12V UPS supply for embedded systems

I want to provide uninterrupted 12DC power to my raspberry pi/arduino based remote system. Rather than using a traditional UPS, I thought a LV DC UPS makes more sense which removes the unnecessary AC-DC-AC conversion.

If I'm not wrong, I need a simple charge controller that charges a 12V battery protecting it against overcharging and over draining. It should also supply the load which I suppose will not exceed 1-1.5A. It will be always on and when power goes out, the battery will supply the load.

Will a simple 12V transformer's rectified output feeding an off the shelf solar charge controller be OK? Say something like this:


Link does not work.
Search for “lead acid battery charger”, or " motorcycle charger" on ebay.
That, and a 12volt/7Ah sealed lead/acid battery (alarm systems) could work.
An Arduino could work a lot longer on that battery with a 5volt micro (<1Amp) DC/DC buck converter, straight onto the 5volt pin.
Don’t about the Pi.

Was this the link?

A solar charger is not usually suited to operation with an AC transformer/ rectifier as it limits charging by shunting excess current. You want a current-limited and voltage regulated power supply of 13.8 V including a diode in its output to prevent back-discharge through the power supply circuit.

The Pi is in fact, powered by 5 V of at least one Amp (depends on model), so a switchmode converter from the battery to 5 V is absolutely the only correct way to go.

If you are using a lead-acid battery it is probably only necessary to use a charger that produces a voltage slightly less than the fully charged voltage. Then as the battery charges the flow of current will automatically decline to near zero.

I would be a lot more careful with other battery types.

There is a lot of useful info at the Battery University


You may look at this product, it have 5V model too.

backup-power-lithium-mini-ups-battery-dc-ups 12V-2A