Is charging my deep cycle battery via the cigarette lighter socket an option?

problem.
When the ignition is turned off, if the battery is still plugged into cigarette lighter it will supply power to all equipment on the accessories circuit.
ie the radio will continue to work even though the key is removed - the power is derived from the battery plugged into the cigarette lighter.(I tried it).

If the aux battery is not being used there should be no probs using cig lighter.
If battery supplying 20 amps and plugged into lighter then fuse blows as accessory circuit trying to charge battery 10A + extra equipment attached to battery 20A from a 20A fused circuit.
Regards
Techie

Hi phatblattery, in short, NO.

First off, your Cigarette socket should be protected by a 10 or maximum, 15 amp fuse. Your AGM battery will pull much more than that when trying to charge if it is low.

Next and more importantly, the cable running to your cigarette socket is going to be way too light to be able to get the voltage needed to the battery to allow the battery to get any real chance at charging.

Cheers

have tried it and didn't work ? why, cause the voltage is too low. It's enough to run something but you'd put bugger all back in a battery with 12.6v let alone current considerations. If you are desperate i have got out of trouble by idling the vehicle and having jumper leads go from the battery connections to the portable battery that way you get the alternator's increase in voltage and enough current to charge the other battery. Though this is a terrible waste of fuel and some may say not good for engine or electronics on the vehicle.

I thank you all for your advice - so I suppose the only proper way is to setup a dual battery system?
Can anyone recommend a good dual battery kit please - I see a lot on ebay going for about $75-00 are they any good?

phatblattery,
you sound like your outa time, so don't jump in and get the job done quickly and wrong, run your fridge etc direct from your new battery while out camping this time...
charge your new battery daily with a set of jumper leads this trip and get a decent battery isolator system installed when you have the time, and more importantly when the installer really has the time to do it!

...BEFORE you go away....

FULLY charge the new battery direct from a 240v battery charger

if you don't have a 240v charger take it back to where you bought it and ask them to do it or any auto electrician as you may need some of their assistance with installation of the new isolator system.

you can overcome the problems of the voltage drop to a standard cig. lighter, by installing one with thicker cable, such as that sold by waeco. should enable you to recharge the battery, as i do.