Or was there ever an empty battery holder tube made for it or the 95 so I could just use my own 18650 cells? I’m not gonna try to open and replace the original pack myself since that’s a PITA and I don’t have soldering workspace anymore.
Replacing the entire tube is a non-economical proposition.
Replacement contact boards (PCBs) could be designed so that any cells can be used within the stock tube. The swap-over would require taking the tube apart and removing the old PCBs and cells, then installing the new components. The dismantling process is fairly easy to do, although normal snap ring pliers won’t work because the diameter of the retaining rings is too large.
I’ll take a look at my dismantled SR90 tubes tomorrow and see about making a swap kit.
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Ok, if you want to keep the stock BMS board and such, not that it’s worth keeping, you could get a spot welder and rebuild the pack in the obvious fashion. Another approach would be to use wire lead 18650s, avoiding the need for a spot welder or soldering directly to cells. Two “3P 18650” packs (in triangular arrangement) with wire leads can be used to replace the stock ones.
As for a new battery carrier, there are several ways to go about it.
The most sensible approach might be to make an insert carrier that goes inside the battery pack (body tube) between the stock contact plates. The stock contact plates and retaining rings will be used as normal, but the BMS board would be omitted from the pack. The stock tailcap could be used as normal, both the battery check function, and the charge port + external 2s charger brick.
No cell balancing will be performed, but protected cells should be used such as the SW34PCB from liion wholesale, which is inexpensive, if not one of their other models. I anticipate no issues using this approach, each cell is individually protected from errant conditions.
The above mentioned arrangement does not actually fit between the stock contact plates though. It does however fit if the rear contact plate is replaced with a new one which is integrated into the cell carrier. This will work fine because the rear contact plate is easily replaced, it’s nothing special. The stock front contact plate we want to keep and use though because it has those thick brass contacts integrated into it, without which the spring contacts in the head would scratch the traces on a normal PCB.
It should be mentioned that the electrical contact board in the head is not adequate as-is, unless they did some kind of a revision at some point. On my unit the center spring overheated and collapsed during normal use:
The center contact spring should be bypassed or replaced with a BeCu spring.
But if the head side contact plate were redesigned entirely and used different contacts, the stock contact plate with the brass contacts would no longer be needed. Going this route would allow for more design freedom. A removable battery carrier could then be used in the body tube. The retaining rings normally present in the body tube can be completely omitted and the carrier could be removed from the body when the tailcap is removed.
In any case though, rebuilding the pack will require pack disassembly and some soldering to be performed, which may be more than the OP wants to perform.
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