It is interesting to read of the capacities some of the batteries in use have out there. I only use either of two LiPo’s 1000 mah each (1 Ah) and can easily get three to four activations from one. Some SOTA folks just use a 500 mah. My use is with a KD1JV radio with receive draw of 30-50 ma or so and transmit at 700 ma or so on CW. My Turnigy Accucell takes the 3S batteries up to 12.6 volts and quits and I rarely drop below about 11.5-11.7 or so after all those QSOs. I have a 2000 mah (2 ah) also but haven’t had much reason to use it. Cheap from Hobby King. Can use them for emergency field welding as well 
Cap
W0CCA
I assumed Lipo
No. LiiFePO4 not LiPO.
Cap,
Sure, when running super efficient radios like the MTRs, a few hundred mAhs is more than enough. Running something like an FT817 which has relays to latch, then you need some serious mAhs!
My MTR-5B is using about 25mA on RX. My home brew RockMite is using around 6mA on RX at 9v, a standard PP3 battery can last me all winter 
Colin
Is it a MTR-? and if yes, did your MTR-? never shown problems with supply voltages higher than 12.00 volts?
Re capacity: I also use 900 and 1000 mAh 3S LiPo’s to power a MTR-3 for all-day activities.
HB9BCB- it is the ATS-4B, operationally (power), not a lot different than the MTR. I have always charged to 12.6 volts, (4.2 per cell at a 3S) have never used the diode drop technique for voltage control and have never had a problem in 130 activations. I may be dangerously playing the odds but they have been good to me so far.
M1BUU- Agreed, I have no experience with the 817 and its power needs, so not saying one size fits all. But some of the 5-10 ampere hour capacities surprise me is all.
Cap
W0CCA
Hi,
interesting thread.
Just to make sure we charge batteries to its maximum capacity and in order to avoid to overcharge or minucharge, here some reference values:
If it is a LIPO:
nominal cell voltage: 3,8 V
Maximum voltage: 4,2 V (fully charged)
i.e.: a 3S batt fully charged= 3 times 4,2= 12,6 V
If it is a LIFEPO4:
nominal cell voltage: 3,3 V
Maximum voltage: 3,6 V (fully charged)
i.e.: a 3S batt fully charged= 3 times 3,6= 10,8 V, and
a 4S batt fully charged= 4 times 3,6= 14,4 V
IMPORTANT: if your charger (i.e. Accucell) has a common mode (not differenciated) for LiPo & LiFePo4 make sure you set the right nominal cell voltage in the user settings menu, that is either 3,8 or 3,3 V depending on the batt you have!
DISCHARGE: stop using the batt (both types) and recharge it when voltage decreases to 3V per cell.
73 de Ignacio
1 Like
If you’re running 100w SSB on HF, you can bet that your 5000mAh will be gobbled up pretty quickly
Regarding running ATS/MTR rigs at 12.6V, I don’t think generally there’s a problem. The earlier rigs used the less robust 2N7000 in the PA, whilst the newer rigs use the slightly more robust BS170. I’ve heard about a number of guys running MTRs with fully charged 3S LiPos and there hasn’t been a problem. I use a dropper diode usually, but I have run straight out of the battery without issue.
The potential problem is that if the antenna load has a significant reactance (mis-match) and you’re giving it plenty of beans, the reflected power might be enough to cause the PA transistors to pop. If your antenna load is fine, then there’s no issue. I always use resonant dipoles. EFHW might cause an issue - tune up at low power output (handy PP3 to power rig for tuning perhaps?) or use the built in tune mode in newer version rigs which cuts the power output automatically.
In practice I’ve found that a 3S lipo soon drops below 12V anyway during use.
73, Colin
As i use more than 15 lipos for different things all 3s at the moment i have to advice not to go lower than 3.6v per cell.
Thats 20-25% left in the battery.
And balance charge every time.
I’ve never had any issue with my ATS/MTRs with 3S packs, even at full Voltage.
When I tune my EFHW, I always have the Tayloe bridge switched in circuit, which by design, presents a 50Ω resistive load.
Keeping the tuning duty cycle low by sending dots also helps.
Should read 4x3.6-14.4V
A couple of days ago, my 4S 4200mAh LiFePO4 battery unexpectedly failed.
At the start of the activation the voltage was down to about 9V, and the battery showed serious „swelling“. (In reality it looks even worse than on the pictures.)
This battery was used for about 1 ½ yrs and served me well during more than 100 activations. It has been treated with care, charging was always done with a balancing charger, with moderate current, up to a final voltage of 3.60V/cell. It has never been discharged to more than 1/3 of its capacity.
Before this acitvation a normal charge cycle was performed.
At home one of the cells showed a deep discharge with less than 2V. I tried to re-charge the battery very carefully, but the damaged cell does not hold the charge and the swelling remains just the same.
So this battery will have to go to the recycling bin.
I am a bit concerned because of the unexpected failure. The only cause I can think of is that the batt was in the car for some days with sub-freezing temperatures – but definitely never below -5 deg C. I wonder if this could be the cause of the damage.
Hello,
That’s not good…
By looking to the coloured thin cables going to the flat white connector used for the balanced charging in the picture of your battery, it looks to me as there are 4 cables: black, white, red and blue. Can you confirm this?
Should that be the case, it means your battery is not a 4S but a 3S.
That may be a reason for the short duration and the damage if you have been charging it as it was a 4S, while it was indeed a 3S.
Your battery doesn’t show any marking on this label
Mine has 4S 2P marked, as you can see on this picture:
and it has 5 thin cables to the white flat connector for balance charge.
73 de Guru
I think I have the same battery and the balance lead has a yellow wire as well as t he others easily seen in Martin’s pic. Maybe my imagination but I think I can see a yellow wire below the loop in the blue wire, but it is well hidden by the yellow/orange background.
I’m recharging my new LiFePo4 battery right now after I used it for my Sunday activation of Mt. Erreniega.
This is the second time I’m charging this battery pack and I wanted to let you know that, although the charger detected it as a 3S on the first charging attempt and I told it to go ahead and charge as it was a 4S, it has correctly detected the battery pack as a 4S today.
That’s good news :-).
73 de Guru
Tom, two years on is it still a very nice product?
I’m thinking of putting my hand into my pocket to replace my SLA’s with some new battery technology and the Deben/Tracer do look very tempting despite the initial outlay, what are your thoughts now you’ve owned one for a while?
psi M0RTZ
I would just like to say thanks to the contributors in this thread, I purchased the ZIPPY Flightmax 8400mAh 4S2P 30C LiFePo4 Pack from Hobby King after reading here & also the Turnegy 8150 charger to go with it.
I took it on my activation of G/WB-005 today & used it to run my FT-857d for just over an hour running 10w continuously & the battery was still delivering a steady 13.2v as I finished & I’m sure it could have gone on for a hell of a lot longer had I wanted to.
So thanks for sharing the info here & I am certainly pleased with my purchase, my legs were particularly happy given the weight saving over my previous slab lead acid cell.
73
Neil