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Well, now, how far apart do they need to be to fit under 30mm? And how wide will that get, assuming 5 cells total?
Yeah those should work
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fishpaper is 0.25mm
so consider the cell diameter 18.25mm
and never forget space for wires. on all sides except bottom.
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Oh… how wide a space do you have then?
you’re getting into my
so about 75mm wide gets you about 30mm high with some tolerances in there.
I was contemplating stagger stack in my second build and practicing it in my first buiild.
I would design and 3d print some holders to help support the odd configuration.
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For now i have this monstruosity. Motors changed and vescs sent for repairs, but the enclosure is from bigben. 545x145x30mm.
Assuming welded packs, it can take 6cells longways, 8 in width for 12s4p, or roughly the same sideways, with 24 cells on each row.
Now, since the enclosure is quite a bit deeper than a 18650 cell, it’s tempting to try some form of double stacking, then see if it’s in any way more efficient than doing 21700/20700 cells
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I think given 145mm of space will fit two 21700s length wise. your best bet is gonna be two rows of 21700s perpendicular to the board.
this would be various ways of running batteries parallel with the board with stagger stacks. in this case I’m not sure it’s helpful.
EDIT: though the 18650x5 stagger stack is the most interesting.
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Thanks for the thorough representation.
18650 seems indeed like the most energy dense option.
21700 longways might be slightly too long for the enclosure too. Just that extra 3cm, absolutely necessary for vescs and wiring.
Can you do one last one with 6 26650? Lifepo is tempting, although it’s range isn’t
Please don’t forget about wires and connections and insulation. This is a grave mistake. The cells are only one part of a battery.
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Brian you should know as good as anyone that no 18650 cell is exactly 18mm in diameter. I’m sure a micrometer will show the very small differences in diameter. I know for this exercise it isn’t important but its something to be aware of
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I’m stupid at math.
My 10s4p 30q pack has 12Ah / 432wh.
I started riding with 40.8v and ended with 38.8v
So i’ve spent 2v = 72wh?
I’ve done 10.76km. 72wh divided by 10.76km is 6.69wh.
Does that mean my average wh/km consumption was 6.69wh/km?
Where did the 2Ah come out of 40.8v and 38.8v? Do you mean volts? By looking at the voltage/discharge charts of a 30Q (this probably isn’t very scientific) I would say you used around 3-4 Ah.
Also remember that the curve for voltage isn’t very linear so towards the beginning/end the voltage will drop much faster.
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Sorry typo. It’s late already, i’ve meant volts.
The primary question is if the average consumption I’ve calculated could be right?
For me it doesn’t feel like it because i’ve been full throttling for like 5 or 6km straight without letting go of the throttle once. Smooth pavement, no wind.
Granted the board i’ve been riding only pulls 12A per motor (not sure about the battery, its a wowgo 2s hobbywing esc)
I’m really not sure but the way I found to calculate consumption is just fully charge the board, use a gps tracker for the distance traveled, fully discharge it, then divide the wh of the pack by the distance traveled. But again that also may not be that scientific.
No. Li-ion batteries (in fact, pretty much all batteries) have a nonlinear discharge curve, which makes it basically impossible to associate a voltage with a state of charge. The cell voltage also bounces back once it’s not under load anymore, further fucking with the accuracy. The only accurate way to do it is via coulomb counting (basically counting how many amps go in/come out of the battery).
The only other reasonably accurate way is to go from 100% full, to 100% empty, and measure your range between those two points. Any other points are not linear, and will screw up your math.
(there is a third way: measuring voltage while under load, and then using that combined with a discharge graph of your cells. But since we have no easy way to measure-monitor voltage under load since we’re focusing on not falling off the board, it’s a moot point.)
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Hey guys, I finished the wiring on my board but my loopkey is too tight, is there anything I can do to loosen it a little ?
Plug and unplug it a few times to wear it in a little bit?
Other than that, not really. It has to be snug to handle the huge currents. You can add an extra lanyard loop or other grippy thing to aid pulling it.
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Make sure you didn’t move the pins inside when soldering. I have a male xt60 connector that slightly melted and it barely fits/comes out, i also have another that doesn’t fit at all.
When soldering the antispark, or any xt connector, best bet is to have it connected in a pair, so that it stays alligned until it cools down. It will fit just like before.
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