battery recon query

[omodos]

happy new year to all, okays not managed to replace whole lock/latch mechanism from last year but for now i can manually unlock driver door and rest open close with fob...since then also starting has been a tad sluggish....starter replaced not too long ago, but battery a long time ago.....quick question if i want to try recon old battery is it agreed not a good idea to do this whilst the battery is plugged in wired in car as the ctek may pump out more during this phase and mess with other electronics in x5?


i dont have a closed space so cant rip out the existing and leave car unlocked and rear open during this process....so could slapping in engine bay a baby working battery from a smaller ie simulate a jump start and then removing old one for service and leaving small one in allow me to lock unlock car you think?