Exploded button battery in DEC2750

[Scandiravian]

I purchased a DEC2750 back in March 2022. I recently noticed that the bios was getting reset when the unit lost power, which 99% of the time means that the onboard button battery has died.

Since the warranty had expired I decided to simply replace the battery myself. When I unmounted the unit from my rack I noticed that something was rattling around inside the case. When I opened it I could see that the button battery has apparently exploded and ripped the battery holder of the board itself (see pictures below).

Obviously this is not ideal. I've cleaned the board and case of any leftovers from the battery, but I'd obviously like to avoid having to redo all my bios configurations every time I have to turn of power for the unit.

I am alright with a soldering iron, so is it possible to fix the board? Perhaps with a new wired battery holder if the original pads are unusable?

[drosophila]

I've read somewhere about the case of a button cell exploding. Seems to be rare but not impossible. Likely it got an internal short due to manufacturing deficiencies, overheated and then went *bang*. That however proves that these are quality batteries, in the way of them being capable of delivering high currents, compared to the cheap things you usually get in stores that have such a high internal resistance that even an LED won't burn out if connected directly across the terminals. Whether this low Ri actually is useful depends on how the hardware works, some boards (very old ones) seem to have powered their chips from that battery for a brief period during boot, and thus cannot boot reliably with one of the cheap ones. Yours seems to boot fine without the battery and thus the cheap ones should suffice.

Anyway, since the board is still working and the pads look fine (the pad that got torn off doesn't seem to have any connection, so it was just for better mechanical stability, unless the vias are unnecessarily tiny), there should be absolutely no issue with replacing the battery holder by any means, so just use the remaining pad (there must be a via inside it), the golden center pad must be the other contact so you could solder directly to those two. From the looks of it, positive goes to the remaining side pad, while negative goes to the golden center pad. Once it works the holder should be secured with power glue to reinforce it mechanically. Since you still have the original holder you could just re-solder it to the remaining pad and glue down the other pad with super glue.

But be very careful with the soldering, especially with too much heat or too long exposition (adjust wattage if any ground planes suck away heat, don't heat it for minutes on end instead, this may make the board delaminate and/or char!), especially with the tiny components sitting right next to the pads, plus be paranoid for any sprinkle of solder that may end up sticking between the tiny pads of the RAM socket or other things. Possibly try to shield them from solder splashing (may happen if the flux got exposed to moisture), maybe using stickers made from paper (avoid plastic to reduce static electricity).