Introduction: 12v Coffee Machine (runs on Car Battery)

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You heard it here first. A coffee machine you can run off a 12v battery. When I found this machine, I wasn't sure this would be possible but after over a year of not using it because I never took the batteries, I made it happen.

MUST HAVE ACCESS TO BATTERY

MUST CONNECT DIRECTLY TO BATTERY

Supplies

The Machine - Awesome little machine

Coffee - For ease. Not fancy, but also the machine comes with a little filter basket that will fit 2 scoops of your own grounds. The coffee bags are more to clean up which is why I usually don't bother with grounds but hey, options.

Some Wire - Use 14 gauge at least. 12 is ideal, BUT I found the internals of the machine use 14. No soldering required because, per Japanese fashion, connections inside the machine made via terminal block, not crimped connections.

Alligator Clips - I used the 15A clips because they fit my terminals better.

Drill and Screwdrivers - I wanted to make mine as pretty as possible so I drilled holes in the plastic housing of the coffee machine so that. See the pictures, choose your design.

Fuse - Ask yourself, did you want a coffee machine or an arc welder? Use a 30 Amp fuse

Step 1: TLDR; Understanding the Machine

This Machine has some cool features. It has the ability to run off 2 different kinds of Makita battery systems, the 18v "LXT" and the 12v "CXT MAX". But, it's not just plug and play. You also need to fool the machine's low voltage protection system. For this reason, disconnect the power source after use so you don't strand yourself after draining your car battery.

So. Cool. The heating element in this case is just a U-Shaped percolator so now it makes sense. The lower voltage may draw slightly more amperage but ultimately the power consumption is the same because it heats until the water is pushed out of the percolator. For this machine, it is also on a timer so you may have to turn it on again if you don't get enough coffee brewed.

Be advised, it is not fast but it is effective.

If you own tools on one of these battery systems, there is a way to leave that battery slot intact. But, I'm afraid my plans disrupt the low voltage protection so watch your battery's levels. The 18v 4.0ah battery gets 2 full cups and so knowing this will help you keep track. Discharging the battery too far can absolutely damage the battery so be gentile.

The low voltage disconnect is actually different between the 2 battery types. So we see that with each battery slot, there are 3 connectors! Why? DC batteries don't have a ground! Odd. Well, here's why. So on the 18V LXT battery, the third leg will be an additional positive (+) lead. When the battery reaches it's low voltage point, the voltage to the 3rd leg will drop to 0v. THE END. Similarly, on the 12v CXT MAX system, the 3rd let will measure ~2.5-3.0v until a certain point of discharge and then, similarly drop to 0v. So, knowing this, we will end up permanently connecting the 3rd leg of the 18V side to the positive (+) side of the battery connection. Even though a running car's battery will not be above 18v, the system will not be indicated to stop brewing. This took em the longest to discover. Many YouTube videos and testing it myself.

Note #1: The Makita tool system family DOES NOT rely on the battery to cutoff the power. It is actually the tool which gets an "indication" from the battery and shuts it down.

Note #2: The positive (+) and negative (-) of the 2 different battery slots are connected so make sure the sliding cover still shields the exposed terminals of the batter slot not in use. Also never plug in both types of batteries but why would you? Right?

Step 2: Simple Connections

Disconnect the battery slot of your choosing and honestly, just remove that insert. Makes for a nice square hole to run wires through and seat your fuse holder.

From the 18V LXT side, disconnect the wires directly from the terminal block and when you insert the new wires, make sure that 3rd leg wire is tucked into the positive (+) side on the terminal block also.

Drill holes for wire output wherever you see fit, be creative. I made mine a little tight so it would also prevent me from yanking on the terminal block inside.

Leave a comment with any questions. Machine works as it did before with the standard Makita batteries, but now, it just connects directly into my car's battery.