Do you need to change the charging circuit to cater for the larger capacity battery?
You must store them charged, but not fully charged either – that will also degrade the cell matrix. Basically, the speed at which a LiPo pack ages (during storage) is based on both storage temperature and state of charge. You are likely ok to store a fully charged RC LiPo battery at room temperature for up to 4 days without doing much damage. Never store a LiPo in a hot car fully charged for an extended time, that will certainly cause damage as I explained earlier, but it worth repeating.
For optimum battery life, store your RC LiPo batteries at room temperature and at about 40-60% charged. That equates to around 3.85 volts per cell (open terminal resting voltage). The actual storage range is likely a little broader than this (I have heard some say numbers as high as 20-80% is fine, but since computerized chargers set the storage charge at 50% (3.85 volts per cell) that's what I recommend and what I follow myself.
Yeah, trying to protect a battery capable of putting out 100A is not particularly easy with limited board space ^-^
I have to say I was slightly surprised when the capacity measurement came out bang on spec like that. Some low cost batteries are notorious for having vastly inflated capacity numbers on the label. Thumbs up for the vendor in this case :-+
Yeah, trying to protect a battery capable of putting out 100A is not particularly easy with limited board space ^-^A 5A polyswitch or something in series will do nicely.
I think a typical polyswitch is rated for 50-100A maximum input and you'd get far more than that if the battery did get shorted, probably 1kA or so.
Although i guess the PCB tracks to the polyswitch will limited the current somewhat. So it might be fine.
I don't know just how significant this effect/damage is but its something that should be checked out as this kind of high discharge RC battery may not be very suitable for a usb powersupply where you want to keep it fully charged in your bag.
I don't know just how significant this effect/damage is but its something that should be checked out as this kind of high discharge RC battery may not be very suitable for a usb powersupply where you want to keep it fully charged in your bag.
The micro can sense the battery voltage and also switch the unit off. So it's possible for the firmware to go into a "storage" mode if you say, try and switch it off when the voltage is above 4.xV or something.
Dave.
Yeah, it would need to have a built in dummy load though.
When plugged into a usb port it would charge to 100% then start a counter which would begin an automatic discharge to 3.8V after 4 days.
yeah, i agree. just have a default max charge volts that's lower than spec.
People can hack the firmware to use 100% charge if they want, or make it a menu option.
Well, it seems that many places recommend storing these high C batteries at much reduced capacity, but I have yet to find any actual definitive data on it.
Are those batteries bundled with a protection circuit of some kind (temperature e.t.c.). Can someone access the the data?
Are batteries for famous tablets/readers available and suitable for your needs?
Alexander.
Then just charge it to 4.05V and accept the battery will never be fully charged, and compromise on life slightly. If charging on USB that would be the likely case, as it will take 4 days to fully charge the 5AH cell from a standard high power USB current of 500mA.
Given the above and the cost of the batteries and this application, is even a potential 20% reduction in capacity over the 1st year a significant concern?
Not a huge concern, if that's the actual figure.
Some people and places have mentioned dangers from doing this, which I doubt in practice is a huge deal, based on the massive size of the RC market.
But once again, I'd like to see definitive data from a reputable source?
If an extended capacity mobile phone battery is a similar cost, potentially less dangerous, and similar capacity (after not needing reduced storage) that might be a better solution?
I see some 10000mAh portable battery phone charger packs on ebay...
Dave.
Not a huge concern, if that's the actual figure.
The Battery University has been recommended as a reliable source of information, though I cannot comment on the knowledge set of those providing the recommendations... <sigh> Why internet, why?
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries (http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries)
Are those batteries bundled with a protection circuit of some kind (temperature e.t.c.). Can someone access the the data?
Are batteries for famous tablets/readers available and suitable for your needs?
Alexander.
na, RC batteries have no protection. It's almost impossible to have protection when you have legitimate loads of up to 200A.
"Hybrid" There's such thing as a hybrid battery :o
USB | disp | rotary encoder | pushbutton | terminals
Dave, reading the comments on youtube, big
single cell Li-iron cells can be found around,
cylindrical and prismatic, in eu there is ev-power.eu
But they don't mention these specific high discharge capacity LiPoly cells, which is what the issue supposedly is with.I was actually under the impression that all LiPo batteries preferred 40 - 70% charge while in storage, even mobile phone and laptop batteries.
