the 3.3 AH SLAB I was given when I started activating (thanks MM0DHY) has finally died and will soon be recycled at the local scrap yard. Reading around the subject it looks like a 3 cell LiFePo4 might be the lightest and safest replacement; does this sound reasonable? I have read elsewhere that zippy packs often have dud cells so wonder what a good choice might be here in the UK. Has anyone recent experience that they can share?
experience will vary from user to user.
It seems that LiFePo4 are the better solution nowadays (more charging cycles and more stable) but I own a cheaper LiPo 3 cell 11,1 Volt 2,2Ah and it keeps running all right with me since 3 years now. I can run my 817 during 2 hours full activation without an issue.
It charges and discharges all right and the 3 cells are balanced and doing good.
Let’s see other opinion, but LiPo are fine and keep some money in the pocket. Just charge them with a proper charger and keep an don’t leave them unattended when charging.
Store them in a safe non-flammable sack.
Same safety measure applies on LiFePo4 too.
I have 2 of the Zippy LiFePO4 4200mAh and find them pretty good. I get about 5-6 hours out of 1 on my 817 and weigh 480gm each and a decent size (you can fit 3 or 4 lengthways on an 817).
I have the Turnigy charger which is similar in look to the one Andy mentioned and that works well too.
The only thing I might add, is that the main connectors on the battery you may wish to swap to powerpoles or the like as I’m not a fan of the ones that come as standard. Seems a little easy to get a short on them.
Can I ask if you have considered an internal LIPO rather than external ones? There is a flat 2.5Ah 11v 3S lipo that sits nicely in the battery bay in the FT817 and by my experience will give a good two hours activation on 5W SSB output.
There are a few articles on the web describing how to add the internal LIPO, some simpler than others.
I went a bit bigger because I can’t always mess around charging it etc. I have had it out on 6 or so activations so far and it still has plenty of juice. I has all the protections for over discharge so now I am just trying to see how long it will last.
I use a Zippy 8400 mAh 4S2P LiFePo4. Great for all radio types, loads of capacity, never emptied on FT817, just under 2 hours on FT450D at 100 Watts SSB. For info: Portable battery choices | VK3ZPF Ham Radio Blog
For light weight hiking I also have a Zippy 2100 mAh 3S1P LiFePo4. OK for FT817 but of no use for any other radio in or out of the shack.
Thanks Andy, and others for confirming my reading or suggesting alternatives. I was particularly interested if anyone was using a 3 cell LiFePo4 battery, giving 9.9v? Does this set up work reliably with an FT817?
I don’t think the 817 achieves full power on 9.9V Colwyn. ISTR it needs nearer 10.5V. There is some variation between 817s and also it depends on the band in use. That is why the 3S LiPO was so popular, even though the voltage varied from about 12.6v down during operation, there was enough to give full output until the battery was discharged. Other sets are much less forgiving, the 857 likes more volts.
A 3S LiPO will power the 817 fine. If you can get one at a good price then there is nothing wrong with them. The 4S LiFEPO does well and can power other radios. If you think you may move to an 857 or other higher power set then LiFEPO is a better bet. Like all these things, there’s no real wrong answer.
I recently bought a 7.8Ahr Minimax lipo battery pack from Home Depot for $50 (see photos). It’s sold for jump starting cars, which really works – I had to use it to start my lawn tractor once. The battery pack has output ports for 12v DC at 200A (400A peak and voltage measures 13.1v fully charged) and a USB port for 5v DC at 2A. It also has an LED flashlight and a built-in charger that accepts 5v DC via mini USB, or 13v DC via a very small barrel connector for use with the supplied auto accessory plug charging cable. The battery is in a hard plastic case, which protects the lipo cells, it’s about 3"x5"x1" and weighs 10.5oz.
I made a cable for the battery from an inline automotive blade fuse holder I got from an auto parts store by adding a ground wire, an EC5 connector to one end that fits the high current output from the battery pack, and PowerPole connectors on the other end to fit my radios (see photo).
I’ve seen similar lipo battery packs for starting cars that have larger amp-hr capacities.
I fly electric fixed-wing and multi-rotor “drones” and handle a lot of lipo batteries. Be careful when using lipo battery packs, especially those that don’t have a hard plastic shell. Lipo batteries can and do “explode,” catch fire, and give off toxic fumes when punctured (exposing the internal chemicals to air), when not charged properly, or overcharged. I have witnessed these things firsthand and so have others on this reflector - Google “lipo fires” to see similar situations. When not in use, I store my lipos in fire-resistant bags specifically designed for lipos, or steel ammunition boxes that I have vented with a small hole for longer-term storage.
If you are going to build your own lipo battery pack, I suggest that you use batteries designed and sold for use in RC cars, which typically have a hard plastic shell to protect the batteries. You should also only use a charger specifically designed for charging lipo batteries. Most that I’ve used automatically stop charging at the proper point. These are sold by the same folks that sell the batteries. Put a fuse in the circuit – lipos store a lot of energy and can discharge at high rates.
The nice thing about the Minimax and similar devices is they address most, if not all the issues I mention above. These light-weight, high-capacity battery packs seem like a near ideal solution for portable operations, but be careful with them.