What To Buy?
Update: Since I first wrote this article, we’ve had both motor/compressor assemblies fail. I don’t recommend this product. Go here for all the details.
Imagine you have a small 4WD truck with 19.5 inch wheels (equivalent to 35’s). You’ve set this truck up as an expedition vehicle and plan to travel indefinitely. Now the truck is 24V and you also have a second battery system set up as 12V.
You need a large compressor because you don’t want to be spending too long re-inflating your tyres.
So what do you get? We narrowed down our choices a little. This is what we decided we needed:
- A continuous 100% duty cycle to speed up tyre inflation. (Duty cycle is the on/off time for a compressor. For example, a compressor that will run for 10 minutes then needs to be rested for 10 minutes to cool down, has a 50% duty cycle).
- Able to pump tyres to at least 90psi (remember, we have a truck with heavy truck tyres).
- A 12 volt compressor. We could have gone for a 24 volt unit, but then it couldn’t be powered from other vehicles.
- A maximum current draw of around 60 amps. Above 60 amps, cable sizes become unwieldy.
- A reliable brand with a solid reputation for reliability.
- A compressor with enough output to run air tools.
After much reading and research, the ARB twin compressor bubbled to the surface.
Portable Or Onboard?
ARB supply the twin compressor in two configurations, on-board or portable. Whilst an on-board compressor is convenient, we chose the portable version – a model CKMTP12.
Why? The portable version is mounted in a sturdy carry case, with the compressor, a 4 litre aluminium air tank, compressor on/off toggle switch, a pump-up kit and air gun all supplied and wired up ready to use. It was better value for money and everything was supplied.
The carry case is compact and everything you need is in the one place. You simply open the lid, connect the alligator clamps to the battery terminals, connect the hose, flick the toggle switch and off you go. No need to search for hoses or the tyre inflation fitting – it’s all there in separate pockets. So we chose the portable unit for convenience and compact storage.
The lid itself is sealed to prevent dust ingress.
So What’s It Like To Use?
This unit actually lives up to the advertising hype. Our truck tyres are 285/70/19.5, which is equivalent to a 35” tyre in the old terminology. The ARB twin inflates each tyre from 45psi to 90psi in just a few minutes.
The air tank earns its keep when you connect the air gun. We often use it to blow out dust and dirt from inside the truck. The tank helps the compressor maintain enough air volume for the air gun to be highly effective.
All hoses, fittings and switches are high quality so everything snaps together neatly and precisely.
Does It Use Much Power?
When running full tilt, the compressor draws 55 amps. This is slightly lower than expected, so we’re happy with this. Each motor is individually wired, so the positive connection at the alligator clamp has two cables and two large in-line 40 amp blade fuses.
The cables do get warm after prolonged usage, but nothing to worry about. Given the length of the cable, the next size cable up would probably be ideal. Still, the cables as supplied are doing their job.
For those of you who are interested in the specs, ARB have a comparison chart with all the vital statistics listed.
Any Problems?
We had one issue, a small manufacturing fault.
Update: We’ve had major issues with our compressor since I first wrote this article. Go here for all the details.
When I first unwrapped the carry case and opened the lid, I noticed the insulation on one of the cables was partially melted. No wires were exposed, but it wasn’t right all the same. Considering we were going to be relying on this compressor in remote places, it had to be in top condition. Plus, you pay a premium for this compressor…
The company I bought it from was reluctant to replace it at first, but eventually agreed after some arm-twisting. I was expecting them to just swap out the cable, but to their credit they gave me a complete new unit.
What Modifications Have We Done?
The alligator clamps were replaced by an Anderson plug. The power board in the truck has a 63 amp circuit breaker that was installed to power a compressor. 6AWG cable runs from the circuit breaker down to an Anderson plug.
I will also make up an adaptor cable using the redundant alligator clamps, another Anderson plug and some 6AWG cable. This way, the ARB compressor can be used on any vehicle.
Any Tips?
We have a couple of tips you might find useful.
Quality Tyre Gauge
Spend a few extra dollars and buy a good quality tyre pressure gauge. Considering the price of new tyres, it’s worth spending a bit extra to know you have the correct pressure.
Under-inflation kills tyres, not to mention the real possibility of blowouts. The sidewall overheats and eventually fails if the tyre is under-inflated.
We had difficulty finding a quality tyre gauge to read the truck’s tyre pressures, given we have to run them up to 90psi. Most gauges only read up to around 75psi. Eventually we found the one pictured. If you’re buying for a 4WD, you’ll have a huge range to choose from. Just make sure you chose a quality brand.
Slime tyre pressure gauges are a good option if you’re after a quality product.
Water In Air Tank
Every air tank collects water. This comes from condensation and is unavoidable. At first I was scratching my head, wondering how to drain the tank. Then in desperation, I read the Instruction Manual. They have a simple procedure for draining the tank, which I won’t go into here.
Suffice to say, sometimes it does pay to read the manual!
Be Gentle
I’m a strong believer in looking after your gear. A small amount of TLC goes a long way.
Keep all air fittings out of the dirt and mud, don’t let the compressor suck in huge mouthfuls of dust, clean the filters occasionally and generally treat the unit with care. This is especially true for tyre gauges – they don’t like being dropped or knocked around.
Would We Buy Another One?
Yes we would. The ARB portable compressor is a high quality piece of equipment. It does the job with ease. Hopefully its longevity will match the overall quality.
Update: I wouldn’t even consider buying another one of these compressors at this stage. It’s a lemon. Go here for all the details.
Do you need something this big for a standard 4WD? Probably not. But it depends on how you set up your 4WD and how you use it. If you already have air tools for example, then you could take these with you when you travel instead of the usual hand tools. Or maybe you have 35” tyres. Maybe you do heaps of sand driving. Or maybe you just want one because you can…
In Summary
Pros:
- High capacity compressor, inflates tyres quickly.
- Can be used to power air tools and an air gun.
- Will work up to 150psi.
- Does not get unacceptably hot.
- Compact carry case means everything you need is in one place.
- Pre-wired and ready to use.
- All items you need are supplied as a package.
- Quality build and design.
Cons:
- Update: Both motor/compressor assemblies have been replaced due to failures since I first wrote this article.
- One of the most expensive compressors on the market.
- Quite heavy to lift and carry around.
Looking for more reviews on 4×4 Accessories? Then go here for more.
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Extensive review and great idea to use the anderson plug. What plug did you go with (50A or higher)? Thanks.
Hi,
Thanks! I used a 50A plug. It’s slightly under-sized, but does the job. Ideally I would have used the next size up, but they’re huge! Cheers, Andrew
Thanks for this explanation and review!
What size breaker and wire would you recommend if you connected the same compressor directly with the battery to the truck bed with an Anderson outlet (approximately 23 feet in one direction)?
Hi, Glad it was helpful!
If I understand your question correctly, I’m assuming you want to:
– run a supply cable from the truck battery to an Anderson Plug outlet. This cable will be 23 ft long.
– run an earth cable back to the battery.
– have a breaker/fuse at the battery end.
Assuming this setup, here’s what you’ll need:
– The ARB twin draws about 55A, so a 60A breaker or fuse will suffice.
– Using the Cable Size Calculator from here, you’ll need 00 AWG cable.
That’s big cable. You could reduce it to 2 AWG by earthing from the Anderson plug to the vehicle’s body instead.
Hope this helps. Cheers, Andrew