Rechargeable car jump starter battery replacement.

[Smart_Guy]

By new here I meant modern, not newly built engines; the technology. My old car's engine is newly rebuilt and has only 100,000km (~62k miles) on it. I broke it in for 5,000km before I started going +80km/h. But regardless, to be clear and possibly go to square one in this part of discussion, I thought modern engines required less amperage to start and mine is not modern (1992). Gotta make sure of portable jump starters in the future.

 

[root]

I'd be dubious of anything that claimed a thousand amp output. Even if you think if has good quality cables.

The conductors would have to be around an inch a across to handle that sort of power!

https://www.powerstream.com/Wire_Size.

Back to the original question...
You should just buy the same battery type.

Don't try to replace with a lithium cell pack, you have the wrong kind of charger.

If your one of these is like my one, (with a torch and accessory sockets, you can usually get a lead with a plug on both ends that connects to your cars lighter socket and plugs into the input so you can float charge as you drive and keep it in good condition.

A bigger lead acid cell is unlikely to fit, and your power draw is probably limited by the internal electronics rather than the battery anyway.