FT817 internal battery

There have been a few posts, and blogs, discussing internal batteries for FT817nds,
is there a consensus for the best option for one?

I see there seem to be a few ‘windcamp branded’ ones on some auction site, however, all of these seem to be from various Chinese sellers, and seem to show a non-UK PSU, they do, however, look quite neat, with a replacement battery cover and socket to plug the charger into.

It’s not something I’d be relying on to power the rig, rather using an external 8ah LifePro4… but ‘just in case’ I should either forget the external battery, or have some other issues with it, it would be nice to have something internal (again) to at least power the thing for a couple of hours. I would prefer, of course, not to have the internal battery burst into flames whilst charging, or discharging :sweat:



Hello Don -

Your ‘no flames’ options could be fairly inexpensive - 6 Alkaline AA in the holder would be fine, or a 6 AA form factor NiMH as offered by Yaesu, or an eBay alternative to the NiMH for a fraction of the price if you don’t mind splicing on the FT-817 connector (so long as you can get a spare off a failed battery).

I did the latter as back-up power for my FT-817 – I paid about £10 for an older style RC-car battery with the same form factor. And the internal charging circuit will work with the NiMH pack.


Hi Don
I have ordered one of the windcamp kits with a view to having a self contained 817 for activations.

I have used an external lipo battery with the 817 for 3 years now, since VK1 joined SOTA in 2013. It seems to be very reliable and long lasting. I limit the charging rate to 1 amp. Takes less than 3 hours to fully recharge.

I think reports of explosions can be attributed to users who don’t use the correct current limited, voltage sensing, voltage balancing charger. Think RC enthusiasts who unfortunately didn’t purchase an appropriate charger and used lead acid car battery techniques to recharge the battery at excessive current levels to get their car or plane going again as quickly as possible.

There have been no reports of such incidents from people using appropriate chargers and methods, none on this forum to my knowledge.

Andrew VK1DA/VK2UH

Andrew and Don -

I’m not sure that appropriate chargers and methods can make up for random manufacturing variations and defects:

(There are lots more stories like this.)

This story from HB9BIN in SOTA News June 2014 should also be considered.

LiPo battery catches fire
On the second evening of our stay we were on the way back from the hotel bar to our room and were quite amazed to see a crowd of people (hotel manager, his assistant, security officers and cleaning personnel, etc.) standing in front of our room’s door with a fire extinguisher and discussing something in a very excited manner. Recalling the large number of videos on YouTube about Lithium-Polymer batteries catching fire, I quickly determined that I was a victim of Murphy’s Law – you should never charge LiPo and LiFePO batteries unsupervised. Because the burning LiPo battery set of a fire alarm, the diligent building services personnel sprayed everything very liberally with the fire extinguisher. We quickly got a new hotel room, but for the rest of our vacation our clothes and my equipment smelled of white powder and the black layer of soot! The unfortunate aspect of this event was that it was exactly the 3-cell LiPo battery for the KX3 that had burned up. Thus, for the rest of my visit, I had to operate with my FT-817ND. In contrast to the KX3, which immediately shuts down if it sees a battery voltage higher than 16V, it accepts a 4-cell LiPo or LiFePO without any problem.

In the end, everyone was happy: the hotel manager was proud to see how well his fire alarm system and the fireproof wall-to-wall carpeting had worked, and I was happy about the fact that I always take a complete backup station with me including battery and charger. It seems like the end of every fairy tale: if the LiPos have not already died, they simply burn up!

Hi Don,
I have been using a HobbyKing Turnigy 2500maH 3 cell (11.1v) LIPO inside my FT817 for over 2 years now without issues. It is great not to have to carry an external battery. I find I can get 3 x 20 minute SSB compressed audio SSB activations from the battery with it dropping to about 30% charge left (I prefer not to take it below that level and with the voltage dropping, this coincides with when the 817 switches to lower power in any case). As this battery is both small and light, I take a spare along, in case I need to operate longer.

I have “spliced” the appropriate Yaesu cable to both batteries and have a simple voltage divider of two 100k resistors to power the green lead. This lead tells the FT817 to not charge the LIPO battery across its output lead if a 12v supply is plugged into the rig (this is very important - the battery can only be safely charged using the charging lead to a balanced charger unit NOT across the output leads). When charging the battery I remove it from the rig and plug it into the proper balanced charger and charge at 1A maximum. I echo Jürgs comment - never leave anything charging when you are not present! Murphy will get you every time and bad initial manufacture of a LIPO (or LifePO for that matter) can cause problems with batteries and we all know one way companies reduce the price of products is not to do QA on them.

I have not gone with any of the replacement panel & battery packages. The one sold in the US, I believe may be manufactured in China for the US company (which may also explain why there is a direct Chinese supplier as well). That being said, the repacement panel with switch and external charging socket is a tidy solution as long as there is a balanced charger built in under the panel (the charging socket appears to be a two pin type - 4 leads are needed to balance charge a 3 cell LIPO).

If LIPO batteries are charged across the output cables or not with a balanced charger, they can be damaged and this may also be the situation where some have exploded. Although there are similar sized LifePO batteries available that would fit into the FT817ND battery compartment, the 3 cell LifePO battery has a lower per-cell voltage and hence a 4 cell rather than a 3 cell version would be needed, which may make it too large to fit in the battery bay. A fully charged 4 cell LifePO may in fact have too high a voltage, in which case some kind of voltage regulation may also be needed.

