It is my understanding that a standard ohm meter will freak out if applied to a battery. On the resistance setting the meter is sending out a voltage and measuring the return voltage to calculate the resistance. Doesn't it require a special meter to check the internal resistance?
I fly all year round in fact more so in the winter because the Copter flies better when its not a 100 degrees outside. I guess the question is how long does QC and other suppliers keep batteries on the shelf before they consider them useless. There is no date on these or a USDA label that saying "best consumed by" Hard to quantify this.
I suspect it's not so simple as a "best before date" as the question of "how long can you keep a LiPo at storage charge," versus, "how long can you keep a LiPo fully charged before you start to impact the number of charging cycles/battery performance." I've not seen any hard data on this, it's all anecdotal and varies with the phase of the moon with the scientific backing of phrenology. Andy
Another follow up question. But first what I am up to. I need to establish a base line of data for my old batteries and my news ones when they arrive. So I figure I would discharge them then charge them and record how much they take. If I understand what you guys are teaching me; if I have a 5000 battery and it is charged from a discharged state the charger should tell me that I have pumped roughly 5000 into it, on a new battery. On an older one I should expect less. I have Hyperion EOS0606i chargers. They have a discharge function. Is it safe to use? The manual is not very clear. I think it says it will take the batteries down to 3.0v per cell. Isn't that too low? Won't that do damage? What voltage would be a good level to discharge them too, either with the charger or on the heli? thanks
I think you may find that the batteries capacity rating is practically much less than the number on the label. For example data, consider the second document here: http://rathergoodguides.com/documentguides.html I was more measuring the amount of charge from fully charged down to 14.0v, which I consider to be the typical flying minimum voltage. I've never needed to use the Hyperion's Discharge capability -- I only use Charge and Store. I would be leery of a LiPo Discharge function until I knew precisely what voltage it would drop the LiPo down to. Andy.
I did it before on that one I think it takes it down to 13.6 which is 3.4 per cell. then stops automatically. I used to use the single hyperion before. I have discharged them with it before. I know that is pretty fickle about letting you do things unsafe with the battery. I have killed my ancillary batteries by leaving plugged into my video TX, that charger wont let you charge them if they are below 3.2 per cell or if there is too much of a spread between cells. Here is a good document from Texas AandM's engineering department. Has a lot of good info in it to answer a lot of the previous questions and has tips techniques for storing and charging. I believe the rule of thumb is never discharge higher than 1C so that would be 6.2 amps for a 6200 and 8A for 8000. I don't believe the Hyperion will let you even go close. If I remember the most it lets you discharge is I think 2A. I haven't done it in a while with that model. http://oes.tamu.edu/web/guidelines/battery/LiPo Procedures.pdf
Seems odd that the Hyperion won't let you discharge them at more than 1C when we fly and the flight load is likely to be 60-100 Amps. I suspect that's because the Hyperion cannot absorb that much energy that fast.... Good PDF on LiPo's though. Thanks, Shaun. Andy.
I am a big fan of Baldrick, so of course I read your rather good guide to Lipos. Obviously I didn’t comprehend as much as I should have so I am reading it again. I am ok with the capacity being less than the label. I just want a base line to record so I know what to expect from each unit. I am testing the Discharge function on a “bench” battery so I don’t kill another one.
The Texas A&M guide is good. I am now building a sand bunker. I believed that the fire extinguisher was to keep the surrounding things from catching fire and not to put out the lipos themselves. Texas A&M confirmed that. My Hyperion will only charge up to 6amps so I am safe from going over 1C Discharge rate can be set from 1A to 0.1A. Doesn’t let me change cut out voltage.
Interesting thing, I am discharging my batteries on my supo duo3 Hyperion 720i. I was cycling through the menus and found this model gives you the resistance of the battery. Not sure how accurate it is. It is claiming that my Quadro 8000 has a resistance of .008Ohms and my Freefly 9000 has .003 ohms. Shaun
I use two 0.5 ohm 1,000 watt (yeah) ceramic resistors in parallel (so they present as a 0.25 ohm resistor). They're same ones I use as the dummy load for the battery discharge tests. Andy.
I heard someone say that new lipo batteries need a break in period of a few cycles. I believe they said that they should not be amped up to hard during the first few flights. Any truth to this?
I've heard that too, but it's hard to know whether it's based on fact or just junk science. I've also heard that LiPo's may not develop their full capacity until after they've been cycled two or three times. That information falls in to the same possible categories, too. Andy.
New information. I assumed my batteries were the victim of my abuse so I purchased a new set. I bought 4 10K 4s from Quadrocopter and 2 8K 4s from HobbyKing. When they arrived I put them on the charger and set them to storage. Monday evening I charged them for a Tuesday early evening fly. When I plug the batteries in they show 16 and change on the Graupner and the battery monitor I put on the balance plug. Again the low battery warnings start right away. My flight data show them in the 14s on engine start. Sometimes they relax up to 15 and change but we are talking 2 minute flights max. I made 5 flights on 4 batteries. First was on a 10k QC, second on a HK 8k, 3rd on a 10k QC, 4th on a 8k HK. I checked everything for heat. The motors were barely warm. It was 49 degrees F outside. The battery wires were not warm at all. I obviously have a short but where? I will disconnect my LEDs and sniff around with the meter for problems. Any suggestions what to look for? Any ideas what could cause this?
John I just ran your weight and setup through ecalc and based on those results a 2-3 minute flight time could be expected. The copter is really overweight for the components you have. A 72% throttle for hover doesn't give you much safety margin.
Shawn are you discharging the batteries at 3.55 per cell to get the 14.2? I've always been leary of discharging too far and have used 3.6/per cell. Just out of curosity why do you choose 14.2?
I'm curious what would happen if you put two of your LiPos in parallel. I always fly dual batteries, and while I'm rarely at your AUW (I'm at 14.8 lbs with the GH3), I have flown her at over 16 pounds and have gotten 8-9 minutes without any battery warnings.
Can you pack some of the sea level cold dense air and send it my way! I'd love to see that kind of battery life. I"m converting to 6S batteries as soon as possible to improve flight times.
Interesting software you have there. Today my rig with camera and a QC10k4s battery weighs in at 15.8 to 16.0 lbs. (Repeatability isn't the best on the bathroom scale) Any idea why the voltage is 16+ and then when I start it immediately drops to 14+, a 2 volt drop. Then under load the voltage decays at a normal rate? Seems a bit odds to me. You calculations say I should expect a 2-3 minute flight time. My Canon 5D II with 24-105 lens weighs in at 3.38 lbs. I have seen several fantastic long videos made with Red cameras. So I looked up a Red Scarlet (forget about a Red One) with a 50mm lens. That would be 7.91 lbs. That is 4.53 lbs more than I am carrying. How in the heck do they do it? I am confused. I used to fly this thing up to an altitude that I best not say publicly and linger there for long periods. There must be something wrong with my rig. But what? I should probably take off the Lego Buzz Light Year I have glued to boom number 1. I didn't weight him but I would guess a few grams.