SMC 28C 4000/5000 Hardcase Lipo part 2
#286
We should get the answer on ROAR approval by the end of this week.
I also got some info about ontrack testing that was done this past weekend. It seems like our 5000 pack was .15 to .20 seconds per lap slower than EnerG 4600s. This is only the first test and we will get more testing done this coming weekend.
Here are some random pack numbers on our 4000s.
sec - av - mAh - IR
421 7.33 4093 7.3
431 7.34 4190 7.1
419 7.33 4073 7.1
432 7.34 4200 7.0
421 7.34 4093 7.2
419 7.33 4073 7.5
I also got some info about ontrack testing that was done this past weekend. It seems like our 5000 pack was .15 to .20 seconds per lap slower than EnerG 4600s. This is only the first test and we will get more testing done this coming weekend.
Here are some random pack numbers on our 4000s.
sec - av - mAh - IR
421 7.33 4093 7.3
431 7.34 4190 7.1
419 7.33 4073 7.1
432 7.34 4200 7.0
421 7.34 4093 7.2
419 7.33 4073 7.5
#289
Lipo warm-up
After readin all of this topic, I had come up with my own lipo warmer.
i use a ceramic heater that has adjustable heat / fan. then i place a rack that holds batteries 8" away. I place them on the "warmer for about 10 min before a run and this gets them up to around 125-140* (case temp)
i have definatly seen a difference by getting them warm before a run, although i dont have solid lap times as i struggle with consistecy still (off-road) I have made believers while running my 13.5 BL in 2wd mod and hangin with them on the back striaght. And yes my car is ROAR legal weight for those who were wondering.
Although, i see a big improvement I still get the "dud" run every other charge cycle.
I do not discharge after a run as we hardly have enuff time.
Great thread and i hope we all can learn more on how to make these work safely.
i use a ceramic heater that has adjustable heat / fan. then i place a rack that holds batteries 8" away. I place them on the "warmer for about 10 min before a run and this gets them up to around 125-140* (case temp)
i have definatly seen a difference by getting them warm before a run, although i dont have solid lap times as i struggle with consistecy still (off-road) I have made believers while running my 13.5 BL in 2wd mod and hangin with them on the back striaght. And yes my car is ROAR legal weight for those who were wondering.
Although, i see a big improvement I still get the "dud" run every other charge cycle.
I do not discharge after a run as we hardly have enuff time.
Great thread and i hope we all can learn more on how to make these work safely.
#290
Tech Champion
iTrader: (261)
After readin all of this topic, I had come up with my own lipo warmer.
i use a ceramic heater that has adjustable heat / fan. then i place a rack that holds batteries 8" away. I place them on the "warmer for about 10 min before a run and this gets them up to around 125-140* (case temp)
i use a ceramic heater that has adjustable heat / fan. then i place a rack that holds batteries 8" away. I place them on the "warmer for about 10 min before a run and this gets them up to around 125-140* (case temp)
If I knew the temp delta at a given degrees C (or F) I'd give this problem to my Calculus students...kids eat these kinds of practical problems up. Then we could find out how long to get to the center of a Tootsie Pop (oops, wrong problem. Who's old enough to remember those ads?). We could find the length of time at what temperature to get a pack thoroughly heated X degrees above ambient.
Anything that is going to effectively warm the batteries EXTERNALLY (as opposed to Danny's method of heating INTERNALLY via aggressive cycling) is going to require a lengthy period of constant exposure to the moderate heat we'll be limited to (can't damage the case) if you want to see even a 140 degree temperature through the pack. Just guessing...an hour plus if we can use 200-ish degree (measured at the case) external heat source.
#291
A friend and I were discussing using high powered infared LEDs in a box system (facing inwards towards the pack) that would fit inside a lipo sack with a small fan to circulate the hot air. If possible, it would be much more power efficient than thermal pads or wires (safer as well from shorts).
It all theory at this time.
By cycling that hot air, it should help warm the pack faster than just letting it sit or being wrapped up inside a thermal element.
It all theory at this time.
By cycling that hot air, it should help warm the pack faster than just letting it sit or being wrapped up inside a thermal element.
#292
I don't think heating the cells is going to be worthwhile in the long run. Unless you're running mod or something that draws a ton of amps the cells aren't under enough stress to maintain the heat anyway. It defeats the purpose of LiPo anyway which is to have batteries that a racer can charge and race. No cycling, no balancing, no heaters, etc.
#293
Tech Fanatic
We just received confirmation that our hard case 5000 and 4000 packs have been legalized by ROAR. It should be on the ROAR site very soon.
#294
Tech Lord
iTrader: (32)
Congratulations guys, that's a strong testament to the quality of your packs.
Davidka: The things you said about LiPo will likely remain true for the average person. For the "serious" racers in classes that value voltage, you're going to see guys do anything they can to get more power for free. Heating packs is really pretty simple, though it does remove some of the simplicity of LiPo. Multiple manufacturers have stated that it won't affect the cells, and it really does bring cold LiPo to life. They can feel very flat for the first run or two otherwise.
Davidka: The things you said about LiPo will likely remain true for the average person. For the "serious" racers in classes that value voltage, you're going to see guys do anything they can to get more power for free. Heating packs is really pretty simple, though it does remove some of the simplicity of LiPo. Multiple manufacturers have stated that it won't affect the cells, and it really does bring cold LiPo to life. They can feel very flat for the first run or two otherwise.
#296
Tech Adept
Are the Dementions the same as posted in the first post in this thread?
#299
I just finished reading the ROAR lipo rules and it says the pack shall be 2 cells in series. I originally thought this must mean the pack had to be 2S1P but if the SMC 5000 pack 2S2P is legal I guess it doesn't?? Does this then mean there are no limits on the number of cells as long as they are configured with 2 cells in series and the whole thing fits within the case dimeansions?