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Home » Workshop » Auto Electrics » 6 Volt to 12 Volt Conversions

6 Volt to 12 Volt Conversions

If we are completely honest 6 Volt electrical systems are a bit of a pain in the backside.  The majority of parts and electrical accessories that are available these days all run on 12 Volts. Whether that is an indicator bulb, electric washer pump or stereo system you can be hard pushed to find a 6 Volt compatible part in a hurry, if at all.

The other issue is that 6 Volt batteries tend to have relatively low Amp Hours, the amount of current available, so power hungry items, such as your starter motor can flatten them in no time at all. The good news is that it is not too difficult to upgrade your system and fit a high capacity 12 Volt battery instead.

Commonly there are two types of 6 Volt system in classic cars:

  • 2 x 6 Volt batteries wired in series, giving a 12 Volt system (as fitted to early Porsche 911/912 and MGA/B
  • 1 x 6 Volt battery found in most pre-war cars and some as late as the mid-1960’s

Replacing 2 x 6 Volt batteries wired in series

In a lot of ways this is the easier job, because the cars electrical system is essentially 12 Volts, although it is getting there by using two 6 Volt batteries. That means that the cars charging system, bulbs and other electrical equipment can continue to be used after the conversion.

We simply find two 12 volt batteries that fit in the battery housings and convert the wiring between them from series to parallel. This gives you double the original Amp Hours, meaning that you gain more capacity to run power hungry upgrades such as stereo systems and it helps massively when starting a car if it has been laid up for a period of time.

It is the very first job we carry out to any 2 x 6 Volt car we own. It massively improves the electrical reliability of the car and makes it easier to start hot or cold.

Single 6 Volt to 12 Volt Conversion.

There is a bit more work involved here. We need to assess the cars electrical components and see what can be converted and what requires replacement. Once a suitable 12 Volt battery has been sourced we turn our attention to the charging circuit.

Generally the car will be fitted with a dyanamo, this would be replaced with a suitable 12 Volt alternator. We would fabricate new brackets, source a suitable belt and check that the wiring is correct and can handle the extra current.

With this in place there are usually 2 main areas that need sorting out:

  • Bulbs – They will all need replacing with suitable 12 Volt equivalents.
  • Clocks/Gauges – These will require minor electrical modification to make sure they are working accurately.

It is uncommon for earlier cars to have too much more in the way of electrical equipment, but the bonus of moving to a 12 volt system is that we can then add:

  • Charging points for navigation units
  • Stereo systems
  • Or any number of other modern gizmos that your heart desires!
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