DC/DC chargers, I thought I needed one.........

[KevinE]

Hi all,

I had a really nice surprise when I went in to buy a DC/DC charger for the CT from a 12V dealer here in Adelaide today & he asked what type of vehicle I was running?

When I told him a Navara & that he'd sold me the VSR & cabling I'm running, he said he didn't think I'd need a DC/DC charger & offered to check the voltage coming through the Anderson on my rear bumper for me just in case.

He checked it & told me I'm fine without a DC/DC charger, to just charge the battery in the CT through the alternator.

I'm pretty stoked!!! I had the cash all ready to buy the charger.

I guess I'm like most other people who aren't auto sparkies, in that I've read heaps & heaps & heaps of posts on the net warning about voltage drop & the need for a DC/DC charger.

The voltage at my main cranking battery registered exactly the same at the Anderson.

Big kudos to the 12V shop for such great service & and saving me $380. He could have just took my money, as I was quite willing to spend it!

 

[OzAssAssin]

That is very interesting mate.

Knowing how much time and money others have spent this is going to be an interesting topic.

 

[Old.Tony]

Must be some decent cabling running from the front of the car. Add some kudos for getting that right, too - more often than not people will say "Oh you're drawing 15A, so 20A cable is MORE than enough" only to find that the voltage drop on 20A cable over 6m is something like 1.49V (figure obtained by a voltage drop calculator, 14Ga wire, 15A load, 6m length).

 

[mitch92]

Did he have a load plugged in or just measure at plug?

If no load there is no volt drop, add a load then you get voltage drop.

V drop = I of circuit X R of cable. No circuit means no current, so no volt drop.

 

[Old.Tony]

Wait, that's an excellent point. Every time I've measured mine, I've had a load on it (and the calc I explained earlier used 15A as a load). I missed that, good catch!

 

[bods]

I'd be testing it under load too, plug the camper in and see what sort of voltage you're getting at the battery with fridge, etc running (or whatever you would have running normally). That will be the real test and you may find you do need one. If you want to mount a solar panel on the camper permanently then it probably wouldn't hurt to get one anyway that has solar input too...

 

[sparra04]

dc/dc will look after your battery and charge it to capacity giving you a longer battery life
an alternator will never completely charge your aux batt
it will work fine
but dc/dc is the preferred method