I used to really like the Quantum Turbo Battery. They recharged your flash gun in a flash which meant that you could keep shooting without missing a shot because the flash gun did not fire.
The first one I owned last me years without any problems. But I would not trust them now. The cells seem to go after 12 months. And if it is not the cells it is the circuit board. Repairs are often over £100 per trip to Fixation.
If you add the initial purchase cost which from memory was about £300 to £400, the numbers do not add up. Getting a Nikon or Canon AA battery pack is more value for money.
With a AA battery pack you can easily swap out any “bad” cell which you can’t in these sealed units.
Over the years I must have also spent a fortune on the cables which would break just by looking at them.
It is no surprise that I have not seen anyone carry one of these or the more modern equivalent, the Turbo 3 on any jobs I have been to where there have been other photographers. It used to be the must have in a press photographer’s bag but it is no more.