|
|
|
| General RC Aircraft Discussion Discuss anything RC related |
Topic Review (Newest First)
|
| 03-17-2016 11:29 AM | |
| stegl |
Re: DISCHARGING LIPOS Please read TjinTech link put up by Daren. 50% charge is 3.85 volts. If you store yours at 3.77v you will be down around 35-40%. Maybe even lower. When I get a moment will do a discharge and see what my Futaba BR3000 says ...... Your battery, your choice. |
| 03-17-2016 11:14 AM | |
| VA6WGO |
Re: DISCHARGING LIPOS * The storage voltage should be around 3.77/3.8V per cell which is approx. 50% of its capacity. * Most packs would get damaged when discharged below 3.4V. The only time that I would cycle a pack is to make sure that the cells are charging a discharging evenly, if the IR changes in one of the cells, chances are that under a heavy current load, one of the cells (or more than one) will swell during flight which may lead to a fire. Cheers, |
| 03-17-2016 11:06 AM | |
| Max |
Re: DISCHARGING LIPOS I hope that wasn't a 14MZ 
|
| 03-17-2016 10:52 AM | |
| stegl |
Re: DISCHARGING LIPOS Here are a couple of examples of what can happen. Never , never and never charge lipos unattended. One was done with the lipo in the transmitter and the other on the bench; was plugged in but the balancer plug was never connected to the charger. Two different situations by different owners not understanding the basics. I believe, but not positive, that with the transmitter fire that the regular NiCad/Nimh wall charger was used and not a correct lipo charger. in any case never charge with the lipo in the transmitter. The charger with the bench fire, was obviously a cheaper charger that did not have a shutdown feature that would not allow charging to start in the first place without the balance plug connected. My Thunder power TP820 has this feature ; so if I try and charge without connecting both plugs it will reject the charge procedure. Other chargers may also have this feature. Something to check out with your brand and model. Here is the old adage: There never is a dumb question ; only a dumb answer ! |
| 03-16-2016 04:57 PM | |
| Daren71 |
Re: DISCHARGING LIPOS This guys site has tons of good info. There are so many chargers out there with a basic discharge/storage feature. Better to be safe than sorry. And in sorry, I mean home or auto fire due to mishandling. Lipos can be cycled, for several reasons, checking internal resistance, or breaking them in. My first few flights on new batteries, I always take it easy. No full throttle, easy flight, land with lots of voltage left. https://sites.google.com/site/tjingu...arging-how-tos |
| 03-16-2016 03:22 PM | |
| Max |
Re: DISCHARGING LIPOS Slight misunderstaning with my previous post. Yea, normal storage is 3.80, but I find when under load, the alarm will ring at 3.6, and when you unplug, it bounces up to 3.8. Which is what I am aiming for. The "rebound" as I call it depends on the load being applied and the condition of the battery. Most people with telemetry on their radios will have already noticed this when they are flying. The telemetry alarm goes off and when they land and stop the motor the voltage is a lot higher than wen the alarm went off. If you discharge at a low rate, say 500mah, it rebounds very little. But if you discharge at 2 amps it rebounds a lot more. The auto bulb runs at about 2A when both elements are lit.(I use a brake/signal lamp) Thus setting my alarm lower than 3.8 when I discharge with a light bulb yeilds 3.8V after I unplug it. Hope that clears things up |
| 03-16-2016 02:55 PM | |
| stegl |
Re: DISCHARGING LIPOS the 3.8 is the absolute lowest I would go with, on up to 3.86 or 3.87 max. I know it doesn't sound like much but as I said earlier lipos really have a very flat voltage curve per cell. Most lipos I have used come storage charged as low as 3.83 to 3.85. The Thunder power charger I use was set for 3.85v. |
| 03-16-2016 01:16 PM | |
| tporter416 |
Re: DISCHARGING LIPOS I agree with stegl, normal storage for a LiPo is around 3.8V/cell. That is what I keep mine at and have had a number of lipo's for years with no issues. After every time I fly at the field, I always connect them to my charger and run a storage cycle. My HiTec charger came pre-programmed for the storage cycle for LiPo's, with a setting of 3.8V/cell. |
| 03-16-2016 10:56 AM | |
| stegl |
Re: DISCHARGING LIPOS Hi Max: From the information I have gathered over the years is that 3.85 volts , under a slight load , is considered to be the suggested storage voltage per cell. When getting down to 3.5 or.6 that is usually around 20-25% charge , approximately . I could be off a bit but if you were to plug in those battery level testers you would find that would be close. Lipos tend to have a fairly flat discharge until you get to the lower 3's and then can fall off quickly . Haveing said that , this depends somewhat to the load or how many amps are being pulled and the condition of your lipo in question. After doing a some research on battery testers , I finally decided to retire ( sell off) my cheap testers and dropped the bundle on a Futaba BR3000 tester which not only is very accurate but also will balance 2 to 7 cells when left connected over 5 or 10 seconds. I guess , just like chargers or anything else .... Features and accuracy cost dollars . Balbir,don't be too hard on on your club member for giving out incorrect information as I see it often and sometimes it may be in the way it is explained. Lol. All batteries have a limited number of cycles . I see were some users over cycle their Nicad or nimh batteries . Some who do a charge , let sit for an hour and then to a cycle down to say 3.1 volts for lipo's ,do this for a capacity test to see if their battery capacity has degraded over time. As the battery gets to the end of its life span this capacity will be reduced. I feel the better way is checking the Internal Resistance or IR of each cell . The lower the IR number the better the lipo can provide power under high loads and the better the performance. Not all chargers can do this and this is what separates the men from the boys in charger features. The IR test should be taken with new cells after the first couple of uses and recorded and can be checked , say every 6 or 8 months to see if the number increases. That way you have an idea as to the health of the lipo. |
| 03-16-2016 10:21 AM | |
| balbir |
Re: DISCHARGING LIPOS cool, thank you gentlemen for all your help. Now I have to go and have a chat with the guy at my club who told me lipos have to be cycled. lol. |
| This thread has more than 10 replies. Click here to review the whole thread. | |
Your Privacy Choices