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FT817 with internal LiPo / Li-ion


I wonder if anyone has fitted a LiPo or Li-ion pack into an ft817 as a replacement ?.

Nigel. G6SFP.


In reply to G6SFP:

I still have 8 AA NiMHs inside the battery case and use an external 4AHr LiPo pack.



In reply to MM0FMF:
I noticed Geoff Passey 2E0BTR has something similar for his FT-817ND. Is the LiPo pack and charger available from where you bought it still Andy e.g. a URL? There’s a bewildering choice, much of it in Chinese English.



In reply to G6SFP:

Hi Nigel,

I seem to recall seeing a Li-ion solution somewhere based on mobile phone technology, but for some reason I discounted it.

I would definitely not recommend using a LiPo internally - charging in-situ is a definite no-no in my book as there is a very serious issue associated with fire risk. I certainly would not want to expose the rig each time the pack is charged, so it would need to be removed each time for charging externally and an element of the convenience of having an internal pack would be lost.

4AH LiPos are small enough to carry separate from the rig and could easily be strapped to it if the intention is to use the 817 like a handheld. I use the internal pack purely for backpack purposes and have a supply of 4AH LiPos as my main external power source. Using one to supply the 817 and another to supply a 20W linear, I get at least 4hrs of activating out of the pair running SSB and still keep above the desired “flat” voltage of 3.7V per cell.

If I rediscover the Li-ion article, I’ll let you know.

73, Gerald

P.S. The last couple of issues of Summitsbase News have information on LiPos and charging should anyone be interested in lightening their load.


In reply to MM0FMF:

Yes I do the same, but I think an internal replacement would be a neater solution. I will butcher a 4ah pack and see if I can make it fit shortly.



In reply to G6SFP:

Butcher… arghhhh!!! Hope you are wearing a flame-proof suit when you do it! I doubt 4AH will fit, but something smaller should do. Personally I would “tinker” as little as possible. Hmmm, that reminds me, I’ve three on charge on the patio unguarded - better see how they are getting on…

73 and take care!



In reply to M6WOW:

I bought my LiPo packs from eBay. I think they are the same RC ones that Gerald uses. The specs were 15C discharge capable (60A in this case), 4Ahr capacity 11.1V nominal. I don’t have the exact details to hand right now but I’ll post them later. The charger is also from eBay and was pence. I think 2 cells and charger cost under £25 inc p&p. It worked out I could buy a simple balance/charger for less than I could buy the components and make it myself. That annoys me and is in principle wrong but the wallet doesn’t lie! I think the charger was under £6.00. They are physically compact and weigh 260g vs. 1.3kg for a SLAB of less capacity.

I don’t worry about charging my phone, either of my laptops or my Icom handy which all have Li technology packs but I do worry about charging these cells. I guess it’s simply the enormous discharge capacity in this case that concerns me in the event of a failure. So I wouldn’t be interested in incorporating a pack into my 817. But that doesn’t mean it’s a bad idea, it doesn’t appeal to my needs. As Gerald says an outboard pack is not a real issue. Probably there is no need for 15C packs as the 817 pulls around 2A max. Driving a linear is a different issue though.

I have some sub-C cell sized 2.2Ahr LiPo cells which I’m now making into some packs. 3 cells should provide about 2hrs SSB operation for an 817 and weigh approx 100gms. I’ll being trying these out over the coming months and will write up how well they work. The cells were “surplus” from rallies so the quality may be variable.



In reply to MM0FMF:

OK here are links for the items I bought. I’m sure these are the same cells that Gerald uses. I’d been meaning to invest in some for some time then there was an article on the Summitsbase site that prompted some further research especially as my SLAB started showing signs of age after some 130ish charge-discharge cycles. The charger is very simple, it supports either 2 cell (2S1P) or 3 cell (3S1P) packs. A classic case of doing exactly what it says on the tin.





I used some Tyco Fast-On connectors on the bare leads as I had some in the junk box. The charger connector is a JST-XH and you can buy ready made cables or the shells and crimps also from eBay. Seach for JST-XH in the radio control section.



In reply to MM0FMF:

Hi Andy
I’m using the same LI-PO Cells 11-1v-4000mAh-15C nice and compact alot better than a slab I have a 14-8v-4000mah LiPo-4-Cell that runs a 2Mtr-50watt Amp this setup will run all week end.

I use the imax B8 charger- see jpg of setup.



In reply to MM0FMF:

Yes they are the 4AH ones that I have Andy. I think there must now be quite a few powering SOTA activations. John GW4BVE has upgraded to a faster charger (see the latest Summitsbase News), but I haven’t bothered as time is not an issue and I don’t bother monitoring mine while charging anyway. I’m quite happy for the car battery (12V input source), 800mA chargers (RCM and e-Sky branded, but in reality the same as yours) and LiPos to sit on the patio for 5 hours. I charge 3 simultaneously. If it rains, I just throw a polythene sheet over the lot as there’s no mains to worry about. I have 3A fuses in the 12V input leads to the charger-balancers as a precaution.

I soldered leads directly to the flying supply leads and have in-line fuses rated at 13A in case of brainfade, but with red and black 4mm sockets on the end, I’d need to be operating in the dark to get the connections wrong or short-circuited.

I checked the voltages after the six summit trip over Tuesday / Wednesday this week and they varied no more than 0.04V between the cells in a pack, most were either 0.01V or 0.02V. One pack had been running a 20W 2m/70cms linear for 4 activations and was still providing over 11V. I certainly like the way these batteries don’t suddenly die on you like SLABs tend to do.

