La Croix Long Range Cruiser Carving Machine

Very interesting to see a different approach to charging/power switch. Do you use two charging sockets to do very fast charge? You have a charger that can max that out and what current ends up going into each cell at max charge rate?

Two charging ports ( each with its own 20A fuse ) on each side of board because

  1. You can charge La Croix board batteries with two separate chargers ( but a rare instance) with no technical worries

  2. Convenience to charge on either side of board either on ground or vertically hanging up

  3. Redundancy if charge fuse blows due to fault outside of board on one charging port (opening enclosure to replace fuse is a pain)

  4. Ability to charge two other ( lower battery capacity) boards on group rides with external DC/DC Converters ( mother ship approach)

The Samsung 21700 50Es have a nominal charge of 0.5C (2.5A) so for 6P = 15A and a max. charge rate of 1C which is 30A for the 6P packs.

But I only intend to charge up to 10A (depending on when the next ride is) with a normal charge of 5A but I can charge up to 20A using two of my chargers - one through each charging port - if required.

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Ahh interesting mothership approach. I’ve always considered mothershippin’ by towing the low capacity boards and have them brake. I would expect pretty much any board/chargers to be able to handle multiple chargers connected at the same time.

yeah - just use one (or two) of these - plug input in your board charging socket and charge other boards with unit output set to 42V ( 10S) and up to 5A CC setting. They are also all over Ebay

DC DC CVCC Boost Module

Nice diagram! Can you please share what do you use as the 1A fuses on the balance leads? I plan to add some on my build as well.

from RS Components - just solder em in balance wires near battery with two layers of heat shrink ( you hope they will never need to be replaced)

link Wire Fuses from RS

close up IMG_4396

IMG_4397

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A few more photos of one of the boards in the group build - this one has a Flipsky anti-spark switch with XT-90s plug and play concept . The electrics are complete in enclosure and it ready to bolt to deck 92053356-A123-4DDC-BCC4-91077C33DB32

IMG_4397

mark%20esc

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One of the main concerns in trying to fit 10S6P 60 21700 cells in the enclosure was deck clearance to the top of the highest point in the packs - particularly in compartments no 2 and 5 ( from front)

IMG_4107

This is the reason why we went with the 4.5 thick rubber strips fixed to the enclosure lip to provide more clearance. This rubber strip also provides very good sealing to inside of enclosure.

%20clamps%20removed

Did a trial fit of enclosure on deck with 20mm high plasticine blobs on cell pack high points with the objective to see how far the blobs compress down to when the deck is bolted on . This test gave approx. 5-7mm compression on the plasticine blobs - so this is the clearance from the highest point of the cells to the deck. Will fill this with some foam rubber .

looking%20down%20deck

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I have considered using these glass fuses for balance wires, but the ones you listed probably have better vibration resistance. Seems like they are well tested.

image

yeah I would never use a glass fuse in the enclosure

This is a great build very innovative and I like the xt90 plug with the anti spark switch.

I like the idea of this in-line fuse, here is the fuse on farnell which I prefer as they deliver for free in some cases https://ie.farnell.com/littelfuse/0251001-nrt1l/fuse-axial-1a-very-fast-acting/dp/2723063RL?st=1A%20Axial%20Fuse

That’s super helpful, thanks! One more question: Why not put the fuse at the end of the wire, i.e. between the wire and the battery? I believe the closer the fuse is to the battery the better as you want to minimize the risk of a short happening somewhere on the wire between the battery and the fuse.

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The fuse is really, really close to the battery, I guess a short in the lead wire between the battery and the BMS can be best mitigated by having the fuse as close to the battery as possible, the pic shows this in essence, the only unprotected part is between the fuse and the actual battery, an inch maybe

Oh right I see what you mean, the fuse could be closer to each terminal

Before I saw this thread, what I considered doing is soldering one leg of the fuse to the battery terminal and the other to the balance wire, so the fuse would be sitting between the battery and the balance wire. That seems the safest way of doing it. I imagine the difference between this and having one inch of wire between the battery terminal of the fuse is marginal. Still, putting the fuse at the very end of the balance wire even seems easier to do, so I wonder if I’m missing any obvious problem with doing it that way.

Not much but the fuse is not flexible like silicone wire so it would need to be mechanically fixed to something.

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seems a bit of good discussion here -which is interesting considering 99% of diy builds dont have any fuses in balance leads !

Well, same as you, I now have this connector on my board to use an external BMS:

First, @mmaner has warned me that he has had several similar connectors and they all broke down.

Second, I’m sure that sooner or later my kids figure that the rounded connector is a perfect fit for a coin. :sweat_smile:

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so why do have the male version with exposed pins and not the female version socket?

Good point. The other way around would make a whole lot more sense, but that’s just the way this particular connector works. The female part doesn’t have the panel mount. I would have to modify it… which might have been worthwhile. I just never really thought of swapping them. Thanks for the idea.