With standard discharge capacity batteries I would not worry about this at all.
If you want real power, stop fannying around with small fry get a batteryspace.com/LiFePO4-Prismatic-Module-3.2V-200-Ah-10C-Rate-640-wh-60.0.aspx mohooo ha ha!!! >:D
Question - is it safe to string two or three same size LiPo cells in series and them treat them as one 7.4 or 11.1V battery, with charging profiles just 3 x (volts, not amps!!) higher?You should always charge each cell separately. Chargers for larger packs have multiple pin charging plugs.
How do you mount wires on the battery. Is it possible to solder direct to the "foil" ?I think not. I tried to solder but without success. In cell phone batteries I only see spot welding.
How do you mount wires on the battery. Is it possible to solder direct to the "foil" ?I think not. I tried to solder but without success. In cell phone batteries I only see spot welding.
If someone knows the best way to connect a wire please let us know. The crocodile clips are not a good option…
It would probably be good to have an external 12-19V input to a separate charger chip, which will enable it to be charged from a laptop PSU easily, and will satisfy most users. Charge time on that would be under 2 hours, and it would be usable while charging ( though at the expense of higher output noise though) without killing USB power delivery, allowing use on a unpowered hub ( common laptop limited ports).2A USB power supplies are very common nowadays given that a lot of tablets use them. Also, 900mA USB 3.0 ports are becoming more common, along with high current (1A or more) USB ports on some new motherboards.
Well "hybrid" NiMH is what the inventors Sanyo marketed them as ,others companies are marketing them also now, some as low self discharge or "LSD NIMH" , (which are mostly sanyo's batteries rebranded, according to some websites).That's a NiMH chemistry tweaked for hybrid vehicles and other high peak current, low self discharge applications. It is more expensive than regular NiMH for the same capacity.
LiFePO4 would be nice, but the charger chips are not cheap and plentiful like LiIon/LiPolyLiFePO4 is much more forgiving than common Li-ion (overcharge would just greatly shorten the life instead of causing thermal runaway), so you can implement the charging and discharge cut off in software. Back it up with the watchdog timer and it should work quite well.
2A USB power supplies are very common nowadays given that a lot of tablets use them. Also, 900mA USB 3.0 ports are becoming more common, along with high current (1A or more) USB ports on some new motherboards.
I ran into the same dilemma when doing another project a while ago. The issue here is to allow detection of dedicated charging port (DCP) to enable higher charging current (as opposed to normal <500mA). Otherwise the charging circuit will blow USB port on a normal desktop/laptop. FT230X has battery charger detection function but I'm still waiting for the new chip to be shipped to test if it is compatible with Android or Apple adaptors. Even if does so, more circuitry will be needed to isolate BCD (maybe even PWREN#/SLEEP#) signal, which could significantly increase cost.It should be pretty easy to just use a microcontroller with USB. When input power is valid, try to establish communication. If that fails, use some GPIOs and resistors to detect if the data lines are shorted to each other. Then just have a GPIO set the current limit on the primary side. And detecting a USB 3.0 port can be as simple as checking if the USB 3 ground is connected.
Feedback on the video.Okay. I have never seen a small rotary encoder and he did want it to be SMALLER not being totally unable to shove it inside a bag or something without fearing for damaged encoders or broken shafts
The display is totally inadequate for what your trying to convey. I agree with ditching the buttons and use a rotary encoder or knob. A lot more intuitive and easier to set. 2X8 is fine if all you want to provide is minimal feedback. Your trying to make the display do way to much. Fail!!!!
It is from HobbyKing. I didn't remembered.
Single 5000mAh cell:For a second I thought that said 18650 and wondered how that could be true... the highest (real) capacity 18650 are currently around 3Ah.
http://www.hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html (http://www.hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html)
Single 5000mAh cell:For a second I thought that said 18650 and wondered how that could be true... the highest (real) capacity 18650 are currently around 3Ah.
http://www.hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html (http://www.hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html)