DC-DC chargers Redarc or Ctek

[LiveFreeAndRoam Avid PP Poster! Find all posts View Profile Close LiveFreeAndRoam]

Andrew, LeighW... Yep, that's a fair enough comment re current draw.

On that, I would be interested to see the results of an ammeter showing what current is being drawn by your aux, from say half to full. Sorry if you've posted elsewhere on this topic, I haven't searched.

LFaR.

[gumboot Avid PP Poster! Find all posts View Profile Close gumboot]

Is your sure power one of the ones which was recalled? Might mean you can get it replaced through ARB or you could get a credit for it and put it towards a BCDC

No mine is before the bad batch.
Cheers

[gumboot Avid PP Poster! Find all posts View Profile Close gumboot]

Wow I go away for a day and all these responses. Thanks Guys much appreciated
I just got Leigh's voltage boster and it is much better now than before.
I was looking at a DC-DC Charger for 2 reasons
1. To better and faster charge the battery. Especically if a fridge is sucking its juice while camping
2. I want to run a solar panel at a later stage and the ctek acts as a solar regulator as well.
But I also see the downsides of it is not reccomended to install Under the bonnet.
So I will hold fire until I test Leigh's Voltage booster some more.

Another question. I have the orginal Toyota start battery and an wet cell excide extreme deep cycle as my aux.
I am looking to put an optima D27F AFGM in as my start and keeping the Wet cell deep cycle aux. Any issues with mixing the types of batterys. I presume the optimas just charge faster. The other option is a Century 4WD HD overlander Wet cell (~$200) verses the optima D27F(~$430ish) . Is the optima worth twice the price?

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Hi gumboot,

If your not going to use the optima to run accessories, just for starting I go
for the century and save some cash.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

What I would really like someone to explain to me is this:

For decades hundreds of millions of cars have been produced and almost all of them would have had an alternator charging the battery, despite the combined wisdom and research capabilities of all the car companies combined; this set up has remained much the same.

So when we decide to put in an auxillery battery we supposidly need a system that can charge the battery in a multi stage arranement to give it optimum charge......... blah blah blah. So whats the difference? why has the system that has worked fine on countless millions of vehicles all of a sudden not up to the job? Yes you need some sort of isolation switch to ensure you don't flatten the crank battery and although I have a Smart battery isolater I could argue that even that is way overkill for the job. So my alternator charges my crank battery until the pre set voltage is reached, then it starts to charge my auxillery............ same thing, differnt battery as far as I can see.

One of the argument is battery life, this is so hard to prove as the variables in why a battery carks it are so varied. Anyway my wifes Rav is nearly 7 years old and still has the OE battery despite only ever being charged by the alternator, how much more life could you expect from a battery?

So tell me what am I missing, whats the hidden secret as to the magic of these DC DC chargers, I read everything trying to work out why they are so good but I just can't work it out

Cheers Andrew

[rob_macca67 Avid PP Poster! Find all posts View Profile Close rob_macca67]

This has been good reading... but I am curious about one thing.... I would have thought one of the main advantages of a DC-DC charger would be the "size" of cable required from the main Battery to the primary side of the DC/DC charger. If u have a Van or a Campertrailer and u want to get your batteries fully charged in the C/T-Van, then installing one of these DC-DC chargers in your CT/Van would be a benefit in the way that u hopefully wouldn't experience the Voltage Drop that may occur given the long cable distance involved from Alternator to Batteries in CT / Van. I haven't looked into the specs, etc, but I assume there would be some input voltage tolerance (ie +/-) while still maintaining the proper output charging voltage...... would that be correct? or am I totally off in my thinking?
rob

[404pug Avid PP Poster! Find all posts View Profile Close 404pug]

Slightly off topic but related..... I run an ABR battery box inside the car and it works fine running off the heavy cable it comes with and with its built in isolator BUT I have found that if it has run the fridge for a day or 2 [as it will with the 105amp gel battery in there] it charges up much faster if I plug the fridge into one of the car sockets rather than into the battery box. ie. all of the charge is going to the aux. battery and none is being lost to run the fridge. This does not have to be done for an overnight stop but if I have been stopped for 2 or 3 days it makes a huge difference to the charge it gets when driving after a big discharge.[V6 not D4D]. Neil

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

This has been good reading... but I am curious about one thing.... I would have thought one of the main advantages of a DC-DC charger would be the "size" of cable required from the main Battery to the primary side of the DC/DC charger. If u have a Van or a Campertrailer and u want to get your batteries fully charged in the C/T-Van, then installing one of these DC-DC chargers in your CT/Van would be a benefit in the way that u hopefully wouldn't experience the Voltage Drop that may occur given the long cable distance involved from Alternator to Batteries in CT / Van. I haven't looked into the specs, etc, but I assume there would be some input voltage tolerance (ie +/-) while still maintaining the proper output charging voltage...... would that be correct? or am I totally off in my thinking?
rob

This is another one of the scientific reasons to install one of these units, for it to be of any value you would need to fit it near the battery in the CT, if you already use one in your vehicle you would need a second for the CT, salesman must love this.

Anyway the trailer argument actually makes it past my basic common sense test, unlike the in car unit as i talked about above. Yes voltage drop is real, we have all seen inverters so we know that you can turn low voltage into higher voltage..... gee this sounds like it might be good thing, should I order one?.......... At this point it might be worth letting people know that I used to be a paid up subscriber of the sceptics society but I discontinued my subscription because I thought they took too much at face value.

