Yaesu FT-4X ‘mobile’ charging

Has anyone has experience of charging a Yaesu FT4X while roaming ? ( think the FT65 is the same setup ). Not sure I want to carry the docking station and mains with me when away and it has no USB-C slot ( £12 quasheng has :joy::joy:)

I probably won’t bring the charger on my trip to rum and will see how long the battery will last, hopefully, three days!


Hi Tim,
Checking the battery elimanators it seems the radio needs 7.4v - does that seem right?

If so you could get one of these:

(put whatever the needed connector is, on it) and then charge from any USB-A socket - as found in most modern cars, aircraft seats, coffee shops hotel rooms or indeed if you have a power bank to charge your phone from, you can use that.

Of course the Yaesu manual states in several places that you are only allowed to use Yaesu accessories with the radio.

73 Ed.


Yes It is a 7.4 Lithium ion, So any charger Capable of handling this should work I guess?

The terminals are on the back of the Battery and there is a T Terminal, which I have no clue what it does:

I would love to know….

I was sort of guessing I might be able to make a small 3D printed clip to attach to the battery and use a mobile lion charger than can also deal with my HF radio and other digital stuff

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T is the contact for the battery internal temperature sensor.
Some chargers use this for detecting damage and stopping the charge - as far as I know.
As long as you don’t go to high in voltage is should be fine. I would make sure that you go 0,1 Volt or so below the max charge voltage. Just to be sure.

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I have also got the FT-65 and FT-4X Tim. I’m not as active as you these days, but if I think I will exhaust one battery capacity I carry both handhelds as they are so lightweight. The other option is to buy a spare battery pack and carry that in the bag. I haven’t checked if any compatible cheaper equivalents are available from other makers than the proper Yaesu branded batteries.

73 Phil G4OBK

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Also a good thought. A charger and powerbank will probably be heavier than a spare battery. So as long as you are not on a multiday offgrid activation that’s probably the easiest option.

When I first read the request I thought “yeah just make a cable to attach the rig to your main SOTA battery”. Then I found out that this radio doesn’t have a DC input socket. :scream: I suppose this is the equivalent of phones that don’t have a headphone socket and was bound to come.

The solutions are:

  1. Don’t buy radios without DC input sockets. Very helpful answer Andy. What I really mean is next radio you or I buy, check it has a DC input if possible. Though I can see there will be fewer and fewer that do as time goes on. viz. 3.5mm sockets on phones

  2. Carry 2 battery packs though possibly expensive.

  3. Get a battery eliminator. I think Yaesu sell one. But as you enjoy 3d printing you can probably print something yourself that will clip in and connect to the terminals. You’ll need a wee something somewhere to provide 7.4V from your nominal “12V” external battery you power your main rig with. That way you can save the battery for when it’s most useful.

I’m trying to think and I don’t think I have seen a ham radio that didn’t have a 12V input. My 1997 vintage Yaesu VX1 has an internal 3.7V LiIon cell but even that had a 12V input. In fact the charger was a 12V 1A transformer (not switched mode) supply and it is 2x bigger and 5x heavier than the radio it charges!

This is an interesting issue and one that more and more will face in the future.


I just bought a second battery for mine and carry it in my SOTA tub… was fairly inexpensive and works great!



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There are plenty of OEM battery eliminators for this radio - AliExpress, TEMU, eBay, Amazon or whichever suits you best. These are designed to plug into a 12V car supply - so the 12v - 7.4v Gubbings are already inside it. I didn’t suggest this earlier as Tim specifically asked for a way to recharge the battery without having to take the charging cradle with him. If running off an external 12v source is an acceptable alternative, then the battery eliminator is probably as good a way as any … as long as Tim has a 12v source with him.

Hmm, the label on this eliminator says it’s a 1750 mAh battery pack and not to destrioy in fire!!

73 Ed.

Thanks for all the comments very useful !

Very useful to know ! Thanks

I’m beginning to think that’s the smartest choice !

My thought / need is for a multi day trip, where I was going to power or re-charge everything from one battery:

  • Recharge vhf radio
  • power hf radio,
  • mobile phone recharge .
  • maybe torch recharge, but that’s exceptional.

I have got a decent lion battery for my HF radio with a 5v buck converter built in and I thought I’d use this.

Maybe buy to buy a better vhf radio or just a second battery !

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Hi Tim,
Two points - be careful with buck converters they can be VERY RF noisy - test it at home before considering it as an option.
The other point is that I’d think of the largest current draw first - the HF radio. As you have a Lithium battery for that already - then come down from that to your other needs - add a car cigarette lighter line socket to that and then you can plug in the battery eliminator to power your FT-4X from the 12V battery and plug in a car USB adapter to act as a smartphone charger source (or anything that is USB rechargeable), if the existing buck converter is noisy.

PS - hopefully the LIon battery that you have is not a 5v one with a converter up to 12v - that would be a less efficient option than starting with say a 12v LifePO4 and coming down to 5v and 7.4v when needed.

73 Ed.

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Ok, so i have had chance to look into this, and interestingly the Charging base has a 12V input, so all you need to do is make a lead with the right connector on iot, and a means of connecting it to your 12V source!

Here is a picture of the base of my FT4X charge stand…

Make a lead to fit this jack, and jobs a good 'un!

If you need it to be in vehicle, then chuck a rubber band over it to keep it all together, and, happy days!




I have the FT65 and bought a second larger capacity battery to act as as a spare. Obviously more tricky for you to get one now you’re on Rum!

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