Let's go back to the beginning in the 1970's. All during my high school years I bought, fixed up and sold 1949 thru 1953 Chevy and GMC trucks. It was during these years that I got my first hand education into how a 6-volt charging system worked or in my case didn't work. I learned all about the yellowish dim headlights, hard starting, (including always parking on a hill) and the constant dead batteries.
All of that hands-on experience led to my invention of a 6-volt alternator in 1985 which solved all of my 6-volt troubles and made new found customers very happy campers. Now there was a simple bolt on solution to bright headlights, easier starting, and the end of dead batteries. All types of 6-volt vehicles could now be made more reliable and fun to drive.
But I had a few customers who wanted to upgrade to 12-volts to add modern stereos and air conditioning. Remember this was over thirty years ago and there was not much available for antique vehicles built in the 1940's and 1950's like there is today. Cars and trucks built in the 1940's and 1950's were still in the "in between" stage, not old enough to be considered collectible but old enough that the aftermarket considered them obsolete.
My customers who wanted to upgrade to 12-volts, wanted to keep and use their original dash gauges. I searched out and finally found a company that would upgrade the factory gauges to 12-volts. Problem solved at least for a while. But over time the cost of sending in gauge clusters to have them upgraded to 12-volts steadily creeped up. When I started offering that service in the mid 1980's it was in the neighborhood of $40.00 per gauge. It eventually got past $100.00 a gauge and I knew it was time to find another solution.
The Runtz was born in 1992 to allow the use of stock 6-volt dash gauges and senders when upgrading a 6-volt electrical system to 12-volts.
So after a year of experimenting with the help of my good friend Dan Schulz (hence the name Rundle and Schulz ) the Runtz was born. A Runtz is a solid state device (for accuracy) and will accept an incoming voltage of between eight and twenty volts, while delivering a constant 7.75 volts to the gauges. I had first hand experience with early voltage regulators that would stick closed causing voltage spikes, so I wanted the Runtz to be "dead on" accurate and able to accept those voltage spikes without damage.
I also added a built -in circuit breaker to protect the dash gauges. A gas gauge foe example, runs on just a quarter of an amp. The Runtz has a built -in circuit breaker that will protect the dash gauges when the current exceeds one amp of current. That way the gauges would be protected from damage in the event of a short in the wiring harness caused from a loose or bare wiring connection. I knew that most 6-volt vehicles are lacking in circuit protection and that fuses are few and far between. A little extra protection would not hurt.
Finally the installation had to be simple and had to work for all types of antique 6-volt vehicles. The Runtz fits on the back of the dash gauge and connects to the accessory wire that comes up from the ignition switch. Simple easy to read (and understand) instructions are included.
A single Runtz installed on the fuel gauge was all that was required for this 50 Plymouth wagon application. The accessory wire from the ignition switch will be installed on the lower stud of the Runtz once the gauge cluster is installed back into the car.
Here are three Runtz installed on a 1950 Ford Dash to protect the temperature, oil pressure, and fuel. Notice how each electrical gauge has its own power wire, very important to insure accurate dash gauge readings. This gauge cluster is ready to be installed back into the car.
You will need one Runtz for each electrical dash gauge because... each gauge draws a different amount of current so in order to have accurate gauges you need to power them separate. I have seen dozens of devices over the years that claim to reduce all of your 6-volt accessories from a single source but have never seen any of them work well and quite a few have burned out dash gauges in the process. It makes sense when you consider that your fuel gauge runs on a quarter of an amp, your heater blower motor requires ten amps of current, and your headlights fifteen amps. If you try and average that all out using a single voltage reducer something is going to get fried.
The Runtz is proudly made in the USA and has been since its introduction in 1992. The price has only increased once in twenty years in part because of the volume of the Runtz I sell. They still retail for less than $20.00. Simply put they work and have become the standard for all 12-volt conversions. I sell them not only to retail and wholesale customers, but to all of the major dash gauge rebuilders. So... if you send you dash gauges in to be rebuilt and upgraded to 12-volts, there is a better than eighty percent chance that your gauge cluster will come back with one or more Runtz installed.
A Runtz in the original packaging with instructions
And then there are the knockoffs...There have been a couple of companies who tried to copy the Runtz over the years without much success. Vintique in California is the most well known offender. The dead giveaway is that the knockoffs are made in China, and they don't reduce the voltage accurately. The knockoffs also have no circuit protection which has resulted in more than a few damaged gauge clusters. They sell the knockoffs for a couple of bucks cheaper than an original Runtz. Be sure you buy a genuine Runtz made in the USA.
Now you know how a simple device became the standard for protecting 6-volt dash gauges when a antique vehicle electrical system is upgraded to 12-volts. You can take pride in knowing that you are buying the original and the best available. You antique vehicle deserves nothing less.