Low cost battery supply.

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ahull
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Re: Low cost battery supply.

Post by ahull » Tue Feb 09, 2016 2:24 pm

mrmonteith wrote:I've got 40+ of these I can deconstruct one of them and see. But now I need to find what a real one has in it. But for the cost of them they'll do what I need anyway.
Not all Ultrafires are fakes, if yours have a capacity of >1400mAh the chances are they are real.

Image

If you want to see what is in a "real" 18650, take a look here.
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mrmonteith
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Re: Low cost battery supply.

Post by mrmonteith » Tue Feb 09, 2016 3:15 pm

Guess I misread it or something. It looked more like take-apart of more fakes. Sounds like so many fakes out there it's hard to distinguish the real thing.

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Re: Low cost battery supply.

Post by ahull » Tue Feb 09, 2016 3:30 pm

mrmonteith wrote:Guess I misread it or something. It looked more like take-apart of more fakes. Sounds like so many fakes out there it's hard to distinguish the real thing.
At least, all of the ones I have encountered so far actually hold a charge.. there are some out there that are filled with sand or flour. You wouldn't think it worth anybodies time to do that, but someone somewhere is making money by filling 18650 shells with dry sand. :roll:
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Re: Low cost battery supply.

Post by mrmonteith » Tue Feb 09, 2016 4:33 pm

ahull wrote:At least, all of the ones I have encountered so far actually hold a charge.. there are some out there that are filled with sand or flour. You wouldn't think it worth anybodies time to do that, but someone somewhere is making money by filling 18650 shells with dry sand. :roll:
I think so that they get past initial obvious differences was the weight issue. The fakes were less than 40g. So by adding sand or flower they pass that test. There's always someone out there finding ways around it.

I just found out our company is possibly being bought. So with that uncertainty I better get used to using what I have. I was hoping to buy a charger/discharger to test these. Oh well.

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Re: Low cost battery supply.

Post by mrmonteith » Thu Feb 11, 2016 11:19 pm

I did a take apart of one of mine. It appears legit as best I can tell. It was multiple layers of what looks like copper with a black coating on one side and a thin clear plastic like layer. Similar to the picture above in a previous post about real 18650s.

50PCS 3.7V 5800mAh 18650 Li-ion Rechargeable Battery For Flashlight From USA

Michael[/quote]

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ahull
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Re: Low cost battery supply.

Post by ahull » Sat Feb 13, 2016 12:43 am

mrmonteith wrote:I did a take apart of one of mine. It appears legit as best I can tell. It was multiple layers of what looks like copper with a black coating on one side and a thin clear plastic like layer. Similar to the picture above in a previous post about real 18650s.

50PCS 3.7V 5800mAh 18650 Li-ion Rechargeable Battery For Flashlight From USA

Michael
The big question is... what is their actual capacity? If they come anywhere close to 5800mAh I'll be very tempted to order some. My quick back of the envelope calculation suggests that fully charged, at 5800mAh per cell, those 50x18650 cells should manage to store about 1kWh (3.6 megajoules) or roughly the energy of 150ml of unleaded petrol, so don't go shorting them out ;) .
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mrmonteith
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Re: Low cost battery supply.

Post by mrmonteith » Sat Feb 13, 2016 1:05 am

ahull wrote: The big question is... what is their actual capacity? If they come anywhere close to 5800mAh I'll be very tempted to order some. My quick back of the envelope calculation suggests that fully charged, at 5800mAh per cell, those 50x18650 cells should manage to store about 1kWh (3.6 megajoules) or roughly the energy of 150ml of unleaded petrol, so don't go shorting them out ;) .
Either I wait until I can get one of those charger/discharger units to test it or send one to someone that has one to test one. I just don't have a real need for one on an ongoing basis I guess.

Michael

Sdack
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Re: Low cost battery supply.

Post by Sdack » Fri Oct 27, 2017 3:30 am

Hey folks,

Can anyone recommend a quality charger for 18650 liPo cells. I'd like to charge 6 at a time if possible for this battery pack

https://www.ebay.com.au/itm/Mobile-Powe ... 4EE1577802

but I want to be confident the cells are being individually monitored and charged correctly, because of the various posts in this thread which warn of poor power distribution among multiple cells in cheap devices.

I'm also interested to find if there's a simple device which I can put inline in the power supply to my time lapse camera rig which will disable the supply from my 6cell LiPo battery pack, once the charge reaches the lower safety limit of LiPo discharge. I'm a novice to electronic components but it seems a simple concept to me.

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Re: Low cost battery supply.

Post by bianchifan » Sun Oct 29, 2017 8:05 am

Sdack wrote:
Fri Oct 27, 2017 3:30 am
Can anyone recommend a quality charger for 18650 liPo cells. I'd like to charge 6 at a time if possible for this battery pack
Serial or parallel?
For parallel you need a parallel loading adapter.
You may buy the most cheap Imax B6 / Clone you can find.
The power is limited to 50W.
But there is an OpenSource project: Cheali Charger.
Originally designed for chargers based on an ATMEGA32 it supports ARM-based chargers also.
You can find CHeali charger on github


If you need more power you may get a more powerful model, up to 2x200W.
But be careful, not all are supported (no ATMega32, Novoton ARM), plz refer the hardware section on github first.

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Re: Low cost battery supply.

Post by Pito » Sun Oct 29, 2017 8:22 am

Can anyone recommend a quality charger for 18650 liPo cells.
The Lowest Quality LION (LQL) charger I use with 4x18650 cells from an old notebook:
1. set the lab power supply at 16.75V (4x4.2V),
2. connect the 4x18650 pack via 4.7ohm/5Watt resistor to the power supply.
The resistor will limit the current to around 1A with discharged cells (4x3.5V), it will not create a constant current, however (the current will drop linearly to almost zero when charged). When "charged" the laboratory power source will maintain the "constant" voltage.
Use at your own risk, no warranties of any kind are provided :)

This is a fairly simple LiPo charger which works:
https://www.rcgroups.com/forums/showthr ... -Schematic
I added a 3A diode in the + rail:
Added Diode.JPG
Added Diode.JPG (14.53 KiB) Viewed 170 times
For a different output voltage set R5/R4.
It charges with a constant current provided by LM317, and when charged to the required voltage the TL413 switches on and it pulls the LM317 down, thus it maintains a constant voltage.
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