Some of the most common problems on the Punto mk2/2b such as Electronic Power Steering failure and poor starting etc can often stem from a poor battery or charging system. When these threads appear, most people are advised to check the condition of their battery/ alternator etc, so this is a quick guide on how to do it with a multimeter.

This guide is intended as a BASIC first step to assessing your battery/ charging system. Proper drop tests can be carried out by garages, sometimes free of charge. These will provide a more accurate picture of your batteries health and a definitive answer to if its faulty/ needs replacing.

Step one
When the car has been sitting (overnight). Pop the bonnet. (dont turn anything on or start the car yet) Set your multimeter to DC volts and place the red probe on the positive battery terminal and the Black probe on the negative battery terminal.


Look at the measured voltage. In this case it is 12.54v. Anywhere between 12.4v and 12.6v indicates that the battery is fully charged. Anywhere below indicates that the battery is either not fully charged, or weak.

Step 2
Start the car with the multi-meter still attached.


The voltage should now rise. In this case to 14.47v

To charge the battery, the alternator voltage output has to exceed a minimum charging voltage. This minimum charging voltage is 13.8v across the battery terminals, or at the output of the alternator. A single lead-acid cell starts to charge at anything over 2.25 volts. Since a 12 volt battery has six cells, any 12 volt lead-acid battery needs at least 13.8v to start to charge. This voltage will be enough to fully charge or maintain the battery on a trickle charge, but charging time will be very long at 13.8v.
To fully charge in reasonable times, the alternator output must be 14.2v to 14.5v as measured across the battery terminals. Charging voltages over 14.7v can prematurely dry the battery by boiling out electrolyte.

Step 3
With the engine still running, Switch on the heater blower motor to full, the rear screen demister, the headlights on and set to full beam.

The voltage should now drop slightly....


In this case to 14.39v. This is now testing that the alternator can keep up under load. If the voltage drops dramatically, or below 13.8v then it may well be that your alternator is faulty.

Parasitic Drain

Another common problem is Parasitic Drain. This is where something is draining the battery whilst the car/ignition is switched off. On punto's, the number one most common cause of this is poorly fitted after market stereo's.

Symptoms of this, is that each morning (or after the car has stood for several hours) the car is sluggish to start, or indeed has a flat battery. But once started, the car runs fun and can be restarted several times throughout the day with no problem.
Having performed the tests described previously re the alternator, you should now test for Parasitic drain.

To do this, set your multi-meter to “amps”.
Disconnect the positive battery terminal. Connect the negative probe of your multi-meter to the battery terminal connector and the positive probe to the actually battery post.


Now look at the reading on your multi-meter.
All modern cars will draw SOME power from the battery when they are turned off. This is due to things like the clock, alarm, live supply for the memory of the radio etc. So a small current draw is acceptable. Its also important to note that you should leave the test for a few minutes as various items (such as the ECU) will turn themselves off after a few minutes, so don’t look at the result straight away.


In this case, the parasitic drain was 1.4 amps. The next step is do disconnect/ remove fuses for the most common items that may be causing it.
I removed the fuse for the radio and the reading fell to 0.01amps. Therefore the radio was the cause.


Hope this is of some help,