Using 12v variable voltage battery on 12v electronic equipment. Will it work?

[no1pubber]

Hi experts thanks for looking at my post. I am building a small satellite finder using a 12v 7"TV and a 12v satellite receiver. The variable output of the battery is 14.4-15v ( **broken link removed** ) I want to use this to power the devices. The tv is rated at 1.2a and the receiver at 1.0a. will i need to solder a resistor to ensure no over volting of the equipment? also what will i need to be able to recharge such a battery. can you use like a car battery charge for this type of thing or charge off of my cigarette lighter socket or a standard adpated 12v power supply?

Thanks for your advice everyone

Mike

 

[MikeMl]

Realistically, at a discharge rate of 2.2A, your proposed 7Ah SLA will run your stuff for only about 2 hours.

The only time the terminal voltage of the SLA will be 14.7V is during heavy charging. If left sitting for a few hours after coming off charge, the open circuit voltage of the SLA will drop to about 13.4V. The voltage of your SLA under load will almost instantly drop to <12.4V. The TV is designed to operate in a car or RV, and will see input voltages of 11.5 to 14.5V if the engine is running. Your problem will be at the other end; does your equipment still work when the battery voltage sags to ~11.0V. You should never discharge your SLA below 1.75V per Cell = 10.5V, ideally stop at 11.0V, or higher.

Recharging an SLA in a running car ALMOST works. Ideally, the charge voltage for the SLA should be 14.7V; your car's alternator will only be putting out ~14.2 to 14.4V. Another problem is exceeding the initial recharging current if you plug a mostly discharged battery into the cigar plug on a running car. The data sheet is emphatic about limiting the initial charge current to only 2.2A