Powering a 12v monitor with what battery?

[Dan Easton]

I have a 17" LCD monitor that can run off a battery.

I know I can't use a car battery, but what sort of battery would be best? Ideally I want to be able to power it for a good 3-4hrs or more, so around 20Ah or more would be good.

It's likely that the battery will go un-used for a few months at a time.

Any feedback at all welcomed.

 

[Bluejets]

More detail on the monitor would be helpful.
Cannot see any problem running off a car battery but that depends on the detail.
If the car battery went unused for months, it would need to be trickle charged/maintained.

 

[Dan Easton]

More detail on the monitor would be helpful.
Cannot see any problem running off a car battery but that depends on the detail.
If the car battery went unused for months, it would need to be trickle charged/maintained.

It's a Sony LMD-A170. Draws no more than 5A at 12V.

A car battery is no good for this sort of application.

 

[Bluejets]

It's a Sony LMD-A170. Draws no more than 5A at 12V.

A car battery is no good for this sort of application.

Perhaps you could enlighten my many years experience on just why that might be.

 

[Dan Easton]

Perhaps you could enlighten my many years experience on just why that might be.

A car battery (also known as a cranking battery) is designed for small bursts of very high current (to crank a car engine) and then be immediately recharged (from the vehicle's alternator once the engine is running). Generally, a car battery is in an almost constant state of full charge and can be damaged when at lower levels of charge.

I'm looking for a battery that can supply a smaller, constant current and be happy to be used to a state of heavy discharge.

 

[Bluejets]

Rubbish.
There are many discharge items in a car that draw small amounts of current when not charging.
Radio, cd player, clock, parking lights etc.etc.
A lead acid battery can sustain discharge down to a terminal voltage of approx. 10V6 before requiring a recharge.
If you are worried you may not be able to monitor this level then perhaps you need to think about voltage monitoring devices as well as most rechargable batteries have a recommended cut-off point.

 

[Harald Kapp]

be happy to be used to a state of heavy discharge.

No battery wil be happy when heavily discharged. Regardless of battery type you'll have to monitor the voltage (as an indication of state of charge) and turn off the load once a critical state is reached.

A sealed lead-acid battery will do the job. These are e.g. used in UPS (uninterruptible power supplies) where they are heavily discharged (but not below their limit) in case of a power outage on the mains.

 

[BobK]

And there are deep cycle lead acid batteries that are designed to be more capable of running smaller currents for a longer time. These are often used in RVs and boats to supply electrical power.

Bob