Thread: DC-DC charger- which one?

Originally Posted by Silenceisgolden

Nor can Drivesafe or Blknight understand it, but it is not that complicated really. The requirements of the house battery and the cranking battery are quite different, and hence different types of batteries are used and require different charging regimes.

If it is so 'simple' then why is it yourself and others do not seem to be able to articulate it?

House battery and Main battery are different "how"?
Because its all the "way back there"?

Again, all data, physics, electrical theory (and practice) show that a house battery can and will be charged if sufficient cabling, clean connections and installation are up to scratch.


By your (and others) arguments - no DBS not utilising a Dc-Dc device can function - yet tens of thousands of vehicles have proven this to be incorrect...

Several users on this forum are running DBS using multiple brands of isolators (Traxide, Redarc etc) and successfully maintained and charged multiple batteries both in vehicle and in trailers/caravan.

We went 10 days on 2 house batteries (2x90ah AGM), linked to 2 aux D34 Optimas in the vehicle, as well as the main factory battery.

When we left the Van had run down to 12.3v (left disconnected for too long pre-trip) and by the time we had done a few hours travel on day 1 was at 12.6v...

Day 2 saw the house batteries and aux at 99% SOC on the gauge....

Considering the system in the van is always drawing (fridge etc) and has no solar currently - this system is working just fine..


A week long trip to Maralinga, without van, saw the Optima set up run camp lighting, audio, fridge (as freezer, mmm Ice creams) without interruption.


For better or worse, my vehicle has never seen a battery charger for a top up, does a combination of short and long drives (M-F the total distance per day is 4.6km) and has a rested voltage at the main of 12.73v as of 15 minutes ago...

The aux system is sitting at 12.74v

Not a Dc-Dc device in sight

Yeah but, specification envy, the driver of all new gadget purchases...triple the cost of the widget for a few % gain in perceived performance and you'll sell them in their thousands... remind me why people buy D4s when there's a perfectly good horse/Model T/series/D1/D2 in their garage...

9 pages in and no one has mentioned installing a Flux Capacitor...worked well in the DeLorean ;-)

Disclaimer: This might not be educational nor factual.

Originally Posted by SimmAus

9 pages in and no one has mentioned installing a Flux Capacitor...worked well in the DeLorean ;-)

Disclaimer: This might not be educational nor factual.

but it is amusing

Originally Posted by Tombie

By your (and others) arguments - no DBS not utilising a Dc-Dc device can function - yet tens of thousands of vehicles have proven this to be incorrect...

Look, no-one is saying that the older technology doesn't work. I have an old technology Defender and it works very well. I also have a new technology D4 and it works better.

That's all there is to it - modern technology usually does have benefits, but that doesn't mean that the old things were complete duds.

But is is silly for users of old technology to state that new technology is all just advertising B/S.

Originally Posted by Silenceisgolden

Look, no-one is saying that the older technology doesn't work. I have an old technology Defender and it works very well. I also have a new technology D4 and it works better.

That's all there is to it - modern technology usually does have benefits, but that doesn't mean that the old things were complete duds.

But is is silly for users of old technology to state that new technology is all just advertising B/S.

A D4 doesnt work any better than a Defender... Especially MY for MY...

And the claim that Dc-Dc is new technology and therefore better is misleading.

Dc-Dc tech has been available for a long time, its just commercially cheap now.

By your logic (implied in the post) - Active ECU controlled Alternators (latest tech) should be superior to old tech (Dc-Dc converters).

There is a claim that the "new tech" Dc-Dc charger works better...
Yet this contradicts the exact benefits of other systems... These Dc-Dc systems introduce:

• Restricted current capacity
• Increased charge time
• Restricted to specific battery type mix (must be selected on unit)

It provides a sub-optimum result for the end user... Both physically and financially... When the capital outlay of improved cabling (biggest issue in poor 12v charging) and connection would see the user happily for reduced cost and complexity.


The biggest benefit to Dc-Dc systems is installers can use sub-optimal wiring and get away with it (most of the time).


Explain to mehow a Bickie Dipper; many of which do only 3-4 hours driving a day, pumping 25ah via a Dc-Dc converter into a battery bank of 2-4 batteries (assume 300-400ah) and free camping using 50% of their capacity - therefore 200ah consumed (tv, laptop, radio, lights, microwave etc) is going to charge their batteries to even remotely 80% SOC in that time?


The only way they will remotely get there is Solar, and a decent amount of it...


Their alternator, unconstrained by a Dc-Dc device would have been throwing much more current out there in that 4 hours....

Originally Posted by Silenceisgolden

But is is silly for users of old technology to state that new technology is all just advertising B/S.

It would only be silly if the new technology had tangible (or indeed any) benefits over the "old" technology.

A perspective from an installer of Thumpers (portable DBS) - clear and to the point. They are another industry player that makes their bread and butter from doing this day in and day out. If Tim's and Dave's extensive experience are not enough to convince then perhaps another similar player will lend weight to convince:

[ame]http://www.home12volt.com.au/uploads/2/6/0/5/2605767/dc_chargers_and_the_alternatives_-_vehicle_charging.pdf[/ame]

In short they do not advocate DC-DC systems. They do advocate properly understanding and assessing when you might need one though.

With respect to D4 alternator voltages sticking at 12.2V, Get the software update and fix the issue so the alternator can do the job it was designed to do. Regardless of whether or not the battery is lasting at this voltage, the point is it will last longer if this is fixed. With the patch installed, there will be no need to have this discussion.