Optima <span class="highlight">Battery</span>.

Google is your friend https://www.youtube.com/watch?v=FaM7exZmzKY

From what little information you have provided a red top is the go but you need to be sure of exactly what you want it to do - as the video says "if in doubt use the yellow top".

So if just for starting etc - then red top, for mixed use, use a yellow top is better.

Go to www.optimabatteries.com and download a brochure, which should include all models specifications including measurements. There is a huge range of prices, it is worth looking at Ebay. I bought another D34, 3 years ago for $380. My first Optima (Yellow Top) is October 2004, still going strong. When not in my vehicle it is (most of the time) hooked up to a Ctek Deep Cycle Charger.
You mention "Start & Run" ? I did not realise Optima made a "Cranking" battery.
You can phone Optima Australia on 0397350039 for proper advice.

2517 John.
What size is the diesel? It is effectively only cranking one cylinder at a time plus engine drag. Does it have glowplugs for cold start or intake air heater?
Is it 4 cylinder or 6cylinder. If cranking a six of same capacity as four, then the six cylinder is easier to crank, ie, smaller dia cylinders on each compression.

If a turbo CRD engine, then it will have less compression to crank than a conventional diesel engine which has higher compression ratio.
Is the starter a direct pinion on the starter shaft OR a geared starter.
A geared starter which uses far less current and is more efficient to crank the same engine and that leaves more to run glows or intake air heater in cold weather and requires a lesser sized battery anyway.
You may not require an expensive battery at all and a good quality dedicated crank battery may suffice at half the cost. If charged properly and not continually cycled down in charge to stress the battery, the battery should last a fair while. Good quality batteries will last, especially if the weather doesn't get real cold.
If the unit is a pump engine the saving money can be dedicated to a small solar panel and charge controller to keep the battery topped up each day when not used.

Hi
If your going to use it for camp power caution.
The capacity is only 75AH last time I checked for the majority of the range.

John - What are the "space restrictions", exactly? - and what is a "medium size diesel?

The maximum dimensions would be a good start. The engine type and size (litres) would be even better, so we know what you're trying to start.

More importantly, what area do you live in, and how cold does it get in the mornings?

Diesels that live in cold places need bigger batteries, because cold diesels are a lot harder to start, than cold petrol engines.

Cheers, Ron.

In my experience the Optima yellow is a pretty versatile battery. In comes in a few configurations which assists fitting into awkward spaces. Used as a deep cycle it is only rated at 75ah but it recharges quicker than some and can survive more discharges (apparently). Important features for your proposed use I suspect are that it comes in 830 - 900 amp CCA (depending which configuration you get) which will start most diesels and doesn't mind the heat of the engine bay. I have one in my v8 diesel that I use as an auxiliary only but I have used it on one occasion to start the car when the main battery died. My vehicle is 8 years old and I have only recently replaced the 1st Optima that was fitted soon after purchase. That doesn't necessarily mean much since it is only used for a fridge but it is testament to its ability to withstand rough roads and the engine bay temps. I was very dubious when it was recommended by Piranha mainly because of the low ah rating but it saved some mods in the engine bay for fitting so I went with it. Since I am now on to my second I guess I am a convert.

Red top for starting , Yellow top for occasional starting and deep cycle use [ fridges ect ] , Blue tops are more for 'marine' applications and come in 2 case versions - the dark grey case is for 'starting' and the light gray case version is for both starting AND deep cycle use .....$$$$ cost per Amp per years make Optima actually very economical ... Wifes 05 Jeep Cherokee 2.8 diesel is still on the original 'Red Top' Optima ....that 14 years ,190,000km driven as a daily driver ....

Thank you all for the information ,I think I will buy a yellow top.