Thumbs are better now. When I cleaned the cells with alcohol it burned like hell under the fingernails but it seemed to help.
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Oh lord, my odysee with the battery goes on. I spent days thinking about the perfect layout and how to connect everything. A lot depended on the enclosure and how I gonna mount it.
I made a decision, will mount it with 4 screws outside of the enclosure so I can easily change the battery and finally I knew how to route all wires. Time to spot weld.
Settings were 35J (as I used with VTC6). The kweld made some beeping noises but I gave it a try and almost got a heart attack because it welded as soon as I touched the nickel because of automatic mode 
.
Then the kweld gave error code and unsuccessful beep code and wrote 0J. Damn WTF! Well I found the reason, an unused wire of the foot switch touched a terminal. Also the white wire is a bit loose.
I think the guy glued the enclosure so did a quick fix with a piece of shrink tube
So far so good, welding with 42.5J
Cooling the lipo with 2 fans which helps a ton. Without it gets quite warm and with fans niot at all.
But the 3s lipo seems aged which is weird. It was used for 2 batteries only within 1-2 years. It doesn’t take long that the welds get noticeably weaker and the lipo needs to get charged to full voltage (12.6V). The first time I re-charged at 11.8V and the second time at 12.2V which is ridiculous. I guess it’s time for a new lipo.
Well i drew (and changed) detailed plans how to weld and connect but forgot to look at them while welding. Now I have to pay the bill, I am an idiot because the second 6s pack is incorrectly welded, I did the series connections on the wrong side. everything is now reversed and the cable routing becomes complicated 
. I was sooo pissed for quite a while but hey life goes on…
It couldn’t get any worse so quickly pull down the masking tape and raise the mood with the sight of the fresh spot welds… or not?
Common! 
Damn, impossible! I am cursed…
No more energy for any wiring or final welds so I call it a day.
What comes next? I’m a bit afraid
I can’t finish a simple 24 cell pack so how do I get faster? Need more pressure so I ordered 120x P42A cells yesterday for another 3 batteries 
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Did you tie the footpedal cable with a ziptie? There a two holes for that.
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Bahaha now these 2 holes make sense, genius!
It’s not my kweld so I didn’t assemble it but always wondered why this footpedal connection is so stupid and not just a normal connector (plug). But with a ziptie it’s OK.
Hold down the footpedal, while you plugin the lipo. You will enter automode in the first place.
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I can’t believe it took many weeks until I finished the battery, it was quite a pain and I should build a second one soon, damn. I am quite satisfied with the final result. The goal was to build the lightest possible and most compact battery including BMS with no cable sticking out.
The final pics are still missing but here is what I have.
First I soldered the bullet connectors and then the wires to the nickel before spot welding
The solder joints look weird because I used a piece of wood to push everything down for a few seconds after soldering to keep the height as low as possible.
For the balance leads of the 6s packs I used wires with JST-PH connectors because XH was too big.
Some wires were too short so I had to solder extensions but the coloured wires made it so much easier to work with. Really foolproof, love it!
Before heat shrinking i put neoprene foam between the 2 packs and taped them together.
Old 12s 5Ah Lipo (vs. 8Ah Li-ion), nice!
The size difference is impressive, also no more cable madness 
Next step was to solder male JST-PH connectors to the BMS. Not that easy with such short wires.
Wiring done, 10A fuse for charging
Only missing part is the charge port but I want to integrate it in the swappable enclosure which is not existing yet. So for now a simple harness where I also can connect a voltage meter during charging.
made adapters from JST-PH to XH so I can monitor cell voltages from time to time and use a balance charger or different BMS if necessary.
The BMS will be mounted on the side of the battery but not yet because there are weird balancing issues. The cells were between 3.50 and 3.53V from factory so I charged with a proper BMS first and left it plugged for 6-8 hours after charging for balancing. Well finally the cell voltages were between 4.18V and 4.23V which is weird. I went for a ride and after discharge the cells were between 3.48V and 3.51V. I guess it’s time for the classic balance charger to get same voltage levels. The small BMS has no balance charging that’s why it’s even more important.
