 3c?
thats like saying " you bought a 500hp car, but its about the about 200 your typically gonna use" and dropping a 250hp motor in it instead

Yes....your 500hp motor that you operate at 40% of its capacity is going to last much longer, and should be more efficient than a 250hp motor operated at 90-100% of capacity.

[zeropointbug]

IMO, this video means nothing without stating the brand name, lol, simply calling it a 'name brand' pack doesn't tell us anything.

[zeropointbug]

Originally Posted by JThiessen

Yes....your 500hp motor that you operate at 40% of its capacity is going to last much longer, and should be more efficient than a 250hp motor operated at 90-100% of capacity.

As for efficiency, can't really say that, depends on displacement, forced induction or not, whether it's a high speed/low torque, or low speed/high torque, anywhere in between, etc.