12 Volt power supply?

I want to put in a power outlet, and I bought an LED Light bar (Sand Rail guys use them all the time due to very low power draw and very bright lighting). Where can I find a 12 volt source that I can tap into for these 2 items? I trust it is somewhere under the dash panel, coming off one of the boxes, just don’t know where a good place to locate it is… Can anyone help out with this? Thanks!

Hello, I’m looking for the same information.

Is there a terminal block etc. to use for power to a radio/12V interter etc.?


If your GEM uses the six cell 12 volt batteries, you could just connect directly to one of these. Be sure to use an appropriate inline fuse at the battery connection. If you have the four cell 8 volt batteries, you may want to connect to the DC/DC converter instead. LED lamps are a great idea for electric vehicles. As far as I know, all of the lamps on a GEM can be converted to LED.


Thanks for the reply. That is what I was guestimating to do, but wasn’t sure if the voltage across the batteries changes at all when the controller kicks in etc.

I know the voltage reads individually on each battery and they can be charged individually. I noticed the increased in voltage when you check downline on each ground using a common positive, and that raised my doubt about using an individual battery for accessory power when it is still connected in series with the others. I forgot most of my high school electronics so many years ago…

Are there any issues with charging if one battery is continually used more than the others? I would certainly expect the life of the one to be shortened, but its just a guess.

Would it be better to tie in at the converter overall, especially if you wanted to power a few circuits?

Voltage variance among the batteries should be minimal. LED lighting is often designed with an acceptable voltage range. Brightness of the LEDs should remain constant within this range. An LED light bar may use 25 watts. On average, LEDs use 10% of the equivalent incandescent wattage. With such small loads, I don’t see any issues with tapping individual batteries. With multiple circuits, I would divide the load amongst the batteries and always use inline fuses.


I am not sure where to tap off the DC/DC converter? Is there wire color, or some type of set wires for doing this (an aux output)? I am more comfortable with this, as opposed to a single battery, as I want to run a GPS, and a phone charger, through 2 power outlets (lighter style), as well as my LED Fog lights through a hard wire and switch. Thanks for the replies thus far!!

I’m considering similar uses - stereo, aux. outlet etc. Maybe an inverter. I don’t have a problem connecting to individual batteries, but am thinking a single source power point to a small fuse panel/resettable breaker may be a cleaner way to go if there is a good circuit to use.

If you are adding an AC inverter larger than 100 watt, definitely connect directly to a battery. If you need a large 12 volt inverter, consider adding one extra battery in parallel so that more 12 volt amps are available. High output inverters are available in 24 volt, which can be connected to two 12 volt batteries or three 8 volt batteries in series. I am interested in finding out how much capacity the GEM’s DC/DC converter has. If your GEM is a 2005 or newer, there is a 12 volt main breaker to tap off inside the cab. Devices with low power consumption are no problem for the DC/DC converter. This is just an electronic voltage reducer that converts 72 volts to 12 volts. Early units were recalled because they got wet and caught fire. One of our GEMs had this problem. The new units appear to be sealed.


Mine is a 2002 with gel batteries and the newer charger - not that it means anything.

I don’t plan on a large inverter - I’ll primarily use it to power my portable boombox for my satellite radio. I may just install a 12v plug and use a plug in invereter. I was just visualizing doing something to add some versatility electrically.


Whatever you guys do, do not go by what Dan said by connecting directly to a battery! that is the worst thing you could do. The battery may be 12volt but its in series and shares a different operating source to create 72 volts, separate grounds and power. Do not cross paths. Connect to the appropriate source through the DC Converter. Call GEM TECH SUPPORT at 866.764.0616 with a VIN so they can tell you where to connect properly without blowing out your light!

I will repeat that the GEM DC/DC converter is not rated for large 12 Volt electrical loads. It was designed for the lighting load, control circuits, and an optional car stereo. Over the years, I have seen the fuse holders melt from overloading. The converter has a 10 amp output fuse which, using Ohm’s Law, yields 120 watts maximum. Not much after the other 12 volt loads are considered. I have seen people try to use the 12 volt outlet with a solar charger not realizing that the converter does not work in reverse. There was a post on another board about a GEM owner who plugged a 12 volt heater into the outlet. I have even seen someone try to use the 12 volt outlet as a way to boost start cars. Basically, if you plan on needing more than 100 watts, find some other way to connect the inverter. Get a higher voltage AC inverter to distribute the load over several batteries, or use the series / parallel battery arrangement described above. Connecting a 10 watt LED light bar through a fuse to one battery will not have any effect on load balance. I deliberately connected our four GEMs this way so that the warning lamp can be used even with the key removed and the vehicle’s electrical system off to conserve power. This is very useful for security and maintenance vehicles.


I have found a source for heavy duty 72 VDC to 12 VDC converters. Having done railroad work for quite some time now, and knowing that many locomotives have 72VDC starting systems, I came across this suppier of converters. Units are available up to 15 amps from Powerstream.

72 volt to 12 volt DC/DC conversion


Dan. I have. 2005. I cannot find the 12v power source in the cab that u r taking about . Please help…