So it begins...... Battery spot welder

[sternwake]

Late last year before I dislocated my shoulder, I was in the process of building a new enclosure for a small lightweight Esk8.
An enclosure for a 10S1P 21700 battery, and I had built the battery.

I was actually using that battery inside my larger 10s2P enclosure, when the board got submerged in the bay.

Basically all work on that enclosure stopped entirely then and there.

This enclosure has a ridiculously huge heatsink, designed for 2 old programmable Vescs. I have some 80mm Hub motors which use a Julet 9 pin connector, often used on Ebike hub motors. I got the extension cables, spliced the three phase wires and the 6 sensor wires for one motoe, and decided to try that motor on a basic 7S ESC and battery.

The motor started making weird clunking noises that just sounded like a broken magnet inside. a physical internal interference. It could be a Mismatched ESC motor. it could be actual physical interior interference. I did not troubleshoot.

Thoughts of getting the Mini operable, again, faded to the background.

I now have known good hub motors which would be better on the mini build, and nothing is really stopping me from picking this project back up, other than when I put my powertrain on my midsize kicktail while working on my long cruiser deck. I disliked how it rode and lost confidence in my ability to ride it safely.

I do want a functioning reliable backup board, and a small lightweight board would be great, and I do have the cells and a battery half constructed for the Mini.

I should be working on it.

But Range brain took hold today.

The thought of strapping my old DMEGC 10s2p to the top of my long cruiser, and putting it in parallel with my BAK45D 10s2P through the charge port, is certainly the easiest way to increase my range.

Some potential issues are the charge port is only rated for and is fused at 10 amps, as is the BMS, and the ESC can pull 24 amps from teh BAK45D.

if put in parallel, I had no real idea what the DMEGC would be able to send to and through the charge port and BAK45D's BMS when I would full throttle accellerate to top speed.

I put the DMEGC pack into the Mini enclosure with some padding, and strapped the enclosure to the deck of my long cruiser.

I have an Anderson powerpole on the DMEGC pack, not fused, but which does go through the DMEGC's BMS.

I plugged a wattmeter in line with the APP, and plugged the DMEGC at 41.7v to the BAK45D at 41.4v, and there was about 0.4 amps flowing.

I put the board on the ground and went for a 1 mile long near full throttle run, by myself, scaring the shit out of myself exceeding 30MPH.

I then did a couple laps on my 'racetrack' where I would accellerate hard, brake hard, turn hard, accellerate hard, several times in a row.

When i stopped, benched the machine, and The wattmeter recorded 3.9 amps max, So basically 40% of the capacity of the charge port, the fuse, and the BMS.

When I stopped the DMEGC was feeding the BAK 0.7 amps, and that eventually tapered to zero and both batteries were 41.19v.

So this current from DMEGC was running through a pretty long distance of 18AWG and 16awg and multiple connectors.

The Main DMEGC output is 10AWG and uses an xt90S antispark connector, and Bypasses the BMS. The BMS is wired for charge only, to the ESC. Standard for Esk8, as the BMS cutting power means No brakes, and potentially streetface when it cuts power at full throttle when one is braced for accelleration.

The DMEGC pack was obviously not sharing the load of the ESC with the BAK battery which is much closer to ESC over 10AWG, and since it was feeding 0.4 amps to the BAK battery before the ride, and 0.7 amps after, it cannot recharge the BAK as fast as the ESC can deplete it, when riding aggressively anyway.

So I have now made a 14AWG xt90 to a 5.5 x 2.5mm barrel jack to plug into the charge port. A much shorter length.
So this should be able to allow more than 3.9 amps to flow from DMEGC to BAK through the charge port, its fuse, and the BAK charge only BMS, but I do not think the 10 amp limit is in any danger of being breached.

Ideal would be a parallel battery connection to the ESC, bypassing the charge port, fuse, and BMS, but that basically means complete functioning enclosure disassembly to add an external XT90 panel mount, and I don't want to disassemble the board, and waste about 3 dozen Zipties which are immobilizing every wire inside.

Anyway. The DMEGC pack was good for about 6.5 miles towing Fiona at moderate speed with my old hub motors and my old 8x3" turf tires which i kept at super low PSI. My BAK45D pack is good for about 10 miles on its own right now, and both together, Should be a considerable range extension, without having to stop and hook up the portable charger, but that is obviously still a possibility too.

So the DMEGC was 187 watt hours new, the BAK is 324 watt hours, and I have the 104Wh 7s2p portable charger that I can plug a 55.4 wH 7s1P into, and the 222 watt hour 3s4P 50E, and 6 power tool batteries at 72 watt hours each I could put in the chariot roll and explore quite the distance from home base.

And I do have boosters galore.

I am also about to make a 6s1P Samsung 50E to power my TS-101 soldering iron which is another 108 watt hours which will be able to power a Vbooster to recharge my ESK8 batteries.



I did test the White booster on the bench with my powermax holding my Dekas at 13.6v, and at 15 amps input was getting me about 4 amps of output, 168 watts, so about 18 more watts than I can get from the Blue booster.

I was losing one volt on the length of 10AWG from Dekas to the booster. I could wire booster directly to powermax, but I like having the Dekas in between to smooth the ripple.

So I am still quite a ways from stressing the charge port or BMS or the cells in terms of rapid charge ability.

If I choose to use the top mounted enclosure, I can basically charge that battery at 4 amps, and and the BAK battery at 4 amps, and then reparallel them and return range twice as fast. Have to be careful they are relatively close in voltage when parallelling them though. or bye bye fuse.

I'll add some photos in the next post.