Just for some counterpoint... 
Although the TVS is cheap, even for quantity 1, the cost of repairing an engine from operator-inflicted problems can be very high. There's a potential hidden cost every time a less-than-skilful operator unbuttons an engine, whether it's to add a TVS or replace a (perfectly good) battery with a BCR.
BCRs are fine, however, new batteries don't need replacing until they're too old to take a full charge.
Even dropping an engine's trucks to replace a traction tire can have unanticipated consequences.
I never recommend opening up an engine unless it's necessary to effect a repair or do something else that is absolutely necessary.
