Charging 18650 Li-Ion Batteries - A New Experience

[Musicmanager]

Hello Guys

I need some advice and I'm hoping there's someone around with experience of 18650 Li-Ion Batteries.

I've got a project on the go for my Grandson which involves 5 separate units each containing an Arduino Nano and an SG90 Servo motor both of which work best at 5vdc

I'm planning on using a single 18650 Li-Ion Rechargeable Battery in each unit with an MC34063 Boost Converter to get from 3.7 to 5vdc and a TP 4056 BMS module for charging with a DPDT switch between the two.

I've tried all this out in prototype and it all seems to work perfectly well, but .. .. .. .. . I've never done anything with this type of battery before and I'm a bit wary of the usual MM type errors that pervade my work and I don't think it will go down too well with the Senior Manager I married if I bump off one or more of the grandkids.

I'd appreciate a perusal of the attached schematic for any errors, glaring or otherwise.

The batteries are marked ' Ultrafire TR 18650 9900mAh 3.7v ' ;

I appreciate the decoupling caps are missing on the schematic, they will be present on the assembly.

Many thanks

S

 

[Pommie]

The batteries are marked ' Ultrafire TR 18650 9900mAh 3.7v ' ;

The best 18650 batteries are around 4000mAh. The Ultrafire ones are a complete ripoff and normally less than 1000mAh. I would buy new ones but would be interested in the actual capacity of your 9Ah batteries.

Mike.

 

[Musicmanager]

Hi Pommie

Thanks for that; I did consider they were probably less than ideal because they were so cheap ! However, whilst at a prototype when I'm not even sure if I can get the whole project to fruit I'd decided they'd do.

As for capacity, I think there's a '9' too many in the markings; This morning I ran one down with a little motor, when the motor stopped, I recharged it with a TP 4056 - rated at n.m.t. 1Amp - ammeter attached went from 800ma down to about 120ma and then it switched to 'fully charged' just under an hour .. .. . my maths isn't brilliant, but that makes sense to me !

S

 

[Pommie]

Whenever I use 18650's I tend to use one of the TP4056 modules off of ebay (<$1 each) and (so far) not had any problems.

Mike.

 

[audioguru]

Here is a video showing what is inside a cheeeep Ultrafire 18650 battery cell. You get what you pay for.

 

[audioguru]

Be careful! The fake battery might explode and/or catch on fire when it is charged.

 

[Ian Rogers]

Hi MM do you want me to send you one of mine.. Like I said 1 x 18650 @ 3400mAh powers my Pi for over two hours playing Golden Axe...

 

[Musicmanager]

Hi Guys

Thank you very much for that warning, it's heeded !

Before I bought a pack of 4, I did consider they might be fake, but was consoled by finding an 'Ultrafire.com' website with quite a range of products and an extensive infrastructure to view. It has to be said also that of all the damning comments on the net, most will only say . .. .. there are SOME Ultrafire batteries that are fake .. .. this is supported by the fact that I have already charged 2 of my pack of 4 to about 800mA without any issue whatsoever, so they may be OK.

BUT … .. .. I'm not going to take the chance, I will dispose of them ( responsibly, of course - drop kick over the garage roof ! ) and acquire some from a reliable source. I much appreciated the advice.

Talking of advice, can I take it that the lack of any negative comment of my schematic means it's OK ??

Thanks again

S

 

[Musicmanager]

Ian .. .. .. .

A very kind offer, Thank you .. however, I will need more than one .. .. ..perhaps you could provide the product ID and a source of supply, if possible ??

Thanks

S

 

[Nigel Goodwin]

Hi Guys

Thank you very much for that warning, it's heeded !

Before I bought a pack of 4, I did consider they might be fake, but was consoled by finding an 'Ultrafire.com' website with quite a range of products and an extensive infrastructure to view. It has to be said also that of all the damning comments on the net, most will only say . .. .. there are SOME Ultrafire batteries that are fake .. .. this is supported by the fact that I have already charged 2 of my pack of 4 to about 800mA without any issue whatsoever, so they may be OK.

BUT … .. .. I'm not going to take the chance, I will dispose of them ( responsibly, of course - drop kick over the garage roof ! ) and acquire some from a reliable source. I much appreciated the advice.

Talking of advice, can I take it that the lack of any negative comment of my schematic means it's OK ??

Thanks again

S

I think if you weigh them, it gives a good idea if they are 'real' or not (fakes are lighter), but that claimed power is nonsense anyway. I bought some from Banggood which claim 4000mAH - and while I've not seriously measured them, they work pretty well - only concern, they are slightly larger than normal 18650's (which is perhaps how they manage a little higher power?).

The ones we buy at work are branded 'Samsung', although I've no idea if that's real or not though we buy them from a UK specialist battery supplier in 100's - not sure of the power rating off hand, but it's not at the top end of 18650's.