Looking for advice on using car batteries to power a system

I have recently found out about an installer using two 12v deep cycle caravan batteries to power a system on a building site, where the gen was turned off during the night, the batteries were then swapped daily and recharged elsewhere.

Was looking for more info on how it would be connected or any advice or someone with experience such as the size of the batteries, recharging, and what equipment used? This would be used only in areas with no access to any other means of power.

It would be used to power a Hikvision TVI DVR, between 1-4 TVI cameras, between 1-4 PIRs and a 4G router. All this equipment is 12v.

As well as means of charging the battery through solar?

Thanks in advance.

I've not done it personally, but know people who have. I think the universal thing people have been doing is to swap the batteries out on a regular basis, not charging them at the same time as running the equipment.

It should be fairly easy to calculate what size batteries are required. If everything is 12V, add up the Amps of everything, work out how many hours you want the system to last for solely on battery energy. Add a margin of error. Add another margin of error

You can either use something such as this: https://www.orangesecurity.com/product/accessories/other-cables-connectors/dc-plug-pigtail/ or https://www.orangesecurity.com/product/accessories/cat5-video-baluns/dc-plug-screw-terminals/

to connect the power into your devices. The router may be the only thing these won't work with - often they have a different size connector. I'm sure you can find what you need for that...or just sacrifice a power supply.