CTEK - Dual Battery Setup & Cig Plug Adaptor
Discussion
Hi all.
Maybe a bit of a niche one here (or maybe I'm overthinking it).
I've got a 2025 Ram pickup truck with a separate 2nd battery for the auto stop start system.
Following its first service, Ram replaced both batteries due to failure (which seems a bit coincidental) so I'm looking how I might be able to maintain them during periods of non use.
Here in the UAE, batteries deteriorate quickly in the heat and so I've always done what I can to keep them tip top. My Panamera is nearly always hooked up to the CTEK over long weekends / trips away. I've always done that via the cig connect adaptor and it's worked fine.
I've tried the Ram via the same method and the CTEK never runs through it's full cycle and (imo) gets pretty hot. Clearly something isn't right or it's just not compatible with this kind of setup.
As I say, quite niche, but I was curious if anyone else had a car with a similar setup.
1. Are some cars (irrespective of dual batteries) just not compatible with the cig connect method?
2. Is it a fruitless exercise even trying to maintain the stop start battery? Should I really be bothering with it?
Cheers
Maybe a bit of a niche one here (or maybe I'm overthinking it).
I've got a 2025 Ram pickup truck with a separate 2nd battery for the auto stop start system.
Following its first service, Ram replaced both batteries due to failure (which seems a bit coincidental) so I'm looking how I might be able to maintain them during periods of non use.
Here in the UAE, batteries deteriorate quickly in the heat and so I've always done what I can to keep them tip top. My Panamera is nearly always hooked up to the CTEK over long weekends / trips away. I've always done that via the cig connect adaptor and it's worked fine.
I've tried the Ram via the same method and the CTEK never runs through it's full cycle and (imo) gets pretty hot. Clearly something isn't right or it's just not compatible with this kind of setup.
As I say, quite niche, but I was curious if anyone else had a car with a similar setup.
1. Are some cars (irrespective of dual batteries) just not compatible with the cig connect method?
2. Is it a fruitless exercise even trying to maintain the stop start battery? Should I really be bothering with it?
Cheers
How do the 2 batteries work together? Are they separate, parmanently combined in parallel (12v), or is there some sort of controller or relay that combines/separates them when needed? I assume there are no 24v shenanigans. Also, what size are they? Are they both the same chemistry (wet, AGM, Lithium)?
I wouldn't assume the cigar lighter socket is connected to either or both batteries while the car is switched off. You could check which battery(s) the maintainer is connecting to by monitoring their voltages - an isolated battery will typically sit below 12.6V and gradually drop, whereas the battery being maintained will typically be around 13V once it has stabilised.
If the maintainer is overheating, that suggests either it is too small for the battery capacity it is trying to maintain, or there is a significant power drain. Some maintainers report how much current they're delivering, and it would be possible to measure the current externally if yours doesn't provide this.
If the maintainer is overheating, that suggests either it is too small for the battery capacity it is trying to maintain, or there is a significant power drain. Some maintainers report how much current they're delivering, and it would be possible to measure the current externally if yours doesn't provide this.
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