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

[sternwake]

oops, misunderstood.
Seems the kayak paddles top out at 260cm, mine is 230, an aluminum shafted POS that i can feel one side flexing way more than the other.

Been perusing carbon shafted options online, but want to see if that 'free shipping' makes a store bought paddle price competitive.and pictures do not replace a hands on feel.

The peel and stick insulative rings for 18650s i ordered are crap, and not what i ordered, and intended to order. basically no rings, just full rounds, and one is 5 rounds side by side.

Nott many e bay options but Amazon's loaded, but liion wholesale has them too, when i orser cells.

Im thinking the 15amp CDR 2600 mah 2.49$ 18650s will be 1200 more mah and likely have a 10amp higher CDR than my existing battery.

[sternwake]

The red 24$ BSW, came with shirt 10awg leads to the battery,~10", and ~20" 10awg leads to the welding tongs.

That nice super flexy high strand count 200c silicone insulation wire.

Instead of ring terminals, it cane with the two-pronged fork to slide around screw. it looked to be aluminum, but i scraped it to find copper, which was 0.712mm thick. Not really well crimped either.

I installed small 10awg tinned ring terminals that were 1.07mm thick, properly crimped, with a smidge of solder to over seam and exposed end strands.. These ring terminals Shoukd be a much lower resistance connection than the tongs. I also added solder between the terminal bridges and brass busbars, and from busbars to Mosfets.

I ordered some antispark XT-90 connectors, and attached one side to the BSW, and the other side, with the antispark 5.6ohm resistor, to an XT 60 connector, which will then easily mate with the 3S LiPo 5.2ah 80C battery, when it arrives.

So the unmodifies BSW is awaiting the lipo battery only. Luca inspected 4 different versions of this Red BSwelder, the most recent two years ago. My version circuit board layout, is different than all of his, so I have no idea what if anything Could/should be done to help prevent/DELAY mosfet smoke ejection. The antispark XT90 might help, it might do nothing. lower resistance through the BSW should help, but might not. It might work awesome, it might not.


The other two BSW's I ordered are newer offerings, and i can transfer tonights upgraded leads to those unkts, easily enough should i eject magic mosfet smoke, or just want to compare.

The XT60 and XT90connectors require soldering the wires to them, and I also added some xt60s to a new inline wattmeter's 12 awg leads.

I was then able to hook up new wattmeter between 7s2p battery and ESC, and see voltage and amperage, and amp peak, and watt peak, and minimum voltage, and amp hours, and watt hours while riding the board.
What i was most interested in, was amp peak and watt peak, but this new dang wattmeter does not record that data. displays watts and amps but does not record their peak. Seems to reset every few seconds. POS.

So i made 45amp APP to XT-60 adapters using new 10awg wire, used my older wattmeter which has 8awg leads and 45amo APP's, hooked it all up, took skate for a ride in power level 4, and 28.9v falls to 25.8v under a 20.38 amp load.

WaTtmeter recorded a 531.8 watt peak and it looked like 6.7 amps to maintain top speed on uktrasmooth new asphalt and no wind.

Pretty well short of the 700wTt claim but that power rating is likely accurate with a 10s battery, not a 7s.

So If the unknown cells in my battery are rated at 10amps CDR , and 2 are in parallel, then their CDR rate is being exceeded, During accelleration.

Battery was losing 4.1v under a 20.38amp load.

in theory a cell with a higher CDR, should hold higher voltage under same amount of load, and have more torque.

Ive decided i want enough battery capacity to go full speed to kayak launch and back, twice, with some room to spare for headwinds both ways.

It might have enough to do that now, barely, really slowing down that last half mile.

I think 14 2600mah 15 amp cdr 18650 cells should fit the bill with no enclosure modification at 2.50$ per cell.

One thingni noticed, was when wattmeter was between battery and ESC, and inhad charging source hooked up, battery voltage was 0.4v lower, than the voktage leaving the charger.

So it seems the BMS is dropoing 0.4v across it, and if i charge to 29.40v, the Battery is 29.0.

But i dont know if it is a charge only BMS, or a cbarge discharge BMS, or if it does active top balancing, or what voltage is starts balancing, if it does so, or what current it might do so with.

But the power supply being ~ 0.4v higher than 4.2v per cell, might be ok, and my earlier alarm at excessive charge voltage, unwarranted.

[sternwake]

The new 7S 25 amp BMS that i ordered, has no documentation, but this listing says recommended charge voltage is 30v. and that cell' equalization' starts at 4.15VPC and 0.04 amps is the max balancing current.

I've not seen any documentation anywhere regarding BMS's saying overvoltage is required for cell balancing, but the BMS in my larger skate input voltage is about 0.4v higher than the XT60 connector that feeds the ESC.


I've no idea what BMS is under the heatshrink in the 7S2P battery. size and shape might be the same as the new one i ordered.

Seems like 0.4v is excessive drop across the BMS, to me.
But that is the same as a Diode, and there has to e something alone tbose lines as the charge port sbows no voltage.

