Are you saying a battery trickle charger/monitor should not be attached to these points under the hood?
No.
I was discussing a *load* (such as a tire inflator), not a charging device.
However, the "it's not fused" still applies.
(We also could move into the philosophical realm of "what i might recommend versus what i might actually do" coupled with "how well does the recommendee understand the operations and consequences of what they're thinking of attaching?"
Personally, i've only used a barely adequate solar-powered battery maintainer. They're so whimpy there's no way they could hurt the Sprinter, and (since i use the 12v socket on the dash) there's a 15 amp fuse in the socket's circuit so that even a "catastrophic failure" of the solar device would be handled "gracefully". In the winter i don't even use that.
What i do for my T1N (which can easily take over 2 months of unattended "sitting there") is go out every month or so (weather permitting) and attach a "real" 4-stage charger to bring the battery up to "full". MB recommends disconnecting both ends of the battery from the Sprinter when charging. I don't do that. I *do* however, visit the Sprinter every half hour or so to see how it's doing. The T1N does not have the easy "negative disconnect" that the NCV3 has.
Mitigating *my* choices is that i street-park, so running 110vac out there as a permanent fixture isn't available. Now that i have 200 watts of solar on the roof, i *could* add a Trik-L-Start kind of device, but i'm not bothering to. A monthly charge or 1 hour errand is more than enough to keep it happy.
--dick