CTEK D250SA running parallel to BLUETTI Charger 1?

[Firedupinside]

Hi all,

First post but long time T6 Campervan owner.

Currently have a CTEK D250SA and Solar set up running to 2 Powersafe BS B14F batteries for power, however I have recently purchased a BLUETTI power bank and am now looking at installing the Charger 1, but not sure if I can run both the CTEK and Charger 1 in tandem off the main battery.

With this in mind and having watched a couple of videos, I’m now thinking if a transfer switch could work where I can run either charger at any one time and not overloading the main battery or the alternator when driving.

My question is, has anyone else done something similar to this and if so how did you wire the system?

Any guidance is appreciated.

Thanks

Jeremy.

 

[CAB]

What would be the total current if both at full chat?

That's what you will be taking from the alternator.

I've no idea what the alternator is rated for, but 1/2 to 2/3 of the rating would presumably be OK.

Welcome to the forum.

 

[roadtripper]

On the plus side the CTEK is relatively low current for a DC-DC charger compared to what's available now.

As a general rule of thumb don't draw more than 1/3 of the rated peak output of your alternator for a leisure system, and remember with losses DC-DC chargers always draw more on the input than they deliver as charging so check your manual. If nothing is mentioned assume 80% efficiency.

The Bluetti manual seems to suggest maximum 50A and the CTEK is 25A, so at 75A draw you're looking at needing a 200A plus alternator ideally, though if you are not regularly loading up both chargers you'll probably be OK on a 180A. If you have the 140A that might be an issue.

The usual solution is to put a small switch in the ignition sense line (as it's much easier there than the high current input line) but the CTEK doesn't have one (the red cable often called the ignition sense just enables the smart alternator behaviour) and as far as I can see neither does the Bluetti charger.

In fact the Bluetti charger manual makes little mention of how it protects the vehicle battery, just that it's "smart" - which is not helpful when planning a leisure system. I'd recommend it takes its power from an ignition switched source, though at a 50A draw that might be tricky.