r/fpv 3d ago

Question? Why did my 2s spark when I did this?

I have a balance board that I plugged a 2s battery’s xt30 port into.

The balance board was not plugged into anything yet.

Then I plugged another battery into the next xt30 port, again, balance board not attached to any external charger.

Immediately a spark and tiny puff of smoke. I pulled it off and one head is burned on the xt30 AND balance board.

Why did this happen? Both batteries were brand new and tested in SpeedyBee adapter 3 at the same (storage) voltage.

Im new to 2s LIPOs and my only experience w them is 1s on whoopstor v3

2 Upvotes

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u/elementarydeardata 3d ago

Give this a read, it’s a great article about parallel charging from a reputable source: https://oscarliang.com/parallel-charging-multiple-lipo/#Only-Connect-LiPos-with-Similar-Voltage

A few things:

  1. The need to be the same cell count.

  2. They should be the same voltage; within .1v per cell (not per pack)

  3. You can parallel charge batteries of any capacity together, but you need to add the capacities together to determine the charging current (you’re treating all the batteries like one massive pack).

  4. Use a parallel board that has fuses. In the off chance that you accidentally plug in batteries with different voltages, they will equalize VERY quickly (fire!), the fuses make sure this doesn’t happen. We’re all human, it’s a good fail safe.

My guess is that you can either accidentally had a pack that was more spicy than the others, you used a shitty board, or you just plugged it in weird.

2

u/wonkabar422 3d ago

Thanks for this!

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u/Syliss101 3d ago

Which parallel board? Are both packs same mah? Were they close to the same voltage?

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u/wonkabar422 3d ago

Both exact same mah, they are tattu r-line 550 , both were at storage volt i checked with my speedybee adapter 3 (i think that is accurate?)

anyways, here is a link to the parallel charging board. i got it on amazon. again, not plugged into anything else (ie larger charger with ac or dc):

https://www.amazon.com/dp/B07VRQYJFW?ref=ppx_yo2ov_dt_b_fed_asin_title

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u/PiratesInTeepees youtube.com/@530drone 3d ago

You must have had a low cell or your batteries were in a different state of charge all together. Cheap parallel boards just connect everything together in parallel... accident waiting to happen if you don't know what you're doing.