Batteries - again !

[tarik]

Evening all,


Am having a silly five minutes and cannot remember which is the better battery.

I am looking at 2 new batteries

120amp 'Leisure' Marine 12v

130amp 'Starter' Marine 12v

which is the better one for the boat?

As ever grateful thanks for all replies

David

 

[yoda]

If it is only for starting an engine then the 130amp 'starter', if it is for a mixture of starting and 'house' use then the leisure battery.

Yoda

 

[pappaecho]

A starter battery delivers hundreds of amps for a short period of time. The battery does not take it well to be heavily discharged. They tend to have closely spaced plates inside.

A deep discharge battery, delivers a steady current over many hours, and can take much higher levels of discharge without harm. These tend to have more robust plates spaced further apart.

The so called leisure batteries are a combination of the two, and are supposed to be near deep discharge specifications. The important thing is that the starter battery is left to do the starting, and the leisure battery can be discharged quite heavily without damage. The obvious thing is say a fridge or inverter which will run even when the voltage has fallen to 11 volts

 

[nigelmercier]

120amp 'Leisure' Marine 12v
130amp 'Starter' Marine 12v
which is the better one for the boat?

Depends if it is for starting the engine, or running the domestics. The clue is in the name

 

[vyv_cox]

Leisure batteries are taller to accommodate a void beneath the plates, into which sulphate can fall when the battery is deep-cycled, to avoid shorting it out. The plates in a leisure battery may be thinner and more numerous, so it is less able to supply big currents but recharges more rapidly. Nowadays there are batteries claimed to lie somewhere between the two, and thus suitable for both duties.

Personally, I almost always start my engine on my domestic bank, which comprises three 110 Ah leisure batteries. They were replaced this season when six or seven years old, so the treatment I give them seems to have done little harm.

 

[Plevier]

Leisure batteries are taller to accommodate a void beneath the plates, into which sulphate can fall when the battery is deep-cycled, to avoid shorting it out. The plates in a leisure battery may be thinner and more numerous, so it is less able to supply big currents but recharges more rapidly. Nowadays there are batteries claimed to lie somewhere between the two, and thus suitable for both duties.

Sorry Vyv, I can assure you it's the reverse. Starter batteries have more thinner plates so that the chemical reactions can proceed quicker and give the higher output currents. This configuration also gives lower internal resistance.

Cycling batteries have thicker plates for better corrosion resistance and paste retention. The higher internal resistance and increased acid diffusion time limit the current. They will also have different separators between plates to lessen the risk of shorts between plates - classically from dendritic growths - again at the expense of internal resistance. A lot of cycling batteries have envelope instead of sheet separators, to catch shed material rather than drop it in the tank.

Small starter battery plates are typically 1.5 -2mm thick, truck batteries 3-4mm (these plates are likley to be the basis of most "leisure" batteries) and flat plate traction batteries 6mm and more. Extreme batteries such as the SBS series (used in some of the DMS Varley RedTop range) designed for aircraft turbine engine starting are as little as 1mm thick.

Most leisure batteries will do starting duties quite happily but you will need a bigger battery for the same cranking current, but in boats we tend to oversize starter batteries hugely anyway.

 

[vyv_cox]

My apologies, I see I had it the wrong way around.

 

[charles_reed]

Sorry Vyv, I can assure you it's the reverse. Starter batteries have more thinner plates so that the chemical reactions can proceed quicker and give the higher output currents. This configuration also gives lower internal resistance.

Cycling batteries have thicker plates for better corrosion resistance and paste retention. The higher internal resistance and increased acid diffusion time limit the current. They will also have different separators between plates to lessen the risk of shorts between plates - classically from dendritic growths - again at the expense of internal resistance. A lot of cycling batteries have envelope instead of sheet separators, to catch shed material rather than drop it in the tank.

Small starter battery plates are typically 1.5 -2mm thick, truck batteries 3-4mm (these plates are likley to be the basis of most "leisure" batteries) and flat plate traction batteries 6mm and more. Extreme batteries such as the SBS series (used in some of the DMS Varley RedTop range) designed for aircraft turbine engine starting are as little as 1mm thick.

Most leisure batteries will do starting duties quite happily but you will need a bigger battery for the same cranking current, but in boats we tend to oversize starter batteries hugely anyway.

Ironically, local "country" batteries, of low tech design have fewer, thicker, plates and besides being cheaper last longer in the marine environment.
Industrial traction batteries would be best of all but one seldom finds boat battery-boxes are the right size or shape.