So it's a pair of small 12V sealed lead acid batteries, and a switch to run them either parallel or in series.
I'm sure it will work as a boost pack if your batteries are low, but I seriously doubt you're going to have much luck starting trucks with completely dead batteries.
That 3400 peak amps is a little misleading. Sure, in 12V you'll have those "peak amps" and maybe 1700 in 24V mode, but what do they mean by "peak"?
As for the "5 seconds starting then wait 3 minutes" is because you're massively overworking the batteries, pulling a lot more current out of them than they are designed to have for load. So the reason for the 3 minutes wait is in order to let the chemistry of the battery do it's work and bring the voltage back up to where you can use it again for a couple more seconds.
The battery inside of them is a 12V 18 AH sealed lead acid deep cycle battery. It is NOT a starting battery designed for repeated heavy starting loads.
Not the exact battery, but here is a page with an identical battery and it's ratings:
Tempest Power Security battery is a Valve Regulated, Sealed Lead Acid Battery. SLA batteries for Burglar and Fire Alarm Systems, Office Machines, Computers, Cash Registers, Solar Power Devices, Telecommunications, UPS Equipment, Emergency Lighting
www.tempestbatteries.com
My recommendation if you're looking for a jump starter pack, buy a pair of 12V packs, preferably lithium. The lithium packs have a much lower self discharge rate, and being a lot smaller they are easier to pack (you can fit a couple of the smaller ones in a 30 cal ammo can in the space next to the battery box under the commander's seat, unless you are already using a 30 cal can in that space for your winch controller and leather gloves...)
As for how to use a pair of 12V packs, hook one to each battery. That's it. Don't make things complicated by trying to figure out anywhere else; one pack hooks to the positive/negative of one battery, and the second pack hooks to the positive and negative of the other battery.
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