I know most of us have cold start issues but i just recently got a new jump starter Its the start all 10k amp its amazing I jumped 13 busses yesterday before needing a recharge just throwing it out there for you guys.
We have the 5000 version of that and we were able to start a 6V92 in a Gillig with two totally bricked 8Ds. This is a huge timesaver for us instead of getting the truck, unrolling the cables, waiting 20 minutes to get the batteries up and so on.
I have 2 of those jumpers. The only things I do not like about them is, the cables could be a little longer, and it times out to quick for me, sometimes by the time I get to the driver seat to crank, it already stops. But they do a good job of jumping off vehicles.