Hey guys. I just received my kweld kit in the mail, excellent service from Keenlab, only took a week from Germany to Aus!
Just wondering if it will run off a flogged evolve gtx battery? Will buy the lipos if I have to but the gtx battery may as well get used if it can…
Recommend are 3S lipos for the kWeld. Double check the max voltage but I think I remember a voltage limit of 25V or something. I wanted to buy a kWeld as well and asked the seller if I could use my 6S packs I have. He said theoretically yes, but lower voltage would be way better.
When I was building I figured that more was probably better. I don’t want them to break and for a personal build I’m not that worried about it taking longer if it’s going to give me a more reliable pack.
If you’ve got it automated more welds is not even more effort.
How many is to many?
My finger hovered over the buy button as well, but I’ve hesitated. Maybe my ignorance I need to explain
If really switched off how does it detect an imbalance? To me this smacks of anti-spark passive drain to detect a voltage difference, wake up and start balancing.
I don’t think there is any leads besides the actual balance leads, so no way to cut this drain via a loopkey of power button
Idk
there is an active drain for sure. the description says:
the static power consumption does not exceed 20uA
Solved with a balance loop key? Or maybe overkill?
How do you manage to spot so much welds without heating up the cathode? Nice clean assembly btw.
Should be interesting to see how many people are using solderless packs too in comparison of spot welded packs 
That’s pretty minuscule if correct, let us know how you get on!
Can you share the leads between the bms and this device I wonder? Can’t see why not
Also wondering the effect of balancing during discharge, no freaking idea on the effects to cell chemistry let alone discharge power
Cheering it on
you can turn that off thankfully!
yes, just parallel the two devices.
We have people using a “charge during ride” additional pack here as well. the charging while discharging doesn´t seem to have an negative effect, so this balance board shouldn´t have an negative effect as well.
theoretically…
Built a machine to do the welds for me. It works slowly and methodically. Heat generated is small, dissipates quickly and there is enough time between the welds that it never gets warm.
I was initially considering cycling with 1 weld on each cell then move to the next and come back after doing all 4 but it was never necessary. During the process the cathode never gets more than warm to the touch (maybe less that 30 degrees but i never measured). Doesn’t matter if it takes a while when it takes no effort. I think each 4p pack takes about 5 mins per end but i spent most of that watching TV so its not really a problem.
^^ This video is sped up about x5 so that its not tedious to watch but you get the idea 
Subscribed!
Maybe I can in a few months 
Are u going to go through testing with a design or sell one already done by a place that is certified?
I got 48 cells I’d like to see as a double stack 12s4p but I can’t weld, is there any way to ship these to be assembled? Or does anyone have a welder they can lend?
Salvaged 30Q cells, ground ends and re wrapped
This one is $8 shipped and it works well for basic tasks. I have one and I’m happy with it.
It takes forever to shrink a heatshrink with a hairdryer.
Lol I gave up and got a heat gun, it takes 4 minutes with a hair dryer each
An example where 10S6P has less sag than 12S5P at 1200watts of power
Someone asked about choosing 10S vs 12S on a different thread,I was curious about it too, so decided to work it out. Posting it here since it’s the most relevant thread.
So from the math it seems like they are pretty comparable. Unless I made a mistake somewhere. On my phone have to double check when I get to work. @Venom121212 says the math is right, but if one of you spots a mistake let me know.
Say you have 60 cells. You can either make pack1:10s6p or pack2: 12s5p. The IR of each cell is the same, say 20milliohms(from 30Q datasheet)and the voltage of each cell is at 4 volts
Now say both the setups are consuming 1200 watts of power. Let current in pack1 and pack2 be i1 and i2 respectively.
Current per cell in pack1: i1/6
Current per cell in pack2:i2/5
Voltage sag total in pack1: 10*(4-0.02i1/6)
Voltage sag total in pack2: 12*(4-0.02i2/5)
Power given of by both the packs are the same
10*(4-0.02i1/6)*i1 =1200
12*(4-0.02i2/5)*i2=1200
Solving the quadratic equation(solve easily on Wolfram alpha) gives i1 and i2 and then you can find the sag in each one of them. Ideally you would plot the sag over different power.
