Author Topic: EEVblog #393 - LiPo Battery Discharge Testing  (Read 27251 times)

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Offline baoshi

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #50 on: December 04, 2012, 03:21:47 pm »
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…

I have been using some special Chinese solder which contains acid in the flux core. These are useful to solder nickel plate onto 18650 battery case if you do not have spot welding machine. It also corrodes iron tip badly :-\
I also heard that goot makes special flux for this purpose, but never test myself though...

 

Online NiHaoMike

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #51 on: December 04, 2012, 05:00:44 pm »
Quote
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.
Quote
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.
Quote
LiFePO4 would be nice, but the charger chips are not cheap and plentiful like LiIon/LiPoly
LiFePO4 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.
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Offline baoshi

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #52 on: December 04, 2012, 06:33:00 pm »
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.



 

Offline jnissen

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #53 on: December 05, 2012, 05:51:59 am »
Feedback on the video.

Why mess with soldering the batteries at all? Just use an accepted hobby standard plug and you can take advantage of the huge variety of packs offered. It makes very little sense to hard tie this pack in place when there are literally 1000's of different pack options with connectors already installed.

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!!!!
 

Online NiHaoMike

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #54 on: December 05, 2012, 03:42:34 pm »
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.
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Offline crispus

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #55 on: December 05, 2012, 07:28:20 pm »
Hi Dave,

Where did you get those batteries?

Thanks
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Offline T4P

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #56 on: December 05, 2012, 07:44:52 pm »
Feedback on the video.
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!!!!
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 doing too much? Like? He's not trying to do an entire UI and seriously that is quite INTUITIVE already, being above to shove that much UI is a good thing and not a FAIL!!! What do you when you're limited for space?
 

Offline aargee

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #57 on: December 06, 2012, 08:06:40 am »
Dave, watch those bare terminals and your wedding ring.

100A (or more) will automatically spot weld the terminals to your ring and heat it up white hot and your finger....
Not easy, not hard, just need to be incentivised.
 

Offline crispus

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #58 on: December 07, 2012, 10:06:52 am »
It is from HobbyKing. I didn't remembered.
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Offline peter.mitchell

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #59 on: December 07, 2012, 03:55:07 pm »
It is from HobbyKing. I didn't remembered.

Single 5000mAh cell:
http://www.hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html
2 Cell pack made from the above single cells:
http://www.hobbyking.com/hobbyking/store/__21001__Turnigy_5000mAh_2S1P_20C_hardcase_pack_ROAR_APPROVED_.html
4 Cell pack made from the above single cells:
http://www.hobbyking.com/hobbyking/store/__15521__Turnigy_5000mAh_4S1P_14_8v_20C_hardcase_pack.html

Buying the 4 cell packs and de-soldering them is better value for money, but a fair amount more work, also the tabs have been trimmed, so they may be a little more difficult to solder/attach.
 

Offline amyk

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #60 on: December 07, 2012, 05:43:58 pm »
Single 5000mAh cell:
http://www.hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html
For a second I thought that said 18650 and wondered how that could be true... the highest (real) capacity 18650 are currently around 3Ah.
 

Offline peter.mitchell

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #61 on: December 07, 2012, 06:54:10 pm »
Single 5000mAh cell:
http://www.hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html
For a second I thought that said 18650 and wondered how that could be true... the highest (real) capacity 18650 are currently around 3Ah.

Best place to look at 18650s http://lygte-info.dk/review/batteries2012/Common18650Summary%20UK.html
 

Offline Otatiaro

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #62 on: December 10, 2012, 09:35:57 pm »
Hi,

I'm working on a prototype that needs built in battery too and was thinking about using these (that I use in helicopters / planes for years).

But I don't have any 2200mAh 20C in stock, would it be possible to have the dimensions of the battery itself and the dimensions of the solder pads (I'm designing a footprint for direct solder on the bottom of the board) ?

Thomas.
 

Offline diablo248

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #63 on: February 19, 2013, 09:54:40 am »
Maybe somebody have datasheet for this battery?
 

Offline diablo248

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Re: EEVblog #393 - LiPo Battery Discharge Testing
« Reply #64 on: February 21, 2013, 08:20:19 am »
Ok I cannot find any datasheet but maybe You know that this single cell battery has got same protection circuit built-in? If not could you recommend me which IC can I use?
 


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