One for the 12v Pro's

Submitted: Sunday, Apr 03, 2011 at 01:57
ThreadID: 85388 Views:4421 Replies:2 FollowUps:7
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Hi all.
I am currently going over my camping power system just to make sure it is up to scratch, and just to make sure it is the best suited for my application.
I currently have a camper trailer with 2 x 100 amp hr AGM mounted on side wired in parralel. Now on my vehicle i only have the cranking battery, but i have an iscolator which once vehicle battery is right, it will send power to the rear of vehicle where there is an anderson plug which conects to anderson plug on trailer which sends charge to batteries. I am buying a new car soon and am wondering if this systems is sufficient and i can pull the vehile based gear out and put in my new car, or maybe there is a better alternative out there, and i update this system. I have read about the CTEK D250s DC to DC and this seems like a reasonable set up. Whilst i have a fair knowledge on 12volt i am not a 12v wizard and would appreciate any feedback on my situation.
My thoughts are that maybe this Ctek thing could be mounted on camper near battteries, with same anderson plug connection to vehicle used. From whaat i can understand i would not need the vehicle Battrey isolator on new vehicle. Does this sound right?
Also would my solar panel be able to also connect to ctek as well.

Hope you can understand.

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Reply By: Member - John and Val - Sunday, Apr 03, 2011 at 08:03

Sunday, Apr 03, 2011 at 08:03
Hi Eli,

Sounds like you already have a good system. The options seem to be to either keep the present controller and vehicle wiring, or to buy a ctek dual 250s for the new install.

Depends on money. Changing up to the ctek should give you better results. It includes the controller for the vehicle charging so you wouldn't need to salvage that from the old vehicle, also the "dual" model includes an MPPT controller for the solar panel, as well, it's a dc-dc charger that will deliver higher charge from the vehicle to the batteries. Lots of advantages. (If you go this way you'd need to bypass or remove the present solar controller.)

Alternatively, you know the present system works, and that's a cheaper solution.

It would be important to have good heavy cable ( at least 6 square mm) running from the engine bay back to the trailer (and good connectors, anderson plugs) whichever way you go.

You might find our Electricity for Camping blog of interest.


J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
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AnswerID: 450145

Follow Up By: Eli J - Sunday, Apr 03, 2011 at 08:51

Sunday, Apr 03, 2011 at 08:51
When you say remove the solar controller, do you mean the regulator. Why would i have to remove this?
FollowupID: 722607

Follow Up By: Eli J - Sunday, Apr 03, 2011 at 09:00

Sunday, Apr 03, 2011 at 09:00
hi John,
The current system does work. What brought me around to thinking of change , was the fact that i have recently forked out a bit of$ for my 2 new AGMs. I want to nurture these little babies, and i have read they do not like to be over charged(like any battery i suppose) This isnt a problem when i am at home as i have a 25amp CTEK. But i was more thinking when travelling on trips. With the set up i have now, there is nothing to monitor the state of the batteries and reduce charge if needed, and for what i can see overcharging batteries and nuking them, doing damage. This is wheree i think this Ctek device comes into play.
Are there advantages of running solar panel into this CTEK device, over your normal panl/regulator set up.
FollowupID: 722609

Follow Up By: Eli J - Sunday, Apr 03, 2011 at 09:21

Sunday, Apr 03, 2011 at 09:21
My solar panel has one of these on it:
FollowupID: 722610

Follow Up By: Member - John and Val - Sunday, Apr 03, 2011 at 11:20

Sunday, Apr 03, 2011 at 11:20
Hi Eli,

The ctek DC250S comes in 2 flavours. I assumed (incorrectly ?) that you were referring to the DC250S Dual which includes a good solar controller (= regulator) as well as the dc-dc charging management. As you already have a good solar controller you don't need that capability in the ctek. The cheaper version without solar capability would be fine and you would continue using your existing solar controller. I mentioned the need to bypass the present controller because if you used two controllers with one feeding the next feeding the battery, they will interact and behave unpredictably.

