Leisure battery problems

[annierich]

We 'inherited' a leisure battery when we purchased our preloved caravan earlier this year. The caravan was new in Feb 07 but the leisure battery is dated 10/06 and we believe it had been used in the previous owner's earlier caravan.

We have had problems with our motor mover and have had 2 new motors and rollers fitted today.

When the battery is fully charged from the mains it reads 14.2. When not connected to the mains today it read 12.9 and when the mover was tested (by the caravan engineer) without the rollers being engaged the readout fell to 11.8. The engineer said that the mover wouldn't really work if the battery readout was 11.6 or so.

My queries are:

1 - Has the 2 year old battery 'had it' and do we need to replace it?

And / or

2 - Would it benefit from a good charge on a battery charger - which was the other suggestion?

Being new caravanners we don't know whether or not a leisure battery should last for more than 2 years.

Many thanks for any replies.

 

[rob_jax]

Hi Annie,

You can ignore the battery reading of 14.2 volts - that's just a memory of the charging voltage and will quickly die away to a normal 12.6 or 12.9 volts (sealed battery).

Since you see 12.9 volts - that implies you have a sealed battery - it's giving the correct voltage for a fully charged battery - all well and good.

But when you try to draw a large current from the battery - such as a motor mover - the voltage drops, which it naturally will do, but such a significant drop means that the battery probably has little capacity.

If a lead acid battery is allowed to sit for any time in a discharged state, then they rapidly poison themselves - a process called "irreversible Sufation" - and effectively the battery is dead.

A top quality charger - like a CTEK has a special mode to reverse "irreversible Sulfation" and regenerate an old battery - but since each battery is different, there is no guarantee of success.

So it appears you have a fully charged battery - but the capacity will have shrunk from a useful 80 AH (or 100AH) to probably just a few Amp Hours...

So I'd suggest trying a new battery - and around 100 AH would be sensible if you intend to use a lot of battery power.

And yes, a good leisure battery should last for several hundred charging cycles - but only if it is stored in a fully charged state - and this means continuous or weekly (or possibly monthly) trickle charging...

Robert

 

[annierich]

Thanks for that very useful reply.