The cell.over voltage prrotection is 4.25v per cell.
I guess ill have to determine what is going on within, once i have built a battery and can hook test leads and the current clamp up easily.

But is seems likely I've only been charging to 4.14vpc instead of 4.2v. Good for cells, bad for achieving max range, which has not been an issue.

The little skate is so fun, just underpowered. Torque limited.
I coukd use that second truck with same hub motor, and put it on front.
would need a dual drive ESC.

The duaL drive 7S ESC in my larger skate has that borrible throttle and brakes.
The motors haVe hall effect sensors, and some esk8 forum members say the HES are used only to get stationary board moving, and to automatically turn the off board to on whennit is oush started manually, and that the brakes imoroved greTky with sensors disconnected.

I pretty much never ask board to start me moving from dead stop, and the push to on feature is more annoying to me than a feature i take advantage of.

So perhaps i can just disconnect the sensors, and have better throttle response and brakes.

Wonder what the risk of magic smoke ejection is by doing so.
Whichh leads me to desiring a backup ESC, and a backuo board capable of towing Fionas water chariot to the bay too.

The cheapest esk8 dual drive ESC is in the 62$ range.
But the oictures all looknthe same, but some say 24 to 36v, othere say 10s onky, some say for belt driven motors some say hub motors.

Wonder if my horrible throttle and brakes are because of the ESC being for belt drive motors and not hub motors.

But my esc, is apparently unicorn tears, i cant find any links anywhere to it or any pictures anywhere online of an ESC with same layout of circuits.

There are 3 different dual drive ESCs on e bay in the 62 to 114$ range.
One of those has a soot on unootted circuit board, where one can add a sokder bridge a ross two terminals and use it wjth a 6s battery, or two other terminals for a 7s battery, and no bridging for a 10s battery.. It said it is for hub motors.

I had to order it, because i could 6s it to drive two 24v kayak thruster motors, or 7s it to use on larger skate, or 10s it for when i decide to make a new enclosure and a 10s battery.

Options, good to have them.

And the super fun miniskate could potentially have 2 motors, driven by a 10S battery, using Molicel p42a 4200 mah cells with a 45 amp CDR.
14 unknown CDR cells of aupoosed 2000mah capacity in a 7s2p bTtery pack gets me to launch and back easily.
7S1P of Molicell p42a should do so with more room to spare, and 10 should laugh at the that task.

so i guess researching and shopping for a 10s BMS is next.

[sternwake]

The 3s 5.2ah lipo battery arrived, at about 11.26v

Trying to charge it at 2.6 to 5.2 amps was difficult, as the tiniest turn of the 10 turn voltage potentiometer on non current limiting source, had amperage skyrocket.

With lead acid charging a 50% Soc healthy battery, increasing voltage by a tenth increases amperage far far less than with new healthy LiiPo.

Which was expected, but perhaps not to the degree i witnessed when voltage potentiometer fiddlin'.

Its also way more than my 3s 18650s 1.5ah cells pulled from failed rRyobi backpack, but granted 1.5 vs 5.2 ah of capacity per cell..

So i kept charge rate to under 1c, mostly and stopped at 12.3v, 4.1vpc.

[sternwake]

So i Deoxited the pins and  bridged  the flimsy power switch and tapered the flat ends of the welding tongs, as recommended by Luca.

Started with a 1ms pulse. no smoke.
Worked uptto 45ms before getting a solid weld with 0.15mm thick nickel strips.

Doubling 0.15 nickel strips, 85 milliseconds was almost enough to weld  both at same time  to battery strongly.  I ciukd rio it off and only 2 of the 6 welds ripped the nickel.

It can go upto 99ms,  But I didnt go there.
i never  noiced any significant heat from the welding pens or coming from soot welder, or the 10awg leads to XT90 connector, or the 10awg to the XT60.
but the XT60 was warm on the 10awg side, and very warm on the battery side which is 12awg.

The 12awg got progressively   cooler away from the XT60. 

It makes sense that this is the hottest most resistive part of the circuit,, but is it poorly soldered at the baTtery factory.  It did seem the red wire was hotter than the blue-.

So I'm likely to snip off some 12 awg,  and solder on a xt60, or perhaps  better yet, an antispark Xt90.

How hard, and what angle to press the pens into nickel strip influences the size and depth strength  of the weld, and how many ms of pulse is required.

And the welding tips do leave behind a smidge of copper and the tip shape, evolves and gets ugly and needs some loving.

Overall, I am satisfied with the performance of the welder, but i think there is a bottleneck at the factory  soldered xt60 from battery, forcing me to use a higher duration setting.

But BSW does say its primarily for battery repair and 0.1 to 0.12mm nickel strips, and at 85 out of 99 i am getting nearly acceptable welds  to a battery doubling 0.15mm strips.

The battery  Voltage reading on BSW itself is accurate at first but becomes about 0.2v less than actual after 15 welds or so, even after the warm 12awg, has cooled off.

   

[rvpopeye]

Good to see the welder working out. Trial of first welds seems to have you in the groove.