Regarding overcharging batteries - At present your batteries are being charged from the vehicle alternator. It will not deliver excessive charging because it's voltage output is controlled to a suitable level. In fact your deep cycle batteries would benefit from a slightly higher voltage than that coming from the alternator. There is also voltage loss in the wiring, no matter how big the cables. (Voltage is the "pressure" that pushes charge into your batteries. Current (amps) is the flow of that charge.) The purpose of a dc-dc charger is to increase the available voltage so as to increase the current flowing into the battery. In addition, the ctek provides the battery management now needed to ensure that it doesn't overcharge the batteries. Your solar panels can deliver higher voltages themselves, so the solar controller (regulator) is there mainly to protect the batteries from overcharging. It is important to have one for this reason, though some of the better ones also convert the voltages so that conditions are optimum for both panels and batteries.



J and V
"Not everything that can be counted counts, and not everything that counts can be counted."
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Follow Up By: Eli J - Sunday, Apr 03, 2011 at 11:49

Sunday, Apr 03, 2011 at 11:49
Hi John

So basically if i was to change to Ctek (to replace car iscolator)i would only be tweaking the system to make it a little more productive and effective. Would i be right in saying the ctek system would better use the power it is fed, meaning better(faster) charge times.

On the Solar side:
Would the solar controller on CTEK be better than the one on panel now.? If so what are the advantages?

Sorry for all questions, i did read your blog and it does seem i have attracted the right person to give me advice so i will pick your brain whilei have your attention. LOL.
FollowupID: 722629

Follow Up By: Member - John and Val - Sunday, Apr 03, 2011 at 13:41

Sunday, Apr 03, 2011 at 13:41
Hi Eli,

Happy to help if I can!

Why change to the ctek dc-dc charger? It will ensure that your batteries are fully charged, which both makes full use of that expensive storage cpacity and extends their life span. (Just how much extra charge you store is hard to judge - depends on the charging voltage from the alternator, which is optimised for the starting battery whose needs are different from those of the deep cycle batteries. That voltage is also determined by temperature, again, to suit the starting battery.) The ctek should deliver a full 20 amps whenever the engine is at fast idle speed or more - that's considerably more than you will get most of the time with your present setup. The ctek also includes a replacement for the isolator you already have so that's no advantage, other than saving the effort of removing it and refitting to your new vehicle.

I think one of the major advantages of using a dc-dc charger is the ability to put in a decent charge (20 amps from the ctek 250) at little more than idling speed. It doesn't seem very green to run the engine just to top up batteries, but if the other option is to carry and run a generator, I think using the generator that's already under the bonnet is a very cost effective way to go.

Would the ctek provide a better solar controller than you already have? From the specs I'm not sure whether your present one is an MPPT gadget. It looks a good unit, but MPPT (Maximum Power Point Tracking) allows the panels to operate at their optimum. I'll look further into it, or maybe someone here can comment. (We are talking about the Phocos CIS controller. It's referred to as pulse modulated and since they also offer an MPPT controller, I suspect that this one isn't MPPT, though still a seriously good bit of gear.) The ctek "dual" version does include an MPPT controller. This will deliver around an extra 25+% over a non-MPPT controller, but then, maybe you've already got one of those!


J and V
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- Albert Einstein

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Follow Up By: Eli J - Sunday, Apr 03, 2011 at 14:26

Sunday, Apr 03, 2011 at 14:26
just look at specs again (Phocos) and it says it has PWM regulation. I think you can only have PWM or MPPT> This article talks a bit about both:
FollowupID: 722648

Reply By: Battery Value Pty Ltd - Sunday, Apr 03, 2011 at 15:33

Sunday, Apr 03, 2011 at 15:33

swapping over the existing setup seems to be the go, as long as the alternator in your new car puts out between 13.6 and 14V constantly. Occasional absorption stage charging (14.4V) is recommended using your mains powered charger.

The second option also is a goer, but only if you don't travel for more than say a couple of months per year.
By saying this I presume there's a fridge being powered by the 2x100Ah AGMs when travelling?

Reason for this is, this particular DC/DC charger can lead to dryout of the batteries because the charger remains in absorption mode for up to 12 hrs instead of the recommended 1.5 to 2.
It's got a low absorption/float switch over current threshold of only 0.4A, so any small constant loads such as a fridge causes the charger to do the wrong thing.
What makes things worse is that as the batteries age, their 14.4V steady state current also increases.
There's a point in time when the combined steady state currents of your 2x100Ah batteries exceeds 0.4A.
Then the 14.4V will be applied for 12hrs regardless of any load connected or not, so the accumulated damage increases even faster.

But as I said in the beginning, if you don't travel extensively, this overcharging issue isn't as serious.

cheers, Peter
AnswerID: 450188

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