I dunno. Sven is quite plausibly responsible here. After all, he's the prime partner in the activity wherein May ran her batteries down. If not for him, she'd easily have enough charge to get to the office and get the darn thing. On the one hand he's 'obligated' to do something if he's serious about not being such a douche to his hookups. But on the other hand that obligation might get him a pass on her 'I-don't-take-charity' response if he does *somewhat* more than absolutely necessary. May would be freaked out if he offered to buy her a new chassis. But she'd accept a new charge cable considering it to be just an indication that this Sven guy isn't a complete ass, and if he went further and got her something major like a new battery pack she might be mad, but she might just think he's overreacting or she might even be happy about it.
If he ambles down to Union Robotics and buys an adapter plug (or a replacement cable, or whatever) that's the minimum he can do as a considerate person. There's no need for him to be hauling May down there if she's safe in his apartment; he can just tuck her into bed with a blanket and head out. So there's no need for her to go through the stress and embarrassment of waking up with Faye and Bubbles worrying over her. They'd worry anyway of course; a proprietary charger cable is probably instantly identifiable to them as connecting Sven and May and indicating that May is or has been in trouble. But May wouldn't have to be in front of them while they worry, where the awkwardness, embarrassment, and self-inflicted stress would make her blow a gasket.
If he gets her a new battery pack, that's a little more into the territory of possibly setting off May's I-don't-want-charity response. And he can't install that himself; that'd be something they'd need to discuss sometime when she's awake, and then she'd go in for the procedure. But right now he's in the situation that would *allow* someone to buy her a new battery pack, and be *LESS* likely to set off that response than anybody else. Again, it's the "being partly responsible for the problem" thing that gets him a pass, except in that scenario he'd be doing more than just the 'being considerate' minimum.