at the price most booster boxes go for.. and their unspectacular performancy on anything bigger than a small auto, I long ago found it was better and cheaper to buy a cheap harbor freight hand cart and a decent 10' set of jumper cables, and a good battery.
bunji the battery to the cart, cut one end of the cables off or uncrimp for reuse, and hook tcem up to the make-yer-own repair end battery cables.
ziptie or screw on a small square piece of plywood or rubber floor matting to clip the cables too ( insulation ).. and there you have a jumper that is more cca / longer than a junky 99$ boost box with a battery the size of your fist inside it.
if you need 24v, just double up the batteries top to bottom using a piece of 2x4 to seperate them and a jumper wire post to oposite post on the bats, and sprad your jump cables top to bottom.. ie series.
usually you can do this setup for on a 12v system using a common grp31 bat and cheapy hand cart and jump cable / ends plus the bunji for about 125$.. just a lil more than the average jumper box that won't start a good size vehicle / tractor.. and certaintly not a farm sized diesel over lawnmower size.... or a big truck.
add a 12v trouble lamp and a cig lighter adapter for about another 15$ and you have light to work with and power for accessories like an air pump.
for another 15$ you could add on a 1.5a float charger to the rig, and just roll back intot he barn and plug in for next use.. or string yer own bat charger over to it... heck.. scab on one of them cheap 9$ air pumps too and have it all. air, lights and power in one spot..
mine is setup that way.. cost me just shy of 150$.. was cheaper than the craftsman power center/booster my mom got for my stepfater.. which wouldn't boost/start his duramax diesel when the battery got weak. i had the cig lighter adapter already, and used a left over wall wart for some cell phone charger.. .5a but is fine to recharge the setup. used a 9$ harbor freight air compressor, and walmart 5yr battery.. almost biggest one they had...
guess you could toss a walkman on there and have tunes too.
extra cost!
soundguy