dc-dc battery chargers explained

rockylizard · Guru

dc-dc battery chargers explained

03_Troopy · Guru

That looks like a pretty good explanation for anyone who wants to understand why a DC-DC charger is a good idea. Well worth posting John

Cruising Cruze · Guru

Hi John

Thanks for that info

It will help a lot of people here

Cheers John

justcruisin01 · Guru

Been running two of these for a few years now, the only way to go.

JC

Vince · Senior Member

I am using a Redarc BCDC1220 DC-DC unit in our Tug and found it works a hell of a lot better than the previous dual system Rotronic setup.

As the info rockylizard has linked we found the DC-DC unit keeps the auxiliary battery charging at the 14.4v while driving, it also has Boost and Float function.

Very happy with the Redarc unit.

Vince

greyhoundtom · Senior Member

Excellent article, thanks for sharing.

Cheers, Tom

Sharke · Senior Member

If you decide to do a DIY installation and you have a late model vehicle like a Toyota or Ford they have a smart alternator installed. Smart alternators are temperature and voltage controlled by the ECU and have a temp sensor in the engine bay also only supply a maximum of 13.v volts to load and maximum to battery. This can be solved by installation of a relay to control start battery. You will need to check if your alternator is smart.
www.baintech.com.au/faq/can-i-use-a-ctek-d250s-dual-in-a-vehicle-with-a-smart-alternator
cheers
Jeff

-- Edited by Sharke on Saturday 19th of September 2015 02:49:41 PM

greyhoundtom · Senior Member

Checked that link but can't see a reference to any listing where you can check if your vehicle has a so called smart alternator.

And while it pushes the use of a relay to switch between two separate power sources, this would be more important in situations where both the cranking battery and the secondary battery are in the same vehicle.

In most instances where the secondary battery system is in a camper or van the connection between the vehicle and the van would be broken anyway, so a relay should not be necessary.

Cheers, Tom

PeterD · Guru

There is no problem working out how your alternator behaves. Get yourself a plug in meter like this one. Plug it in before you start the motor. Observe the meter after starting the motor. If the system voltage drops to less than 13.8 V at any time whilst you are travelling then you need that that relay if you wish to use the D250S

And while it pushes the use of a relay to switch between two separate power sources, this would be more important in situations where both the cranking battery and the secondary battery are in the same vehicle.

This system is for remote use in vans and trailers. Standard basic DC-DC chargers use the drop in alternator system voltage to isolate the charger from the starting battery when the motor is switched off. The problem is the newer vehicles drop the system voltage to below the D250S running voltage. The relay contacts route the alternator supply to the solar input and the regular alternator input is ignored. This fix is specific to the D250S and most likely will not work with other models.

greyhoundtom · Senior Member

Thanks Peter, as always clearly explained.

I'm getting a great education about the functions and pitfalls of low voltage, batteries, and charging systems in this place.

Cheers, Tom

mr glassies · Guru

i have a 40 amp one in my van

dibs