Battery power for Smalls?

[Dipstick]

Hello,

Just curious. Is it possible to run a Smalls printer with an SLA 7 Amp hour battery if even for a short period of time? I have a couple of these batteries and was wondering if I could use them to power the printer."

-Mike

[RetireeJay]

Yes, that should work. The 12V specification is actually fairly loose on the up side, so a fully charged lead-acid battery at 14.5V is no problem. The Hot End draws about 40 watts, and probably everything else doesn't add up to more than another 40 watts, as long as you don't have a heated bed. Thus, 80 watts at 12V = 6.7 amps, meaning one battery could theoretically provide power for about an hour. If you connect the battery in parallel with your mains supply, then this would give you a chance to finish a small print or initiate an orderly shutdown if you have a large print in process. Perhaps a very good idea if you are in an area where the mains supply is unreliable. If you think this will be a frequent occurrence, I'd strongly suggest getting one of those very cheap digital voltmeters so you can monitor the voltage and shut down the printer when the battery drops below 11 volts or so. (Mooselake has posted about very cheap voltmeters).

[Dipstick]

Thanks Jay.
Don't have a heated bed.....Yet. I have 4 of this type battery if needed.
I have many of those very cheap digital voltmeters.

[Mooselake]

Overcharging SLA batteries can cause them to outgass and eventually fail. Do a little research on the desired charge voltage for your type of battery if you need to, adjust your power supply to be no more than that voltage, and it should work fine. Google battery university if you need more info.

As I write this I'm sitting in a small trailer powered with a couple 100Ah deep cycle batteries in a ham radio contest (waiting for 20m to come back up...), next to an old mine hoist in a national park. No mains connection, and the guy with the generator went home for the night, so the radio, tuner, light, and logging computer are all running off the batteries. When they run down it'll be time to take a nap until the generator gets fired back up. Internet is complements of a local wireless ISP through the club's mesh logging network. Yep, it's 2017's amateur radio field day weekend. 50s and rain, June in da UP.

Kirk

[Dipstick]

Thanks Kirk. I will do a little more research on the batteries. I know a little bit about them.
Are you off the grid then?
Mike

[Mooselake]

Only for part of the weekend, but I'm not sure you're off the grid if you have Internet access.

The batteries lasted longer than I could. 20 years ago I could operate all night, today not so much. Batteries were at 12.55v when I pulled out the blankets at 2am. Bands weren't very good anyway

Kirk