Yaesu FNB-78, CD-24 and PA-26 Batteries and Charging Options

The FT-897D is a very flexible radio with different options to suit differing requirements, one of which is portability.

The radio itself is bulkier than its smaller brother (FT-857D) even though they contain the same circuit boards. The bulk comes in the form of a robust case, better control panel and large carrying handle. An empty area at the base of the radio is kept free for options such as the internal PSU (FP-30) and the internal batteries (FNB-78)

These all produce extra weight and bulk but DO provide a much more robust radio.

The FNB-78 Batteries are sold in single form and generally you would need two of them, these are known as A and B battery. They both fit internal under the cover on the base of the radio and are attached to the circuit board using a simple molex style connector. On the rear of the battery is the charging point and this extend out through the back of the radio to allow the charger to be connected, whilst leaving the batteries in situ.

The FNB-78 is a Japanese made NiMH battery, rated at 4500mAh at 13.2 Volts Charged, 11 Volts Discharged the recommend charger current is 1400mA. I mention that it is Japanese made because they make batteries far better than the other cheap rubbish made in places like China. The same applies to the CD-24 and the PA-26 they are all made in Japan.

As you may have gathered already the FT-897D does NOT charge the batteries whilst the radio is connected to a PSU. The charging system is separate to the radio.

As far as i can tell the cable to the radio provides only power and voltage sensing. This may seem a little backward in this day and age, but battery chargers are notoriously noisy and to add a charging system to the radio and screen it would have been very expensive and not to mention heavy.


Some food for thought:

You cannot charge the batteries via the Radio.

You can only charge one battery at a time (unless you have 2 chargers)

You should NOT be charging the battery you are currently using to run the radio.

An Red LED on the control panel lights when the battery is charging and goes out when the battery is charged.

An Amber LED is lit on the control panel when that battery is being used, when the amber light flashes you should re-charge the battery to prevent over discharge.

If you have 2 batteries in your radio, the LED will be Amber for battery you are using and Green for the battery you are not using (unless its on charge)

As for solar charging in the field, in my opinion this is pointless. You could wire up a system via a solar charge controller with ease, but it simply wont do the same job as the CD-24 and you stand a very good chance of damaging the expensive batteries. I have used folding solar panels for a few years now, they are very expensive for what they are, but you do get very good power from a light weight flexible package.

My panels are 30W each at 1.6A so connected together in parallel i get 60W at 3.6A at between 12-16VDC. I use these to charge mobile phones etc using a CLA. However for larger more complex devices, you are best using a charge controller and a small 7ah or larger battery, so in the day i set the panels up and charge the battery(s) up using the controller, then at night i can run 12v devices direct from the battery or use a small 300W Pure Sine Wave Inverter to run other items such as a laptop or the CD-24 via the PA-26 or direct from the battery.

I have not found a suitable method for charging the Yaseu FNB-78 batteries in the field.

The CD-24 has 2 inputs :

1 HF6 female connector for DC Input of 13.8V from a desktop PSU

1 DC (Laptop Style) Connector for a 24V input.

I have no idea as to why Yaesu chose the use a 24V input i would imagine it was to encourage the purchase of the PA-26 Charge Adaptor!

The PA-26 takes a 100-240V Supply and outputs to 24V 1.8A

So in short, the CD-24 takes a 13.8V supply via a HF6 connector (so you can charge using the PSU you use for the radio) or via the PA-26 at 24V 1.8A the output from the CD-24 is 16.5V at 1.4A now like any charger i would imagine that this output changes to suit the requirements of the battery? And the various pins on the cable to the charge port on the battery give me an idea that at least one of the pins is for voltage and temperature measurement.

Remember the FNB-78 batteries support up to 20W of power output from the radio. Which is plenty for me, and my license restricts my usage to 10W until i sit the next exam.

Please let me know if anyones else has an options for charging the FNB-78’s!

3 thoughts on “Yaesu FNB-78, CD-24 and PA-26 Batteries and Charging Options

  1. Hi James,
    I liked the article. The FT-897 is listed as 3.9kg, but I bet that is naked! Do you happen to know what the weight of two FNB-78s might come to?
    Chris Hart

  2. If you have panels that can output up to 16V, I think you can just use them to feed the CD-24 directly. I have opened my CD-24 and I saw that the 24V input has some extra circuitry but the 13.6V input goes directly to the switching regulator which feeds the charging circuit. And since the battery voltage in a car can be all over the place, I assume that the CD-24 is quit resistant against voltage variations. So I would just hook up your solar panels directly to the 13.6V input of the CD-24.

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