After it passes my common sense test next is, will it pass my "past experiences test". So here is the situation, I have a hydraulic tipping trailer with a hydraulic pump unit that is effectivly run using a starter motor, not sure on the actual amperage draw but its a lot, 3 figures for sure. The battery in the trailer is charged through my Anderson plug direct wired to the cranking battery using wire that by anyones measure is so pathetically small that I may well be asked to leave the forum for embarrising myself and bringing shame to the forum, its 5mm squared (which is what a local sparky suggested many years ago). Anyway a couple of years ago I was shifting a lot of dirt, load the trailer with a Front end loader, drive 3k tip it off, reload at that spot with crusher dust, drive 3kms tip off and around we go again. 30 trips so 60 tips in 1 day. When I went to tip the very first load the battrey barely had enough power to turn the pump and I had to manually help lift the front of the trailer to get it to tip, anyway with each succesive tip things just got better and better as the battery charged up.

So my point is, I had no DC DC charger, a flat battery to start, running an accessory with a huge current draw and wire hooking it up that is pathetically small and yet it worked. Crikey just imagine if had used the generally recommended 6 B&S cable.

Now why was it that I was going to waste.... eer i mean spend money on a DC DC charger? Buggered if I can work it out.

EDIT: one of my favourite things is a scientific theory called Occums Razor, this basically says that no more things need to presumed exist than absolutely nescessary. The best interpertation of this and the one I use is that, If there are 2 answers that satisfy all the criteria of a question the simplest answer is usually the correct one.

Cheers Andrew

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

This has been good reading... but I am curious about one thing.... I would have thought one of the main advantages of a DC-DC charger would be the "size" of cable required from the main Battery to the primary side of the DC/DC charger. If u have a Van or a Campertrailer and u want to get your batteries fully charged in the C/T-Van, then installing one of these DC-DC chargers in your CT/Van would be a benefit in the way that u hopefully wouldn't experience the Voltage Drop that may occur given the long cable distance involved from Alternator to Batteries in CT / Van. I haven't looked into the specs, etc, but I assume there would be some input voltage tolerance (ie +/-) while still maintaining the proper output charging voltage...... would that be correct? or am I totally off in my thinking?
rob

The thing to rememebr is a 20A charger will draw around 24A at 13.8V, a 40A charger around 46A.

The lower the input voltage the more current it will draw, so basically you need to size the supply
cables accordingly to minimise voltage drop, if your going to do this and have a suitable supply
voltage from your alternator to start with what have you gained?

On the other hand if you have a very low supply voltage that can't be corrected then a DC DC
charger might be a solution.

[rob_macca67 Avid PP Poster! Find all posts View Profile Close rob_macca67]

Yep.... that's what I thought but "if" u have cable that is rated to carry that sort of current or more, but over a long distance the voltage drops to below or equal to the nominal Terminal voltage of the Aux battery in the Van, I would have thought this is where a DC-DC charger in the Van would come into it's own......would this be correct or not?

rob

The thing to rememebr is a 20A charger will draw around 24A at 13.8V, a 40A charger around 46A.

The lower the input voltage the more current it will draw, so basically you need to size the supply
cables accordingly to minimise voltage drop, if your going to do this and have a suitable supply
voltage from your alternator to start with what have you gained?

On the other hand if you have a very low supply voltage that can't be corrected then a DC DC
charger might be a solution.

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Yes in that situation a DC DC charger would be an option.

[120D4D Avid PP Poster! Find all posts View Profile Close 120D4D]

At this point it might be worth letting people know that I used to be a paid up subscriber of the sceptics society but I discontinued my subscription because I thought they took too much at face value.

What a gem Andrew.

one of my old lines "I used to be indecisive but now im not so sure..."

[Alan McDermid Lurker Find all posts View Profile Close Alan McDermid]

Hi,

I went through the same research process and ultimately decided on the Ctek unit mainly because it came highly recommended by a retired (so no commercial bias) and very experienced senior motor mechanic. I too wondered just how and where to mount it, particularly as in real life it is larger than the photos indicate, and came up with the novel idea of mounting it with heavy duty velcro on top of the fuse box allowing enough slack to get to the fuses if necessary. I have dome about 50,000 km including some long hot days of driving in northern WA and it is a snug and unaffected by the engine heat as the day it was installed. By using the multi step charging (i.e. battery grooming) process I am confident I will get 1-2 years more life out of my expensive batteries. BTW I recommend you get the four pole Ctek unit because I believe you can attach a solar panel to it. Hope this helps.

[BNEGXL Member Find all posts View Profile Close BNEGXL]

"Buy the science"

For those of us with a few years up, it reminds me of Peter Brock's "Energy Polariser".

Agree or disagree, you can convince yourself either way.

Re the canceled subscription to the Sceptics Society, I rarely laugh out loud over a forum post, that got me. What a cracker!

Along those lines, my brother often says, "Just because I'm paranoid doesn't mean they're not out to get me".

I'm not sure who "they" are, perhaps the energy polariser people?

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

"Buy the science"

Re the canceled subscription to the Sceptics Society, I rarely laugh out loud over a forum post, that got me. What a cracker!

I am glad you got a laugh, event though it was the Truth and not a joke

The thing that really convinces me that these things are really not nescessary in 99% of situations is threads like this. I put up a couple of fairly controversial posts telling it as I see it. I would have thought given the knowledge base on this forum that if I was way off the mark someone would tear my arguments to shreds. This isn't the first thread that I have said similar things in and no one wants to argue with me.

I could easily come up with a scenario where these chargers would solve someones problems, but I could come with an easier, cheaper and more reliable answer in any of those situations I can think of.

Cheers Andrew