Ah okay I see. Yea I dont think that will be a huge problem in my application
Do you guys think that using a buck converter from 48 to 12v then run a 12v inverter would be terribly inefficient?
The 48v options are so expensive and large/heavy.
I think this “situation” is quite unique. So what do u think would happen if “next cell group” or battery would be “a bit further” from the “main pack”?
I think electricity would flow anyway it would be a question about how much extra sag or power limit it would create
Yeah it will be pretty inefficient…
The problem is you would be converting from 50V DC to 12V DC to 120AC to 42/50V DC. Each step has losses. And when you have problem regulators in line like that they are always drawing a small amount of current. If you have just a single regulator, it won’t pull any current with no load. But if you have them back to back, they feed each other continuously with a “ghost” current. Example: I have a 50V to 12V BEC that draws zero amps with nothing plugged in. But if I plug in a 12V to 5V regulator into the BEC it still pulls some current, even if nothing is plugged into the 5V rail
Do you have a serious need for the 120V AC? What I think is a better solution is to keep your backpack at DC voltage and then just down-regulate if needed. For charging 12S boards, you can hook up your 12S backpack-battery directly. For a 10S board or otherwise, just use a step-down converter to choose your preferred DC voltage. If you still wanted 120V AC I would have it be an external option that plugs into the step-down converter
TL;DR… DC to DC to AC to DC is messy
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these generally have USB outputs, 0.5-2a absolute max. at 5v, that’s 2.5-10W of charging power. For a 12s battery that’s about 0.05 - 0.2a charging current, which works out to 25-100 hours of charging, assuming full sunlight for 24 hours, which obviously isn’t going to happen. The solar thing has been tried a few times and it doesn’t really work out.
EDIT: and that’s assuming 0% power loss when converting up to 50V
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You can avoid AC altogether if all you want to do is provide board charging, along with a booster to 60V, the dps5015 with 60V input can output 50V which will give 4.16v/cell for 12S. You can mount the control/module to be accessable externally with ports, and program multiple charging profiles you can just select for whatever you wanna charge
https://www.amazon.com/dp/B076ZJX1YZ/ https://www.amazon.com/dp/B0744BT79M/ https://www.eevblog.com/forum/testgear/testreview-of-power-supply-frontend-dps5015-50v15a/
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Okay so I am not going to put an ac inverter on just yet. I’ll save that for later. Here is some progress.
I spent a while breaking down old packs and re heat shrinking them so they look nice and don’t short together. I went with a 12s9p with all 25r cells.
I had a bunch of dead cells which I threw out. These are all in the 3.8-3.9v range. I’m using the cutout from the drone to house the battery, I will also be using fire proof wrap and more shock absorption. I also attached my waist strap
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What weigh do u predict for this bag / batt pack? 108cells sure is a lot…
PS do u use mudguards for your emtb? Seeing just the chains on the wheel, for the board in background 
It weighs in at 11lbs in total right now and it is super comfortable I could have added more cells I feel like.
I don’t have mud guards, do you have any to recommend
11lbs doesnt sound that bad.
Well, im “fabricating” my own now, though they are super ghetto with screws and aluminium pipe attaching the fender / curved shape.
Otherwise there are a few designs for evolve type hangers and tires, if u got the commitment, ask some of the korean guys to send u the files if they can, they do have really nice, robust design in my opinion l.
Looks a bit like these overpimped japanese trucks (the board with all the lights)… but well… It sort of suits the style of the overall board
Top view for these flat fenders dont look that good, I agree… so curver shape is better but im not sure where to find one for bigger tires
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That looks pretty cool. For my purposes I don’t need fenders, I expect to get messy when I ride. That trampa is 4wd so no reason to fight it
quick question.
if the extended pack is made of up different cells, would the main pack and extended pack, when connected together, balance each other as you drained them?
that’s to say, let’s say the main pack installed on the board is made up of 30q cells, has continuous discharge of 100a. the extended pack, let’s say, are made up of reclaimed cells, has discharge of 80a. when connected together, would they discharge at different rates, but would get balanced out since they’re connected in parallel?
That’s an interesting question. I think they would drain at the same rate. I feel like that’s a good theoretical question. But both of these packs are 25R so that shouldn’t matter in my case
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The draw would differ only if it hits a point where the load induces a different resistance between the packs, all other things being equal
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cool, it’s just this idea of yours had me thinking about an extension pack that would go top center of the board, made of cheaper cells but at like a 7 to 10p configuration.
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but that delta would only be momentary until the two packs get to equilibrium?
Time, I’m not sure about. If it’s a large P pack we’re also talking about pretty high loads to get to that point. If they’re huge 25r,30q packs you would need to be sustaining crazy amps
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25R and 30Q have different internal resistance. You would always be drawing more power from the 30Q as the 25R have a higher resistance.
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A little off topic, assuming a 5a charger what would the time to full difference be between a 10s4p and 10s7p both 30q?
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7p-4p=3p 3px3ah=9ah 9ah/5a=1.8hr 1hr 48min
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