Battery To Battery (dc To Dc) Chargers

[widu13]

Hi All,

This topic has been done to death, but...looking at LOTS of posts; specifically the CTEK 250S series, advice has changed over time since 2016 including the posts from the top contributors and pros and I have observed that posts exist with a few different wiring scenarios. This is of interest as I am considering swapping out the Durite VSR already installed on my conversion and I am hoping to use the existing +ve cable from the Leisure batt so I don't need to pull the camper apart to install more wire. The wiring scenarios already in use on the forum are:

1. Vehicle +ve to CTEK +ve, CTEK -ve to Leisure -ve with no ignition live feed (Shown in the installation instructions)
2. Vehicle +ve to CTEK +ve, CTEK -ve to chassis Earth with no ignition live feed
3. Recommendations for both of the above WITH ignition live feed (With 1, above shown in the installation instructions)

Does the -ve need to be common or will chassis earth suffice?

Running on the premise that the charger is smart, if an ignition feed is not fitted, then surely that will simply pull from the Veh batt and cause the Alternator to kick in anyway and not pull with the engine off? Or is it a case that the charger will simply act as a VSR if there is no ignition feed and not charge the Leisure batt fully?

My questions are:

1. Can I successfully use a CTEK option 1 or 2 above without the ignition feed to minimise cabling up and reuse existing wiring?

2. Can I use the same cabling scenario for a Victron (which has monitoring)?

Cheers

 

[Deaky]

The ignition feed is required to signal to the CTEK that you have a smart alternator installed. If you don’t connect it you may as well stick with the VSR that’s already installed

The chassis earth will suffice.. it is common after all .

 

[Dellmassive]

1. Vehicle +ve to CTEK +ve, CTEK -ve to Leisure -ve with no ignition live feed (Shown in the installation instructions)
2. Vehicle +ve to CTEK +ve, CTEK -ve to chassis Earth with no ignition live feed

- these are effectively the same, the chassis IS the common ground so Starter battery, leisure battery, DC-DC all need to be connected to the chassis on one way or another . . .

"3. Recommendations for both of the above WITH ignition live feed (With 1, above shown in the installation instructions)" - if you have stop/start then you will need an ignition feed for this system to work effectively.

"Does the -ve need to be common or will chassis earth suffice?" - yes it needs to be common, the chassis ground will be common.



.

"Running on the premise that the charger is smart, if an ignition feed is not fitted, then surely that will simply pull from the Veh batt and cause the Alternator to kick in anyway and not pull with the engine off? Or is it a case that the charger will simply act as a VSR if there is no ignition feed and not charge the Leisure batt fully?" - sort of . . . . it will follow this Algorithm. - but in practice you will need the ignition feed or it will not "kick-in" unless the ECM decides to charge the starter battery.

.




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1. Can I successfully use a CTEK option 1 or 2 above without the ignition feed to minimise cabling up and reuse existing wiring? -- yes it will sort of work, but not very efficently.


2. Can I use the same cabling scenario for a Victron (which has monitoring)? - yes.



more info:

Dellmassive`s -- "how I Done It" -- Thread

Kit List And Stuff -- How I Done It & What I Use --

Dc-dc Charger (for Leisure Battery) -- How I Done It --

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[widu13]

Thanks both, exactly as I thought; but some of the scenarios above were reporting the smart charger fully working without the ign feed and I could not figure out how. The answer clearly is that is doesn't.

I think I'm favoring the Victron. Any reason to chose one over another from the 5 or so main players? They all seem around the same money.

 

[Dellmassive]

weve got them listed here > Dc-dc Charger (for Leisure Battery) -- How I Done It --

mainly personal preference.

I've personally tested the Victron, Renogy & Redarc . . . . all are great.

Ctek, Sterling, Ring etc etc are all popular.

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The Cteck, Votonic & Renogy will reverse charge the starter from Solar if thats any concern.

My personal Opinion is Victron Kit is Awesome.

The Renogy is a great All-In-One.

The Redarc is Powerfull in a Small Package.

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