What's inside? Jaykay Trucks + possible revival

[Linny]

A friend got a set of these Jaykay trucks. For the uninitiated, these were the true stealth components for a stealth build.

Four cells fit in the truck hangar, and two hubs connect to the hangar. You could do a 4wd with 8 cells too.

So after a few years, the battery is dead dead. I was given a chance to try and save it, so i opened it up.

The cells seem to be spot welded in a 4s1p to a custom PCB. Both ends of the PCB has 3 pogo pin tabs where i believe it connects to the phasea of the motor. Also, the PCB then has a raised nickel button where it connects to a pogo pin on the inside of the hangar hole, which then connects to the pivot cups pogo pin, to the baseplate where the USB C is to charge. I have to be very careful on making sure that they align properly when putting it back.

I am going to see if a P42A cell can fit in the hangar slot. If yes, i will carefully dismantle the Samsung 40T cells and replace it with those.

[Pecos]

Those are so weird and cool. Watching this space

[Mikenopolis]

Where’s the BMS and ESC in that thing?

[jack.luis]

I think both are that PCB going along the length of the cells

[glyphiks]

This screaming for better cells than p42a!!

p42a is like bottom of the barrel in these times

[jack.luis]

@glyphiks

p42a is like bottom of the barrel in these times

Damn

[tuckjohn]

Dang, those trucks are such a work of art! Can’t wait to see the repair.

Aye, they deserve at least 40PL’s or something

[Linny]

Hmm, what cell would you recommend instead?

[glyphiks]

Reliance RS50

[jack.luis]

Which is the cell had the group buy with the really suspicious results?

[Pecos]

If the 50s had dropped in price id say that but the rs50 is better and cheaer. Its such a battery siper you might be able to use the 6000mah vapecell. Seems to perform well at 15a and delivers 5.4ah at that continuous rate.

Rs50 is probably the easiest best option right now. It just seems to hit that sweet spot for cool discharge at 20-40a a cell with really good capacity at that same discharge. Making my first pack with them so i don’t have a lot of experience with their real world performance but the mooch tests got me excited

[SternWake]

21700’s have been growing in length and width.

The series connections on the sides of the can suggest there is little room to stuff them inside the hanger lengthwise.

Even if the cells will not approach their CDR in this application, I’d personally still want one which runs cool, which the Samsung 40t is comparatively not known for.

If capacity is more a concern than temperature or CDR/voltage sag, the EVE 58E could be a good contender, but 60C max.

But how much extra length and width can be fit inside?

[b264]

If it doesn’t fit, it doesn’t matter how it performs. I also wouldn’t want reliability or safety compromises because the cells are too big. Clearly, this isn’t designed to have extra space.

[Pecos]

Just my observation, the rs50 are smaller than the bak45d in circumference. Stacked side by side

Rs50 left grey. Bak45d pink right

[Pecos]

Another concern might be the heat of the weld. I found out the bak45d cells require a huge amount of energy to weld well.

I have test cells of the rs50 showing up soon to test as well but i was blasting the 45d cells at 160j to get a good tear off on .2mm nickel that welded p45bs at 32j. It was absolutely baffling and amazing how quickly the heat was dissipated by the cells but the welds were look hot af. Further evidence that a good spot weld is about the test and not the look

[SternWake]

I never thought to put my calipers on My 21700’s, but just put some tape on mine and re-zeroed them.

I have several BAK45D A04 version on hand.

#1 ( non CCC labelled) is 21.19 to 21.26mm in diameter, not perfectly round, and is 70.58mm long

#2 ( Non CCC labelled) 21.17 to 21.30 in diameter, and is 70.49 long

#3 (CCC) is 21.19 to 21.23mm in diameter, 70.47mm long

#4 (CCC) is 21.12 to 21.32mm in diameter, 70.54mm long

#1. EVE 40PL (CCC) 21.12 to 21.16 in diameter, 70.10 long

#2 EVE 40PL (CCC) 21.08 to 21.18 in diameter, 70.05mm long

#3 EVE 40PL (CCC) 21.11 to 21.19 in diameter, 70.09mm long.

#1 Tenpower 50ME 21.08 to 21.22 mm diameter 70.64 long

#2 Tenpower 50 ME 21.12 to 21.20mm diameter 70.63 long

Samsung 50E 20.99 to 21.30 diameter, length is NA as it is a test weld cell and the can and positive tab is now convex.

So it looks like none of the cells are perfectly round, and all also vary in length too.

When I welded My 10s2P BAK45D (non CCC) I used 0.1mm copper and 0.1 Nickel plated steel sandwich and a cheap welder with a cheap 3s weld LIPO that basically failed on the last few welds, leaking electrolyte. I was nearly maxxing the welder pulse duration out, and it seemed the positive tabs required more pulse duration than the cans did, and that was ~15 to 20ms more than on P42A and DMEGC-26E, which I wrote off to the well aged Lipo, but 32 compared to 160 joules is a huge difference.

Samsung 40T(5) on 18650bs says 70.00 mm long and 21.4mm diameter.

[Linny]

This information is good, thanks everyone! Ideally i’d like to choose a cell that is similarly sized to the 40T or smaller by a bit. I had to lightly tap the battery pack with a soft hammer to get the pack out, it’s a very snug fit.

[b264]

@SternWake

I never thought to put my calipers on My 21700’s, but just put some tape on mine and re-zeroed them.

Reminds me of this

@b264

[SternWake]

Am retracting my 58E ‘possibility’ at as much as 70.95mm long and 21.65mm in diameter

[fessyfoo]

tightest enclosure ever.