a lot of companies have been saying that for the past 6 months. also i got a parcel from usps a couple weeks ago which arrived in like a week. could be thats the issue just been waiting ages for this package to come.
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Is it a good idea to run an external charger/BMS combo and plug in the batteries and balance cables? I’m thinking about a simpler charging system for my dual 6S LiPo packs in series, as I currently have to charge them separately using a balance charger, which is very slow. However, I don’t have enough space to fit a BMS in the box, so I want to bundle it onto the charger instead. Here’s what I’m thinking:
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Adapt the 13 pin balance leads to 2 separate 7-pin JST connectors, so I can plug them in separately to each LiPo
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Build some sort of charger to XT90 connector that connects to the BMS, so I just unplug the whole series from the ESC
Would this work? Or is there a better way to charge them?
Why not make the box bigger?
I haven’t been able to find one slightly bigger. It’s either all around the same size, or the next size up which is considerably bigger in all dimensions. It’s currently the perfect size for the batteries, which I’m happy about.
But you could cut a hole in one side for the BMS and fiberglass over it. Some BMS are very very small.
You could also opt out of a BMS entirely and just use four of these balancing boards. They are tiny.
Then have just a fused two-wire charge port.
Ehh that’s a lot of work though, and it’s way easier to just duct tape the BMS onto the charger brick. I’m mostly concerned with tight wire routing, since 10AWG is not easy to bend in tight spaces.
In theory I could fit it in the ESC enclosure, but then I’d have to carry the balance wires up through the umbilical.
These look interesting. So I’d attach two of them onto the balance leads of each LiPo? Then in my wiring use a parallel adapter to hook up a charge port with fuse?
Yes.
You’d wire the charge port to the ESC power wires, except before the loopkey, not after it. And put a fuse in series with the 2 wire charge port itself.
Those balance boards are basically the smallest you can get with off-the-shelf parts.
Oh crap if I do this I actually need to build a proper loop key. I’ve just been unplugging my batteries when I’m done since they’ve all got XT90S connectors, and I need to charge them removed anyways. The ESC does have a switch, so I guess it’s fine to leave it plugged in all the time, and I can unplug the umbilical to cut power if needed.
Sabre sells a really good loop key
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Making one isn’t difficult, it’s finding a place to put it in the circuit. Honestly I think unplugging the umbilical is fine for me. It’s got an XT90S, and it’s inline to the entire circuit rather than needing a separate offshoot for a loopkey.
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I made one for my friend with a 3d printed keychain loop
But I guess going back to the original question, are there any downsides to having the BMS external? All that changes are where the connectors are right?
This is how i charge my lipos.
External bms. Since i have to open/renove the box either way to charge the battery or swap it out i have it external.
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Looks good, I’m not totally sure about the regenerative braking on that so I’d turn it off in the vesc tool
Regen on the battery should be fine. 1C continuous is safe for them, and that’s already 14A. I’ve seen people charge at up to 2C, which is already way higher than the regen I have set.
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Yes; nigh impossible to waterproof, large nightmare of connections and easy to accidentally connect something the wrong way.
Some folks (@glyphiks maybe?) have charge port connectors that include all the balance wires, you could also go that route. But I would just put 4 balance boards in there and use a 2 wire charge port.
Ah ok I see. I have to open the enclosure anyways to charge since there’s only one hole in it for the umbilical, so I’m not worried about water resistance as all connectors will be safely stored inside the box during use. I was planning on going the same way that @xsynatic showed above, only I might omit the XT90 input entirely for a direct connection to the charger.