Solving I get:
Current: i1:30.79amps and i2:25.65amps
Current per cell: 5.131 and 5.13
Voltage: v1:38.97 and v2:46.76
Sag: 104-38.97 = 1.03 volts and 124-46.76=1.24 volts
So blanket statement like there is more sag is 10S, assuming the same total capacity, is not true. I gave 1 realistic example that shows the opposite.
I would stick to 10S so as not to cause issues with cheaper ESC.
people selling batteries:
if youre selling the 4pack pcb youre under the 100 watthour limit and don’t have to comply with expensive testing of the design. you are supposed to mark the package and do other stuff but it is legal to ship them with your making them. If you connect those packs of 4 and sell them its now more than 100watthours and youd have to get the design tested before could be shipped legally but there’s a loophole for “prototypes” of under 100!
PROTOTYPE BATTERY BUILDING AND SHIPPING REG (from https://www.govregs.com/regulations/49/173.185)
:
(e) Low production runs and prototypes. Low production runs (i.e., annual production runs consisting of not more than 100 lithium cells or batteries), or prototype lithium cells or batteries, including equipment transported for purposes of testing, are excepted from the testing and record keeping requirements of paragraph (a) of this section, provided:
(1) Except as provided in paragraph (e)(4) of this section, each cell or battery is individually packed in a non-metallic inner packaging, inside an outer packaging, and is surrounded by cushioning material that is non-combustible and non-conductive or contained in equipment. Equipment must be constructed or packaged in a manner as to prevent accidental operation during transport;
(2) Appropriate measures shall be taken to minimize the effects of vibration and shocks and prevent movement of the cells or batteries within the package that may lead to damage and a dangerous condition during transport. Cushioning material that is non-combustible and non-conductive may be used to meet this requirement;
(3) The lithium cells or batteries are packed in inner packagings or contained in equipment. The inner packaging or equipment is placed in one of the following outer packagings that meet the requirements of part 178, subparts L and M, of this subchapter at the Packing Group I level. Cells and batteries, including equipment of different sizes, shapes or masses must be placed into an outer packaging of a tested design type listed in this section provided the total gross mass of the package does not exceed the gross mass for which the design type has been tested. A cell or battery with a net mass of more than 30 kg is limited to one cell or battery per outer packaging;
(i) Metal (4A, 4B, 4N), wooden (4C1, 4C2, 4D, 4F), or solid plastic (4H2) box;
(ii) Metal (1A2, 1B2, 1N2), plywood (1D), or plastic (1H2) drum.
(4) Lithium batteries, including lithium batteries contained in equipment, that weigh 12 kg (26.5 pounds) or more and have a strong, impact-resistant outer casing or assemblies of such batteries, may be packed in strong outer packagings, in protective enclosures (for example, in fully enclosed or wooden slatted crates), or on pallets or other handling devices, instead of packages meeting the UN performance packaging requirements in paragraphs (b)(3)(ii) and (iii) of this section. The battery or battery assembly must be secured to prevent inadvertent movement, and the terminals may not support the weight of other superimposed elements;
(5) Irrespective of the limit specified in column (9B) of the § 172.101 Hazardous Materials Table, the battery or battery assembly prepared for transport in accordance with this paragraph may have a mass exceeding 35 kg gross weight when transported by cargo aircraft;
(6) Batteries or battery assemblies packaged in accordance with this paragraph are not permitted for transportation by passenger-carrying aircraft, and may be transported by cargo aircraft only if approved by the Associate Administrator prior to transportation; and
(7) Shipping papers must include the following notation “Transport in accordance with § 173.185(e).”
waiting to hear back from a place that sells the packaging for “prototype” legal shipping… https://www.clsmith.com/hazplus-hazardous-material-packaging/battery-packaging/lithium-ion-battery-packaging/prototype/small-prototype/
