24 volt to 12 volt

**Lionelgee** · 21st October 2013, 03:26 PM

Hello All,

One of my Series 3 Land Rovers came with a semi-installed Nissan SD-33 diesel. It also came without a starter motor. I know very little about Nissan Patrols however a battery place online suggest the battery is a N70 12 volt so does this meant the Nissan MQ patrols had two batteries which were wired in series?

I have looked around various places and the Nissan SD 33 was in the MQ Nissan Patrol and they are wired for 24 volts starter motor, glow plugs and alternator.

Is there a way to run two 12 volt batteries temporarily in series so they make 24 volts while the starter is cranking over and then revert back to two single circuit 12 volt batteries once the engine is running.

Or would I simply be better off keeping all the engine operation areas at 24 volts and then wire in a 24 to 12 volt regulator-converter-resistor that feeds into all the Land Rover standard 12 volt system?

I want to be able to get the engine running and the vehicle drivable even only up to bush basher status before deciding what to do with it. I do not think the vehicle has ever run since it was semi-converted and I bought it as a deceased estate. So I can't ask the bloke who was in the process of restoring it.

Kind Regards
Lionel

**Lotz-A-Landies** · 21st October 2013, 03:34 PM

Yes there is a device that does exactly that. Or you can do it yourself, the second battery gets wired up with change over relays, similar to those used in electric winches. The primary battery is still to earth and the second battery changes over to series as the starter is switched.

You could also find a 12V starter and replace the alternator with a 12V one. e.g. Isuzu 4BD1 powered trucks are 24V in Australia and 12V on the US (and Land Rovers) so there may be a 12V starter that fits your engine.

How often do you use the glow plugs anyway? (You can run them on 12V but they will take longer to get to temp.)

**Lionelgee** · 21st October 2013, 03:55 PM

Originally Posted by Lotz-A-Landies

Yes there is a device that does exactly that. Or you can do it yourself, the second battery gets wired up with change over relays, similar to those used in electric winches. The primary battery is still to earth and the second battery changes over to series as the starter is switched.

You could also find a 12V starter and replace the alternator with a 12V one. e.g. Isuzu 4BD1 powered trucks are 24V in Australia and 12V on the US (and Land Rovers) so there may be a 12V starter that fits your engine.

How often do you use the glow plugs anyway? (You can run them on 12V but they will take longer to get to temp.)

Hello Lotz-A-Landies,

Thank you for the information and the suggestions. Looks like I will be looking over on the states-side for their 12 volt parts. Especially since I do not have the starter motor in the first place. I could use the 4BDI alternator in Baldrick my 2.25 litre diesel so I can run the brake booster I bought awhile ago. It also saves me visiting the place that sells batteries and tyres and buying another N70 battery - but that is another story ... a Series 3 Battery story in fact....

A new non-OEM starter motor here in Australia is close to $400. This amount is $100 less than what I paid for the vehicle a couple of years ago!

Kind Regards
Lionel

richard4u2 · 21st October 2013, 06:01 PM

would it be worth dropping down to a wreckers and have a look at a Nissan 12v petrol and a 24v starter motors and see if they are different in size and fitting etc.

**mick88** · 21st October 2013, 06:54 PM

Have you chatted to an auto electrician?
If you can pick up a 24 volt starter cheap there may be some way you can modify a 24volt starter to make it a 12 volt!
I am only guessing but worth investigating as there is always someone who knows their way around a problem.

Cheers, Mick.

**V8Mitch** · 21st October 2013, 08:07 PM

The mq in my yard is running an sd33 and 12 volts from the factory, the later models ran 12 volts, the change happened when they were face lifted in 84? Look for mk patrol parts, although they are not officially known as an MK that's what everyone called them.

**Lionelgee** · 21st October 2013, 10:24 PM

Originally Posted by V8Mitch

The mq in my yard is running an sd33 and 12 volts from the factory, the later models ran 12 volts, the change happened when they were face lifted in 84? Look for mk patrol parts, although they are not officially known as an MK that's what everyone called them.

Hello VB Mitch,

Do you know where I could find out the engine number to model to determine between an MQ and an MK?

I assumed it was a 24 volt system because that is all the information I found on the internet. Type in "MQ Nissan Patrol SD 33" and the 24 volt starter motors are the only ones that seem to come up for sale. I do not know what type of Patrol the engine was taken out of. Thanks for the tip I will see what happens when I type in MK...

Oh and where is the engine number on a SD 33 so I can find it?

Kind Regards
Lionel

Thread: 24 volt to 12 volt

Thread Tools

24 volt to 12 volt

Bookmarks

Bookmarks

Posting Permissions