I planned a swappable enclosure but had no time and prefered to go jumping in dirt park instead of wasting more time. It ended like with the last setup, 2mm double sided self adhesive EPDM foam for the battery and butyl tape for the esc’s, glued to the 4mm plywood which is connected to the deck with 2 narrow velcro strips 
.
Looks dangerous but after covering it with a sheet of 2mm foam and closing the velcro loops it looks like an enclosure and safe.
From my adventures in dirt park I’ll write in the next post so back to the battery and my first impressions. It’s obvious a 12s2p of P42A is not a high performance battery but still not bad. I could feel the difference to the former 5Ah 25C Lipo on hard acceleration but it’s not a big difference. But I have to say that I use quite lame settings (45A motor and batt). On my regular MTB this battery would suck. However for this build it’s sufficient especially for the ultra light weight.
The biggest downside is massive voltage sag but no wonder. At 60-80A from battery it sags 6-7V. At dirt park I usually use 30-60A from battery so about 5V sag. But it is not really a problem. I was scared that due to voltage sag I could hit hard cutoff but this is not the case. When reaching soft cutoff even 100% throttle is not enough to hit hard cutoff because the power is reduced.
I discharged to 42V and then the voltage sag was too big for hard acceleration. But I rode (jumped) 13km (8miles) which is great and had much longer fun than with the 5Ah Lipo. I need more rides for better judgement but in any case it’s an improvent and time to say good bye to puffed Lipos.
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Looking good!
But why even to use that small bms?
Just use a normal balance bms externally as „balance charger“. That’s 10sec extra work to plug in the two 6s jst plugs for charging and no need to buy more bms for all the other packs you plan to build.
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External BMS?
I use an OG antispark switch because I’m even too lazy to unplug power wires or a loopkey
First I wanted to do it with external BMS and VGA connectors like you. But they are too big for my taste and I prefer to just plug in a barrel connector for charging. Also mobile charging is easier.
I bought 2 of this small BMS, they are dirty cheap
I have Bestech BMS for 80€ and many other BMS and all of them have awful plastic balance cables. The small cheap BMS came with high grade silicone balance wires
However, of course for bigger battery packs (bigger than 2p or 3p) I prefer to use a better BMS with balance charging for sure. Just for the tiny battery pack I need a tiny BMS.
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hell ya, circumcising your deck!
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Ah new vocabulary for me 
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Late update, forgot to post about dirt park which I visited 2 times.
I found my personal limit and the limit of the board 
The jump line on the right side is the biggest and steepest line shaped for BMX. I was too scared and thought it would be suicide if I would try it. I mean it’s like facing a wall and not a dirt jump. Not to mention that these jumps are doubles with gaps.
And this is the smallest jump of the line
I had fun with 2 other dirt jump bike guys and one encouraged me and said “you can do this” all the time and after 10 times I believed it , then he bridged the gap with a piece of wood and it was my time.
I was scared to death but did it and it was really easy with correct speed, what a relief!
Then I repeated the jump about 10 times, always a combination of fear and fun which is weird. I made logs and for this jump you need to ride 40km/h (25mph) to clear the gap which is sick. It’s very sketchy with 8" tires at this speed and I consider trying 9" although it adds weight. Or increase the pressure, usually I jump/ride with 40psi.
The second time in dirt park I was not in the same shape and practised jumping in reverse instead. It feels ridiculous because I can’t do it. After a while the success of the day was that I could lift all wheels a tad. It is weird when the weight is on the “front” truck when jumping. I have to practice a lot, also riding fakie for 180’s.
Then I jumped the big one at the end but was too slow and landed 2 times on the wood wtih the rear wheels. The impacts were pretty heavy and loud and finished the rear truck . On heelside the axle bent so much that the gears got stuck. Fortunately the glue of the motor gear gave up instead of harming the gears. Good that I bought a replacement truck last month.
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I guess jumping is really what puts the trucks to the test. Will be good to see how Airs hold up to jumping over time
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I also swapped the baseplate because I thought there is some improvement, it looked different.
My euphoria was dampened when i realized that simply the washer was missing from factory. So I used the washer from the old truck
Found out that I have threaded inserts which exactly fit the unused holes on the deck
So why not. My plan was to use the threads for mounting something for cable managment/strain relief
Then it was time to close everything. And finally mount those beauties
White lithium grease on the gears and graphit grease inside around the edges. This helps catching dust if it enters.
