It turned out nice and looks pretty solid (at least in the pictures). I ordered boards and parts the other day, so I'm just waiting for those to arrive now. I'll report back and share my experience after getting one together -
//Ken ________________________________ From: M100 <m100-boun...@lists.bitchin100.com> on behalf of Brian K. White <bw.al...@gmail.com> Sent: Tuesday, September 19, 2023 10:18 PM To: m100@lists.bitchin100.com <m100@lists.bitchin100.com> Subject: Re: [M100] rexcpm battery I have repaired my REXCPM and now the github readme includes pics that show a good way to mount a qwiic connector and where to connect bodge wires if you want to take on the challenge of such small loose wires going to such small places. All 4 solder points are at least a reasonable chip leg, no soldering directly to delicate traces. So the wires are reasonably robust in the end. You can install & remove the rexcpm module without straining the wires. I will probably further secure them with glue sometime later but haven't yet. I don't think it's worth it just to get the connector if your original pins are still intact, even though the connector is more convenient in the end, but since my original pins rotated and broke their traces anyway, I had to do a bodge wire repair anyway. And mounting the connector seems to be solid enough by super-glueing it to the top of a chip, and by using one of the black versions of the connector which I think is a material that the glue can stick to easier. The natural colored ones look like they might be something no glue will stick to. The black ones feel like they have some glass filler, and can be scuffed to a rough texture. Seems to be pretty solid so far though I'm not testing-to-destruction just to find out. :) single https://www.sparkfun.com/products/14417 10 pack https://www.adafruit.com/product/4208 My rexcpm is running and working so I can resume testing battery life. I think it's safe to order pcbs if you want now. The dupont breakout cable is a good solution for keeping the REXCPM side of things simple and stock, and adding the single wire for gnd is easy, reasonably safe against blunders, and leaves the REXCPM still compatible with it's original bus board and cable. So the bus board can keep the qwiic connector. I have tested the 102/200 board now too. good to go. I don't have a pcbway or gerbers up for that yet but will shortly. -- bkw On 9/19/23 04:29, Brian K. White wrote: > My boards came in and at least the model 100 one works fine. > > There's room, but no good way to solder the qwiic connector to the > REXCPM, so the most practical way to handle the REXCPM side is just > use the pre-made adapter cable that has female dupont sockets, and > stick them right onto the original pins. > > For the GND wire, you can treat it as optional and leave that wire > unconnected, or add a single solid-core wire to the big cap for the > gnd connection. If you use 23 gauge solid core wire, or maybe a size > or so thicker, the wire is stiff enough to hold it's shape and thick > enough for a female dupont socket to stick onto it and not fall off. I > used 23 gauge wire from some solid core ethernet cable and that was > about perfect. Other common sources, thermostat wire, doorbell wire. > > Take a 25mm piece of wire, strip 3mm on one end and bend it sharp 90 > degrees, strip 6mm on the other end, poke the wire in between the cap > and the 3 pins and solder the short bent end to the cap. > > Then the 4 female dupont wires go like this: > > black (GND) -> wire on cap > red (/WR) -> closest pin to cap > blue (RAM) -> middle pin > yellow (RAM_RST) -> furthest pin from cap > > > > It turns out you have to be very careful not to strain the original > pins on the REXCPM.. They rotate pretty easily and break the via free > inside the pcb, and then the traces break. > > At one point I was stuffing the gnd wire down from the top in between > the pin and the cap, and that put sideways strain on the pin. > > My REXCPM doesn't work now unless I hold the pins a certain way to > cause them to make contact. > > I have to desolder a few parts to figure out where two of the traces > go so I can find where to run bodge wires. Fixing the original traces > right where they broke at the base of the pins is probably too fragile > now that the vias are moving like that. > > Maybe I'll just remove the pins, fix the existing traces where they > broke, and solder flexible wires instead of pins where the pins used > to go, and secure the solder joints with glue or epoxy. Hopefully the > combination of the glue and the flexible wire, and being super careful > from now on, will be enough to keep the traces from breaking again. > > So I think the battery board is fine, and the cable connection at > least for model 100 is practical enough (I'd prefer a matching > polarized connector instead of 4 individual wires, but there is just > no good way to add that tiny connector that won't be too delicate and > just break in no time) but my rexcpm is out of commission and I can't > do any further real testing to get real current and voltages etc right > now. > > I did have it fully hooked up and running briefly before I twisted the > pins. > > I can't test the 102/200 board right now, and the pre-made > qwiic-dupont cable is only 150mm, not long enough to reach all the way > from the board to the rexcpm. You could add short male-female dupont > extensions/jumpers, but that's kind of annoying. > > For the 102/200 board, really maybe for both boards, maybe it's better > to just go down to 2 or 3 cells and full size generic 4-pin headers > instead of the qwiic connectors. > > It does work fine for the 100 version though since there is a pre-made > cable that is long enough all in one piece. > > I've updated the github with bom and pcbway links, and gerber zip for > the model 100 version. > > I say it's safe to order the 100 version at least. > > The 102/200 version I haven't worked out how best to connect to the > REXCPM yet. > > https://github.com/bkw777/REXCPM_UPS >
