Smallest starter battery.

[Momac]

. these days you can get dual purpose starter and leisure batteries.

Many are like that and have a very good CCA as well as good Ah.
My starboard domestic bank starts the starboard engine so the dual purpose type is what I use .

I think far higher than necessary CAA is the way to go. So the battery will still have enough energy after its original performance has diminished with age.

.

 

[jwfrary]

I use the 55ah orbital starting battery from exide. Has more cca than the 140 flooded batteries it replaces.

The 95 ab start stop variety will also suit very well.

 

[noelex]

The spiral wound (or orbital) AGM batteries are the way to go if you want maximum starting current in the smallest form/weight factor in a lead acid battery.

The spiral winding of the plates provides a greater plate surface area in a small space. Plate surface area is what determines short term current capacity (if other factors are equal). AGM chemistry provides the highest short term currents of the readily available lead acid types. So a combination of these two technologies will deliver what you want. Note: for the highest deep discharge capacity the opposite is best with thick plates performing better.

The most common brand of spiral wound batteries are the Orbital brand and they make models with very thin spiral wound plates specifically for providing high starting currents in small form factors. Other brands such as Exide use the same construction methods, often at lower prices.

Using this technology a battery such as this 50Ahr 800 CCA Exide model:
Exide EM 1000 - autobaterie » www.prohifi.cz
will reliably start a 100Hp marine diesel engine even in cold weather. You can go smaller especially with lower HP engines. Even smaller (around 30Ahr) spiral wound AGM batteries are available and these will work with a 50HP and lower marine diesels, but they tend to be speciality items. These very small 30Ahr batteries can be slow to source when a replacement is needed. Sometimes start batteries can fail with little waring so It is generally worth sticking to a readily availible sized battery.

Lithium start batteries are smaller and lighter again than lead acid chemistry, but these have other drawbacks in this application.

 

[jwfrary]

The spiral wound (or orbital) AGM batteries are the way to go if you want maximum starting current in the smallest form/weight factor in a lead acid battery.

The spiral winding of the plates provides a greater plate surface area in a small space. Plate surface area is what determines short term current capacity (if other factors are equal). AGM chemistry provides the highest short term currents of the readily available lead acid types. So a combination of these two technologies will deliver what you want. Note: for the highest deep discharge capacity the opposite is best with thick plates performing better.

The most common brand of spiral wound batteries are the Orbital brand and they make models with very thin spiral wound plates specifically for providing high starting currents in small form factors. Other brands such as Exide use the same construction methods, often at lower prices.

Using this technology a battery such as this 50Ahr 800 CCA Exide model:
Exide EM 1000 - autobaterie » www.prohifi.cz
will reliably start a 100Hp marine diesel engine even in cold weather. You can go smaller especially with lower HP engines. Even smaller (around 30Ahr) spiral wound AGM batteries are available and these will work with a 50HP and lower marine diesels, but they tend to be speciality items. These very small 30Ahr batteries can be slow to source when a replacement is needed. Sometimes start batteries can fail with little waring so It is generally worth sticking to a readily availible sized battery.

Lithium start batteries are smaller and lighter again than lead acid chemistry, but these have other drawbacks in this application.

I'm using a pairs of em1000 to start 355hp and 500hp cummins. No problems whatsoever, it's all about cca, by the time the batteries flat the starter will have overheated anyway!

 

[Rappey]

A mercedes c250, 2.1 litre, 202hp, 500nm of torque ,stop/start uses a 80a/h battery .800 cca.

 

[BabaYaga]

The most common brand of spiral wound batteries are the Orbital brand

You may have meant to write Optima brand?

 

[noelex]

You may have meant to write Optima brand?

Yes, sorry, it was the Optima brand that I was thinking about.
Orbital is the name Exide uses for their spiral wound batteries.

 

[KREW2]

I used one of these small and it can be laid down flat.

Odyssey PC1100 Extreme Series Battery (ER40) (ODS-AGM40E)

 

[Spirit (of Glenans)]

I don't understand why you're trying to get the 'smallest' possible battery if not restricted by size or weight? It seems as if you're purposely trying to introduce jeopardy! And having to replace a battery that proves to be too small/problematic would ultimately be false economy.

I've used Tayna in the past and would recommend on both price and service.

There can be rational reasons for this decision, for instance, I am following this thread because I have it in mind to replace my starter battery with a smaller one to fit into the neighbouring cavity of the under-bunk internal moulding in my Dufour 30 Classic, and then replace the existing service and starter batteries, (one of each), with a pair of leisure batteries of the same dimensions, so as to have a larger service battery bank in the existing space that they occupy. I'm not looking for the "smallest", just one that will fit into a given space and still do the job.

 

[pandos]

I used one of these small and it can be laid down flat.

Odyssey PC1100 Extreme Series Battery (ER40) (ODS-AGM40E)

A good example that MCA and CCA. Are different.

I would think that size would not be adequate.

As said above I will be going with Paul's recommended 096 size in Hankook or similar AGM. With about 800cca..

 

[Tranona]

There can be rational reasons for this decision, for instance, I am following this thread because I have it in mind to replace my starter battery with a smaller one to fit into the neighbouring cavity of the under-bunk internal moulding in my Dufour 30 Classic, and then replace the existing service and starter batteries, (one of each), with a pair of leisure batteries of the same dimensions, so as to have a larger service battery bank in the existing space that they occupy. I'm not looking for the "smallest", just one that will fit into a given space and still do the job.

That is a very sound reason for having a small engine start battery. The idea of big batteries dates from the time when 2 batteries were fitted and used for both engine and domestic with the dreaded 1.2.both switches. Now that having 2 dedicated banks is the norm and the engine battery is used solely for starting there really is no need for a high capacity start battery, particularly as modern diesels are instant starters. My first Bavaria had factory fit 75ah engine start and 2*110ah domestic. Now with the developments of batteries for stopstart cars there is a bigger choice of small AGMs that are good for engine start.

The ultimate is Red Flash type high powered batteries which I will use in my GH. Although expensive it means that I can get 2*95ah AGMs and the Red Flash in one location with the shortest possible cable runs and avoid having to build another box in another location. The saving in cabling alone is more than half the extra cost of the battery.