Also white lithium grease here
Also switched from V1 to V3 hubs
Then it was time to visit dirt park.
After a short time the new truck started to sound like shit. My grandmother’s squeaky doors were nothing compared to this. Also the kingpin got loose several times unfortunately as usual with Matrix II trucks. This is my fifth Matrix II truck but this extreme squeaking noise is new to me. Trampa bushings make similar noises after a while or some months but not that loud. I hope that some grease will help.
After some time in dirt park the left rear wheel started to make strange noises and there was play back and forth so I thought the glued motor gear gave up. I kept on riding with the goal to loosen the gear completely so I need no blow torch to remove. It didn’t work.
At home I opened the wrong right side first. After this mistake I checked the play on the left side to be sure it was left. After disassembling I realized the motor gear is not loose at all.
I mounted the wheel gear again to check play and it was gone. What? Well the play was because the bolts came loose or I have not tightened them enough. The new design of the gear is with a milled aluminium part and it can move/rotate a bit if the bolts are not 100% tight and therefore the play.
I have unnecessarily disassembled everything, well done!
The current total board weight is 12.53 kg (27.62 lbs) which is not bad.
I want to try to jump with 9" in dirt park for science and checked the weight difference.
With the light 9" tires the total weight difference is below 1kg, quite nice. But no idea how bad the difference in torque is with bigger tires on this setup.
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Well, put everything together and wanted to ride but realized the left motor mount shifted and is crooked. So disassembled everything once again, degreased and mounted it straight. After cranking down the bolts hard it’s crooked again. These Matrix II driving me crazy. I decided to leave it as it is and hope the gear won’t break.
So far this esk8 year is very disappointing for me, last year I was in good shape and thought I could improve my skills this year. But this was just a dream, hopefully I find time the next 3 months to ride a little more. Then it’s winter again. Damn…
Sorry for this useless post
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DIY be like that sometimes 
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Heads up buddy, better times will come 
I have a broken motor and didn’t got a new one since 2 months.
Stuff happens all the time
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Things can get frustrating sometimes.
Let’s hope for a mild winter so that there will be no off season or as minimum a long summer season.
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Thanks for your kind words guys, got some motivation to finish things
Disassembled the rear truck because of the extreme squeaking noises. I rode this truck for about 1 hour so I was surprised to see this signs of wear.
Also the bushings wiggle inside the holes so I checked the previous baseplate, better fitment but…
The dark spots are roughened aluminium and not dirt.
So kept the new baseplate and greased every moving part including shockblocks. Greasing shockblocks was a bad idea so I had to degrease afterwards. Put a ton of threadlocker on the kinpin and pray that this helps against loose nuts.
Board is ready to ride tomorrow if it’s not raining.
I realized that on the former hanger the welds were not strong enough and the tube is wiggeling .
True, often it’s also FIY (fix it yourself) but that’s why I like DIY because you can solve most issues.
Hopefully not APS, just reminded Bruno that I’m waiting for replacement since over 13 months. I know a german guy who is waiting since 2 years .
Yes please, winter time is skate park time and you don’t sweat. No idea why I was complaining
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That wear in your baseplate looks… I mean… Wtf??
Yes sir… You’ve got yourselve 100points🤣
But today i’ve got a UPS ref. number🤔 it says from APS… Suspicious
The whole f’king week its raining like shit at my place… Hope you get a better week.
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Some magic happened
APS responded quickly with an excuse and tomorrow morning they send me a replacement motor after 13 months. I didn’t expect this after such a long time so I’m quite happy.
Talking about motors… 3 months ago I ordered 2x 63100 battle hardened freerchobby motors from aliexpress. I paid 92€ each plus 35€ shipping. DHL wanted 100€ tax so total cost were more than 300€.
Well, one motor came damaged (bent shaft/rotor) and both are not battle hardened which is fraud IMO! I claimed the broken motor and the missing battle hardening. After over than 2 months they agreed to send me at least 1 new motor by slow shipment (I asked several times but never got an answer about missing battle hardening). 1 week ago I paid additional 40€ for fast shipping and it isn’t shipped yet. WTF! And I’m sure my friends at DHL want me to pay tax and fees again if the seller ever ship it.
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