Halfords switching power supply to power a Ring Automotive RAC610 12V Analogue (Tyre) Compressor

[MM]

Yesterday I ordered a Ring Automotive RAC610 12V Analogue Compressor from Amazon, because I cannot pump my car tyres up manually at the moment due to recovery from an operation.

It so happens that about three years ago I bought a Halfords switching power supply model RL-816U, with the following spec:

AC Input: 220-240V ~ 50Hz 0.7A DC Output: 13.6V +/- 5A 68W

The power connector is just like the cigarette lighter in a car.

So I reckon, instead of plugging the tyre pump into the in-car cigarette lighter socket, I should be able to plug it into the Halfords unit instead.

Anyone see a problem with this plan?

Cheers!

MM

[Andy Burns]

elsewhere, I see the compressor is 85W

Why not run it from the car's cigar lighter? (with the engine running to avoid flattening the battery).

[Tim+]

+1. Can't quite see why you wouldn't want to just run it from your car's battery.

Tim

[Dave Liquorice]

I guess you want to use the compressor for something else away from the car not the implied car tyre inflation?

If the 85 W quoted is correct thats at least 7A @ 12v. The current draw will depend on how hard the compressor is working, which will be related to output pressure. The higher the output pressure the more work the compressor has to do so it will draw more current.

[Andrew Gabriel]

These also take one hell of a switch-on surge. SMPSUs tend to need to be specially designed to be able to deliver large switch-on surges.

I use one of the portable jumpstarter packs with a built-in sealed lead acid battery and compressor. The trouble is finding a good one; many of them are complete crap, and have fake batteries which are a tiny fraction of the capacity which their size and markings claim, and some of the compressors and tyre valve couplers are crap too.

[Norbert Thistlethwaite]

I bought a Clarke 910 jumper/compressor, after about 2 years, I was unable to charge the unit.

OT but why don't you see mains tyre compressors at a reasonable price? Perhaps there's no demand.

[Dave Plowman (News)]

I have one bought from Lidl many years ago - when Lidl stores were pretty rare round here. It appeared exactly the same as the Halfords one - but half the price. It still works just fine for tyres, but no longer can deliver enough current to start a car. Excellent value at 20 quid. ;-)

[John Williamson]

Yes. SMPS's of that standard don't like motors, and what's the current draw of the compressor at full pressure?

Mine pulls about twice what your PSU is capable of.

[Andrew Gabriel]

Lead Acid batteries need care. Stick one on the shelf for 2 years, and it will likely be dead, especially if it wasn't fully charged to start with. I always try to recharge mine as soon as possible after use. Flattening one is bad news too, for its longevity. You need to periodically top it up, but overcharging (as some of the cheap chargers which come with these can easily do) will also wreck a SLA battery. I usually charge mine from an accurate voltage and current limited bench supply, and never used the wallwart which came with it and has no voltage or current limiting (other than its own internal resistance). Some come with crap batteries, as I said.

[Andrew Gabriel]

The one I bought from CPC many years ago was good enough quality that I decided to buy a new deep discharge SLA battery for it when the original battery died. It was probably 6 years old at the time, but I had also got rather behind in keeping it topped up. The new battery cost more than a new jumpstarter, but new jumpstarters are often poor quality now.

[MM]

I was worried about blowing the car's accessory socket. This isn't actually a cigarette lighter any more. The Suzuki sales guy explained, when I bought the car new in 2011, that Suzuki don't fit them any more, because people were connecting all manner of accessories to them when the socket was only rated high enough to heat the lighter's element. So now Suzuki call it an accessory socket (or words to that effect, since the actual owner handbook is in the car outside).

I'm glad I asked, because if the Halfords unit isn't powerful enough, I'll just use the car's socket with the engine running.

MM

[Adrian]

There's a fuse on the socket power feed, isn't there? We can, I think, safely assume that the wiring is rated to withstand a load that's below the fuse's rating.

[John Williamson]

The element on a cigarette lighter is, IIRC, normally a couple of hundred watts.

The normal rating for the "accessory socket" is at least 10 amps, probably 20. The actual rating should be in the manual, or you may need to phone your local dealer.

You shouldn't need the engine running unless you run the compressor for an hour or two, and as even the tyres on my Land Rover only take a quarter of an hour from dead flat to running pressure...

[The Other Mike]

"below" ???

[Brian Gaff]

Depends on the starting current of the pump and how sensitive the psu is to overload. I'd say try it and see. Surely the psu must have protection against short circuits health and safety etc.

Brian

[Dave Plowman (News)]

Yes - the output devices usually blow long before any risk of fire.

[Dave Liquorice]

Which can be reduced by starting the compressor off load, then attaching the output line to the tyre.

Only when protected by a fast acting fuse.

[MM]

Oh, well, that's good to know, too. Thanks.

MM

[Norbert Thistlethwaite]

The jumper had good use for the first 12 months and was regularly charged. When the old car was replaced, the Clarke 910 was little used.

It was only used for the occasional tyre topping up. Maybe the battery-condition gauge was faulty and tyre use was a greater drain than indicated.

[MM]

Update: Just received my electric tyre pump (Ring Automotive RAC610

12V Analogue Compressor) from Amazon! It works brilliantly. Highly recommended. I plugged it into the "lighter"socket and used it with the engine running. So much easier than the foot pump.

MM