Will this work, 12v Cigarette inverter to trickle charger to Spare battery?

khampson

Hi, Will this work, 12v Cigarette inverter to trickle charger to Spare battery?

I have a spare 70ah car battery that I use for addition lighting, I use it for less than 2 hours per day, Ive given it a full charge so to keep it topped up can I use the 150w inverter that I have thats plugs into the cigarette lighter socket and then plug a trickle charger into that, and connect it to the spare battery to keep it topped up?

The cigarette sockets only works while I am driving, I drive for 5 hours+ a day and the back light is not always needed.

so will this work?

Thanks

vaio

yep but you'll lose the efficiency of the inverter plus the efficiency of the charger and that's before you start looking at whether the inverter is suitable for powering a charger.

Better to just connect the spare battery direct to the main vehicle charging system either direct or via the cig lighter

khampson

How would I connect the battery directly to the cigarette socket and charge it successfully without under or over charging it?

marlot

The best way would be a split charge relay - that's how towbar wiring feeds the caravan batteries.

Something like the ones on here: http://www.vehicle-wiring-products.eu/VWP-onlinestore/accessories/towing.php

They need to be wired to the main battery with heavy guage wiring, with a fuse as close to the original battery as you can get it. Any towbar fitter could wire one up for you.

khampson

Trouble is its a company vehicle and I can't make any modifications to, this is why I'm searching for a solution.

Cheers

forgotmyname

If you had a 120AH vehicle battery charging a small 40Ah battery thats not fully flat, You may get a fully charged 40Ah battery before the larger vehice battery dies.

But then how will you charge the 120Ah battery??

And inverters are not designed to be used with chargers. They are not very efficient and adding a charger to that equation is even worse.

If you cant modify the vehicle where do you plan on fitting the spare battery? It will need to be bolted in to prevent it moving in an accident.

khampson

I have a solid bulkhead to prevent anything entering the driving area if I was in an accident, the battery would be secured in the back, as for charging an 120ah battery as you put it, I would hope the vehicle alternator would recharge it while I was driving, I do about 150 to 200 miles a day.

Jakg

Yes you can do it, but it's a really REALLY bad idea.

The only way I would recommend is by using a split-charge relay, but that is going to need some (small) modification to the vehicle.

sillygoose

So from what I understand is that whilst using the vehicle normally, you want to charge another car battery in the back of the vehicle to use for some lighting when the engine is off?

First must point out be careful of charging lead acid batteries in an enclosed place, vented or even sealed type (if faulty) can give off hydrogen gas and there can be an explosion risk. (ventilate!)

Moving on, there are a type of booster charge cable that goes from the cigarette lighter socket of one vehicle to the cigarette lighter socket of the other. Due to fuse limits these cannot carry enough to start the flat car but enough current to put some decent charge in the battery to get it to start after a good while.

LIKE THIS

One of these would make a good way of giving your 2nd battery a top up. Obviously your 2nd battery doesn't have a lighter socket fitted but it wouldn't be hard to connect an accessory lighter socket to it using...

LIKE THIS

mikey72

I've a 300W inverter, an older version of http://www.maplin.co.uk/300w-12v-inverter-with-usb-charge-socket-518798
I use with lap top, phone, and ipod chargers.

Should work a battery charger, providing the charger is ok with the inverter output. 150W should give enough power for even the biggest of battery chargers, a Lidl or Aldi version of the CTEK charger is only about 4 A.

If you have a power point in the back of the van, (to plug the inverter in,) just plug the spare battery into it, using a smart split charge relay,
http://www.towsure.com/product/SelfSwitching_Combination_Relay and you can leave it wired in permanently with no wiring mods to the van.

Premier_2

sillygoose wrote: »

...First must point out be careful of charging lead acid batteries in an enclosed place, vented or even sealed type (if faulty) can give off hydrogen gas and there can be an explosion risk. (ventilate!)...

Transit vans have their batteries under the drivers seat.

I remember in days gone by, original Minis had their battery in the boot ... and the mini estate had the battery under the rear seat.

I don't recall many of these vehicles exploding