Brain fart considered dangerous (to life, house, batteries, and mainboard)

Hi all,

I have to confess to something so mindbogglingly stupid I have taken a few days to write this up. So please poke fun, just be aware I’m really feeling pretty stupid already, no jokes needed :see_no_evil:

So, my Reform arrived a while back and I’m having a lot of fun with it. Since I’ve been following the updates pretty closely, and Lukas has been great with giving updates, I knew what to expect and the actual hardware matched my expectations. :blush: The only thing I’d change for now is to have nibbed keycaps for the index fingers, and I think the rest of the layout things I’m just too used to can be done in software.

HOWEVER: this is the very first time I’m handling 18650 batteries directly, and despite Lukas’ best possible effort to impress on the reader of build guide & manual that these are dangerous to handle I must have made just about every mistake you can make when assembling the machine.

For starters, I bridged the contacts of neighbouring cells with my hand (ouch) which quickly made me realize that yes, these suckers are indeed quite powerful. I read some of the posts here about batteries, checked, and none of the cells in question were damaged, so lucky me. But I wasn’t finished with the stupidity.

I was already tired when I started building the machine. Yes dear reader, you are right, keep screaming “don’t do it” at your screen, I do the same writing these lines.
So when all inside the case was done, I proceeded to install the batteries. I read the notice to make sure I put them in the right way around, checked the indicators on the battery boards, and then… my brain did a thing which I’ll summarize as this internal dialog:

– So, it says be careful with the polarity, huh?
– Yeah, makes sense. Good thing I paid attention to that when taking the batteries out before assembly.
– Oh, I did?
– Yeah, pretty sure about that.
– Well I am very tired. But I mean, it also stands to reason that the part of the battery that’s slightly covered in a collar must obviously be the negative pole, right?
– Right, that makes total sense, sleep deprived brain. Let’s go with it.

Maybe it’s a good moment now to go scream into a bucket or something before continuing on… :slightly_smiling_face:

So after this little pause of thought, I proceeded to install the batteries, diligently making sure to put them into the corresponding slots the wrong way around.
You can imagine the surprise of the mainboard circuitry when I plugged in the battery packs and 28V flowed through it backwards. Sparks flew, and there was even a small puff of smoke. The whole shebang. :tada:

I quickly yanked two batteries, one out of every pack, and regrouped. There was discoloration on the fuses. I took that as a good sign; these are cent items, and were actually easy to replace. After doing that, and placing the batteries back into the holders, this time the right way around, everything magically seemed to just work. Except the batteries didn’t charge when wall power was plugged in. I only noticed that when the reform suddenly switched off on me.

So here I am, with a fresh set of LiFePo4s, a Nitecore charger, and a habit of regularly opening my laptop to slowly charge the batteries when needed. Not exactly sustainable, especially since I have travel coming up again.

The mainboard looks fine, at least I haven’t spotted any damage. So… if anyone has an idea where I could/should look more closely (even if it is “the replacement mainboard section in the MNT store”) I’m all ears.

Thanks for reading, hope your nerves didn’t suffer too much. :slightly_smiling_face:

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I managed to fry the trace between the battery pack headers a few weeks ago. Resulted in issues similar to yours, so that might be worth checking.

Thanks for sharing, this is the type of mistake I could see myself making when tired. I wonder if the new protected battery boards provide any protection against batteries installed backwards? I’m only a hobbist (no formal electronics education or work experience), but I would think diodes between the cells would provide some protection against accidentally installing the batteries backward. I know there is some forward voltage drop across a diode that would result in some power loss and need other circuit adjustments

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I think I found it! Well, let’s say I found one part that definitely suffered. It’s the D2 diode next to the LTC6803-4 battery monitor (?).

Here it is IRL, through my cheapo macro lens stuck on top of my :potato: phone cam:

Guess I’ll fix that first and then see if everything is good after that or whether I need to continue debugging.

By the way I had another close call with deep discharge the other day, due to a busy weekend where I forgot the charging schedule. Got all of the cells back from the dead though, with the help of a nitecore charger. :slightly_smiling_face:

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