Adding a dc battery

[Raven52]

The current system of our fifth wheel includes a dc group 27 battery, a 100 watt solar panel & a honda 2000 watt generator. The battery was purchased in July 2019 & had average usage for 2 months. It never dropped below 50%. I've read that batteries should be new when connecting in parallel. Would the existing battery be considered still new?

[twinboat]

Yes, its new enough.

It sounds like you treated it well and paralling another with it will do no harm.

[John Hilley]

It should be fine, but it would be a good idea to load test it to establish a baseline.

[Camper25]

I would test it and be sure it is ok.

[Mark_K5LXP]

Something to know is the new battery may not test as well as the used one. It takes a few cycles to "break in" a new battery.

Mark B.
Albuquerque, NM