DC to DC chargers

Hello Kav,

I have just installed a CTECK 250S Dual. I have installed as well a Victron Energy BMV-602S battery monitor which is displaying the voltage on starter and house battery as well as the amperage going in/out the house battery.

My problem is:
The CTEK is wired as on my sketch in the post www.oka4wd.com/may-2012-otr/313-solar-panel-support . No solar panel connected yet.
However, the CTEK power LED is glowing but the other LED's are not glowing showing that the batteries are being charged. After I start the engine the battery monitor does show that the house battery is being charged but not the starter battery.
I am a bit confused if my wiring is incorrect, I have to double check that.

I thought I write to you since you have a similar setup. Any idea what could be wrong?

Hi OIA, I just got back from 14 days out bush in the OKA, a few hours ago and am a bit Tired at the moment. Not sure what the problem is for you, but I'll have a look tomorrow when I'm in the workshop.

I had some problems with CTEK when the alternator was on as in it loaded up the alternator and sometimes the battery warning light flickered, but I did not do too much driving when we got to the destination and had it on solar mainly. I need to check out the wiring from alternator and auxiliary something is amiss there somewhere.

Check your wiring though, you should see the battery light up when the battery you want to charge is connected and your alternator source is connected. If that's ok and still don't see the lights on, just do a basic setup and bypass anything else to confirm the CTEK is not faulty. By this I mean disconnect auxiliary battery from oka wiring and run a neg and pos from CTEK, then run neg and pos from starter battery for the alternator supply. Start oka and both lights should come on.

Then you can confirm that unit is working. Check the sample wiring setups that came with the manual too, might help.

See how you go
Regards Kav

P.S with my 2 x 200w panels and the 2 x 120ah batteries I has ample power to run a 45L engle as fridge and a 35L engle as freezer for fish fillets to take home. A few days with no sun and a lot of days partial sun. Very happy with the setup and the CTEK as solar regulator. I could see what was going in and coming out on the displays I made with the use of shunts.

Kav

OiA, I don't want to hijack your discussions with Kav, but an observation, there's something fishy going on here.

On your original sketch I think you are showing the service and alternator battery connections swapped around. The "service" battery is the aux/house battery and the "alternator" battery is the starter battery. That might explain the lights glowing oddly.

The CTEK manual confusingly shows some configurations the other way round. I think Installation #4 is the one you want but it's not how the Oka is wired.



The problem seems to be that in an Oka dedicated starter battery set up (which you seem to have as per your sketch), the alternator is actually connected directly to the aux/service battery (and therefore supplies all the Oka electrical needs and domestic loads, except the starter motor) with the charge relay connecting the starter battery in parallel. This is the reverse of what you want, which is presumably the starter battery being charged direct from the alternator and the aux/service battery(s) being charged from the CTEK via solar or the alternator.

In your set up, the CTEK will be charging the starter battery only. It's not a huge job to rearrange the wiring but it is confusing. I don't have a CTEK to try so I hope Kav can throw some light on this.

Yes I see that too on OIA diagram seem to be wrong way round. I used the same setup as the one you have shown in your post David.

After traveling for the last weeks in and out of the bush I came back to reinvestigate why the CTEK is not doing what I think it should do. Despite my faulty sketch in my other post I have wired the batteries to the correct CTEK terminals.

Unfortunately I saw Davids comment just today stating that the alternator charging cable is wired to the aux battery and not to the starter battery in an OKA.

This might be the problem and I will run a wire to the starter battery to test.

Shows me again that I just have to study the wiring diagrams more careful.

Thanks all for the advice and information. I ditched the brand new 'uber' battery and re-configured what I had left. I ended up with SuperCharge marine batteries for the main and start battery's. Both of these are pretty new (less than 12 months old). For the 'house' battery(s) I have the 2 X 66 Ah Optima Blue Tops (which used to be the vehicle batteries) paralled as house battery 1 and 3 X 40 Ah conventional AGM's as house battery no 2. All batterys are connected together when the engine is running and are charged from the original 55 Amp alternator which gives a much better (14.2 V) output with a new and tight drive belt.
With the engine off the solar switches in to charge the house batterys.
The solar set up is fairly simple 2 X 120 watt panels each feeding its own MPPT regulator and house battery. Automatic relay switching connects/disconnects the panels and alternator when the engine runs. All very simple and redundant should components fail. Manual switching is available to connect solar only to panels if reqd.
The 12 V LED lighting is connected to the main OKA battery, the 40 litre Engel/Cool Zone is connected to house battery 1 and 17 litre Engel (freezer) to house battery 2.
We have just returned from 7 weeks travelling around the centre and this setup has worked perfectly in auto mode. The minimum voltage the house batterys got to was 12.3 volts so we had plenty of reserve and the Optimas charge very quickly so even short hops don't leave us with undercharged house batterys. It worked so well that I'm considering removing the 3 X 40 Ah AGM's and having one Optima as each house battery.

Deano

Dean
I would leave the solar connected all the time, any charge is free!! Using the alternator uses fuel and also wears it ever so slightly.
12.3v is getting pretty close to the magic 50% discharge point of 12.2v which is best to observe for longer battery life.

Was trying to post the new wiring diagram but it the PDF is not displayed correctly. Will try to post a JPG.

Not trying to suck eggs, but to avoid misleading results, don't forget the terminal voltage is an indication of the state of charge only after the battery is left unloaded and uncharged for an hour or more.

Thanks, the minimum voltage I'm referring to is the worst case, ie. taken in the morning before the engine is started or the solar has kicked in and after running the fridge and freezer all night. Also I don't reload the fridge until the morning to a/. minimise fridge noise overnight and b/. to be nice to the batterys.

I take the point re just running on solar all the time and using the alternator only as a last resort but I reckon the ability to have fully charged batterys as soon as possible out weighs the small savings on alternator wear and fuel consumption that may otherwise be attained. The other problem (using solar all the time) is that it's not 'set and forget' unless I put in a low volts sensor on each house battery to cut in the alternator or an alarm and by this time the batterys flat already. But having said that, with the OKA parked up for a few months I'll turn the Engels back on and see if the batterys hold up.

Another benefit with the solar and smart regulator is that the house batterys stay fully charged when parked up so no sulphation /flat battery issues here.

Deano

Actually solar is set and forget as long as you size the system to suit the load. When I set up the house system in 374 it was designed to be standalone and has been for three years now. We are all electric, no gas, diesel cooktop, HWS and central heating, 12v 130l fridge, LED lighting, 1800w PSW inverter which supplies the electric jug, toaster, wall warts, laptop chargers and occasional use of the inductive cooktop. We have on occasion also heated the hot water with spare solar via the inverter and 240v element. 500w of solar through a PL40 controllaer keep 480ah of AGM batteries well charged,in fact they have never been below 12.4 volts in three years. I'm about to swap the AGM's for Lithiums which will give up to 50% capacity increase, weigh less then half the AGM's and charge quicker. The Lithiums DO need close monitoring re charge and discharge points as they can be damaged at both points.