FT-897D / FNB-78 charging options?

[AC4RD]

I got an FT897D a month ago; I really like the radio overall.  I'm using it mostly for portable use, either with my riding mower's battery or with a regular power supply and an extension cord.

Since I'm often using the radio outside, I'm mildly interested in buying the FNB-78 internal battery pack for this radio.  At $100, the battery pack is a bit expensive but not too bad.  But what I've read suggests that, in addition to the battery, I would also need the proprietary charger, another $100+, either from Yaesu or from W4RT.

Are there any other (cheaper) options for charging the FNB-78 packs?  Has anybody homebrewed a charger for the packs, or modified it so the battery pack is charged when the radio is connected to 13.8VDC? 

Thanks!  --ken ac4rd

[N6DMR]

Hi,

Try the CH-UN180 from http://www.batteryspace.com/

Multi-Current Universal Smart Charger for 9.6V - 18V NiMH Battery Packs    CH-UN180                              1   $30.95   
Component: Temperature sensor ( 70 C, BEC Male plug ) for Smart NiMH Charger with cable / Connector   1   $3.99   

I would also purchase at least one spare Thermister as well.

I use this setup on my FB-78 and it is a nice solution.

They also have a lot of info on their website on NiMH battery charging.  Best method is a thermister controlled negative delta T which is what the CH-UN180 is.  It will work for mulyiple style of packs and is sufficient to charge the 11 cells in the FB-78.

Duane
K3AL

[KU3X]

I use my FT-897D portable all summer long. Before I purchased the rig I looked into the internal batttery packs. I thought it was a neat idea, and it is. BUT....they are not cost affective! First of all, with the internal batteries you are limited to only 20 watts out. That's really plenty of power but I didn't want to be limited. I use a 17 ah gel cell. You can sometimes find them at hamfests, used for around $20. Even if you get one new, it will cost you less than one internal battery. I forget the model number and brand, but someone even makes a 22 ah gel cell and it's the same size of the 17 ah battery.

I run my FT-897D at the 50 watt level or 5 watt level. 50 watts is only 3 db down from 100 watts and that's only 1/2 of an S unit. The guy on the other end will never see the difference between 100 watts and 50 watts. I've already ran the rig at 100 watts on the 17 ah battery and had an afternoon of fun. At 50 watts out you will have much less of a current drain on your external battery.

Bottom line, it is much more cost affective to use a 17 ah gel cell than it is the internal battery pack. You can get a small wall wart charger at Harbor Freight for around $8. I have three of them, one for the ham radio batteries, one for the motorcycle and one for the garden tractor.
Have fun with the rig running portable.
Barry, KU3X

[KB1SUB]

Thanks for the ideas everyone.  I just bought the CH-UN180 charger and the kit it now includes a temperature sensor and a few extra cables.  With a little modification to one of the extra cables, adding a 6-pin female microphone plug with a locking ring and soldering the red wire to pin 3 and the black wire to pin 1, the CH-UN180 passes as a <$40 substitute for the Yaesu battery charger.

-Kevin, KB1SUB

[AC4RD]

Thanks for the input, everybody!   I wound up continuing to use the riding mower's battery until it got too cold to play radio outside.  :-)  For big events, I'd carry a 120v PS outside and hook it to a long extension cord, so I could run full power.

Now that North Carolina is warming back up, I may rig up another portable operating position outside.  :-) 

[KJ6VQR]

Another possibility is to use an R/C Lipo pack. For my ft-857 I use 3S packs (20C is fine) in parallel to get 10 AH, or 4S in series connected to an Astron DC to DC converter.

I spent 3 hrs atop a mountain during my first SOTA activation and only burned thru 30% of the Lipo's capacity. The whole time it put out 13.8V.

You can get them pretty cheap at hobbypartz.com