The battery builders club

No way to know as it depends on the current level, the cells, cell temps, and the age/condition of the cells. It’s not easy to send a high-performance pack into runaway just by shorting it but it can be done. Could be a second, could be a minute.

But in my completely uninformed opinion, with no real data to support it, the VESC would blow its pcb traces or components and break the connection before the pack went into runaway.

Only if it will open quickly enough at the estimated short-circuit current level at the anticipated ambient temp.

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i was reading about micro solid state protection devices… wht do you think about those?

Link?

Anyone have a 12s4p or 12s6p pack for a top box for sale?

If not who’s the go to person to get a custom battery done?

Been looking at skp they seem to do great stuff

If you can tolerate going 18S, ive got an 18S4P topmount pack for sale lol.

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Yea super strong the copper stayed on the cell as the rest ripped away. Fyi its alot harder to bend or tear 0.5mm copper than you may think.

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If it’s still available in a few weeks I might go for that, it’s just a little bit out of my price range rn, being as id have to get a new vesc too :pensive:

I just lost my job so I was going to go with something like that but not anymore

I set an erpm limit on the esc, and spun it up unloaded, when it reached the limit very suddenly, there was a click from the motors - wrong signal or potentially a lockup.

One of the battery in 10awg cables literally blew off the PCB, and it’s about a cm shorter than the other cable which stayed attached…


It also got hot enough that it put a hole through the aluminium heatsink…

@tuckjohn had a similar failure on his d100s, same esc, except his went up in flames for no apparent reason during chill riding.

edit: i got a replacement from makerx on the way

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Pics for reference. Maybe we should start a thread


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Oh geeeeezee that’s wild. My test was with a stormcore and those are not aluminum PCBs. Maybe that’s the difference? Either way this info is very valuable and new to me.

What firmware were you both running at the time?

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both of us on 6.02

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Havnt played with this board for a hot minute so thought i should bring it out only to discover this.

Little charge… on the lawn why not… little ride…

Damn. Course of action? Replace BMS first before pulling it apart?

Pull it apart now?

Get well clear of the whole thing and build a new battery?

What amount of variation is the bms allowing? Id decrease it and see how it goes then while charging

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Hello,

I am looking to build a battery pack using molicel p42A in a 10s2p format and holding the cells using the battery holder brackets that you buy on amazon. I am looking to discharge 60 amps in total which means each connection will probably need to handle 30 amps. However, since I am using the battery holder brackets, I don’t think I can spot weld nickle and then solder copper wire for the connection.

I was thinking of using 0.5mm thick copper sheets and cutting them with a width of 7mm and a length of 30mm which after calculating, gives about 40amps max. Do you guys think this would work or is there a better way to go about this?

Thanks!

Why would that be the case? Got pics of the brackets you’re using? Got pics of your planned layout?

How would you attach this to the cells?

I am looking to use something like this. For the copper sheets, I was looking to discharge the cells to storage voltage and then solder the copper to the cells.

That’s a terrible idea. Soldering directly to cells is ALWAYS going to damage the internal chemistry of the cell, the voltage doesn’t matter. Soldering directly to cells should never be done.

If I were you, I would either modify those cell frames to remove the bits of plastic that are preventing you from using a single piece of wide nickel, or I would buy new cell frames that dont prevent you from using a single piece of wide nickel. Then I would cut a single piece of wide nickel (probably 0.2mm thickness and 30mm width or more) and spot weld that to the cells.

Alternatively, you could use the ladder nickel that those cell frames are designed for. Looks like it’s designed for 10mm strips between the cells. If that is not enough current capacity for you, you could double up on the nickel for each connection. Stacking nickel like this makes it harder to get a decent spot weld so it’s not ideal, but it’s doable.

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Idk man have you assessed the datasheet?

Thank you for the advice, I think the ladder nickel would prob be easier. I haven’t used ladder nickel before is the current capacity calculated the same way as normal nickle strips?

Alternatively would this configuration be better?

Yes, just compare the cross-sectional area of the current path.

It would be if it were built correctly :melting_face:

Sorry, not to be a dick but that pic shows an unsafe battery. All those crossing connections, balance wires tangled up over the solder joints, etc, is all super dangerous, especially in esk8. I recommend reading through this thread to learn the best practices of esk8 battery building. I know it’s a lot, but you’ll pick up on the common themes pretty quickly.

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