I would love to see that spreadsheet. Care to share it?
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Wonāt let me upload spreadsheets (ods files) here; says photos only
Theyāre calling the Sanyo NCR20700A a āhigh current cellā but the only rating I can find is 6A and thatās from 2008. And I donāt know where to even buy it
The 48Gās claim to fame would be āgrams per amphourā if not for the LG MJ1 being better for that metric. The 48G doesnāt seem to offer any benefits to esk8.
Stick with 30Q for 3P to 6P, and 35E for 7P or more
30T make sense for 2P only
Good thing I manage to figure out that level status. Imma get these cells when they release cause I need to drop from 24 cells to 50 cells. I know Iāll get shafted for capacity for a 12S2P configuration.
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So Brian, for my 44" inch Mauna Super Cruiser, long range around the bay, and San Francisco Hills, the 35E will be the best battery option?
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definitely not.
the 35e has continuous discharge of 8a, maybe 10a. even if you build a 4 or 5p pack, you pack discharge will be limited to 40, maybe 50a pushing it.
going up hills, especially going from a stop up a hill, demands the highest current draw. limiting your current delivery to 50a, which would be 25a per motor in a dual setup, may not be enough.
in comparison, the 30q in a 4p pack would have 80a continuous, or 40a per motor in a dual setup.
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You forget the diference between battery and motor current, you can easily start on a hill with 40A, if you use 80A on each motor you can keep that up to 25% duty cycle, at 50% you are down to 40A on each motor, you will not climb the hill at top speed for sure since duty cycle can be roughly linear with % of top speed
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I understand, the comparison I was making is for the cells. yes, the 35e has a larger capacity but is less performing. for that same price bracket why under power your board, especially in high power demand builds.
also, in dual the 35e in a 4p, thatād make it 20a batt max per motor
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Not unless youāll be running at least 7P deep, no. At 3P to 6P, the 30Q looks better. At 2P, VTC6 looks better.
Unless you have some unique space restraints (which you might) that limit you to certain numbers of either 18650 or 21700 or 20700 cells, Iād use 30Q
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Brian, I was thinking 10S5Pā¦so according to you, that falls into the 30Q,
ā¦and according to Joeā¦
in comparison, the 30q in a 4p pack would have 80a continuous, or 40a per motor in a dual setup.
ā¦that cell also fit my motoringā¦
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I have a question that has probably been asked but Iād like some fresh responses since we have some new much better performing cells available now.
So as it was pointed out earlier, some cells are good for a small pack, other for a large pack, some for their high discharge ability, others for their range, and so onā¦ SOā¦ is it possible to create day a pack with equal quantities of battery cells? Like a 12s2p Samsung 30T +12s2p Samsung 30Q +12s2p Sanyo 20700A/B
12s6p with mixed mAh, discharge rates, Amps, etcā¦
Iām sure this is probably possible, but itās it practical or a good idea at all?
I imagine it is much simpler using the pack than charging it since some of the batteries have different capacities etc, but if you were to wire each type of battery as itās own so each one can be charged individually, and then be able to combine them to make a 12s6 battery so you have all the positive benefits from each, and then hopefully where each battery is lacking, another battery pack would be able to cover that area, thus creating a battery pack with only pros and the only con being the extra work youād have to do to charge them separately and then reconnecting them back up, which really would not be difficult at allā¦ So is this a good idea, had anyone tried anything like this before? Or is there something Iām missing that makes this is not impossible, nearly impossible?
Have you tested any of these cells??? Please donāt make suggestions based on datasheets of cells youāve never used. Thatās how esk8 ended up with using 25Rs in the first place.
I suggest looking up why itās a bad idea to mix cells
Bad idea man and thereās quite a few reasons but simply put some cells have different capacity and discharge so imagine having a 3000 mah and 2500mah cell of course you will run the 2500mah cell down before the 3000mah, thatās not including potential problems with cell chemistry and other reasons
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Got it, thanks for the explanation!
Nope; research for my own purposes. Currently in the process of testing it. Iād appreciate if you offered constructive criticism instead of destructive criticism. I could just as easily not say a word and keep this information to myself. Please let us know your test results!
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I cannot share my test results as they are work related. I can tell you that reading datasheets wrong can lead to big issuesā¦:
Official specifications: Standard discharge capacity: min. 3000mAh (1.5A charge 0.1A cut-off, 0.6A discharge, 2.5V cut-off) Rated discharge capacity: min. 2650mAh (4A charge 0.1A cut-off, 10A discharge, 2.5V cut-off) Nominal voltage: 3.6V Charge voltage: 4.2V Standard charge: 1.5A charge 0.1A cut-off Rated charge: 4A charge 0.1A cut-off Max. continuoys discharge: 35A at 25Ā°C Discharge cut-off voltage: 2.5V Cycle life: 250 cycles to 60% at 35A discharge. Cell weight: 69.0g max Cell dimension: Height: Max: 70.40mm, Diamter: max. 21.22mm Operating temperature (surface): Charge 0Ā°C ~ 50Ā°C (Recommended <45Ā°C), Discharge -20CĀ° ~ 80Ā°C (Recommended <60Ā°C) Storage temperature: 1 month: -20Ā°C ~ 60Ā°C, 3 months: -20Ā°C ~ 45Ā°C, 1 year: -20Ā°C ~ 25Ā°C
Iām always looking at charge cycles (for true cost calculations) and max charge rate, for brakes (hub motorsā¦). Weird numbers! I guess the specāed cycle life is at a bananas discharge rate, probably quite a bit better at 10-20a.
If these 2 numbers were better, itād sit nicely between 30q and A123.
Thatās the problem, they donātā¦ At least, not with out sagging from 4.2 down to 3.2 voltsā¦
These cells are good because unlike at only 15 amps per cell, the 30q goes to 2.65 Ah, while the 30T still goes to 3 Ah.
I donāt use 18650ās cause I canāt get enough power from them. Unless I do a 12s6p, 18650s donāt deliver enough power for my 4wd boards. And my board is already 25 pounds with a lipo equivalent to a 12s3p.
So in my case, this cell is much needed.
Also, if you wanted a small, lightweight board with some power still, you can do 12s1p and 12s2p configs and still deliver ok acceleration.