I got my initial ideas from Glenn VK3YY at his blog here - FT-817 Low Cost Lipo Battery | VK3YY

73 Ed.

I didn’t see that in 2014, it is very sobering to realise that such things have occurred with the small batteries we use for SOTA radios. I wonder what conclusions we can draw from that charging incident - does HB9BIN still use lipo batteries, if so what changes has he made that allow him to feel confident about managing the risk.

I am also curious to know whether the battery exploded, or did it start to ooze and smoke, or did it set fire to materials in the hotel room that then started to produce smoke. Ie. What set off the smoke detector?

I have not looked at the YouTube clip yet. I would want to know what type of battery it was in the car and what was going on at the time (eg. Was it under charge?). Not doubting it happened but I think it is worth being fully informed.


Andrew VK1DA/VK2UH

These 2900 mAh rechargeable AA batteries are an option. I state OPTION not a set in stone replacement.

73 Chris M0RSF

1 Like

Hello Chris

Thank you very much for the video. I will be trying that out soon.

Nick G4OOE

AA’s, actually, AAA’s won’t fit in the battery box. I got eight years of use out of a similar set but recently replaced them with another set as the capacity was starting to drop.


This exemplifies why I will have nothing to do with LIPO batteries. As I have often said in this reflector, they are far too dangerous. However, most contributors to this forum are in denial about the risks.

I wonder how much the hotel manager charged HB9BIN for the damage to his room?

Walt (G3NYY)

Risks can be evaluated. A car carries enough petrol to incinerate both car and driver, that is a real risk, but a small one. I would assume that users of LiPO have evaluated the risks and decided that they are worth taking. You have to weigh the anecdotal evidence of problems against the number of users that have had no problems.


I’m not disputing the valid concern you have Walt. I think Brian’s right though, let’s not forget the risks of carrying an extra 5 KG of SLAB. I’ve chosen the LiFePO4 route to save my back and try to control the fire/explosion risks. But each to their own informed decision - thank goodness for choice.

Walt’s problem is that he is suffering from the “luck” of having been the 1 in how many million who has a failure. That tends to blind you to how many millions are not having an issue.

Here’s the simple skinny low-down on the LiPo risk. Somewhere around 4 million people fly somewhere everyday. I’m going to be generous and say on 75% have a mobile phone with them. So 3 million LiPo cells are allowed on planes everyday. That ignores tablets and laptops and spare batteries.

If the phones were dangerous to the degree Walt likes to imply, we’d not be bringing them on board now would we.

I would caution against using a LiPO within a rig’s case. You need to see your LiPO. I own about 10 Chinese LiPO’s and after a few years of service noticed evidence of my first failure - the external wrapper around the LiPO had visibly swelled up. I immediately took it out of service.

Barry N1EU

maybe we are moving away of the thread… but just in case, I always store my Lipo in a LiPo Safe bag at home or when charging. Cheap and safe (fireproof).

I believe I could use a small safe bag that fits inside the FT817.
In my situation I always use the batt externally by the connecting cable. I understand having it inside reduces the package but I like removing the battery after every activation.

Never had an issue after 3 years. When I see the batt swells (a sign of ageing) I will put it to a electronics store that collects and recycle them appropriately and buy the next one.

73 de Ignacio

Modern NiMH cells offer 2-2.6Ah capacity in AA size, don’t suffer from self-discharge, provide constant output and enough current to run 5W without any issues, are comparable in weight with LiPo, are safe and most importantly, can be charged using the FT-817 internal timed charger (so no fancy charger necessary). The FT-817 internal changer can be easily modified to chage at a higher current so it won’t take more than necessary. I find it a much more elegant solution to just replace the original Yaesu battery with a set of 8 Eneloop cells, 2.5Ah lasts you a few good hours of continuous operation.


As I said, AA batteries. That’s with me rushing to post before heading out to work.

73 Chris M0RSF

Hi Andy

A problem with the phone and laptop analogy is that manufacturing standards do vary and it is not certain that the quality control around phone and laptop batteries is equaled by the quality control for RC batteries.

During the NiCd days we often talked about the “memory effect” and it certainly appeared to be real for anyone with a HT that was not fully discharged and fully recharged every time. But against that, the word was that NiCd batteries were used in spacecraft and no memory effect was observed with them. This difference was put down to manufacturing standards, with the cheap NiCd AA cells we often used for radio and other purposes being made to what we could call “lower standards”.

So the question is whether the same effect is in operation with LiPo and LiFePO batteries. I can’t see why it would be any different. Lithium ion technology appears to be more stable and proven than Lithium polymer.

I have a LiFePO4 4.2AH battery that is quite puffed up, it has gradually puffed up during the 2 years I have owned it. While it still works normally, reading of people immediately recycling batteries in such states makes me wonder what the danger level actually is. What is going on in a battery that has expanded in such a way and is it an indication of impending failure or is it just that it was charged wrongly and one cell expanded due to being overcharged? Is it a dangerous battery to carry in my backpack, charge in my radio shack and even to use on a summit? Or is it just showing signs of premature age and should be replaced as a precaution anyway?

I don’t know whether there are definite 100% answers to any of these questions.

Andrew VK1DA/VK2UH

Or a few years ago, the non-sealed lead-acid batteries!

Lets also not forget that the safest solution in the world will always fail is someone plays stupid buggas with it.

Respect your decision Walt, but I am not “in denial”, I take appropriate precautions and use that substance that is more valuable than platinum - common sense.


As I have said many times, “Cheap”, “Quality”, “China”: pick any two.

It doesn’t matter if you are a Tier 1 customer like Apple or buying RC cells from Lucky Foon Jolly Manufacturing Company, the same applies, “cheap”, “Quality”, “China”.