Now, nothing is safe from a stray short. Modern NIMH batteries, particularly the ever-popular low self-discharge types, will gladly give you 10 amps. In a pack, they can burn up thin wire. They won't last long, and the heat probably isn't good for them either, but there's a common myth, probably from when the tech was less mature, that they are a safer chemistry in that aspect, too. Lithium-Ion and NIMH are both susceptible to burning things up from that kind of failure, today (also lead acid, but lead acid are big and heavy, and people are used to respecting the dangers of those batteries). Most Lithium chemistries suffer from potential for thermal runaway, with fire and noxious fumes, on top of that, though.
