Thread: 24v and 12v?

Yes I think the blue 100" which was on ebay recently (and purchased by a forum member) was setup this way..

For the sake of simplicity I would keep to one voltage though..

You can use a 24v starter with a series/parallel switch and two 12v batteries. You use a 12v alternator and don't have to change the rest of the electrical system. Easy way to get one is from a truck wrecker. Commonly used on Cummins engines.

Originally Posted by Brian Hjelm

You can use a 24v starter with a series/parallel switch and two 12v batteries. You use a 12v alternator and don't have to change the rest of the electrical system. Easy way to get one is from a truck wrecker. Commonly used on Cummins engines.

Half the amps to do the same job - no wonder they burn out the contactor when 12V Starters are fitted. This was the only recurring problem with the Isuzu engined Land Rover I ever heard of.

Bob

Inverter is the wrong description/name for a DC to DC voltage converter - inverters convert DC current to AC current.

You can buy switchmode DC to DC voltage converters for this application.



IMHO a better alternative is the Redarc charge equaliser - the power draw from a DC to DC voltage converter is limited to what you purchase, and larger units more expensive.

The following diagrams from Redarc show some (there are other) ways to connect the charge equaliser:





With the Redarc charge equaliser, 2, 12V batteries are connected in series for 24V (same as normal 24v system). The 24V system (starter, alternator, winch etc.) is connected across both batteries. The 12V system is connected to the lower battery (the one that the earth lead connects to).

The Redarc charge equaliser, maintains equal charge in both batteries, even though more power is drained from the lower battery - without it the lower battery would not be charged fully or the upper battery would be overcharged.

Slightly off topic, but interesting and relevant information found on the Redarc site are the following diagrams:









These applications for a vehicle with 12V system, provide dual jumper lead connectors for 12V and 24V. They could be used with the 24V circuit connected to a 24V starter on an Isuzu - the alternator and other vehicle electrics would be 12V.

SBI12 in the above diagrams is a smart battery isolator. CE20 is a charge equaliser.

It's not just electrical issues with the truck setup. The truck flywheel housing has the starter mounted lower, so it fouls on the chassis when fitted to a Landy.

Cheers, Murray

John
Did you mean the 12v system is connected to the lower battery,as you've mentioned 24v twice?I'm a bit confused.

Murray
I realise the chassis needs notching but how much depends on which starter I use,either a gear reduction or direct drive one.The direct drive one would need less notching as they're more compact.

Cheers Eric

Originally Posted by THE 109

John
Did you mean the 12v system is connected to the lower battery,as you've mentioned 24v twice?I'm a bit confused.

...

Cheers Eric

Yes, it was a typo.

I realised some of the post was poorly written so have edited it and added some other information.

Hello.
I`m the mug who brought the bitsa of Ebay.It has both 24 volt and 12 volt alternators.The 24 volt is only for the starter motor and a couple of gauges.The 12 volt runs every thing else.So it has two 12 volt battery's in series? to create 24 volt under the passenger seat and a 12 volt battery behind the cab, under the tub.Between the seats is the two battery isolators.It starts by a push button.Good point of this set up is you won`t ever run the start battery flat winching or using accessory`s like a fridge or lights.Also the 24 volt starter has a ton of grunt for starting.Motor has glow plugs, but never used.Fires before it even cranks over.
Cheers Hall