ChooChoo Short AT small batch GB_Completed

[deucesdown]

I was spazzing out about this in the PM thread. Gonna bring it here (if you don’t mind @rey8801)

@deucesdown

Unity needs about 80mm.

For 180mm wide, lining up the cells top to bottom:

• 180mm / 18mm = 10 x 18650.
• 180mm / 21mm = 8.57 x 21700

430mm long. with same orientation:

• 430 / 65 = 6.6 cells (rounded down that’s 60 cells. delete 1 row for esc is 50 cells)
• 430 / 70 = 6.14cells (rounded down 48, delete 1 row for esc is 40 cells)

I don’t think we can get 10 x 18650 in one row, and I don’t think deleting 1 row is enough for bms. Hm… I see why 12s3p 21700 with bms on top is interesting.

The 11s4p layout, that’s 44 cells. 13s3p is 39 cells, which I think would leave room for a red waterproof 13s bms. 3p is a bit of a stretch with 30Q, but VTC5A should be okay. Too bad nkon is gone for US…

EDIT if we could fit 10 cells across (will probably have to route 1-2mm on the sides) 12s4p with no bms or bms on top is possible.

For 13s3p with 9 cells across it’s good. 10 cells across makes layouts ugh.

IMO this decks is laser focused for a compact lightweight build.

@deucesdown

brainstorming layouts, 18650

10 wide probably requires routing

@deucesdown

(EDIT renumbered the groups for a possibly workable series layout)

This could work. 7,8,12 are tricky and it’ll be VERY tight. But all enclosures end up very tight, right?

Unity has a built in switch. METR pro fits into Unity. That leaves the receiver and charge port and if you have room fuses, connectors.

Revisiting this. Mostly organizing and tracking my thoughts.

For 21700, 21x9 == 189 which means 4.5mm relief on each side. The cells are cylindrical so we could route it at an angle or even curved. Lengthwise, 70x5 = 350 which leaves 80mm for esc and allows 13s3p.

I want nummies for this if at all possible. Don’t have a lot of personal experience, but expectations are needing more torque due to diameter, and wh/mile increasing 1.5-2x? So need both discharge-amps and capacity? Lol.

For me, I don’t need big top speed or huge range with this build.

cell	layout	discharge A	wh	difficulty	notes
30Q	12s3p	60A	388.8	EASY
30Q	13s3p	60A	421.2	EASY
VTC5A	12s3p	75A	324	EASY
VTC5A	13s3p	75A	351	EASY
P26A	13s3p	75A	351	EASY	better than VTC5A, on sale at $4/cell on 2/2/2020
LG HG6 20650 3AH	12s3p	90A	362	EASY	on sale $2, wh calculated at 2.8ah/cell
LG HG6 20650 3AH	13s3p	90A	393	EASY	on sale $2, wh calculated at 2.8ah/cell
30Q	12s4p	80A	518.4	HARD	need to route, creative wiring
-	-	-	-	-
30T	12s2p	70A	259.2	EASY	30T can do 35A discharge. light. low range.
P42A	12s2p	60A	362.9	EASY	30A discharge 4.2ah/cell
30T	13s2p	70A	280.8	EASY	30T can do 35A discharge. light. low range.
P42A	13s2p	60A	393.1	EASY	30A discharge 4.2ah/cell
30T	12s3p	105A	388.8	HARD	no routing, very creative wiring
40T	12s3p	75A	518.4	HARD	no routing, very creative wiring
P42A	12s3p	90A	544.3	HARD	no routing, very creative wiring
30T	12s3p	105A	388.8	HARD	route ~5mm each side, easy wiring
40T	12s3p	75A	518.4	HARD	route ~5mm each side, easy wiring
P42A	12s3p	90A	544.3	HARD	no routing, very creative wiring
-	-	-	-	-
A123 M1A	15s2p	70A-ish	227.7	EASY	lol! Have cells on hand. Tall.
A123 M1B	15s2p	70A-ish	247.5	EASY	M1B is 2.5AH vs M1A 2.3AH

Nothing jumping out as a clear winner. Well maybe VTC5A 13s3p… I have 30Q on hand, and that’s a strong argument. But I can see arguments for 30T and 40T.