Craig. 30 amps max for a pack.... I think I can show you what such a pack does in a high power 4WD 4 Graupner speed 900 driven FEATHER.

http://www.bugs.nl/media/album/view.php?&path=L3J3L2JydXNzZWwyMDA3L2JlLWJhYnMvV2V 0ZW5zY2hhcHNFeHBvXzA0MS5KUEc=http://www.bugs.nl/media/album/view....L2JlLWJhYnMvV2 V0ZW5zY2hhcHNFeHBvXzA0MS5KUEc=

http://www.bugs.nl/media/album/view.php?&path=L3J3L2JydXNzZWwyMDA3L2JlLWJhYnMvV2V 0ZW5zY2hhcHNFeHBvXzA0Mi5KUEc=http://www.bugs.nl/media/album/view....L2JlLWJhYnMvV2 V0ZW5zY2hhcHNFeHBvXzA0Mi5KUEc=

In other words, youll need at least 4 parallel in a heavy with a decent reduction gearing. And even then , even a good current limited speedo (like the current Sidewinder) will get those packs very very hothot.