Is it ok to connect air compressor directly to battery?

[oznut]

Hi all,
Just ordered a portable air compressor from eBay. It has a battery alligator clamps for power connection.

Question : can I connect them directly to the FL2 battery as is or do I need to disconnect something else first? Any gotchas that I should be aware of?

I am not electrical/mechanically minded and having a look at what is connected to the FL2 terminal has me a bit worried as all my other car's terminal connection seems to be "simple" in comparison to what is on the FL2.

Sorry if this seems to a newbie/silly question. Thanks

[drivesafe]

Hi oznut and while you can connect any positive wiring/cabling to your cranking battery’s positive terminal, nothing should be connected to the negative terminal of MOST new vehicles, not just Land Rovers.

Connect you compressor’s positive clamp to the cranking battery’s positive terminal.

Then connect the compressor’s negative clamp to a good earth point in the engine bay, preferably close to the battery.

Don’t forget to have your motor running while you use your compressor.

[weeds]

dont forget a fuse

[oznut]

Thanks drivesafe ...but where would you consider a good earth point? ..sorry for the silly question

[oznut]

Thanks Weeds but should there be a separate fuse for the compressor outside of the fuses currently in the car? If so, where should it be installed?

Btw. is getting a separate battery an option or will the battery run out of "juice" before inflating a max of 4 tyres say if we go driving on sand? Any way of changing the clamps to a cigarette lighter plug? ...8o)

Apologies for the dumb questions.

[weeds]

Thanks Weeds but should there be a separate fuse for the compressor outside of the fuses currently in the car? If so, where should it be installed?

Btw. is getting a separate battery an option or will the battery run out of "juice" before inflating a max of 4 tyres say if we go driving on sand? Any way of changing the clamps to a cigarette lighter plug? ...8o)

Apologies for the dumb questions.

the compressor will probably have an inline fuse already fitted........if not you will need to wire one inline

you shouldn't need a second battery, as drivesafe mention just keep the motor running this way your alternator will do all the work and your batter will stay fully charged

[PhilipA]

Btw. is getting a separate battery an option or will the battery run out of
"juice" before inflating a max of 4 tyres say if we go driving on sand? Any way
of changing the clamps to a cigarette lighter plug? ...8o)


A compressor of any size other than a tiny tiddler will demand far more current than the 10 amps that can go through a cigarette lighter plug. The compressor should have written on it how many CFM it is and/or amps. If it could be run by a cigarette plug it would probably have one fitted.

Unless you want to go to the trouble of adding HD wiring the battery clamps are probably best for you.

Regards Philip A

[oznut]

Thanks Weeds and PhilipA ...

Yeah my "Kmart special" compressor which I had for years had a ciggie plug .. but it is slow and only good for topping up my car tyres and our bikes and other inflatables.. I do not believe my Dr Air Pro Flow fit into the tiny tiddler category.

Any thoughts on where is a good earth point?

[loanrangie]

Just pick a spot close to the battery where there is already an item bolted to the body or a lonely bolt on its own.

[PhilipA]

If the Dr Air Pro flow is the same as my Aldi 150L per minute job then it can take up to 50AMPS when under load.
This takes some serious wiring and Anderson plugs.
Make sure you have the motor running .
Regards Philip A

[mikehzz]

Drivesave, why isn't it advisable to connect directly to the negative terminal? Connecting to the body near it would almost be the same thing I would assume. Just interested to know. Cheers.

[oznut]

Hmm..I might pick the bolt that the earth wire is attached to from the battery then...hopefully nothing blows up..thanks heaps guys ..the warning in the handbook re connecting 12v devices directly to the battery might cause sparks and explosion had me worried.. 8) ..hence the post ...

[Tombie]

Drivesave, why isn't it advisable to connect directly to the negative terminal? Connecting to the body near it would almost be the same thing I would assume. Just interested to know. Cheers.

Modern vehicles have a sensor in the negative lead which interfaces with the vehicles to ensure regulated charging.

Connecting directly to the battery screws this load monitoring and can cause problems.

[Tombie]

Hmm..I might pick the bolt that the earth wire is attached to from the battery then...hopefully nothing blows up..thanks heaps guys ..the warning in the handbook re connecting 12v devices directly to the battery might cause sparks and explosion had me worried.. 8) ..hence the post ...

Why not wire up a 50a Anderson up the front there... Will make life easier in the future!

[drivesafe]

Hi oznut and not using the negative terminal when jump starting is an international industry wide precaution for exactly what you suspected.

If a battery has been worked hard, like a flat cranking battery is when try to start a motor, it will gas and there is than the potential of an explosion.

Just look for a stud with a cluster of earth wires connected to it and your have your earth point.


Hi mikehzz and the earth lead on many new vehicles, including most new LRs, is used to monitor the state of the cranking battery.

If you place any loads on this cable, other than that of what the battery is going to create, you can cause erroneous readings of the battery which can lead to battery being under charged or over charged.

[oznut]

Thanks for the explanation drive safe...with the MY13 FL2, there is an earth strap coming from the negative terminal of the battery to a bolt next to the battery, would that bolt be ok to connect to? Please see picture by stownrow ..thanks

Freel2.com - View topic - Extra earth strap now fitted as standard (http://www.freel2.com/forum/topic16694-15.html)

[oznut]

Thanks to all for your advise, my compressor arrived today and I connected it to the bolt attached to the earth strap (leading from the neg battery terminal) and it did not spark or explode..8) ...wahoo ..thanks again all