Testing times - preparing for the end of lockdown
by Barney Donohew

The recent coronavirus-related lockdown has not only dramatically affected our lives and car use but also our cars. The RAC (a British automotive services company) reported that during the lockdown, one in ten cars in the UK sat completely unused, and millions of others were used far less than normal. For us in the automotive industry, this means we could be seeing many more related faults than usual in the coming weeks and months, such as flat batteries, seized brakes, deformed tyres, etc.

Braking issues are fairly easy to diagnose, and often self-evident to the customer, so I'll assume you can navigate your way through your customers’ potential concerns there.

Batteries have a natural self-discharge or internal chemical leakage. Couple that effect with an additional parasitic drain or a suitably long period without a charge, and you have a sure-fire way of increasing battery sulfation. The net effects are not only a lower state of battery charge but also a lower state of battery health.

With high-performance vehicles and tyres, it is not uncommon that the tyres deform when sat in one place for a long period of time. This creates flat spots that produce a very noticeable vibration through the steering wheel or in the cabin when the vehicle is on the road. Furthermore, the likelihood of deformation increases when the ambient temperature increases, as has been the case for many during the Covid-19 lockdown.

You’re probably well aware of all these issues and their causes, so I apologize for giving you potentially unnecessary information. However, your customers might not be. Particularly when it comes to the invisible deterioration of their vehicle battery or the reasons for the costly replacement of a set of tyres.

This means your diagnostic methods may face greater scrutiny; “...but my battery/brakes/tyres have only done a few thousand miles...” In cases like these, it really helps to give customers hard evidence of both your diagnosis and the fix.

So, with all that in mind, wouldn’t it be great if you had a tool that could give you definitive diagnostic conclusions for these types of issues while providing your customers with all the reassurance they need?

We think that our PicoDiagnostics application is that tool.

When faced with any potential battery-related issues, you can very quickly connect your PicoScope to the vehicle. All you need is a test lead to the battery terminals and a current clamp around the battery earth or battery positive leads. Then you can run the Battery, Starting and Charging test in PicoDiagnostics to locate the fault.

If the result of the test is inconclusive, we recommend you fully charge the battery, switch the ignition and headlights on for 5-10 minutes and then repeat the test (with the headlights off). Anything less than a normal battery state of charge or normal battery health in the retest suggests a battery fault. After making any necessary replacements, you can very quickly confirm a successful fix with another test.

PicoDiagnostics allows you to print test reports, which you can then show your customer to explain the cause of the original fault as well as the confirmed fix (see the figure below). This is a great way to build trust between you and your customer.

But PicoScope isn’t just about testing electronics. By connecting an accelerometer from our NVH kit you have a powerful tool for finding wheel, tyre, powertrain, auxiliary system and engine related faults.

Any significant defect with the structure or surface of a tyre will cause it to produce substantial vibrations through the car body. If these vibrations are reported by the customer, you can quickly confirm any suspicion of a tyre-related issue by placing an accelerometer on the seat rail and carrying out a quick road test (with a PicoScope and the NVH software running).

The NVH test allows you to look at all the contributions to the overall vibration (e.g. from all the tyre, transmission and engine rotations) across the full set of possible rotation rates (frequencies) all at the same time. This is called frequency analysis.

A flat spot will cause a disturbance that occurs once per rotation of the wheel. Therefore, its contribution to the overall vibration will occur at the tyre rotation rate, expressed in hertz (one hertz equals one cycle per second).

So if we see that the greatest contribution to the overall vibration is at the frequency that matches the wheel rotation speed, we know it is likely that one or more tyres have a single defect at some point in their structure or on their surface.

When it comes to a flat spot caused by a car sitting idle for a long period of time, no amount of wheel balancing will totally compensate for the deformation and its effect would remain visible in the NVH tool frequency analysis. This provides you with justification to replace the tyres.

As per the Battery, Starting and Charging test, you can print reports of any NVH tests, both pre and postfix (see the extracts in the figure below) to show your customer your diagnostic conclusions and the confirmed fix.

When it comes to confirming the need to replace an almost new battery or hundreds or even thousands of pounds worth of tyres then the PicoDiagnostics tool and the evidence it can provide can feel almost priceless.

And best of all is that all this comes for free (with no charges for updates) when you purchase a PicoScope.

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