73, Gerald


In reply to G6SFP:


Have you considered safe LiFePo4 batteries? I use some without protection for portable work, and you can find small packs that might fit an 817 at:


Of course you can also check places like www.batteryspace.com

LiFePo4 is much more stable then LiPo or regular Li-ion, has almost the same low self discharge characteristics and increasingly a similar power to weight ratio.

The A123 cells are famous for their high current capabilities. You could try working something out with them, or you could find the AA sized LiFePo4 3.5v cells at batteryspace and work out something with those cells.

I looked at different lithium solutions that could work internally with the 817 for a while, but in the end I decided against lithium as at the time much of the stuff that would fit inside an 817 had similar power to weight ratios to the best AA NiMH cells.

Most of the time lately I have been running 4 3.5v (or 3.7v) 10AH LiFePo4 cells with 100w rigs…you can pics of my battery on the flickr and youtube sota sites.

73 & let us know what you come up with,


In reply to N2YTF:

Interesting but… very expensive and lower capacity than RC helicopter packs. The advantage that you get using an FT817 is that you don’t need 13.8V for full output. Anything over 10.7V will produce full output. This means you can use any LiPo with 3 cells as the voltage starts around 12.6V and drops to 10.5V when discharged.

The 4S1P A123 would be needed for an FT817 as the 3S1P pack has too low a voltage for full output. This means that you would have to pay approx $70 more and carry 100g more than using an RC helicopter pack for less operating capacity. It doesn’t make sense to me to power the 817 that way.

For 100W rigs then it’s a different story. There you find most sets need near 13.2V for full output and decent linearity and that leads into the merry-go-round of which cells, how much power is needed really, weight vs. operting life. If I was stuck on using an existing 100W rig I’d be looking at making a buck/boost regulator so I could use the LiPo cells. Or I’d make a PA to go with the 817 and use one LiPo for that and 2 for the PA.

It’s the phenomenal power to cost ratio of the RC helicopter packs that makes them so desirable. The fact they weight so little is the icing on the cake.



In reply to MM0FMF:
I have started using a ‘Helicopter’ 4s LIPO pack with my FT857. I am using a couple of blocking diodes to reduce the initial voltage from the pack, and after about an hours activating, I unplug the diodes and use the 4s pack directly connected to the radio. Results, so far have been quite good, with dual summit activations possible from the same battery pack, running typically 50Watts on ssb. Not very scientific, but simple (like me!). I invested in a good quality balance charger (which was very cheap, given the complexity) and have been able to keep the LIPO batteries happy during charge and discharge.
4s LIPO weight is 348g.


In reply to MM0FMF:
I am definately going to look into the helo packs again to see if I am still afraid of them. I saw a guy at the 2009 Dayotn Hamvention running a 500w HF backpack off of Li-Po packs. I have a pic of him on my flickr page.

Keep in mind that the new prismatic LiFePo4 packs have a somewhat similar power to weight ratio to the regular li-po, and the LiFePo4 cells are said to get about 2000 cycles, compared to about 300 cycles for the regular li-po.

I thought the cycle lifetime was a big issue at first, until I realiazed that the rate of advancement in battery tech is so quick right now that keeping your pack for 2000 cycles may not make sense…esp if you only use 100 or less cycles a year.

Tom- right now TF/N2YTF


In reply to G4OIG:
I now have exactly the batteries and charger that Andy specified. I’ll make up a connector for the FT817 with fuse and half a power pole connector and connect the Li-Po cells to the other half.
I’ve no car battery spare. Is it safe / acceptable to connect the balanced charger off the Watson power supply with a fused long lead? I intend to charge the battery on the patio with a polythene sheet cover handy.
If in doubt ask…

David 2E0DAI


In reply to M6WOW:

I use my charger connected to a variable PSU set to about 12V rather than a 13.8V supply. The rating label on the charger says 11.5- 13.5V hence the use of a 12V supply. The current drawn was never much more than 1A so you don’t need a big PSU. If you haven’t got a variable PSU you can simply put a diode in series with one of the leads. A 1N5401 would do or any silicon power diode of over 1A rating. That will drop the voltage by 0.9V or so. Unless you happen across a Schottky diode in error! If you haven’t got a single power diode you can use 1/4 of a bridge rectifier pack.



In reply to MM0FMF:

Seems to me that SLABs are becoming an endangered species amongst SOTA activators. Can’t remember which summit I last used one on - probably TW-004 where I managed to carry a 12AH one some 50m horizontally from the car. I think my 3.3AH SLABs have mould growth on them.

73, Gerald


In reply to G4OIG:

I very briefly considered using a 21 a.h SLAB, but decided not to risk a hernia! I still use a 13 a.h with a 12 a.h Yuasa as a spare. I admit it slows me down a bit!


Brian G8ADD


In reply to G4OIG:

Seems to me that SLABs are becoming an endangered species amongst SOTA
activators. Can’t remember which summit I last used one on - probably
TW-004 where I managed to carry a 12AH one some 50m horizontally from
the car. I think my 3.3AH SLABs have mould growth on them.

I must say I have found my 3.3 Ah SLAB more than adequate for a couple of 50-QSO activations between charges. It weighs in at just 1 kg. But then I never run more than 5 watts, mostly CW, with an FT817ND.

Walt (G3NYY)


In reply to G3NYY:

But then I never run more than 5 watts

But then you’ve never been up any big mountains yet either! :slight_smile: