View Full Version : Battery Questions

1st Jun 2015, 00:06
I love my FT-817nd but the internal batteries don't last very long. On receive only I can get a few hours from them but on transmit it is a different story altogether especially if I use "high power" (5 watts). For the past couple years I've been using a 7AH SLAB (gel cell) and it can last longer than I can. However the SLAB finally died and I'm looking to replace it.

My first thought was to use Lithium Ion for the lighter weight for the same power output. But I've discovered in my research that they put out too much voltage, over 14.6 on full charge, which I understand could damage my radio. I've recently heard that LiFePO batteries put out 13.8 volts which is just right. The drawback of course is cost and they require a special charger but they are long-lasting and I could justify the cost if they are really safe for my rig. I'm also considering just biting the bullet weight-wise and getting another SLAB since they are reliable and cheap.

So... has anyone here actually used LiFePO batteries for portable operation? How safe are they for my rig when fully charged?

Any advice from experience or pointers to good information would be very welcome!

1st Jun 2015, 00:33
I'm no expert. But here's what I think!
I've got two 8.4Ah LiFePo batteries to run my FT817, 857 & 897 rigs. The reason being they give the right voltage to safely run my rigs & they give more voltage for longer compared to SLAB's which drop off more quickly. Also they are a lot lighter.

That said I have read that over the lifetime of usage the SLAB does work out far far cheaper. But, size & weight certainly redraws the balance in my opinion, even for short strolls from the car park to an operating position. For those who climb hills even more so.

I've only recently started to use mine but have had no problems & I'm really pleased with my choice.

I know others have been similarly pleased which is what prompted my choice.


1st Jun 2015, 02:23
Thanks Ian,

I just looked on Amazon and it appears I can get a 7.2Ah LiFePo4 battery with charger for about $100. Way more than a SLAB but about 1/4 the weight! I think I'll probably go this route.

1st Jun 2015, 07:00
I've either got one or two of 8400mAh LiFePo4 packs coming. I'm not sure just how many as Google Maps caused Irefox to crash part way through the order, and even though I had not got as far as the "Pay Now" button it still put the PayPal payment through. I'll see what happens when I get to the warehouse to pick up the order.

1st Jun 2015, 09:10
I use a 8400mAh LiFePo4 pack for my /P man pack.

I've been using it for around 18 months with no issues. Before that, I used a LiPo (with a home-brewed diode based voltage dropper) and a 7Ah SLAB. I would no go back to either now that I've used the LiFePo4. It's much lighter than the SLAB and much less likely to explode if miss treated than a LiPo! The LiFePo4 construction could have been designed fro radio with it's consistent output voltage and the shallow discharge curve means you can pull more A from the battery before the voltage drops to an unusable level.

I get my packs from Hobbyking which is a US store with world wide warehouses. Here's a link to the US stock of the battery and charger that I use with great success:

http://www.hobbyking.com/hobbyking/store/__20645__ZIPPY_Flightmax_8400mAh_4S2P_30C_LiFePo4_ Pack_US_Warehouse_.html
http://www.hobbyking.com/hobbyking/store/__78385__Turnigy_Accucell_6_50W_6A_Balancer_Charge r_LiHV_Capable_US_Warehouse_.html

Here's a few pics of it in the man pack:

245 244 246

1st Jun 2015, 14:11

Thanks for the links! The prices look pretty good for a LiFePO4 battery pack. The charger looks better than the one I was considering from Amazon.

1st Jun 2015, 14:43
Worth bearing in mind that the charger I linked to does not come with a AC supply and will need a 12v - 19v DC input (I use an old 19v laptop PSU when I travel, the car accessory socket when out and about and my home PSU when at home).

Personally I think it is more versatile than a mains charger plus I can use my 200Ah solar charged marine battery to charge the LiFePo4 and then look all smug for being "green"!

1st Jun 2015, 15:29
Worth bearing in mind that the charger I linked to does not come with a AC supply and will need a 12v - 19v DC input (I use an old 19v laptop PSU when I travel, the car accessory socket when out and about and my home PSU when at home).

Personally I think it is more versatile than a mains charger plus I can use my 200Ah solar charged marine battery to charge the LiFePo4 and then look all smug for being "green"!

I have a ton of 12V+ wall wart and larger power supplies. I don't throw them out when the device they came with dies, I just put them in a box in the basement! I've also been thinking about a 45watt solar panel system and being able to use the charger with that would be nice.

