Can I Run An Appliance From a 24v Battery?

Question

First, a little backstory. My wife is planning to operate a booth at some craft fairs and we require power for a piece of equipment (Silhouette Cameo, a computer controlled vinyl cutting machine). We've done this once before with success at a show that had power provided. However, other shows do not provide power.

The Cameo’s AC to DC pack states that it provides 24v power at 1.25 amps.

My initial thinking is that you could run two 12v batteries in series to provide the power, then at the end of the day, let them recharge overnight and have them ready for the next day. I have a few questions on the practicality and feasibility of doing this.

First off, what kind of battery can I use? I’ve read a few things on the web stating that certain batteries are not good for this application (ie: car batteries). Is this an applicable battery?

https://www.amazon.com/ExpertPower-EXP1270-Rechargeable-Lead-Battery/dp/B003S1RQ2S/ref=pd_lpo_23_bs_tr_t_2?_encoding=UTF8&psc=1&refRID=NV9MYPMB3E5Q6JT65SZS

Secondly, as batteries don’t provide a straight up 12v as they describe, and the voltage differs based on the amount of charge they are holding, can this damage the appliance? If so, is this what a regulator can help with?

Pardon if anything I’m saying comes off as incredibly stupid as I only understand electronics at a very basic level. My hope is that connecting two 12v batteries directly to the Cameo’s DC input will work without damaging it, and if not, a little regulator chip ( like this: http://www.jameco.com/z/7824T-Major-Brands-Standard-Regulator-24-Volt-2-2-Amp-3-Pin-3-Tab-TO-220_51414.html ) would be enough to supply a steady current to the machine with no risk of damage.

Thanks in advance for any help.

Answer 1

Just get two car batteries and put them in series. That should be close enough to 24 V to run the device. It is quite unlikely that ±1 V will cause any trouble, although there is no guarantee of that.

Since the power supply is rated for 1.25 A, you know the device won't draw more than that. Even assuming the full current draw for 8 hours, that comes out to 10 Ah. You don't want to run car batteries down very far, but even small car batteries can do well more than that. 30 Ah is a "small" car battery, and two of those should be just fine with 10 Ah drained from them. Overnight should also be plenty of time to charge them back to full.

Answer 2

First, instead of regular car batteries to get that ~24VDC, use deep discharge batteries. Second, 12V lead acid batteries are fully charged at between 14.4 and 14.8 VDC gassing point. Third, yes, two 12VDC batteries in series can properly supply this instance with plenty of power to get you through the day. You only have to supply the current requirements. Fourth, your goal would still be better realized with one 12VDC battery and a buck/boost supply or three 12VDC batteries regulated down to 24. Fifth option, use 18650 batteries stacked in series to make between 23 to around 26 VDC. Stack parallel banks to obtain the current you need for the day or use multiple sets. @user253751, how do you get +2.4 VDC from two 12 volt series-connected lead acid batteries? 2.24VDC each from 12 cells results in 26.8 VDC. A 12 volt lead acid battery produces barely any voltage above 12.2 after having been removed from a charger for 15 minutes.

Answer 3

It's a moot point anyway because the voltage going in on the power connector is regulated in all instances unless the regulator itself can't handle the added watt or two of dissipation or there are capacitors directly across the input rated for 25 volts, either scenario of which is highly unlikely. https://batteryuniversity.com/learn/article/charging_the_lead_acid_battery