Lipo batteries need to be properly looked after to live long and be safe - balance charge, don’t overcharge, don’t over-discharge and store with half charge. But what do people do in practice? Have you broken the rules and got away with it, or do you regret not storing the batteries properly, for example.
Are 18650 batteries actually Li ion rather than Lipo? They are very similar technologies but with a different electrolyte. Li ion have higher energy density but can’t supply the very high currents that Lipo can. Confusingly, I’ve read that Lipo are safer and also that Li ion are safer!
I bought my first 4AH LiPOs of Chinese origin in 2009. They have served me well. I killed one by leaving the 817 switched on between two summits… several hours in fact. The others still work though at reduced capacity as you might imagine for old ones… I guess around 2.5AH. I have bought a couple of 2.2AH LiPOs since.
Initially I used small chargers running off a small 12V PSU, providing a balanced charge at 0.8A. A couple of activations would take them down to around 3.7V per cell where they were left until the next outing.
For the past 5 or so years I have used an iMax B6 charger as this also charges my 4.2AH LiFePO4 batteries. I use a charge rate of 1.5A max for all types of battery, regardless of capacity. After an activation I use the storage voltage facility, but often the batteries are already sitting at the required voltage.
I use fireproof bags for transporting LiPOs on planes, but don’t bother when charging them. I’ve never noticed any significant rise in temperature when charging. All my batteries are fused close to the battery. Taking care with their handling and keeping charge rates low appears to be key to their longevity.
Almost same as Gerald. We have the same LiPos bought around the same time and used similar low current chargers. I’m sure the low charging current is what has enabled my 2x 2009 era LiPos to still be viable. I take one with me in the SOTA box as an emergency in case when leaving the car I realise the main battery is still connected to the charger. The charge current was low enough that it took some considerable time to charge a fully discharged pack.
18650 packs used to get charged the same way. I made them up into 3 cell packs. The first ones I bought at a Blackpool rally in 2013. They’re 1800mAh and were new. 6 for £5. When I tried them they were open circuit. I stripped one and found a single cell BMS and removing that the cell was fine. I made 2 packs that worked so at the next Blackpool rally bought another six. Charged primarily on the same charger. Not used much now apart from power a Raspberry Pi and Iridium modem in the field.
4200maH LiFePo, I have 2 from Hobby King and a Imax B6 charger. LiPos were a revelation after SLABs and LiFePos the same to LiPos. As slow charging seems to have kept my LiPos running for a long time, I charge them on a low current. A fully discharge pack takes longer than the default 3hr charge timeout.
I recovered another 12x 18650 cells out used laptop batteries. The BMS was toast in one 9x 18650 addon battery and that yielded 9x 2200mAh cells. Another USB battery pack yield 3x 2600mAh cells.
I have often left packs fully charged but stored inside. I haven’t noticed any drop in life. the 2009 LiPos are not as good as new but they are nearly 13 years old! 18650 have much higher internal resistance and you can see the terminal voltage drop more when the 817 TXs than the other packs.
Fireproof bags when the LiPo packs fly with me. But recently I have relied on the 18650 cells in a USB powerbank. I bought a few from eBay that take 3 cells. For flying I fill the power banks with 18650 and put them in my carry on luggage. I’ve had the LiPo packs in fireproof bags swabbed many times when flying and questions asked a few times. The powerbanks are such a common site in airport Xray images they get allowed through. Once at my destination, the 18650s come out of the powerbank and into a 3x cell holder with the same power connector as my LiPo / LiFePo cells.
So always low current charge. Never leave them flat. Try to keep them at room temp until you are activating. Works for me, YMMV.
Same story here.
I slow charge my LiPos with either my Imax B6 or my Imax C3 compact charger which has fixed rate charging for 2S or 3S batteries at 650mA.
Only in recent times have I bothered to discharge my packs to around 3.85v per cell for storage. In the past I’d do an activation and then leave the lipo alone until I needed it again for the next activation, at which point I’d give it a charge up to full.
My chargers both cut off when full charge is reached, so it’s pretty hard to over charge a battery. There’s so much energy in a lipo that it’s pretty hard for me to over discharge one. I did buy a special voltmeter for my 5S amplifier battery to keep an eye on the voltage, but to be honest, I run out of energy before the battery does!
As for storage, I reckon that as long as the battery isn’t fully charged, it should be OK.
I have 1 LiFe 4200 and 1 LiPo 5000. both are 4s2p
They have both been in use for 10 years now for SOTA and back yard testing.
My balanced charger is a Turnigy A cell 6 and all this kit has been very reliable.
I usually charge my batteries the night before I do SOTA and leave them sit half charged until the night before my next SOTA experience. I mostly only use them for a couple activations before swapping out to the other battery and don’t run them down too much. But I can easily get 3 activations in the same day from one battery.
Down side of the 4S LiPo is it fully charges to 16 volts so I need voltage dropping diodes in series in my power lead.
Ian vk5cz …
I have one 4S 50C 6000 mAH LiPO, which I only rarely use when I want to run high power. I charge it with a lab power supply at the required 16.8VDC. It draws 1A while charging and drops to 0.1A when complete. Have had it almost 4 years now, never had any problems.
I think the media attention of the danger of these batteries is overblown. Yes, there were a few faulty batteries made in the past and yes, you must ensure your charger does not fail or overcharge.
Otherwise i prefer them for SOTA (rather than LiFePO4) because they are lighter, less bulky and cheaper.
Indeed. That makes my answer so irrelevant that I’ve deleted it. Sorry for not reading your post correctly. Still, a very interesting topic.
I have been using LiPOs for almost 10 years now. I always use the required balanced charger. The earlier 5000 mAH 4S ones started to bulge after about 4 years, so I responsibly disposed of them before anything nasty happened. At the cost, the LIPOs are worth buying and replacing more often when compared to LifePOs but they also need some method (diode(s) Buck convertor or LM regulator) to get the voltage to the required range for the radio).
I now use “Hardcase LIPOs” which gives some (but not total) protection against expansion with age.
Recently I have come across the LiHV version of the LIPO which gives around 12.5V in its 3S version.
The earlier LIPOs were charged using just the sensor lead (i.e. not over the thick leads) more recently newer LIPO chargers are charging the batteries quicker by using the output leads as well, limiting the charge rate of cells that are charging too quickly by applying resistance across specific cells via the sensor leads. This may improve the life expectancy of the battery as well as increasing the speed of the charge cycle.
Me too. I have two Tracer (hard case) 4Ah LiPOs and charge them only with the supplied Tracer charger. I never discharge them deliberately between activations to lower their ‘storage’ voltage. They don’t get discharged much after an hour or so tx’ing and rx’ing CW with my KX2. I don’t consider my typical inter-activation time (a week or so) ‘storage’ time.
The Tracer data sheet states a lot of requirements about charging / discharging but lowering the storage voltage isn’t one of them. The older one is 4-5 years old and I’ve seen no drop in performance. Indeed, had I discharged the battery to half voltage between activations I believe I would have gone a long way towards its ~300+ charge/discharge cycles lifetime.
Tracer LiPos are expensive but as often in life, you get what you pay for.
I have had my Turnigy Graphene 10,000mAh 4S for 7 years and is still giving good performance.
I consider it to have a hard life as it is used for contesting twice per week ( 2.1/2 to 3.1/2 hours each contest) as well as occasional SOTA activity.
I always balance charge at 5A
Never have used the storage charge option, not even when we were in lock-down.
I’m also interested in Li ion batteries so I will start another thread for that.