Monitoring a charge cycle now…
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So the Low Voltage Protection kicked it an 38.5V (which is good).
Also as soon as the Low Voltage protection is active you will see the actual voltage of the SOURCE not the Stepped up voltage which is also very nice.
I was able to charge at a constant 4A - it was getting quite hot so 4A is the absolute maximum I will try with this pcb
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be aware that your bms won’t pull Max current when the board is more than like 70% full. when configuring the boost converter, try have your board and completely dead or close to dead (if you’re using your board to test amperage of course)
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what are you using to switch the box on and off?
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I wanted to use a resettable fuse and some overengineered sh*t… however
I ended up just using a 20A Switch and it’s working fine without sparks or any other issues
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Well yeah… can’t trust that step up converter…
I was just charging my battery after climbing around 800 meters altitude so my battery was close to zero. Plugged in my portable charger.
All seemed fine… 4A… all of a sudden the current limiting failed and everything burned down. Now the step up converter is broken and I have a weekend of fixing ahead…
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I know I said it before but here it goes again.
Find a way to put 2 XT90 plugs on the battery box like Trampa does it. I am sure you will find a way to fit everything.
That way you can just plug another battery without having to open the box and you get 100% efficiency.
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I know that might be the “cleanest solution”
However I rather have a portable 12S2P in my backpack than another 12S4P replacement pack or swapped out pack.
And I also would like to use it on both my longboard and my mountainboard. So I have to make it work… hopefully the next PCB will not have those current limiting issues… 
Just ordered the beefier 1500W variant…
lets see how this goes…
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you sure this wasn’t a failure of the plug itself which fucked the boost converter? it seems weird that it’d do that
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@mynamesmatt
I am not sure why the Amps should rise to 20A suddenly because the plug failed ?
the short circuit protection of the BMS and the Step Up would have shut down instantly.
It was really charging at 20A and I guess the BMS was trying to disippate the heat through some MOSFETs and the plug and the wire instantly melted down which then later caused a short circuit which then gladly made the charger (and the BMS) actually shut down.
Let’s hope I have more luck with the 1500W version.
I know the DC Jack and the cable can handly 5A for many many hours (I always use the same type of higher amp jacks and thicker cables for many years on different projects).
However I am currently disassembling the PCB from my case and I will have a short look if I can find the failed part…
But I imagine it might be any or all of the multi-function ICs and none of the passive components…
Will replace the TL494 (PWM Controller).
I can get those quite cheap and try if I can make it work again…
New 1500W pcb is ordered as well. let’s hope that this project keeps on living…
My bet would be that the plug short due to having poor contact with vibrations when you are riding
At least in my experience these converters have a limit on the input amps no matter how high you set the trimpot, since you have a big voltage diference between input and output the output gets limited, but when shorted the output voltage that the converter sees in lower, so it can boost to a lot higher current without going over the input current limit
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Why not keep the separate battery and put in parallel every few volts? I did ohms law above for what would be the charge current with a pretty big voltage difference between the packs but if they were plugged together more often you could lower and control what the current would be.
If I was going to sit on the side of the road charging I’d at least want to charge at the max current. At leaaaast the max stated charge rate which I think was 12a. And looking at the data charging at higher current w a low state of charge seems far from dangerous and probably have more cycles doing that and only going to 4.1 max voltage
can’t get any simpler. Everything breaks.
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I don’t charge while riding. It is impossible both space wise and mounting wise. When I use my MTB its mostly really rocky steep mountain trails.
there has to be some further testing for sure as soon as my new PCB arrives.
Hope the 1500W type does not have all of the problems that my earlier PCB had right from the get go
I’m not suggesting charging while riding but just taking your battery out of ur backpack and plugging into the other in parallel after every 20 min or something. Leave it there for 10 min. Repeat. What’s the downside to that?
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