Midland desktop charger requirements

How can I find the power draw from a Midland GXT1000 desktop charger? I don’t see it in the specs anywhere.

The reason is that we have a radio box that we have mounted 5 chargers and ten radios in. The box can be plugged into an outlet and all chargers come on and charge. This worked good as in my old car I had a 110 outlet standard in the vehicle and could plug the box in and let it charge while driving as well as plugging in at home. My new car doesn’t have that.

What I’d like to do is modify the wiring and add a 12v jack onto the box so I can plug the box into the cars 12V power supply while maintaining the 110 plug as well. Right now the chargers are plugged into a multi-plug power strip inside the box.

My idea is to add a new 12v power bus in the box that is wired to a cigarette lighter power adapter that when plugged in would power the bus in the car. All the chargers would be wired to the bus.

The 110 multi-plug strip would be removed and a single plug would be installed and one desktop adapter plugged in that would then power the 12v power bus.

Question 1: Can 5 chargers charging 10 radios run off one 12V 10amp vehicle power supply?

Question 2: Can a single 110 adapter (sold with the desktop chargers) power the 12 V bus and supply enough power for all 5 chargers? Or would I need 2 adapters? Or 3 adapters?

We use these radios in the woods so we want to be able to charge them from a vehicle. When we get home, we want to carry the box inside and be able to plug it in to house current to charge over night.

The attached pic shows only three chargers and 6 radios, but we now have 5 chargers and 10 radios in the box.

Your choice would be a 12-volt inverter, plugged in to the power bar and use the existing desktop chargers, or 12-volt aftermarket chargers that plug directly into the MIC/CHG jack of the radio. For fastest charging, the desktop chargers would be best.

The Midland dual AC charger needs 9 watts input and outputs 300mA. Assuming five chargers at 10 watts each, you need an inverter rated for 100 watts minimum. (Most inverter ratings give you the peak draw rating, not the steady draw, so take you maximum power requirement of 50 watts and double it.) You can get some pretty inexpensive 130-watt and 150-watt inverters that plug directly into the 12-volt outlet in a vehicle. No reason why this shouldn’t work. Charger power requirements are modest in comparison to things like lights, coolers or power tools.

I would be inclined to trust a good quality 150-watt inverter over those eBay 12v chargers.

Thank you for the suggestions!

Actually I’m installing a 2000 W inverter. We have a K-cup machine the draws 1450 W that we want to be able to use.

But we’d really rather go with 12V power to power the radio box in the vehicle. The desktop chargers come with a 12V cigarette lighter plug and cord so I know they’ll work right off of 12V.

So at even 10 watts at 12v that is .83 amps per charger. So 5 chargers would only require a 5 amp circuit. A 12v, 10 amp circuit should cover that.

If each 120V adapter outputs 300mA at 12v can one supply 5 chargers though?

The wall wart power supply is marked 9V 300mA I think - therefore all the radios will need less than that to charge, as there’s likely to be some over capacity - so probably 4 radios will only be around an Amp - If you have 10A to play with - that’s a lot of charging power isn’t it!

So I think I’m going to install a converter into the radio box to convert the AC to 12v DC to power the bus strip. Then I don’t need to worry about using the AC adapters at all. Should all take up less room too which could give me room for more radios or add in USB chargers.

I’m thinking of using this converter.


This steps down to 12VDC, 150W and at <$20 is priced right. This should be plenty to power the 5 desktop chargers. What I haven’t figured out is if i need some type of circuit on the 12v output side of the converter to block power from entering the converter from the 12V side when the 12V DC side is powered by the vehicles 12 V system.

Rather than even worrying about adding some kind of automatic protection circuit I think I’ll just build in a two position switch. Position A will take the feed from the AC converter, position B will take the feed from the 12v vehicle supply. Can’t have both on at the same time so i just flip the switch to the AC side when I plug in at home. Flip it to DC side when I load into the vehicle.