I just gave up on Li-ions and went back to Lipos because of voltage sag. And I didn’t want to have a 6-8 pound battery
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They are rated at 50A, but in reality, they are more like 25A from what I have seen on other forums and real world testing.
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So are there any 26650 cells out there with real continuous ratings that are more than 25a?
Looking through what Mooch said about 26650s, and he seems to think they are all vastly over exaggerated… I’m looking for 100 amp con or higher for the whole pack, as I’m trying to reduce sag…
A123 systems ANR26650M1-B 2500mAh - 70A
Not sure what the measured discharge amps are, but they are higher, with the cost in capacity at only 2500mAh.
Digging further - this looks like an excellent cell for us, if you do some in parallel for better mileage.
Mooch:
[quote]This is an extraordinary cell that I am rating at 30A. My maximum vaping amps (MVA) rating is 70A. The two cells I received from EnerCig and the two from Nkon appear to have come from the same batch.
The datasheet has a “maximum continuous discharge” rating of 70A in the datasheet. But at that temperature, about 85°C, the cell will have a significantly reduced cycle life. This rating is an absolute maximum, not a level you should operate the battery at for every cycle. To allow direct comparison against other batteries I am rating this cell at a level, 30A continuous, which limits the temperature to 60°C to ensure good cycle life. Above this temperature the cell’s aging accelerates significantly. The cell can easily be pulsed at levels above 80A though.
This cell’s lithium-ferrous-phosphate (LFP) chemistry is the safest of the Li-Ion chemistries we use. While this should never be used as an excuse to do so, these A123’s can take a lot of abuse before going into thermal runaway. If they do go into runaway their reaction isn’t as violent as the other chemistries.
The voltage of this cell is very steady for most of the discharge, very similar to LiPo’s. This is great for unregulated/mechanical mod users. The iJoy 4200mAh 26650 is a better choice for vaping at up to about 40A though.[/quote]
What sl33py said. A123 26650 are 70a continuos and not too bad in capacity
A couple caveats it seems… primarily the reverse construction and 3.3v nominal not 3.7v!
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So it seems like 26650’s might not be the solution after all… I wouldn’t really gain anything and maybe loose range since I would be at 7500 mah with the A123 instead of 10000 mah with the 18650s.
Lipos seem to be better in the short run…
I can agree with @Namasaki , I have a Basen 6s2p pack and while the range is great on flat, of course it does have a lot of sag. Maybe 3p might be okay at 12s, but likely you will still have some sag.
I haven’t fully tested the range, but on this 6s2p I feel like I can get 15-20km.
My daily commute is 9kms and depending on if I do a route with hills or not, I have between 50-70% when I’m back home.
Basically I think it’s safe to assume that you can only get the amount of amps as an 18650 from these cells. So if its the same space as 12s4p, go with that for less sag.
I think voltage sag is one of the main challenges we face with esk8 design. Even my 10s 60C Lipo pack capable of 300a cont sags a little when going up hills. Still, much less than anything else I’ve tried so far. Accelerating up a 15% grade, total voltage only drops around 1 volt. That’s only 1/10 volt per cell.
@Namasaki is definitely the master. Specs seem a little out there, and I would be very wary of any Li-Ion batteries on ebay, but the brand and size are not unheard of (@Namasaki’s build) : http://www.electric-skateboard.builders/t/diy-battery-pack-using-basen-26650-hi-drain-li-ion-cells/4973.
Let’s get @anorak234 opinion on this I just built him 2 6s1p packs and I’m curious how they’re riding?
One is riding great (the perfectly balanced), haven’t done extensive testing with the other yet because it’s been raining on/off in the bay area recently. Gets about 4.5 miles of range (1000mah/mile). Both of my packs are with the 4500mah 26650s
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Oh snap you’re getting 4.5 miles per pack? That’s crazy. Is it on that short board with the bindings?
Yep. Rides like a dream - especially with the bindings. Starts at 24.4 and ends at 21.6, no problems in between. To be fair it is on flat ground, medium speed. I’ll post test runs if i can get some in this week
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Just did some range testing on my board today. Got 21kms on a 26650 6s2p.
Capacity is good on these cells, voltage sag is bad…
I’m with you there - trying to figure out if I can reconfigure my esc it seems to stop temporarily if voltage sag hits nominal voltage
I thin if you ran your packs in Parallel you’d have less sag
I’ve been thinking about that too. My 12S4P packs weigh 5 pounds, which makes me wonder what 12 10ah lipos would weigh and what kind of footprint that would have. Cycle life is a trade-off though from what i understand.
The same here. I’m half temped to go back to lipos because I can fit a larger pack with lipos than lion in the same space. I need to make a decision soon though as I need to build another battery pack soon for my next board to test the vesc-x with.