So far estimate range seems pretty good. I’m able to get at least 30 miles from a full charge. For comparison my previous 21s6p P45b was 26 cells more and got me about 24-26 miles. Lighter riding with 2wd will net you about 20-30% more range since you’re not averaging +50wh/mi. 
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Without modification that’s the best you’ll get in that enclosure. Just make sure the parallel connections on the split groups is as robust as the series connections and it should work fine though.
The only insanity i can think of to avoid two split groups is to make two 10s1p batteries and parallel the balance wires. Not sure if that’s really going to be less work or a smaller fit. 20s1p would be
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Does anyone have a few Samsung 30T sitting around? Preferably 8 at least 6. Either new or very lightly used.
edit: no longer looking. Forgot I had 40 more somewhere.
Looks a lot like the awithz welders…
Are those a piece of shit? If it does 0.2 with no issues I am more than happy.
By all reports the awithz welders seem to be excellent, i just wonder if this is a rebrand or an entirely different machine
Cell PCBs is it still a thing? I tried to search for some,but seems impossible. Anything to replace that?
What’s popular now is a single PCB for the entire pack. Requires specifically shaped nickel and the willingness to order a large PCB.
I can buy these, or are they custom ordered from somewhere?
Where can I find a manual for the P20B there is none in the box none online? What are the AWithZ P20B Welding Parameters for Farad Capacitor Spot Welder? Without a manual I would be guessing and wasting a lot of material.
The manual my P20B came with is pretty unhelpful.
What thickness material are you trying to weld?
The spot welding copper thread has a lot of the settings I determined.
You will need some practice, even If I tell you the exact settings i used on X thickness material , as the pressure used and tip shape and distance between electrodes are all variables and will differ amongst different users.
At first, Just worry about the gear setting and use a single pulse.
A trapazoidal razor blade can help one to get the settings fairly close, before trying on real cells, and one can easily see the underside. When not enough poweris used one weld will be more prominent than the other. Go up in 20 gear increments until both welds are getting near the same size as seen from opposite side of razor, then one can play with preheating and interval and ‘intermittent’ to refine the result.
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Anyone looking to build a 10s3p for my build? Or if you got an extra I’ll buy it off you.
You can find the manual here translated by me.
https://diy500amp.com/products/awithz-p20b-spot-welder-14-6-kw
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What’s the thoughts on an rs50 reliance for a high performance cell for a potential race board? Also could use some direction on programming. I saw battery mooche’s bench test on it. From my understanding, Even though it’s advertised for 70a, its performance seems to drop after 50a and heats up. But it’s has the punch of a p42a but 20-25% longer run time. I’m running a d100s with 6485 reachers 173 kv. Would i want to dial the battery amps back a little from the advertised 70a?
Hey guys, so I finally got my build to the point where I could connect the BMS for the first time. A JK BD4A17S4P. I got the main B- proper/permanently connected, temp sensor, power button, P1 (having 15 pins - B- to B14), and then finally P2 which only has the last/leftmost pin used for my build - B+ (same as pin 15/B14 on P1) - when connecting that the pin went POFF! 
(No charger or power draw connected ofc)
I’ve measured everything thrice (before and afterwards) and all seems ok. Could it be faulty BMS? Any other ideas or experiences with these BMSes?
I reached out to the aliexpress dealer who asked me about the pack current. I said its a 14S4P with Samsung INR18650-30Q which are rated 15A each so max should be 60A.
They said “oh you shouldve used a larger BMS for that”. Well my controller is just 40A (and my motor 32A) so surely a 40A BMS should be ok? And surely shouldn’t blow up no matter the max current of the pack?
Any help appreciated..
Confirm that this is the model bms you are using? The manual covers up to the 24s version - are the balance header pins the same as on your bms?
The p2 header above is different from the 17s 20s and 24s models but is only shown in the cad drawings so your pin count should be lower than the photo
In the wiring diagrams everything under 15s has no connection to the second header and the last most positive cell in series is connected but no leads are shorted or split. Only 15-24s show using the second (p2) header and then the last most positive cells is then also jumped to the left most (p2 12) pin.
It sounds like you connected the 15 pins on header p1 to the battery (0 to most negative and 14 to the most positive) then added another jumper to the p2 header? If i am understanding you correctly then you wired it wrong and possibly damaged the bms.
The two headers appear to be isolated from each other and the connection to the battery on p2 also powers or activates the bms’s circuits that run the higher p count configurations. You could be lucky and have only damaged the wiring but if you have any doubts about your ability to judge the level of damage to the bms you should replace it. I would suggest you do.
Then correct the wiring and try again.
There is a significant gap between what is spelled out in the diagrams in this manual and what is needed to actually hook up this bms in all its configurations. There is a lot of assumed knowledge so even if you think you got it - post some pics and questions here first 
not a guarantee you will get perfect answers but we try our best. No shame - we’ve all been there
Edit: ya that bms MODEL should be fine assuming the surge or burst current of your setup doesn’t cause it to trip when used for discharge protection.
Never plan to use the maximum rating of a cell - it is tested and rated for a single cell in free air and those metrics reflect only that. A cell used in a pack will always have worse thermal performance in all metrics. The performance will vary greatly depending on the arrangement - a brick pack and a flat pack and a double vs single stack will all perform differently.
Look at the design you plan to use and how theyre packed, tighter packing means derate more and monitor more closely. I personally plan in a 18s4p loose flat pack for 40a peak and 20a constant discharge for a 160a/80a build with the rs50 and feel it is a conservative max rating.
There are too many variables to give a straight answer - you will have to try and monitor and remember to build for the whole life of the pack - not just the new fresh pack. Build in your safety margins NOW 
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