A couple of last (hopefully) Duetto questions

by Jonny_80 Mon Apr 22, 2013 5:10 pm

Hi
Our trip is now a matter of weeks away, and I just have a couple of electrical based questions.
Might sound stupid, but when on 12v mode, does the fridge run off the vehicle battery. I am assuming it does as it only works once in the ignition is turned.
Also, we have mini inverter thing to charge mobile phone, camera and notebook from the cigarette lighter. But we were thinking of getting one of these so we can charge these of hab battery too.
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Do people think this is a worthwhile investment, bearing in mind we are going to be going for 6 months to a year? We are planning to do a fair amount of non campsite stopovers so not wanting to drain the hab battery in between campsite stop overs too much. I have no idea how much of a strain, say charging a laptop will put on the hab battery. Likewise we dont want to drain the vehicle battery and will probably need the sat nav plugged in a lot of the time when we are on the move.
Any help would be gladly received.
Thanks again
Jonny

by HildaB Mon Apr 22, 2013 5:30 pm

Hi,
Just looked into our manual regarding the 12v fridge question. It says " make sure that the fridge is not operating on 12v when parked, otherwise you will drain the vehicle battery in a short time". So it seems it does work off the vehicle battery but only when on the move. Sorry cannot help with your other question, hope someone will be able to. up!

by Jonny_80 Mon Apr 22, 2013 5:33 pm

As I suspected, Hilda. Thanks for confirming.
Cheers
J

by -mojo- Mon Apr 22, 2013 5:57 pm

Jonny_80 wrote:
Also, we have mini inverter thing to charge mobile phone, camera and notebook from the cigarette lighter. But we were thinking of getting one of these so we can charge these of hab battery too.
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Should work Ok, but one observation about inverters - if you're using one to power the original charger for the phone, camera and notebook then you will be making significant power losses going up to 240V and then back to low voltage DC via the charger. I would not be surprised to see losses of 30-40% in that situation.

From an efficiency point of view it's better to get just one DC-DC converter if a suitable one is available. These days for many cameras and phones, this should just be a standard 12V to 5V USB converter.

by gj1023 Mon Apr 22, 2013 9:31 pm

Re phone charging , I have connected with a fuse, a multiple cig lighter with usb slot to the hab battery. I can charge up anytime , if more than Usb connection need I just plug in a Poundland Usb cig plug.

As for running the fridge of 12V, it should only run on 12v when the engine is running , reason being to stop the hab battery running down

by jennyandpeter Mon Apr 22, 2013 9:31 pm

We are using a lipo battery pack that has a 22 amp hour capacity while being the size of a thick paperback book, powers a laptop and charges phones ect . They are designed for powering video cameras for weeks away from mains.

by Tommy-Darcy Tue Apr 23, 2013 3:49 pm

Our fridge (1996 Duetto) only works on 12v when the engine is running. The red light on the fridge switch shows this. When not on hook up, we just use the gas to power the fridge which if not set too cold is proving to be quite economical.

Hope this helps, we too are on a very extended tour..............if things run flat like phones/lap top then we just can't be reached, heaven up!

by Peter Brown Tue Apr 23, 2013 4:23 pm

Jonny_80 wrote:Might sound stupid, but when on 12v mode, does the fridge run off the vehicle battery. I am assuming it does as it only works once in the ignition is turned.
Also, we have mini inverter thing to charge mobile phone, camera and notebook from the cigarette lighter. But we were thinking of getting one of these so we can charge these of hab battery too.
[You must be registered and logged in to see this link.]
Do people think this is a worthwhile investment, bearing in mind we are going to be going for 6 months to a year? We are planning to do a fair amount of non campsite stopovers so not wanting to drain the hab battery in between campsite stop overs too much. I have no idea how much of a strain, say charging a laptop will put on the hab battery. Likewise we dont want to drain the vehicle battery and will probably need the sat nav plugged in a lot of the time when we are on the move.

When the engine has started an electric relay operates to connect the vehicle battery 12v to the fridge. Another relay connects the leisure (habitation) battery to the vehicle battery so they both charge together from the engine alternator. When the engine stops both relays revert to 'off'. The habitation 12v electrics are disconnected from the leisure battery during this time to prevent damage from the high alternator voltage.

It is best to charge the things you speak of from the mains whilst on hook up or from 12v from the vehicle supply when the engine is running - you can get mulitway 'cigar lighter' connectors to help with this and, as suggested earlier, a dc-dc converter is best for the laptop ( [You must be registered and logged in to see this link.] ) and 12v chargers for the phones.

If you are not on hook up and are parked up for a couple of days I would not recommend charging a laptop from the leisure battery as you will take a lot of its capacity (if you have a second leisure battery and solar panel you might get away with it) but you should be ok charging a phone for a couple of hours.

Enjoy your trip.

Peter

by Jonny_80 Thu Apr 25, 2013 1:58 pm

Thats all really helpfull. Thanks a lot. Greatly appreciated

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