1st Jun 2015, 15:54
In my Power article you can see the charger I use, is pretty similar to Matt's except that it has a built in 110v-220v AC power supply too. Can be picked up very cheaply from ebay here in the UK, I'm sure it can in the States too.

1st Jun 2015, 17:38

I use the same battery as Matt (my /P power guru!) but I used the IMAX B6AC V2 Professional Balance Charger/Discharger from HobbyKing (now updated to V2, need to check if thats the model I in fact have!). This gives the option of charging from mains or 12v supplies so like Matt I could recharge from my big Leisure battery (or his if he isn't looking) or vehicle battery if required.

I also bought a battery alarm to prevent discharge below a safe level, apparently deadly to LiFePo batteries, HobbyKing™ Cellmeter-6 Lipo/Life/Li-ion Cell Checker & Alarm, was the item I bought.

Oh, & of course all have been retrofitted with Anderson Powerpole connectors. Keeps it all safe from crossed polarity & helps when swapping/sharing kit when working with others. Power pole appears to almost be the default system used by Hams.



2nd Jun 2015, 08:30
The charger Ian references is the same one as in my article, can definitely recommend it.

3rd Jun 2015, 20:40
After an "online chat" with an "advisor" from Hobby King I sorted out my order last evening and picked up the battery today :-) FIrst job was to fit a ballancer plug that fits my Thunderpower TP-1010C which I use for charging model aircraft batteries.
It is currently sitting powering my KX3 with the KX3 display showing 12.8V. My multimeter says 12.91V at the battery terminals. Key Down at 10W on 7Mhz KX3 says 12.2V but multimeter says 12.80V. I think there is a diode or something in the supply rail that creates that extra volt droop on load.
I also checked the PX3 spec to make sure it is OK with the slightly higher supply voltage of a freshly charged LiFePo4 pack.

4th Jun 2015, 15:39
Hello Group!

At this moment, I use a Li-Ion battery (around 500 grams weight), which provides 12/16/19 V and 3A peak current. The capacity is somewhere at 23Ah, enough to work at least 6 hours with a FT-817. In the bellow picture, the battery is on the top of LDG, in the charge process, the FT being supplied by an additional lead battery.


With the voltage switch set on 12V, the FT display shown 12.7 - 12.8 V during RX, while on TX the voltage drops at 12.2 - 12.4 V. For 13.8V supply voltage, I switch to 19V but helped by a small home made regulator. I don't use very often because it gets very hot after 30 mins of use.

10th Jun 2015, 21:45
Sherman,, evening 20:40 utc my end.....The SLAB replacement is the best option. Fiddling and adding different capacitance and voltages is definite a no no for that units design. Rather use it save - knowingly it will work when needed. If I may give advice - I am using a small 3x3 portable solar panel for those out to no where field days, use 2 radios if possible and be assured 1 will always be on charge whilst other in use. Depending you guys weather patterns of coarse... Good Luck 73...L

4th Dec 2015, 00:51
How long is your Zippy battery lasting?

4th Dec 2015, 08:41
The 8.4Ah Zippy LiFePo4 pack gives me around 3-4 hours operating at 100W when using voice modes. The longest outing i've had with it to date is around 6 hours using digimodes at 15W and it still had some juice left in it.

I now have 2 of them which is still less than the weight of a single 7Ah gel battery.

14th Dec 2015, 09:08
I use that 8400mAh LifPo4 battery for my FT-857D.

The advice I got was that for the FT-817 you are better off with a 3 cell LiPo battery that has a voltage less wasteful and more suitable for the 817.

17th Dec 2015, 08:42
I use both a 3S LiPO and a 4S LiFePo for the FT-817ND and I prefer the LiFePo as it's discharge curve is flatter. The LiPo will sometimes drop me to lower powerabout 2/3 through the discharge cycle on the rig as the voltage drops, and I don't have that problem with the LiFePo.

When coupled with the safety advantages of the LiFePo, I'll only recommend LiFePo packs from now on.

My Zippy 4400mAH pack is good for several days days reasonably heavy use on the FT-817.

Cracking battery.

17th Dec 2015, 15:50
I ended up purchasing a very inexpensive 12aH SLAB to get through the fall. I have a LiFePo on my Christmas list but don't know if Santa will come through. I sure would appreciate the lower weight of the LiFePo vs the SLAB, that thing is heavy (but it can power my FT-817nd for hours).