12v battery for electric fencing

What sort do I require ?

The official answer is a deep cycle or leisure battery. This type of battery is well suited to electric fencing .
A deep cycle or leisure battery has thicker plates and is able to handle a greater level of discharge ,ie you can take more power out of the battery before the battery gets damaged.

Typically 85 Ah to 100 Ah ( amp hour )is fine

So what is your unofficial answer :

If you already own a spare car battery then it can be used . As long as it is producing enough power the energsier will run , The down side is car batteries really should not be taken below 80% of there capacity ie if you have a 85Ah battery you should only remove 20% or 17Ah . If you do take too much power the battery will get damaged and its capacity will be reduced in the future
Bottom line is it is silly to purchase anew battery if already own one that will do the job, but if it is not looked after you will kill it quickly.

What do you mean the battery will get damaged ?

If any 12v battery has too much power removed there is a change in the chemistry of the battery. This change will cause the lead plates to become covered in crystals (sulfation) This in turn will reduce the batteries capacity so it can hold less power.
Whilst this process does not happen over night it does happen steadily so allowing a new battery to have too much power removed  could measurably reduce its capacity in 3-4 months. The reverse is a battery that is looked after can give years of service.

So how long can I use the battery for ?

It does depend on the size and power of your energsier , and the capacity and condition of your battery.
This is a guide for indication purposes only . Based on a 85 Ah battery
For 0.25 J energsiers  recharge 4-5 weeks
For 0.5 J energisers  recharge 2-3 weeks
1J Energisers 2 weeks.

The most extreme example i can give is the A4 12v energiser that needs to have a 85 Ah battery recharged every 3-5 days , but it is a very powerful unit.

What about the cold?

Yes low temperatures do effect batteries , during cold periods your battery will benefit from more regular recharging

How do they get recharged .

A 12v charger is required , this plugs in to the 240v mains and converts this power to 12v . The power output of the charger is measured in amps .  The higher the amp output the faster the battery will recharge .
Most chargers are intelligent so that as the battery “ fills” up it backs off the amount of power it is putting in till the battery is full and the charger is not putting in any power

How Green are 12v batteries ?

From a recycling point of view  pretty good , as long as the old battery is taken to a recycling centre .
the lead can be removed from the old battery  re smelted in to a new battery. the acid can be recycled for other purposes .

The power you recharged the battery with still has to come from a power station……..
How does solar work with 12 V batteries

The solar panel creates electricity from  sun light.
This electricity is then stored in the 12 volt battery which makes it available for the electric fencing energizer to use.
In electric fencing there are two ways to approach the use of solar power.

Solar assist:
This is when a solar panel is used to ensure the battery is topped up during the summer months. In this scenario it is unlikely that the solar panel would be able to keep the Energizer running for the whole of the winter period. The way round this is to give your 12 volt battery a top up from the mains during the darkest months.

Full solar:
If a electric fencing system is specified correctly it is entirely possible to have solar power charging batteries for 365 days a year  so the battery does not require any external assistance.
A possible use for this application is to protect young trees from pest animals such as deer and sheep.
An electric fence that is running from a full solar set up will cost significantly more than a simple solar assist.

We have 12v deep cycle batteries – farmcare uk

10 w solar panels get fro electric fencing  – farmcare uk

The above is written as a basic  guide and is no way a complete work. 
It is my hope that this will encourage users to look after there batteries a little better so they last longer and so save them selves money and time repairing electric fences .