Need help from someone that knows modern cash registers. I'm looking for an inexpensive modern cash register with tape printout, preferably with ink ribbon and a cash drawer. The kicker is the internal mechanism has to be entirely 12V. Most modern cash registers run on either 5V, 12V or 18V or a combination there of. I need one that is entirely 12V (ie. a single leg on the transformer to 12V) and can be easily converted to run on 12V battery for a farmers market. Can anyone help me with a brand and model number that would fit this bill?

no but samsung do a battery operated till [i have one in a hospital that they put on a trolley and push round the wards]
running time will cover a days trading then recharge over night

You could use an inverter. Cash registers are low power machines so you only need a cheap simple inverter

and how many cash registers have you seen damaged by inverters over the years registerman?
the square wave inverters tend to spike the power supplies within the till - ive written off 3sharp 213's this year so far and repaired many others.

if there was no alternative then yes, i agree but why risk it when there is a machine out there designed to fill that niche?

Fair enough. I thought they had improved in recent years. I have a few customers using them and they have been reliable, but they may be on pure sine wave inverters then.

The coolest & in my opinion the best portable Lithium Polymer battery powered cash registers are the RCH FLEA which is a handheld with a thermal printer or the ONDA which is a bit bigger but has 15 depts & really simple to program, the new portable Touch Me version is now out which has a touch screen fully programable keyboard, these work great & not had any issues with these apart from the batts need replacing after 18-24 months.