Can CTEK CT5 Battery Charger Be Left On RV's Battery All Winter?

Updated 07/08/2025 | Published 07/01/2025

Question:

Can I leave the CT79FR charger connected to my 2022 Grand Design Imagine XLS 22RBE all winter in Michigan? Scott in Traverse City, MI

asked by: Scott

Expert Reply:

Hey Scott, absolutely! The CTEK CT5 smart battery charger # CT79FR is designed exactly for that kind of scenario. Its a smart charger that switches to a maintenance mode once your battery is fully charged, so it won’t overcharge or dry out your lead-acid or AGM batteries over long periods. We've had plenty of customers use chargers like this when a trailer/RV is in storage, so it'll work great for that.

If you're storing outdoors, just make sure your connections are protected from snow or water. Let me know how you like the new CT5 if you end up going with it!

expert reply by: Andrew N

CTEK CT5 charger applications
(click to enlarge)

Carol

7/8/2025

Hey Scott. I’ve got a trailer on the CT5 in my unheated pole barn all winter. It stayed plugged in from December through April and kept my AGM battery at around 12.8V the whole time. No issues in spring startup. Just make sure your terminals are clean before connecting, I've heard that's important.

Andrew N.

7/8/2025

@Carol Thanks Carol, appreciate you sharing that! You’re absolutely right, corrosion at the terminals is one of the biggest culprits for battery drain over the winter. The CT5's maintenance mode makes it a great set-it-and-forget-it option for long winters.